//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "instcombine"
-#include "llvm/Transforms/Scalar.h"
-#include "InstCombine.h"
+#include "llvm/Transforms/InstCombine/InstCombine.h"
+#include "InstCombineInternal.h"
#include "llvm-c/Initialization.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/Analysis/CFG.h"
#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/EHPersonalities.h"
+#include "llvm/Analysis/GlobalsModRef.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/MemoryBuiltins.h"
+#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/IR/CFG.h"
#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/IntrinsicInst.h"
-#include "llvm/Support/CFG.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/IR/ValueHandle.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/PatternMatch.h"
-#include "llvm/Support/ValueHandle.h"
-#include "llvm/Target/TargetLibraryInfo.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
#include <algorithm>
#include <climits>
using namespace llvm;
using namespace llvm::PatternMatch;
+#define DEBUG_TYPE "instcombine"
+
STATISTIC(NumCombined , "Number of insts combined");
STATISTIC(NumConstProp, "Number of constant folds");
STATISTIC(NumDeadInst , "Number of dead inst eliminated");
STATISTIC(NumFactor , "Number of factorizations");
STATISTIC(NumReassoc , "Number of reassociations");
-static cl::opt<bool> UnsafeFPShrink("enable-double-float-shrink", cl::Hidden,
- cl::init(false),
- cl::desc("Enable unsafe double to float "
- "shrinking for math lib calls"));
-
-// Initialization Routines
-void llvm::initializeInstCombine(PassRegistry &Registry) {
- initializeInstCombinerPass(Registry);
-}
-
-void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
- initializeInstCombine(*unwrap(R));
-}
-
-char InstCombiner::ID = 0;
-INITIALIZE_PASS_BEGIN(InstCombiner, "instcombine",
- "Combine redundant instructions", false, false)
-INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo)
-INITIALIZE_PASS_END(InstCombiner, "instcombine",
- "Combine redundant instructions", false, false)
-
-void InstCombiner::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.setPreservesCFG();
- AU.addRequired<TargetLibraryInfo>();
-}
-
-
Value *InstCombiner::EmitGEPOffset(User *GEP) {
- return llvm::EmitGEPOffset(Builder, *getDataLayout(), GEP);
+ return llvm::EmitGEPOffset(Builder, DL, GEP);
}
-/// ShouldChangeType - Return true if it is desirable to convert a computation
-/// from 'From' to 'To'. We don't want to convert from a legal to an illegal
-/// type for example, or from a smaller to a larger illegal type.
-bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
- assert(From->isIntegerTy() && To->isIntegerTy());
-
- // If we don't have TD, we don't know if the source/dest are legal.
- if (!TD) return false;
-
- unsigned FromWidth = From->getPrimitiveSizeInBits();
- unsigned ToWidth = To->getPrimitiveSizeInBits();
- bool FromLegal = TD->isLegalInteger(FromWidth);
- bool ToLegal = TD->isLegalInteger(ToWidth);
+/// Return true if it is desirable to convert an integer computation from a
+/// given bit width to a new bit width.
+/// We don't want to convert from a legal to an illegal type for example or from
+/// a smaller to a larger illegal type.
+bool InstCombiner::ShouldChangeType(unsigned FromWidth,
+ unsigned ToWidth) const {
+ bool FromLegal = DL.isLegalInteger(FromWidth);
+ bool ToLegal = DL.isLegalInteger(ToWidth);
// If this is a legal integer from type, and the result would be an illegal
// type, don't do the transformation.
return true;
}
+/// Return true if it is desirable to convert a computation from 'From' to 'To'.
+/// We don't want to convert from a legal to an illegal type for example or from
+/// a smaller to a larger illegal type.
+bool InstCombiner::ShouldChangeType(Type *From, Type *To) const {
+ assert(From->isIntegerTy() && To->isIntegerTy());
+
+ unsigned FromWidth = From->getPrimitiveSizeInBits();
+ unsigned ToWidth = To->getPrimitiveSizeInBits();
+ return ShouldChangeType(FromWidth, ToWidth);
+}
+
// Return true, if No Signed Wrap should be maintained for I.
// The No Signed Wrap flag can be kept if the operation "B (I.getOpcode) C",
// where both B and C should be ConstantInts, results in a constant that does
I.setFastMathFlags(FMF);
}
-/// SimplifyAssociativeOrCommutative - This performs a few simplifications for
-/// operators which are associative or commutative:
-//
-// Commutative operators:
-//
-// 1. Order operands such that they are listed from right (least complex) to
-// left (most complex). This puts constants before unary operators before
-// binary operators.
-//
-// Associative operators:
-//
-// 2. Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
-// 3. Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
-//
-// Associative and commutative operators:
-//
-// 4. Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
-// 5. Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
-// 6. Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
-// if C1 and C2 are constants.
-//
+/// This performs a few simplifications for operators that are associative or
+/// commutative:
+///
+/// Commutative operators:
+///
+/// 1. Order operands such that they are listed from right (least complex) to
+/// left (most complex). This puts constants before unary operators before
+/// binary operators.
+///
+/// Associative operators:
+///
+/// 2. Transform: "(A op B) op C" ==> "A op (B op C)" if "B op C" simplifies.
+/// 3. Transform: "A op (B op C)" ==> "(A op B) op C" if "A op B" simplifies.
+///
+/// Associative and commutative operators:
+///
+/// 4. Transform: "(A op B) op C" ==> "(C op A) op B" if "C op A" simplifies.
+/// 5. Transform: "A op (B op C)" ==> "B op (C op A)" if "C op A" simplifies.
+/// 6. Transform: "(A op C1) op (B op C2)" ==> "(A op B) op (C1 op C2)"
+/// if C1 and C2 are constants.
bool InstCombiner::SimplifyAssociativeOrCommutative(BinaryOperator &I) {
Instruction::BinaryOps Opcode = I.getOpcode();
bool Changed = false;
Value *C = I.getOperand(1);
// Does "B op C" simplify?
- if (Value *V = SimplifyBinOp(Opcode, B, C, TD)) {
+ if (Value *V = SimplifyBinOp(Opcode, B, C, DL)) {
// It simplifies to V. Form "A op V".
I.setOperand(0, A);
I.setOperand(1, V);
Value *C = Op1->getOperand(1);
// Does "A op B" simplify?
- if (Value *V = SimplifyBinOp(Opcode, A, B, TD)) {
+ if (Value *V = SimplifyBinOp(Opcode, A, B, DL)) {
// It simplifies to V. Form "V op C".
I.setOperand(0, V);
I.setOperand(1, C);
Value *C = I.getOperand(1);
// Does "C op A" simplify?
- if (Value *V = SimplifyBinOp(Opcode, C, A, TD)) {
+ if (Value *V = SimplifyBinOp(Opcode, C, A, DL)) {
// It simplifies to V. Form "V op B".
I.setOperand(0, V);
I.setOperand(1, B);
Value *C = Op1->getOperand(1);
// Does "C op A" simplify?
- if (Value *V = SimplifyBinOp(Opcode, C, A, TD)) {
+ if (Value *V = SimplifyBinOp(Opcode, C, A, DL)) {
// It simplifies to V. Form "B op V".
I.setOperand(0, B);
I.setOperand(1, V);
Constant *Folded = ConstantExpr::get(Opcode, C1, C2);
BinaryOperator *New = BinaryOperator::Create(Opcode, A, B);
+ if (isa<FPMathOperator>(New)) {
+ FastMathFlags Flags = I.getFastMathFlags();
+ Flags &= Op0->getFastMathFlags();
+ Flags &= Op1->getFastMathFlags();
+ New->setFastMathFlags(Flags);
+ }
InsertNewInstWith(New, I);
New->takeName(Op1);
I.setOperand(0, New);
} while (1);
}
-/// LeftDistributesOverRight - Whether "X LOp (Y ROp Z)" is always equal to
+/// Return whether "X LOp (Y ROp Z)" is always equal to
/// "(X LOp Y) ROp (X LOp Z)".
static bool LeftDistributesOverRight(Instruction::BinaryOps LOp,
Instruction::BinaryOps ROp) {
}
}
-/// RightDistributesOverLeft - Whether "(X LOp Y) ROp Z" is always equal to
+/// Return whether "(X LOp Y) ROp Z" is always equal to
/// "(X ROp Z) LOp (Y ROp Z)".
static bool RightDistributesOverLeft(Instruction::BinaryOps LOp,
Instruction::BinaryOps ROp) {
if (Instruction::isCommutative(ROp))
return LeftDistributesOverRight(ROp, LOp);
+
+ switch (LOp) {
+ default:
+ return false;
+ // (X >> Z) & (Y >> Z) -> (X&Y) >> Z for all shifts.
+ // (X >> Z) | (Y >> Z) -> (X|Y) >> Z for all shifts.
+ // (X >> Z) ^ (Y >> Z) -> (X^Y) >> Z for all shifts.
+ case Instruction::And:
+ case Instruction::Or:
+ case Instruction::Xor:
+ switch (ROp) {
+ default:
+ return false;
+ case Instruction::Shl:
+ case Instruction::LShr:
+ case Instruction::AShr:
+ return true;
+ }
+ }
// TODO: It would be nice to handle division, aka "(X + Y)/Z = X/Z + Y/Z",
// but this requires knowing that the addition does not overflow and other
// such subtleties.
return false;
}
-/// SimplifyUsingDistributiveLaws - This tries to simplify binary operations
-/// which some other binary operation distributes over either by factorizing
-/// out common terms (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this
-/// results in simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is
-/// a win). Returns the simplified value, or null if it didn't simplify.
+/// This function returns identity value for given opcode, which can be used to
+/// factor patterns like (X * 2) + X ==> (X * 2) + (X * 1) ==> X * (2 + 1).
+static Value *getIdentityValue(Instruction::BinaryOps OpCode, Value *V) {
+ if (isa<Constant>(V))
+ return nullptr;
+
+ if (OpCode == Instruction::Mul)
+ return ConstantInt::get(V->getType(), 1);
+
+ // TODO: We can handle other cases e.g. Instruction::And, Instruction::Or etc.
+
+ return nullptr;
+}
+
+/// This function factors binary ops which can be combined using distributive
+/// laws. This function tries to transform 'Op' based TopLevelOpcode to enable
+/// factorization e.g for ADD(SHL(X , 2), MUL(X, 5)), When this function called
+/// with TopLevelOpcode == Instruction::Add and Op = SHL(X, 2), transforms
+/// SHL(X, 2) to MUL(X, 4) i.e. returns Instruction::Mul with LHS set to 'X' and
+/// RHS to 4.
+static Instruction::BinaryOps
+getBinOpsForFactorization(Instruction::BinaryOps TopLevelOpcode,
+ BinaryOperator *Op, Value *&LHS, Value *&RHS) {
+ if (!Op)
+ return Instruction::BinaryOpsEnd;
+
+ LHS = Op->getOperand(0);
+ RHS = Op->getOperand(1);
+
+ switch (TopLevelOpcode) {
+ default:
+ return Op->getOpcode();
+
+ case Instruction::Add:
+ case Instruction::Sub:
+ if (Op->getOpcode() == Instruction::Shl) {
+ if (Constant *CST = dyn_cast<Constant>(Op->getOperand(1))) {
+ // The multiplier is really 1 << CST.
+ RHS = ConstantExpr::getShl(ConstantInt::get(Op->getType(), 1), CST);
+ return Instruction::Mul;
+ }
+ }
+ return Op->getOpcode();
+ }
+
+ // TODO: We can add other conversions e.g. shr => div etc.
+}
+
+/// This tries to simplify binary operations by factorizing out common terms
+/// (e. g. "(A*B)+(A*C)" -> "A*(B+C)").
+static Value *tryFactorization(InstCombiner::BuilderTy *Builder,
+ const DataLayout &DL, BinaryOperator &I,
+ Instruction::BinaryOps InnerOpcode, Value *A,
+ Value *B, Value *C, Value *D) {
+
+ // If any of A, B, C, D are null, we can not factor I, return early.
+ // Checking A and C should be enough.
+ if (!A || !C || !B || !D)
+ return nullptr;
+
+ Value *V = nullptr;
+ Value *SimplifiedInst = nullptr;
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+ Instruction::BinaryOps TopLevelOpcode = I.getOpcode();
+
+ // Does "X op' Y" always equal "Y op' X"?
+ bool InnerCommutative = Instruction::isCommutative(InnerOpcode);
+
+ // Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
+ if (LeftDistributesOverRight(InnerOpcode, TopLevelOpcode))
+ // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
+ // commutative case, "(A op' B) op (C op' A)"?
+ if (A == C || (InnerCommutative && A == D)) {
+ if (A != C)
+ std::swap(C, D);
+ // Consider forming "A op' (B op D)".
+ // If "B op D" simplifies then it can be formed with no cost.
+ V = SimplifyBinOp(TopLevelOpcode, B, D, DL);
+ // If "B op D" doesn't simplify then only go on if both of the existing
+ // operations "A op' B" and "C op' D" will be zapped as no longer used.
+ if (!V && LHS->hasOneUse() && RHS->hasOneUse())
+ V = Builder->CreateBinOp(TopLevelOpcode, B, D, RHS->getName());
+ if (V) {
+ SimplifiedInst = Builder->CreateBinOp(InnerOpcode, A, V);
+ }
+ }
+
+ // Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
+ if (!SimplifiedInst && RightDistributesOverLeft(TopLevelOpcode, InnerOpcode))
+ // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
+ // commutative case, "(A op' B) op (B op' D)"?
+ if (B == D || (InnerCommutative && B == C)) {
+ if (B != D)
+ std::swap(C, D);
+ // Consider forming "(A op C) op' B".
+ // If "A op C" simplifies then it can be formed with no cost.
+ V = SimplifyBinOp(TopLevelOpcode, A, C, DL);
+
+ // If "A op C" doesn't simplify then only go on if both of the existing
+ // operations "A op' B" and "C op' D" will be zapped as no longer used.
+ if (!V && LHS->hasOneUse() && RHS->hasOneUse())
+ V = Builder->CreateBinOp(TopLevelOpcode, A, C, LHS->getName());
+ if (V) {
+ SimplifiedInst = Builder->CreateBinOp(InnerOpcode, V, B);
+ }
+ }
+
+ if (SimplifiedInst) {
+ ++NumFactor;
+ SimplifiedInst->takeName(&I);
+
+ // Check if we can add NSW flag to SimplifiedInst. If so, set NSW flag.
+ // TODO: Check for NUW.
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(SimplifiedInst)) {
+ if (isa<OverflowingBinaryOperator>(SimplifiedInst)) {
+ bool HasNSW = false;
+ if (isa<OverflowingBinaryOperator>(&I))
+ HasNSW = I.hasNoSignedWrap();
+
+ if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
+ if (isa<OverflowingBinaryOperator>(Op0))
+ HasNSW &= Op0->hasNoSignedWrap();
+
+ if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
+ if (isa<OverflowingBinaryOperator>(Op1))
+ HasNSW &= Op1->hasNoSignedWrap();
+
+ // We can propagate 'nsw' if we know that
+ // %Y = mul nsw i16 %X, C
+ // %Z = add nsw i16 %Y, %X
+ // =>
+ // %Z = mul nsw i16 %X, C+1
+ //
+ // iff C+1 isn't INT_MIN
+ const APInt *CInt;
+ if (TopLevelOpcode == Instruction::Add &&
+ InnerOpcode == Instruction::Mul)
+ if (match(V, m_APInt(CInt)) && !CInt->isMinSignedValue())
+ BO->setHasNoSignedWrap(HasNSW);
+ }
+ }
+ }
+ return SimplifiedInst;
+}
+
+/// This tries to simplify binary operations which some other binary operation
+/// distributes over either by factorizing out common terms
+/// (eg "(A*B)+(A*C)" -> "A*(B+C)") or expanding out if this results in
+/// simplifications (eg: "A & (B | C) -> (A&B) | (A&C)" if this is a win).
+/// Returns the simplified value, or null if it didn't simplify.
Value *InstCombiner::SimplifyUsingDistributiveLaws(BinaryOperator &I) {
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
- Instruction::BinaryOps TopLevelOpcode = I.getOpcode(); // op
// Factorization.
- if (Op0 && Op1 && Op0->getOpcode() == Op1->getOpcode()) {
- // The instruction has the form "(A op' B) op (C op' D)". Try to factorize
- // a common term.
- Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
- Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
- Instruction::BinaryOps InnerOpcode = Op0->getOpcode(); // op'
+ Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
+ auto TopLevelOpcode = I.getOpcode();
+ auto LHSOpcode = getBinOpsForFactorization(TopLevelOpcode, Op0, A, B);
+ auto RHSOpcode = getBinOpsForFactorization(TopLevelOpcode, Op1, C, D);
+
+ // The instruction has the form "(A op' B) op (C op' D)". Try to factorize
+ // a common term.
+ if (LHSOpcode == RHSOpcode) {
+ if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, C, D))
+ return V;
+ }
- // Does "X op' Y" always equal "Y op' X"?
- bool InnerCommutative = Instruction::isCommutative(InnerOpcode);
-
- // Does "X op' (Y op Z)" always equal "(X op' Y) op (X op' Z)"?
- if (LeftDistributesOverRight(InnerOpcode, TopLevelOpcode))
- // Does the instruction have the form "(A op' B) op (A op' D)" or, in the
- // commutative case, "(A op' B) op (C op' A)"?
- if (A == C || (InnerCommutative && A == D)) {
- if (A != C)
- std::swap(C, D);
- // Consider forming "A op' (B op D)".
- // If "B op D" simplifies then it can be formed with no cost.
- Value *V = SimplifyBinOp(TopLevelOpcode, B, D, TD);
- // If "B op D" doesn't simplify then only go on if both of the existing
- // operations "A op' B" and "C op' D" will be zapped as no longer used.
- if (!V && Op0->hasOneUse() && Op1->hasOneUse())
- V = Builder->CreateBinOp(TopLevelOpcode, B, D, Op1->getName());
- if (V) {
- ++NumFactor;
- V = Builder->CreateBinOp(InnerOpcode, A, V);
- V->takeName(&I);
- return V;
- }
- }
+ // The instruction has the form "(A op' B) op (C)". Try to factorize common
+ // term.
+ if (Value *V = tryFactorization(Builder, DL, I, LHSOpcode, A, B, RHS,
+ getIdentityValue(LHSOpcode, RHS)))
+ return V;
- // Does "(X op Y) op' Z" always equal "(X op' Z) op (Y op' Z)"?
- if (RightDistributesOverLeft(TopLevelOpcode, InnerOpcode))
- // Does the instruction have the form "(A op' B) op (C op' B)" or, in the
- // commutative case, "(A op' B) op (B op' D)"?
- if (B == D || (InnerCommutative && B == C)) {
- if (B != D)
- std::swap(C, D);
- // Consider forming "(A op C) op' B".
- // If "A op C" simplifies then it can be formed with no cost.
- Value *V = SimplifyBinOp(TopLevelOpcode, A, C, TD);
- // If "A op C" doesn't simplify then only go on if both of the existing
- // operations "A op' B" and "C op' D" will be zapped as no longer used.
- if (!V && Op0->hasOneUse() && Op1->hasOneUse())
- V = Builder->CreateBinOp(TopLevelOpcode, A, C, Op0->getName());
- if (V) {
- ++NumFactor;
- V = Builder->CreateBinOp(InnerOpcode, V, B);
- V->takeName(&I);
- return V;
- }
- }
- }
+ // The instruction has the form "(B) op (C op' D)". Try to factorize common
+ // term.
+ if (Value *V = tryFactorization(Builder, DL, I, RHSOpcode, LHS,
+ getIdentityValue(RHSOpcode, LHS), C, D))
+ return V;
// Expansion.
if (Op0 && RightDistributesOverLeft(Op0->getOpcode(), TopLevelOpcode)) {
Instruction::BinaryOps InnerOpcode = Op0->getOpcode(); // op'
// Do "A op C" and "B op C" both simplify?
- if (Value *L = SimplifyBinOp(TopLevelOpcode, A, C, TD))
- if (Value *R = SimplifyBinOp(TopLevelOpcode, B, C, TD)) {
+ if (Value *L = SimplifyBinOp(TopLevelOpcode, A, C, DL))
+ if (Value *R = SimplifyBinOp(TopLevelOpcode, B, C, DL)) {
// They do! Return "L op' R".
++NumExpand;
// If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
(Instruction::isCommutative(InnerOpcode) && L == B && R == A))
return Op0;
// Otherwise return "L op' R" if it simplifies.
- if (Value *V = SimplifyBinOp(InnerOpcode, L, R, TD))
+ if (Value *V = SimplifyBinOp(InnerOpcode, L, R, DL))
return V;
// Otherwise, create a new instruction.
C = Builder->CreateBinOp(InnerOpcode, L, R);
Instruction::BinaryOps InnerOpcode = Op1->getOpcode(); // op'
// Do "A op B" and "A op C" both simplify?
- if (Value *L = SimplifyBinOp(TopLevelOpcode, A, B, TD))
- if (Value *R = SimplifyBinOp(TopLevelOpcode, A, C, TD)) {
+ if (Value *L = SimplifyBinOp(TopLevelOpcode, A, B, DL))
+ if (Value *R = SimplifyBinOp(TopLevelOpcode, A, C, DL)) {
// They do! Return "L op' R".
++NumExpand;
// If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
(Instruction::isCommutative(InnerOpcode) && L == C && R == B))
return Op1;
// Otherwise return "L op' R" if it simplifies.
- if (Value *V = SimplifyBinOp(InnerOpcode, L, R, TD))
+ if (Value *V = SimplifyBinOp(InnerOpcode, L, R, DL))
return V;
// Otherwise, create a new instruction.
A = Builder->CreateBinOp(InnerOpcode, L, R);
}
}
- return 0;
+ // (op (select (a, c, b)), (select (a, d, b))) -> (select (a, (op c, d), 0))
+ // (op (select (a, b, c)), (select (a, b, d))) -> (select (a, 0, (op c, d)))
+ if (auto *SI0 = dyn_cast<SelectInst>(LHS)) {
+ if (auto *SI1 = dyn_cast<SelectInst>(RHS)) {
+ if (SI0->getCondition() == SI1->getCondition()) {
+ Value *SI = nullptr;
+ if (Value *V = SimplifyBinOp(TopLevelOpcode, SI0->getFalseValue(),
+ SI1->getFalseValue(), DL, TLI, DT, AC))
+ SI = Builder->CreateSelect(SI0->getCondition(),
+ Builder->CreateBinOp(TopLevelOpcode,
+ SI0->getTrueValue(),
+ SI1->getTrueValue()),
+ V);
+ if (Value *V = SimplifyBinOp(TopLevelOpcode, SI0->getTrueValue(),
+ SI1->getTrueValue(), DL, TLI, DT, AC))
+ SI = Builder->CreateSelect(
+ SI0->getCondition(), V,
+ Builder->CreateBinOp(TopLevelOpcode, SI0->getFalseValue(),
+ SI1->getFalseValue()));
+ if (SI) {
+ SI->takeName(&I);
+ return SI;
+ }
+ }
+ }
+ }
+
+ return nullptr;
}
-// dyn_castNegVal - Given a 'sub' instruction, return the RHS of the instruction
-// if the LHS is a constant zero (which is the 'negate' form).
-//
+/// Given a 'sub' instruction, return the RHS of the instruction if the LHS is a
+/// constant zero (which is the 'negate' form).
Value *InstCombiner::dyn_castNegVal(Value *V) const {
if (BinaryOperator::isNeg(V))
return BinaryOperator::getNegArgument(V);
if (C->getType()->getElementType()->isIntegerTy())
return ConstantExpr::getNeg(C);
- return 0;
+ return nullptr;
}
-// dyn_castFNegVal - Given a 'fsub' instruction, return the RHS of the
-// instruction if the LHS is a constant negative zero (which is the 'negate'
-// form).
-//
+/// Given a 'fsub' instruction, return the RHS of the instruction if the LHS is
+/// a constant negative zero (which is the 'negate' form).
Value *InstCombiner::dyn_castFNegVal(Value *V, bool IgnoreZeroSign) const {
if (BinaryOperator::isFNeg(V, IgnoreZeroSign))
return BinaryOperator::getFNegArgument(V);
if (C->getType()->getElementType()->isFloatingPointTy())
return ConstantExpr::getFNeg(C);
- return 0;
+ return nullptr;
}
static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
if (!ConstIsRHS)
std::swap(Op0, Op1);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
- return IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
+ if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I)) {
+ Value *RI = IC->Builder->CreateBinOp(BO->getOpcode(), Op0, Op1,
SO->getName()+".op");
+ Instruction *FPInst = dyn_cast<Instruction>(RI);
+ if (FPInst && isa<FPMathOperator>(FPInst))
+ FPInst->copyFastMathFlags(BO);
+ return RI;
+ }
if (ICmpInst *CI = dyn_cast<ICmpInst>(&I))
return IC->Builder->CreateICmp(CI->getPredicate(), Op0, Op1,
SO->getName()+".cmp");
llvm_unreachable("Unknown binary instruction type!");
}
-// FoldOpIntoSelect - Given an instruction with a select as one operand and a
-// constant as the other operand, try to fold the binary operator into the
-// select arguments. This also works for Cast instructions, which obviously do
-// not have a second operand.
+/// Given an instruction with a select as one operand and a constant as the
+/// other operand, try to fold the binary operator into the select arguments.
+/// This also works for Cast instructions, which obviously do not have a second
+/// operand.
Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
// Don't modify shared select instructions
- if (!SI->hasOneUse()) return 0;
+ if (!SI->hasOneUse()) return nullptr;
Value *TV = SI->getOperand(1);
Value *FV = SI->getOperand(2);
if (isa<Constant>(TV) || isa<Constant>(FV)) {
// Bool selects with constant operands can be folded to logical ops.
- if (SI->getType()->isIntegerTy(1)) return 0;
+ if (SI->getType()->isIntegerTy(1)) return nullptr;
// If it's a bitcast involving vectors, make sure it has the same number of
// elements on both sides.
VectorType *SrcTy = dyn_cast<VectorType>(BC->getSrcTy());
// Verify that either both or neither are vectors.
- if ((SrcTy == NULL) != (DestTy == NULL)) return 0;
+ if ((SrcTy == nullptr) != (DestTy == nullptr)) return nullptr;
// If vectors, verify that they have the same number of elements.
if (SrcTy && SrcTy->getNumElements() != DestTy->getNumElements())
- return 0;
+ return nullptr;
+ }
+
+ // Test if a CmpInst instruction is used exclusively by a select as
+ // part of a minimum or maximum operation. If so, refrain from doing
+ // any other folding. This helps out other analyses which understand
+ // non-obfuscated minimum and maximum idioms, such as ScalarEvolution
+ // and CodeGen. And in this case, at least one of the comparison
+ // operands has at least one user besides the compare (the select),
+ // which would often largely negate the benefit of folding anyway.
+ if (auto *CI = dyn_cast<CmpInst>(SI->getCondition())) {
+ if (CI->hasOneUse()) {
+ Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
+ if ((SI->getOperand(1) == Op0 && SI->getOperand(2) == Op1) ||
+ (SI->getOperand(2) == Op0 && SI->getOperand(1) == Op1))
+ return nullptr;
+ }
}
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, this);
return SelectInst::Create(SI->getCondition(),
SelectTrueVal, SelectFalseVal);
}
- return 0;
+ return nullptr;
}
-
-/// FoldOpIntoPhi - Given a binary operator, cast instruction, or select which
-/// has a PHI node as operand #0, see if we can fold the instruction into the
-/// PHI (which is only possible if all operands to the PHI are constants).
-///
+/// Given a binary operator, cast instruction, or select which has a PHI node as
+/// operand #0, see if we can fold the instruction into the PHI (which is only
+/// possible if all operands to the PHI are constants).
Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
PHINode *PN = cast<PHINode>(I.getOperand(0));
unsigned NumPHIValues = PN->getNumIncomingValues();
if (NumPHIValues == 0)
- return 0;
+ return nullptr;
// We normally only transform phis with a single use. However, if a PHI has
// multiple uses and they are all the same operation, we can fold *all* of the
// uses into the PHI.
if (!PN->hasOneUse()) {
// Walk the use list for the instruction, comparing them to I.
- for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
- UI != E; ++UI) {
- Instruction *User = cast<Instruction>(*UI);
- if (User != &I && !I.isIdenticalTo(User))
- return 0;
+ for (User *U : PN->users()) {
+ Instruction *UI = cast<Instruction>(U);
+ if (UI != &I && !I.isIdenticalTo(UI))
+ return nullptr;
}
// Otherwise, we can replace *all* users with the new PHI we form.
}
// remember the BB it is in. If there is more than one or if *it* is a PHI,
// bail out. We don't do arbitrary constant expressions here because moving
// their computation can be expensive without a cost model.
- BasicBlock *NonConstBB = 0;
+ BasicBlock *NonConstBB = nullptr;
for (unsigned i = 0; i != NumPHIValues; ++i) {
Value *InVal = PN->getIncomingValue(i);
if (isa<Constant>(InVal) && !isa<ConstantExpr>(InVal))
continue;
- if (isa<PHINode>(InVal)) return 0; // Itself a phi.
- if (NonConstBB) return 0; // More than one non-const value.
+ if (isa<PHINode>(InVal)) return nullptr; // Itself a phi.
+ if (NonConstBB) return nullptr; // More than one non-const value.
NonConstBB = PN->getIncomingBlock(i);
// insert a computation after it without breaking the edge.
if (InvokeInst *II = dyn_cast<InvokeInst>(InVal))
if (II->getParent() == NonConstBB)
- return 0;
+ return nullptr;
// If the incoming non-constant value is in I's block, we will remove one
// instruction, but insert another equivalent one, leading to infinite
// instcombine.
- if (NonConstBB == I.getParent())
- return 0;
+ if (isPotentiallyReachable(I.getParent(), NonConstBB, DT, LI))
+ return nullptr;
}
// If there is exactly one non-constant value, we can insert a copy of the
// operation in that block. However, if this is a critical edge, we would be
- // inserting the computation one some other paths (e.g. inside a loop). Only
+ // inserting the computation on some other paths (e.g. inside a loop). Only
// do this if the pred block is unconditionally branching into the phi block.
- if (NonConstBB != 0) {
+ if (NonConstBB != nullptr) {
BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
- if (!BI || !BI->isUnconditional()) return 0;
+ if (!BI || !BI->isUnconditional()) return nullptr;
}
// Okay, we can do the transformation: create the new PHI node.
NewPN->takeName(PN);
// If we are going to have to insert a new computation, do so right before the
- // predecessors terminator.
+ // predecessor's terminator.
if (NonConstBB)
Builder->SetInsertPoint(NonConstBB->getTerminator());
BasicBlock *ThisBB = PN->getIncomingBlock(i);
Value *TrueVInPred = TrueV->DoPHITranslation(PhiTransBB, ThisBB);
Value *FalseVInPred = FalseV->DoPHITranslation(PhiTransBB, ThisBB);
- Value *InV = 0;
- if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
+ Value *InV = nullptr;
+ // Beware of ConstantExpr: it may eventually evaluate to getNullValue,
+ // even if currently isNullValue gives false.
+ Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i));
+ if (InC && !isa<ConstantExpr>(InC))
InV = InC->isNullValue() ? FalseVInPred : TrueVInPred;
else
InV = Builder->CreateSelect(PN->getIncomingValue(i),
} else if (CmpInst *CI = dyn_cast<CmpInst>(&I)) {
Constant *C = cast<Constant>(I.getOperand(1));
for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV = 0;
+ Value *InV = nullptr;
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
InV = ConstantExpr::getCompare(CI->getPredicate(), InC, C);
else if (isa<ICmpInst>(CI))
} else if (I.getNumOperands() == 2) {
Constant *C = cast<Constant>(I.getOperand(1));
for (unsigned i = 0; i != NumPHIValues; ++i) {
- Value *InV = 0;
+ Value *InV = nullptr;
if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i)))
InV = ConstantExpr::get(I.getOpcode(), InC, C);
else
}
}
- for (Value::use_iterator UI = PN->use_begin(), E = PN->use_end();
- UI != E; ) {
+ for (auto UI = PN->user_begin(), E = PN->user_end(); UI != E;) {
Instruction *User = cast<Instruction>(*UI++);
if (User == &I) continue;
ReplaceInstUsesWith(*User, NewPN);
return ReplaceInstUsesWith(I, NewPN);
}
-/// FindElementAtOffset - Given a type and a constant offset, determine whether
-/// or not there is a sequence of GEP indices into the type that will land us at
-/// the specified offset. If so, fill them into NewIndices and return the
-/// resultant element type, otherwise return null.
-Type *InstCombiner::FindElementAtOffset(Type *Ty, int64_t Offset,
- SmallVectorImpl<Value*> &NewIndices) {
- if (!TD) return 0;
- if (!Ty->isSized()) return 0;
+/// Given a pointer type and a constant offset, determine whether or not there
+/// is a sequence of GEP indices into the pointed type that will land us at the
+/// specified offset. If so, fill them into NewIndices and return the resultant
+/// element type, otherwise return null.
+Type *InstCombiner::FindElementAtOffset(PointerType *PtrTy, int64_t Offset,
+ SmallVectorImpl<Value *> &NewIndices) {
+ Type *Ty = PtrTy->getElementType();
+ if (!Ty->isSized())
+ return nullptr;
// Start with the index over the outer type. Note that the type size
// might be zero (even if the offset isn't zero) if the indexed type
// is something like [0 x {int, int}]
- Type *IntPtrTy = TD->getIntPtrType(Ty->getContext());
+ Type *IntPtrTy = DL.getIntPtrType(PtrTy);
int64_t FirstIdx = 0;
- if (int64_t TySize = TD->getTypeAllocSize(Ty)) {
+ if (int64_t TySize = DL.getTypeAllocSize(Ty)) {
FirstIdx = Offset/TySize;
Offset -= FirstIdx*TySize;
// Index into the types. If we fail, set OrigBase to null.
while (Offset) {
// Indexing into tail padding between struct/array elements.
- if (uint64_t(Offset*8) >= TD->getTypeSizeInBits(Ty))
- return 0;
+ if (uint64_t(Offset * 8) >= DL.getTypeSizeInBits(Ty))
+ return nullptr;
if (StructType *STy = dyn_cast<StructType>(Ty)) {
- const StructLayout *SL = TD->getStructLayout(STy);
+ const StructLayout *SL = DL.getStructLayout(STy);
assert(Offset < (int64_t)SL->getSizeInBytes() &&
"Offset must stay within the indexed type");
Offset -= SL->getElementOffset(Elt);
Ty = STy->getElementType(Elt);
} else if (ArrayType *AT = dyn_cast<ArrayType>(Ty)) {
- uint64_t EltSize = TD->getTypeAllocSize(AT->getElementType());
+ uint64_t EltSize = DL.getTypeAllocSize(AT->getElementType());
assert(EltSize && "Cannot index into a zero-sized array");
NewIndices.push_back(ConstantInt::get(IntPtrTy,Offset/EltSize));
Offset %= EltSize;
Ty = AT->getElementType();
} else {
// Otherwise, we can't index into the middle of this atomic type, bail.
- return 0;
+ return nullptr;
}
}
return true;
}
-/// Descale - Return a value X such that Val = X * Scale, or null if none. If
-/// the multiplication is known not to overflow then NoSignedWrap is set.
+/// Return a value X such that Val = X * Scale, or null if none.
+/// If the multiplication is known not to overflow, then NoSignedWrap is set.
Value *InstCombiner::Descale(Value *Val, APInt Scale, bool &NoSignedWrap) {
assert(isa<IntegerType>(Val->getType()) && "Can only descale integers!");
assert(cast<IntegerType>(Val->getType())->getBitWidth() ==
// If Scale is zero then it does not divide Val.
if (Scale.isMinValue())
- return 0;
+ return nullptr;
// Look through chains of multiplications, searching for a constant that is
// divisible by Scale. For example, descaling X*(Y*(Z*4)) by a factor of 4
// 0'th operand of Val.
std::pair<Instruction*, unsigned> Parent;
- // RequireNoSignedWrap - Set if the transform requires a descaling at deeper
- // levels that doesn't overflow.
+ // Set if the transform requires a descaling at deeper levels that doesn't
+ // overflow.
bool RequireNoSignedWrap = false;
- // logScale - log base 2 of the scale. Negative if not a power of 2.
+ // Log base 2 of the scale. Negative if not a power of 2.
int32_t logScale = Scale.exactLogBase2();
for (;; Op = Parent.first->getOperand(Parent.second)) { // Drill down
APInt::sdivrem(CI->getValue(), Scale, Quotient, Remainder);
if (!Remainder.isMinValue())
// Not divisible by Scale.
- return 0;
+ return nullptr;
// Replace with the quotient in the parent.
Op = ConstantInt::get(CI->getType(), Quotient);
NoSignedWrap = true;
// Multiplication.
NoSignedWrap = BO->hasNoSignedWrap();
if (RequireNoSignedWrap && !NoSignedWrap)
- return 0;
+ return nullptr;
// There are three cases for multiplication: multiplication by exactly
// the scale, multiplication by a constant different to the scale, and
// Otherwise drill down into the constant.
if (!Op->hasOneUse())
- return 0;
+ return nullptr;
Parent = std::make_pair(BO, 1);
continue;
// Multiplication by something else. Drill down into the left-hand side
// since that's where the reassociate pass puts the good stuff.
if (!Op->hasOneUse())
- return 0;
+ return nullptr;
Parent = std::make_pair(BO, 0);
continue;
// Multiplication by a power of 2.
NoSignedWrap = BO->hasNoSignedWrap();
if (RequireNoSignedWrap && !NoSignedWrap)
- return 0;
+ return nullptr;
Value *LHS = BO->getOperand(0);
int32_t Amt = cast<ConstantInt>(BO->getOperand(1))->
break;
}
if (Amt < logScale || !Op->hasOneUse())
- return 0;
+ return nullptr;
// Multiplication by more than the scale. Reduce the multiplying amount
// by the scale in the parent.
}
if (!Op->hasOneUse())
- return 0;
+ return nullptr;
if (CastInst *Cast = dyn_cast<CastInst>(Op)) {
if (Cast->getOpcode() == Instruction::SExt) {
// Scale and the multiplication Y * SmallScale should not overflow.
if (SmallScale.sext(Scale.getBitWidth()) != Scale)
// SmallScale does not sign-extend to Scale.
- return 0;
+ return nullptr;
assert(SmallScale.exactLogBase2() == logScale);
// Require that Y * SmallScale must not overflow.
RequireNoSignedWrap = true;
// trunc (Y * sext Scale) does not, so nsw flags need to be cleared
// from this point up in the expression (see later).
if (RequireNoSignedWrap)
- return 0;
+ return nullptr;
// Drill down through the cast.
unsigned LargeSize = Cast->getSrcTy()->getPrimitiveSizeInBits();
}
// Unsupported expression, bail out.
- return 0;
+ return nullptr;
+ }
+
+ // If Op is zero then Val = Op * Scale.
+ if (match(Op, m_Zero())) {
+ NoSignedWrap = true;
+ return Op;
}
// We know that we can successfully descale, so from here on we can safely
// Move up one level in the expression.
assert(Ancestor->hasOneUse() && "Drilled down when more than one use!");
- Ancestor = Ancestor->use_back();
+ Ancestor = Ancestor->user_back();
} while (1);
}
+/// \brief Creates node of binary operation with the same attributes as the
+/// specified one but with other operands.
+static Value *CreateBinOpAsGiven(BinaryOperator &Inst, Value *LHS, Value *RHS,
+ InstCombiner::BuilderTy *B) {
+ Value *BO = B->CreateBinOp(Inst.getOpcode(), LHS, RHS);
+ // If LHS and RHS are constant, BO won't be a binary operator.
+ if (BinaryOperator *NewBO = dyn_cast<BinaryOperator>(BO))
+ NewBO->copyIRFlags(&Inst);
+ return BO;
+}
+
+/// \brief Makes transformation of binary operation specific for vector types.
+/// \param Inst Binary operator to transform.
+/// \return Pointer to node that must replace the original binary operator, or
+/// null pointer if no transformation was made.
+Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) {
+ if (!Inst.getType()->isVectorTy()) return nullptr;
+
+ // It may not be safe to reorder shuffles and things like div, urem, etc.
+ // because we may trap when executing those ops on unknown vector elements.
+ // See PR20059.
+ if (!isSafeToSpeculativelyExecute(&Inst))
+ return nullptr;
+
+ unsigned VWidth = cast<VectorType>(Inst.getType())->getNumElements();
+ Value *LHS = Inst.getOperand(0), *RHS = Inst.getOperand(1);
+ assert(cast<VectorType>(LHS->getType())->getNumElements() == VWidth);
+ assert(cast<VectorType>(RHS->getType())->getNumElements() == VWidth);
+
+ // If both arguments of binary operation are shuffles, which use the same
+ // mask and shuffle within a single vector, it is worthwhile to move the
+ // shuffle after binary operation:
+ // Op(shuffle(v1, m), shuffle(v2, m)) -> shuffle(Op(v1, v2), m)
+ if (isa<ShuffleVectorInst>(LHS) && isa<ShuffleVectorInst>(RHS)) {
+ ShuffleVectorInst *LShuf = cast<ShuffleVectorInst>(LHS);
+ ShuffleVectorInst *RShuf = cast<ShuffleVectorInst>(RHS);
+ if (isa<UndefValue>(LShuf->getOperand(1)) &&
+ isa<UndefValue>(RShuf->getOperand(1)) &&
+ LShuf->getOperand(0)->getType() == RShuf->getOperand(0)->getType() &&
+ LShuf->getMask() == RShuf->getMask()) {
+ Value *NewBO = CreateBinOpAsGiven(Inst, LShuf->getOperand(0),
+ RShuf->getOperand(0), Builder);
+ return Builder->CreateShuffleVector(NewBO,
+ UndefValue::get(NewBO->getType()), LShuf->getMask());
+ }
+ }
+
+ // If one argument is a shuffle within one vector, the other is a constant,
+ // try moving the shuffle after the binary operation.
+ ShuffleVectorInst *Shuffle = nullptr;
+ Constant *C1 = nullptr;
+ if (isa<ShuffleVectorInst>(LHS)) Shuffle = cast<ShuffleVectorInst>(LHS);
+ if (isa<ShuffleVectorInst>(RHS)) Shuffle = cast<ShuffleVectorInst>(RHS);
+ if (isa<Constant>(LHS)) C1 = cast<Constant>(LHS);
+ if (isa<Constant>(RHS)) C1 = cast<Constant>(RHS);
+ if (Shuffle && C1 &&
+ (isa<ConstantVector>(C1) || isa<ConstantDataVector>(C1)) &&
+ isa<UndefValue>(Shuffle->getOperand(1)) &&
+ Shuffle->getType() == Shuffle->getOperand(0)->getType()) {
+ SmallVector<int, 16> ShMask = Shuffle->getShuffleMask();
+ // Find constant C2 that has property:
+ // shuffle(C2, ShMask) = C1
+ // If such constant does not exist (example: ShMask=<0,0> and C1=<1,2>)
+ // reorder is not possible.
+ SmallVector<Constant*, 16> C2M(VWidth,
+ UndefValue::get(C1->getType()->getScalarType()));
+ bool MayChange = true;
+ for (unsigned I = 0; I < VWidth; ++I) {
+ if (ShMask[I] >= 0) {
+ assert(ShMask[I] < (int)VWidth);
+ if (!isa<UndefValue>(C2M[ShMask[I]])) {
+ MayChange = false;
+ break;
+ }
+ C2M[ShMask[I]] = C1->getAggregateElement(I);
+ }
+ }
+ if (MayChange) {
+ Constant *C2 = ConstantVector::get(C2M);
+ Value *NewLHS = isa<Constant>(LHS) ? C2 : Shuffle->getOperand(0);
+ Value *NewRHS = isa<Constant>(LHS) ? Shuffle->getOperand(0) : C2;
+ Value *NewBO = CreateBinOpAsGiven(Inst, NewLHS, NewRHS, Builder);
+ return Builder->CreateShuffleVector(NewBO,
+ UndefValue::get(Inst.getType()), Shuffle->getMask());
+ }
+ }
+
+ return nullptr;
+}
+
Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
- if (Value *V = SimplifyGEPInst(Ops, TD))
+ if (Value *V = SimplifyGEPInst(Ops, DL, TLI, DT, AC))
return ReplaceInstUsesWith(GEP, V);
Value *PtrOp = GEP.getOperand(0);
// Eliminate unneeded casts for indices, and replace indices which displace
// by multiples of a zero size type with zero.
- if (TD) {
- bool MadeChange = false;
- Type *IntPtrTy = TD->getIntPtrType(GEP.getPointerOperandType());
-
- gep_type_iterator GTI = gep_type_begin(GEP);
- for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end();
- I != E; ++I, ++GTI) {
- // Skip indices into struct types.
- SequentialType *SeqTy = dyn_cast<SequentialType>(*GTI);
- if (!SeqTy) continue;
-
- // If the element type has zero size then any index over it is equivalent
- // to an index of zero, so replace it with zero if it is not zero already.
- if (SeqTy->getElementType()->isSized() &&
- TD->getTypeAllocSize(SeqTy->getElementType()) == 0)
- if (!isa<Constant>(*I) || !cast<Constant>(*I)->isNullValue()) {
- *I = Constant::getNullValue(IntPtrTy);
- MadeChange = true;
- }
+ bool MadeChange = false;
+ Type *IntPtrTy =
+ DL.getIntPtrType(GEP.getPointerOperandType()->getScalarType());
+
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (User::op_iterator I = GEP.op_begin() + 1, E = GEP.op_end(); I != E;
+ ++I, ++GTI) {
+ // Skip indices into struct types.
+ SequentialType *SeqTy = dyn_cast<SequentialType>(*GTI);
+ if (!SeqTy)
+ continue;
- Type *IndexTy = (*I)->getType();
- if (IndexTy != IntPtrTy) {
- // If we are using a wider index than needed for this platform, shrink
- // it to what we need. If narrower, sign-extend it to what we need.
- // This explicit cast can make subsequent optimizations more obvious.
- *I = Builder->CreateIntCast(*I, IntPtrTy, true);
+ // Index type should have the same width as IntPtr
+ Type *IndexTy = (*I)->getType();
+ Type *NewIndexType = IndexTy->isVectorTy() ?
+ VectorType::get(IntPtrTy, IndexTy->getVectorNumElements()) : IntPtrTy;
+
+ // If the element type has zero size then any index over it is equivalent
+ // to an index of zero, so replace it with zero if it is not zero already.
+ if (SeqTy->getElementType()->isSized() &&
+ DL.getTypeAllocSize(SeqTy->getElementType()) == 0)
+ if (!isa<Constant>(*I) || !cast<Constant>(*I)->isNullValue()) {
+ *I = Constant::getNullValue(NewIndexType);
MadeChange = true;
}
+
+ if (IndexTy != NewIndexType) {
+ // If we are using a wider index than needed for this platform, shrink
+ // it to what we need. If narrower, sign-extend it to what we need.
+ // This explicit cast can make subsequent optimizations more obvious.
+ *I = Builder->CreateIntCast(*I, NewIndexType, true);
+ MadeChange = true;
}
- if (MadeChange) return &GEP;
+ }
+ if (MadeChange)
+ return &GEP;
+
+ // Check to see if the inputs to the PHI node are getelementptr instructions.
+ if (PHINode *PN = dyn_cast<PHINode>(PtrOp)) {
+ GetElementPtrInst *Op1 = dyn_cast<GetElementPtrInst>(PN->getOperand(0));
+ if (!Op1)
+ return nullptr;
+
+ // Don't fold a GEP into itself through a PHI node. This can only happen
+ // through the back-edge of a loop. Folding a GEP into itself means that
+ // the value of the previous iteration needs to be stored in the meantime,
+ // thus requiring an additional register variable to be live, but not
+ // actually achieving anything (the GEP still needs to be executed once per
+ // loop iteration).
+ if (Op1 == &GEP)
+ return nullptr;
+
+ signed DI = -1;
+
+ for (auto I = PN->op_begin()+1, E = PN->op_end(); I !=E; ++I) {
+ GetElementPtrInst *Op2 = dyn_cast<GetElementPtrInst>(*I);
+ if (!Op2 || Op1->getNumOperands() != Op2->getNumOperands())
+ return nullptr;
+
+ // As for Op1 above, don't try to fold a GEP into itself.
+ if (Op2 == &GEP)
+ return nullptr;
+
+ // Keep track of the type as we walk the GEP.
+ Type *CurTy = Op1->getOperand(0)->getType()->getScalarType();
+
+ for (unsigned J = 0, F = Op1->getNumOperands(); J != F; ++J) {
+ if (Op1->getOperand(J)->getType() != Op2->getOperand(J)->getType())
+ return nullptr;
+
+ if (Op1->getOperand(J) != Op2->getOperand(J)) {
+ if (DI == -1) {
+ // We have not seen any differences yet in the GEPs feeding the
+ // PHI yet, so we record this one if it is allowed to be a
+ // variable.
+
+ // The first two arguments can vary for any GEP, the rest have to be
+ // static for struct slots
+ if (J > 1 && CurTy->isStructTy())
+ return nullptr;
+
+ DI = J;
+ } else {
+ // The GEP is different by more than one input. While this could be
+ // extended to support GEPs that vary by more than one variable it
+ // doesn't make sense since it greatly increases the complexity and
+ // would result in an R+R+R addressing mode which no backend
+ // directly supports and would need to be broken into several
+ // simpler instructions anyway.
+ return nullptr;
+ }
+ }
+
+ // Sink down a layer of the type for the next iteration.
+ if (J > 0) {
+ if (CompositeType *CT = dyn_cast<CompositeType>(CurTy)) {
+ CurTy = CT->getTypeAtIndex(Op1->getOperand(J));
+ } else {
+ CurTy = nullptr;
+ }
+ }
+ }
+ }
+
+ // If not all GEPs are identical we'll have to create a new PHI node.
+ // Check that the old PHI node has only one use so that it will get
+ // removed.
+ if (DI != -1 && !PN->hasOneUse())
+ return nullptr;
+
+ GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(Op1->clone());
+ if (DI == -1) {
+ // All the GEPs feeding the PHI are identical. Clone one down into our
+ // BB so that it can be merged with the current GEP.
+ GEP.getParent()->getInstList().insert(
+ GEP.getParent()->getFirstInsertionPt(), NewGEP);
+ } else {
+ // All the GEPs feeding the PHI differ at a single offset. Clone a GEP
+ // into the current block so it can be merged, and create a new PHI to
+ // set that index.
+ PHINode *NewPN;
+ {
+ IRBuilderBase::InsertPointGuard Guard(*Builder);
+ Builder->SetInsertPoint(PN);
+ NewPN = Builder->CreatePHI(Op1->getOperand(DI)->getType(),
+ PN->getNumOperands());
+ }
+
+ for (auto &I : PN->operands())
+ NewPN->addIncoming(cast<GEPOperator>(I)->getOperand(DI),
+ PN->getIncomingBlock(I));
+
+ NewGEP->setOperand(DI, NewPN);
+ GEP.getParent()->getInstList().insert(
+ GEP.getParent()->getFirstInsertionPt(), NewGEP);
+ NewGEP->setOperand(DI, NewPN);
+ }
+
+ GEP.setOperand(0, NewGEP);
+ PtrOp = NewGEP;
}
// Combine Indices - If the source pointer to this getelementptr instruction
//
if (GEPOperator *Src = dyn_cast<GEPOperator>(PtrOp)) {
if (!shouldMergeGEPs(*cast<GEPOperator>(&GEP), *Src))
- return 0;
+ return nullptr;
// Note that if our source is a gep chain itself then we wait for that
// chain to be resolved before we perform this transformation. This
if (GEPOperator *SrcGEP =
dyn_cast<GEPOperator>(Src->getOperand(0)))
if (SrcGEP->getNumOperands() == 2 && shouldMergeGEPs(*Src, *SrcGEP))
- return 0; // Wait until our source is folded to completion.
+ return nullptr; // Wait until our source is folded to completion.
SmallVector<Value*, 8> Indices;
// intptr_t). Just avoid transforming this until the input has been
// normalized.
if (SO1->getType() != GO1->getType())
- return 0;
+ return nullptr;
+ // Only do the combine when GO1 and SO1 are both constants. Only in
+ // this case, we are sure the cost after the merge is never more than
+ // that before the merge.
+ if (!isa<Constant>(GO1) || !isa<Constant>(SO1))
+ return nullptr;
Sum = Builder->CreateAdd(SO1, GO1, PtrOp->getName()+".sum");
}
}
if (!Indices.empty())
- return (GEP.isInBounds() && Src->isInBounds()) ?
- GetElementPtrInst::CreateInBounds(Src->getOperand(0), Indices,
- GEP.getName()) :
- GetElementPtrInst::Create(Src->getOperand(0), Indices, GEP.getName());
+ return GEP.isInBounds() && Src->isInBounds()
+ ? GetElementPtrInst::CreateInBounds(
+ Src->getSourceElementType(), Src->getOperand(0), Indices,
+ GEP.getName())
+ : GetElementPtrInst::Create(Src->getSourceElementType(),
+ Src->getOperand(0), Indices,
+ GEP.getName());
+ }
+
+ if (GEP.getNumIndices() == 1) {
+ unsigned AS = GEP.getPointerAddressSpace();
+ if (GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
+ DL.getPointerSizeInBits(AS)) {
+ Type *PtrTy = GEP.getPointerOperandType();
+ Type *Ty = PtrTy->getPointerElementType();
+ uint64_t TyAllocSize = DL.getTypeAllocSize(Ty);
+
+ bool Matched = false;
+ uint64_t C;
+ Value *V = nullptr;
+ if (TyAllocSize == 1) {
+ V = GEP.getOperand(1);
+ Matched = true;
+ } else if (match(GEP.getOperand(1),
+ m_AShr(m_Value(V), m_ConstantInt(C)))) {
+ if (TyAllocSize == 1ULL << C)
+ Matched = true;
+ } else if (match(GEP.getOperand(1),
+ m_SDiv(m_Value(V), m_ConstantInt(C)))) {
+ if (TyAllocSize == C)
+ Matched = true;
+ }
+
+ if (Matched) {
+ // Canonicalize (gep i8* X, -(ptrtoint Y))
+ // to (inttoptr (sub (ptrtoint X), (ptrtoint Y)))
+ // The GEP pattern is emitted by the SCEV expander for certain kinds of
+ // pointer arithmetic.
+ if (match(V, m_Neg(m_PtrToInt(m_Value())))) {
+ Operator *Index = cast<Operator>(V);
+ Value *PtrToInt = Builder->CreatePtrToInt(PtrOp, Index->getType());
+ Value *NewSub = Builder->CreateSub(PtrToInt, Index->getOperand(1));
+ return CastInst::Create(Instruction::IntToPtr, NewSub, GEP.getType());
+ }
+ // Canonicalize (gep i8* X, (ptrtoint Y)-(ptrtoint X))
+ // to (bitcast Y)
+ Value *Y;
+ if (match(V, m_Sub(m_PtrToInt(m_Value(Y)),
+ m_PtrToInt(m_Specific(GEP.getOperand(0)))))) {
+ return CastInst::CreatePointerBitCastOrAddrSpaceCast(Y,
+ GEP.getType());
+ }
+ }
+ }
}
// Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
// We do not handle pointer-vector geps here.
if (!StrippedPtrTy)
- return 0;
-
- if (StrippedPtr != PtrOp &&
- StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
+ return nullptr;
+ if (StrippedPtr != PtrOp) {
bool HasZeroPointerIndex = false;
if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
HasZeroPointerIndex = C->isZero();
if (CATy->getElementType() == StrippedPtrTy->getElementType()) {
// -> GEP i8* X, ...
SmallVector<Value*, 8> Idx(GEP.idx_begin()+1, GEP.idx_end());
- GetElementPtrInst *Res =
- GetElementPtrInst::Create(StrippedPtr, Idx, GEP.getName());
+ GetElementPtrInst *Res = GetElementPtrInst::Create(
+ StrippedPtrTy->getElementType(), StrippedPtr, Idx, GEP.getName());
Res->setIsInBounds(GEP.isInBounds());
- return Res;
+ if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace())
+ return Res;
+ // Insert Res, and create an addrspacecast.
+ // e.g.,
+ // GEP (addrspacecast i8 addrspace(1)* X to [0 x i8]*), i32 0, ...
+ // ->
+ // %0 = GEP i8 addrspace(1)* X, ...
+ // addrspacecast i8 addrspace(1)* %0 to i8*
+ return new AddrSpaceCastInst(Builder->Insert(Res), GEP.getType());
}
if (ArrayType *XATy =
// to an array of the same type as the destination pointer
// array. Because the array type is never stepped over (there
// is a leading zero) we can fold the cast into this GEP.
- GEP.setOperand(0, StrippedPtr);
- return &GEP;
+ if (StrippedPtrTy->getAddressSpace() == GEP.getAddressSpace()) {
+ GEP.setOperand(0, StrippedPtr);
+ GEP.setSourceElementType(XATy);
+ return &GEP;
+ }
+ // Cannot replace the base pointer directly because StrippedPtr's
+ // address space is different. Instead, create a new GEP followed by
+ // an addrspacecast.
+ // e.g.,
+ // GEP (addrspacecast [10 x i8] addrspace(1)* X to [0 x i8]*),
+ // i32 0, ...
+ // ->
+ // %0 = GEP [10 x i8] addrspace(1)* X, ...
+ // addrspacecast i8 addrspace(1)* %0 to i8*
+ SmallVector<Value*, 8> Idx(GEP.idx_begin(), GEP.idx_end());
+ Value *NewGEP = GEP.isInBounds()
+ ? Builder->CreateInBoundsGEP(
+ nullptr, StrippedPtr, Idx, GEP.getName())
+ : Builder->CreateGEP(nullptr, StrippedPtr, Idx,
+ GEP.getName());
+ return new AddrSpaceCastInst(NewGEP, GEP.getType());
}
}
}
// %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
// into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
Type *SrcElTy = StrippedPtrTy->getElementType();
- Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType();
- if (TD && SrcElTy->isArrayTy() &&
- TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType()) ==
- TD->getTypeAllocSize(ResElTy)) {
- Value *Idx[2];
- Idx[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext()));
- Idx[1] = GEP.getOperand(1);
- Value *NewGEP = GEP.isInBounds() ?
- Builder->CreateInBoundsGEP(StrippedPtr, Idx, GEP.getName()) :
- Builder->CreateGEP(StrippedPtr, Idx, GEP.getName());
+ Type *ResElTy = PtrOp->getType()->getPointerElementType();
+ if (SrcElTy->isArrayTy() &&
+ DL.getTypeAllocSize(SrcElTy->getArrayElementType()) ==
+ DL.getTypeAllocSize(ResElTy)) {
+ Type *IdxType = DL.getIntPtrType(GEP.getType());
+ Value *Idx[2] = { Constant::getNullValue(IdxType), GEP.getOperand(1) };
+ Value *NewGEP =
+ GEP.isInBounds()
+ ? Builder->CreateInBoundsGEP(nullptr, StrippedPtr, Idx,
+ GEP.getName())
+ : Builder->CreateGEP(nullptr, StrippedPtr, Idx, GEP.getName());
+
// V and GEP are both pointer types --> BitCast
- return new BitCastInst(NewGEP, GEP.getType());
+ return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
+ GEP.getType());
}
// Transform things like:
// %V = mul i64 %N, 4
// %t = getelementptr i8* bitcast (i32* %arr to i8*), i32 %V
// into: %t1 = getelementptr i32* %arr, i32 %N; bitcast
- if (TD && ResElTy->isSized() && SrcElTy->isSized()) {
+ if (ResElTy->isSized() && SrcElTy->isSized()) {
// Check that changing the type amounts to dividing the index by a scale
// factor.
- uint64_t ResSize = TD->getTypeAllocSize(ResElTy);
- uint64_t SrcSize = TD->getTypeAllocSize(SrcElTy);
+ uint64_t ResSize = DL.getTypeAllocSize(ResElTy);
+ uint64_t SrcSize = DL.getTypeAllocSize(SrcElTy);
if (ResSize && SrcSize % ResSize == 0) {
Value *Idx = GEP.getOperand(1);
unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
// Earlier transforms ensure that the index has type IntPtrType, which
// considerably simplifies the logic by eliminating implicit casts.
- assert(Idx->getType() == TD->getIntPtrType(GEP.getContext()) &&
+ assert(Idx->getType() == DL.getIntPtrType(GEP.getType()) &&
"Index not cast to pointer width?");
bool NSW;
// Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
// If the multiplication NewIdx * Scale may overflow then the new
// GEP may not be "inbounds".
- Value *NewGEP = GEP.isInBounds() && NSW ?
- Builder->CreateInBoundsGEP(StrippedPtr, NewIdx, GEP.getName()) :
- Builder->CreateGEP(StrippedPtr, NewIdx, GEP.getName());
+ Value *NewGEP =
+ GEP.isInBounds() && NSW
+ ? Builder->CreateInBoundsGEP(nullptr, StrippedPtr, NewIdx,
+ GEP.getName())
+ : Builder->CreateGEP(nullptr, StrippedPtr, NewIdx,
+ GEP.getName());
+
// The NewGEP must be pointer typed, so must the old one -> BitCast
- return new BitCastInst(NewGEP, GEP.getType());
+ return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
+ GEP.getType());
}
}
}
// getelementptr i8* bitcast ([100 x double]* X to i8*), i32 %tmp
// (where tmp = 8*tmp2) into:
// getelementptr [100 x double]* %arr, i32 0, i32 %tmp2; bitcast
- if (TD && ResElTy->isSized() && SrcElTy->isSized() &&
- SrcElTy->isArrayTy()) {
+ if (ResElTy->isSized() && SrcElTy->isSized() && SrcElTy->isArrayTy()) {
// Check that changing to the array element type amounts to dividing the
// index by a scale factor.
- uint64_t ResSize = TD->getTypeAllocSize(ResElTy);
+ uint64_t ResSize = DL.getTypeAllocSize(ResElTy);
uint64_t ArrayEltSize =
- TD->getTypeAllocSize(cast<ArrayType>(SrcElTy)->getElementType());
+ DL.getTypeAllocSize(SrcElTy->getArrayElementType());
if (ResSize && ArrayEltSize % ResSize == 0) {
Value *Idx = GEP.getOperand(1);
unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
// Earlier transforms ensure that the index has type IntPtrType, which
// considerably simplifies the logic by eliminating implicit casts.
- assert(Idx->getType() == TD->getIntPtrType(GEP.getContext()) &&
+ assert(Idx->getType() == DL.getIntPtrType(GEP.getType()) &&
"Index not cast to pointer width?");
bool NSW;
// Successfully decomposed Idx as NewIdx * Scale, form a new GEP.
// If the multiplication NewIdx * Scale may overflow then the new
// GEP may not be "inbounds".
- Value *Off[2];
- Off[0] = Constant::getNullValue(Type::getInt32Ty(GEP.getContext()));
- Off[1] = NewIdx;
- Value *NewGEP = GEP.isInBounds() && NSW ?
- Builder->CreateInBoundsGEP(StrippedPtr, Off, GEP.getName()) :
- Builder->CreateGEP(StrippedPtr, Off, GEP.getName());
+ Value *Off[2] = {
+ Constant::getNullValue(DL.getIntPtrType(GEP.getType())),
+ NewIdx};
+
+ Value *NewGEP = GEP.isInBounds() && NSW
+ ? Builder->CreateInBoundsGEP(
+ SrcElTy, StrippedPtr, Off, GEP.getName())
+ : Builder->CreateGEP(SrcElTy, StrippedPtr, Off,
+ GEP.getName());
// The NewGEP must be pointer typed, so must the old one -> BitCast
- return new BitCastInst(NewGEP, GEP.getType());
+ return CastInst::CreatePointerBitCastOrAddrSpaceCast(NewGEP,
+ GEP.getType());
}
}
}
}
}
+ // addrspacecast between types is canonicalized as a bitcast, then an
+ // addrspacecast. To take advantage of the below bitcast + struct GEP, look
+ // through the addrspacecast.
+ if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(PtrOp)) {
+ // X = bitcast A addrspace(1)* to B addrspace(1)*
+ // Y = addrspacecast A addrspace(1)* to B addrspace(2)*
+ // Z = gep Y, <...constant indices...>
+ // Into an addrspacecasted GEP of the struct.
+ if (BitCastInst *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))
+ PtrOp = BC;
+ }
+
/// See if we can simplify:
/// X = bitcast A* to B*
/// Y = gep X, <...constant indices...>
/// into a gep of the original struct. This is important for SROA and alias
/// analysis of unions. If "A" is also a bitcast, wait for A/X to be merged.
if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
- APInt Offset(TD ? TD->getPointerSizeInBits() : 1, 0);
- if (TD &&
- !isa<BitCastInst>(BCI->getOperand(0)) &&
- GEP.accumulateConstantOffset(*TD, Offset) &&
- StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
+ Value *Operand = BCI->getOperand(0);
+ PointerType *OpType = cast<PointerType>(Operand->getType());
+ unsigned OffsetBits = DL.getPointerTypeSizeInBits(GEP.getType());
+ APInt Offset(OffsetBits, 0);
+ if (!isa<BitCastInst>(Operand) &&
+ GEP.accumulateConstantOffset(DL, Offset)) {
// If this GEP instruction doesn't move the pointer, just replace the GEP
// with a bitcast of the real input to the dest type.
if (!Offset) {
// If the bitcast is of an allocation, and the allocation will be
// converted to match the type of the cast, don't touch this.
- if (isa<AllocaInst>(BCI->getOperand(0)) ||
- isAllocationFn(BCI->getOperand(0), TLI)) {
+ if (isa<AllocaInst>(Operand) || isAllocationFn(Operand, TLI)) {
// See if the bitcast simplifies, if so, don't nuke this GEP yet.
if (Instruction *I = visitBitCast(*BCI)) {
if (I != BCI) {
I->takeName(BCI);
- BCI->getParent()->getInstList().insert(BCI, I);
+ BCI->getParent()->getInstList().insert(BCI->getIterator(), I);
ReplaceInstUsesWith(*BCI, I);
}
return &GEP;
}
}
- return new BitCastInst(BCI->getOperand(0), GEP.getType());
+
+ if (Operand->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+ return new AddrSpaceCastInst(Operand, GEP.getType());
+ return new BitCastInst(Operand, GEP.getType());
}
// Otherwise, if the offset is non-zero, we need to find out if there is a
// field at Offset in 'A's type. If so, we can pull the cast through the
// GEP.
SmallVector<Value*, 8> NewIndices;
- Type *InTy =
- cast<PointerType>(BCI->getOperand(0)->getType())->getElementType();
- if (FindElementAtOffset(InTy, Offset.getSExtValue(), NewIndices)) {
- Value *NGEP = GEP.isInBounds() ?
- Builder->CreateInBoundsGEP(BCI->getOperand(0), NewIndices) :
- Builder->CreateGEP(BCI->getOperand(0), NewIndices);
+ if (FindElementAtOffset(OpType, Offset.getSExtValue(), NewIndices)) {
+ Value *NGEP =
+ GEP.isInBounds()
+ ? Builder->CreateInBoundsGEP(nullptr, Operand, NewIndices)
+ : Builder->CreateGEP(nullptr, Operand, NewIndices);
if (NGEP->getType() == GEP.getType())
return ReplaceInstUsesWith(GEP, NGEP);
NGEP->takeName(&GEP);
+
+ if (NGEP->getType()->getPointerAddressSpace() != GEP.getAddressSpace())
+ return new AddrSpaceCastInst(NGEP, GEP.getType());
return new BitCastInst(NGEP, GEP.getType());
}
}
}
- return 0;
+ return nullptr;
}
-
-
static bool
isAllocSiteRemovable(Instruction *AI, SmallVectorImpl<WeakVH> &Users,
const TargetLibraryInfo *TLI) {
do {
Instruction *PI = Worklist.pop_back_val();
- for (Value::use_iterator UI = PI->use_begin(), UE = PI->use_end(); UI != UE;
- ++UI) {
- Instruction *I = cast<Instruction>(*UI);
+ for (User *U : PI->users()) {
+ Instruction *I = cast<Instruction>(U);
switch (I->getOpcode()) {
default:
// Give up the moment we see something we can't handle.
case Instruction::BitCast:
case Instruction::GetElementPtr:
- Users.push_back(I);
+ Users.emplace_back(I);
Worklist.push_back(I);
continue;
// We can fold eq/ne comparisons with null to false/true, respectively.
if (!ICI->isEquality() || !isa<ConstantPointerNull>(ICI->getOperand(1)))
return false;
- Users.push_back(I);
+ Users.emplace_back(I);
continue;
}
case Intrinsic::lifetime_start:
case Intrinsic::lifetime_end:
case Intrinsic::objectsize:
- Users.push_back(I);
+ Users.emplace_back(I);
continue;
}
}
if (isFreeCall(I, TLI)) {
- Users.push_back(I);
+ Users.emplace_back(I);
continue;
}
return false;
StoreInst *SI = cast<StoreInst>(I);
if (SI->isVolatile() || SI->getPointerOperand() != PI)
return false;
- Users.push_back(I);
+ Users.emplace_back(I);
continue;
}
}
if (InvokeInst *II = dyn_cast<InvokeInst>(&MI)) {
// Replace invoke with a NOP intrinsic to maintain the original CFG
- Module *M = II->getParent()->getParent()->getParent();
+ Module *M = II->getModule();
Function *F = Intrinsic::getDeclaration(M, Intrinsic::donothing);
InvokeInst::Create(F, II->getNormalDest(), II->getUnwindDest(),
None, "", II->getParent());
}
return EraseInstFromFunction(MI);
}
- return 0;
+ return nullptr;
}
/// \brief Move the call to free before a NULL test.
// would duplicate the call to free in each predecessor and it may
// not be profitable even for code size.
if (!PredBB)
- return 0;
+ return nullptr;
// Validate constraint #2: Does this block contains only the call to
// free and an unconditional branch?
// FIXME: We could check if we can speculate everything in the
// predecessor block
if (FreeInstrBB->size() != 2)
- return 0;
+ return nullptr;
BasicBlock *SuccBB;
if (!match(FreeInstrBB->getTerminator(), m_UnconditionalBr(SuccBB)))
- return 0;
+ return nullptr;
// Validate the rest of constraint #1 by matching on the pred branch.
TerminatorInst *TI = PredBB->getTerminator();
BasicBlock *TrueBB, *FalseBB;
ICmpInst::Predicate Pred;
if (!match(TI, m_Br(m_ICmp(Pred, m_Specific(Op), m_Zero()), TrueBB, FalseBB)))
- return 0;
+ return nullptr;
if (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE)
- return 0;
+ return nullptr;
// Validate constraint #3: Ensure the null case just falls through.
if (SuccBB != (Pred == ICmpInst::ICMP_EQ ? TrueBB : FalseBB))
- return 0;
+ return nullptr;
assert(FreeInstrBB == (Pred == ICmpInst::ICMP_EQ ? FalseBB : TrueBB) &&
"Broken CFG: missing edge from predecessor to successor");
if (Instruction *I = tryToMoveFreeBeforeNullTest(FI))
return I;
- return 0;
+ return nullptr;
}
+Instruction *InstCombiner::visitReturnInst(ReturnInst &RI) {
+ if (RI.getNumOperands() == 0) // ret void
+ return nullptr;
+
+ Value *ResultOp = RI.getOperand(0);
+ Type *VTy = ResultOp->getType();
+ if (!VTy->isIntegerTy())
+ return nullptr;
+
+ // There might be assume intrinsics dominating this return that completely
+ // determine the value. If so, constant fold it.
+ unsigned BitWidth = VTy->getPrimitiveSizeInBits();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ computeKnownBits(ResultOp, KnownZero, KnownOne, 0, &RI);
+ if ((KnownZero|KnownOne).isAllOnesValue())
+ RI.setOperand(0, Constant::getIntegerValue(VTy, KnownOne));
+ return nullptr;
+}
Instruction *InstCombiner::visitBranchInst(BranchInst &BI) {
// Change br (not X), label True, label False to: br X, label False, True
- Value *X = 0;
+ Value *X = nullptr;
BasicBlock *TrueDest;
BasicBlock *FalseDest;
if (match(&BI, m_Br(m_Not(m_Value(X)), TrueDest, FalseDest)) &&
return &BI;
}
- // Cannonicalize fcmp_one -> fcmp_oeq
+ // If the condition is irrelevant, remove the use so that other
+ // transforms on the condition become more effective.
+ if (BI.isConditional() &&
+ BI.getSuccessor(0) == BI.getSuccessor(1) &&
+ !isa<UndefValue>(BI.getCondition())) {
+ BI.setCondition(UndefValue::get(BI.getCondition()->getType()));
+ return &BI;
+ }
+
+ // Canonicalize fcmp_one -> fcmp_oeq
FCmpInst::Predicate FPred; Value *Y;
if (match(&BI, m_Br(m_FCmp(FPred, m_Value(X), m_Value(Y)),
TrueDest, FalseDest)) &&
return &BI;
}
- // Cannonicalize icmp_ne -> icmp_eq
+ // Canonicalize icmp_ne -> icmp_eq
ICmpInst::Predicate IPred;
if (match(&BI, m_Br(m_ICmp(IPred, m_Value(X), m_Value(Y)),
TrueDest, FalseDest)) &&
return &BI;
}
- return 0;
+ return nullptr;
}
Instruction *InstCombiner::visitSwitchInst(SwitchInst &SI) {
Value *Cond = SI.getCondition();
+ unsigned BitWidth = cast<IntegerType>(Cond->getType())->getBitWidth();
+ APInt KnownZero(BitWidth, 0), KnownOne(BitWidth, 0);
+ computeKnownBits(Cond, KnownZero, KnownOne, 0, &SI);
+ unsigned LeadingKnownZeros = KnownZero.countLeadingOnes();
+ unsigned LeadingKnownOnes = KnownOne.countLeadingOnes();
+
+ // Compute the number of leading bits we can ignore.
+ for (auto &C : SI.cases()) {
+ LeadingKnownZeros = std::min(
+ LeadingKnownZeros, C.getCaseValue()->getValue().countLeadingZeros());
+ LeadingKnownOnes = std::min(
+ LeadingKnownOnes, C.getCaseValue()->getValue().countLeadingOnes());
+ }
+
+ unsigned NewWidth = BitWidth - std::max(LeadingKnownZeros, LeadingKnownOnes);
+
+ // Truncate the condition operand if the new type is equal to or larger than
+ // the largest legal integer type. We need to be conservative here since
+ // x86 generates redundant zero-extension instructions if the operand is
+ // truncated to i8 or i16.
+ bool TruncCond = false;
+ if (NewWidth > 0 && BitWidth > NewWidth &&
+ NewWidth >= DL.getLargestLegalIntTypeSize()) {
+ TruncCond = true;
+ IntegerType *Ty = IntegerType::get(SI.getContext(), NewWidth);
+ Builder->SetInsertPoint(&SI);
+ Value *NewCond = Builder->CreateTrunc(SI.getCondition(), Ty, "trunc");
+ SI.setCondition(NewCond);
+
+ for (auto &C : SI.cases())
+ static_cast<SwitchInst::CaseIt *>(&C)->setValue(ConstantInt::get(
+ SI.getContext(), C.getCaseValue()->getValue().trunc(NewWidth)));
+ }
+
if (Instruction *I = dyn_cast<Instruction>(Cond)) {
if (I->getOpcode() == Instruction::Add)
if (ConstantInt *AddRHS = dyn_cast<ConstantInt>(I->getOperand(1))) {
for (SwitchInst::CaseIt i = SI.case_begin(), e = SI.case_end();
i != e; ++i) {
ConstantInt* CaseVal = i.getCaseValue();
- Constant* NewCaseVal = ConstantExpr::getSub(cast<Constant>(CaseVal),
- AddRHS);
+ Constant *LHS = CaseVal;
+ if (TruncCond)
+ LHS = LeadingKnownZeros
+ ? ConstantExpr::getZExt(CaseVal, Cond->getType())
+ : ConstantExpr::getSExt(CaseVal, Cond->getType());
+ Constant* NewCaseVal = ConstantExpr::getSub(LHS, AddRHS);
assert(isa<ConstantInt>(NewCaseVal) &&
"Result of expression should be constant");
i.setValue(cast<ConstantInt>(NewCaseVal));
return &SI;
}
}
- return 0;
+
+ return TruncCond ? &SI : nullptr;
}
Instruction *InstCombiner::visitExtractValueInst(ExtractValueInst &EV) {
if (!EV.hasIndices())
return ReplaceInstUsesWith(EV, Agg);
- if (Constant *C = dyn_cast<Constant>(Agg)) {
- if (Constant *C2 = C->getAggregateElement(*EV.idx_begin())) {
- if (EV.getNumIndices() == 0)
- return ReplaceInstUsesWith(EV, C2);
- // Extract the remaining indices out of the constant indexed by the
- // first index
- return ExtractValueInst::Create(C2, EV.getIndices().slice(1));
- }
- return 0; // Can't handle other constants
- }
+ if (Value *V =
+ SimplifyExtractValueInst(Agg, EV.getIndices(), DL, TLI, DT, AC))
+ return ReplaceInstUsesWith(EV, V);
if (InsertValueInst *IV = dyn_cast<InsertValueInst>(Agg)) {
// We're extracting from an insertvalue instruction, compare the indices
}
if (LoadInst *L = dyn_cast<LoadInst>(Agg))
// If the (non-volatile) load only has one use, we can rewrite this to a
- // load from a GEP. This reduces the size of the load.
- // FIXME: If a load is used only by extractvalue instructions then this
- // could be done regardless of having multiple uses.
+ // load from a GEP. This reduces the size of the load. If a load is used
+ // only by extractvalue instructions then this either must have been
+ // optimized before, or it is a struct with padding, in which case we
+ // don't want to do the transformation as it loses padding knowledge.
if (L->isSimple() && L->hasOneUse()) {
// extractvalue has integer indices, getelementptr has Value*s. Convert.
SmallVector<Value*, 4> Indices;
// We need to insert these at the location of the old load, not at that of
// the extractvalue.
- Builder->SetInsertPoint(L->getParent(), L);
- Value *GEP = Builder->CreateInBoundsGEP(L->getPointerOperand(), Indices);
+ Builder->SetInsertPoint(L);
+ Value *GEP = Builder->CreateInBoundsGEP(L->getType(),
+ L->getPointerOperand(), Indices);
// Returning the load directly will cause the main loop to insert it in
// the wrong spot, so use ReplaceInstUsesWith().
return ReplaceInstUsesWith(EV, Builder->CreateLoad(GEP));
// and if again single-use then via load (gep (gep)) to load (gep).
// However, double extracts from e.g. function arguments or return values
// aren't handled yet.
- return 0;
-}
-
-enum Personality_Type {
- Unknown_Personality,
- GNU_Ada_Personality,
- GNU_CXX_Personality,
- GNU_ObjC_Personality
-};
-
-/// RecognizePersonality - See if the given exception handling personality
-/// function is one that we understand. If so, return a description of it;
-/// otherwise return Unknown_Personality.
-static Personality_Type RecognizePersonality(Value *Pers) {
- Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
- if (!F)
- return Unknown_Personality;
- return StringSwitch<Personality_Type>(F->getName())
- .Case("__gnat_eh_personality", GNU_Ada_Personality)
- .Case("__gxx_personality_v0", GNU_CXX_Personality)
- .Case("__objc_personality_v0", GNU_ObjC_Personality)
- .Default(Unknown_Personality);
+ return nullptr;
}
-/// isCatchAll - Return 'true' if the given typeinfo will match anything.
-static bool isCatchAll(Personality_Type Personality, Constant *TypeInfo) {
+/// Return 'true' if the given typeinfo will match anything.
+static bool isCatchAll(EHPersonality Personality, Constant *TypeInfo) {
switch (Personality) {
- case Unknown_Personality:
+ case EHPersonality::GNU_C:
+ // The GCC C EH personality only exists to support cleanups, so it's not
+ // clear what the semantics of catch clauses are.
+ return false;
+ case EHPersonality::Unknown:
return false;
- case GNU_Ada_Personality:
+ case EHPersonality::GNU_Ada:
// While __gnat_all_others_value will match any Ada exception, it doesn't
// match foreign exceptions (or didn't, before gcc-4.7).
return false;
- case GNU_CXX_Personality:
- case GNU_ObjC_Personality:
+ case EHPersonality::GNU_CXX:
+ case EHPersonality::GNU_ObjC:
+ case EHPersonality::MSVC_X86SEH:
+ case EHPersonality::MSVC_Win64SEH:
+ case EHPersonality::MSVC_CXX:
+ case EHPersonality::CoreCLR:
return TypeInfo->isNullValue();
}
- llvm_unreachable("Unknown personality!");
+ llvm_unreachable("invalid enum");
}
static bool shorter_filter(const Value *LHS, const Value *RHS) {
// The logic here should be correct for any real-world personality function.
// However if that turns out not to be true, the offending logic can always
// be conditioned on the personality function, like the catch-all logic is.
- Personality_Type Personality = RecognizePersonality(LI.getPersonalityFn());
+ EHPersonality Personality =
+ classifyEHPersonality(LI.getParent()->getParent()->getPersonalityFn());
// Simplify the list of clauses, eg by removing repeated catch clauses
// (these are often created by inlining).
bool MakeNewInstruction = false; // If true, recreate using the following:
- SmallVector<Value *, 16> NewClauses; // - Clauses for the new instruction;
+ SmallVector<Constant *, 16> NewClauses; // - Clauses for the new instruction;
bool CleanupFlag = LI.isCleanup(); // - The new instruction is a cleanup.
SmallPtrSet<Value *, 16> AlreadyCaught; // Typeinfos known caught already.
bool isLastClause = i + 1 == e;
if (LI.isCatch(i)) {
// A catch clause.
- Value *CatchClause = LI.getClause(i);
- Constant *TypeInfo = cast<Constant>(CatchClause->stripPointerCasts());
+ Constant *CatchClause = LI.getClause(i);
+ Constant *TypeInfo = CatchClause->stripPointerCasts();
// If we already saw this clause, there is no point in having a second
// copy of it.
- if (AlreadyCaught.insert(TypeInfo)) {
+ if (AlreadyCaught.insert(TypeInfo).second) {
// This catch clause was not already seen.
NewClauses.push_back(CatchClause);
} else {
// equal (for example if one represents a C++ class, and the other some
// class derived from it).
assert(LI.isFilter(i) && "Unsupported landingpad clause!");
- Value *FilterClause = LI.getClause(i);
+ Constant *FilterClause = LI.getClause(i);
ArrayType *FilterType = cast<ArrayType>(FilterClause->getType());
unsigned NumTypeInfos = FilterType->getNumElements();
// catch-alls. If so, the filter can be discarded.
bool SawCatchAll = false;
for (unsigned j = 0; j != NumTypeInfos; ++j) {
- Value *Elt = Filter->getOperand(j);
- Constant *TypeInfo = cast<Constant>(Elt->stripPointerCasts());
+ Constant *Elt = Filter->getOperand(j);
+ Constant *TypeInfo = Elt->stripPointerCasts();
if (isCatchAll(Personality, TypeInfo)) {
// This element is a catch-all. Bail out, noting this fact.
SawCatchAll = true;
break;
}
- if (AlreadyCaught.count(TypeInfo))
- // Already caught by an earlier clause, so having it in the filter
- // is pointless.
- continue;
+
+ // Even if we've seen a type in a catch clause, we don't want to
+ // remove it from the filter. An unexpected type handler may be
+ // set up for a call site which throws an exception of the same
+ // type caught. In order for the exception thrown by the unexpected
+ // handler to propogate correctly, the filter must be correctly
+ // described for the call site.
+ //
+ // Example:
+ //
+ // void unexpected() { throw 1;}
+ // void foo() throw (int) {
+ // std::set_unexpected(unexpected);
+ // try {
+ // throw 2.0;
+ // } catch (int i) {}
+ // }
+
// There is no point in having multiple copies of the same typeinfo in
// a filter, so only add it if we didn't already.
- if (SeenInFilter.insert(TypeInfo))
+ if (SeenInFilter.insert(TypeInfo).second)
NewFilterElts.push_back(cast<Constant>(Elt));
}
// A filter containing a catch-all cannot match anything by definition.
continue;
// If Filter is a subset of LFilter, i.e. every element of Filter is also
// an element of LFilter, then discard LFilter.
- SmallVectorImpl<Value *>::iterator J = NewClauses.begin() + j;
+ SmallVectorImpl<Constant *>::iterator J = NewClauses.begin() + j;
// If Filter is empty then it is a subset of LFilter.
if (!FElts) {
// Discard LFilter.
// with a new one.
if (MakeNewInstruction) {
LandingPadInst *NLI = LandingPadInst::Create(LI.getType(),
- LI.getPersonalityFn(),
NewClauses.size());
for (unsigned i = 0, e = NewClauses.size(); i != e; ++i)
NLI->addClause(NewClauses[i]);
return &LI;
}
- return 0;
+ return nullptr;
}
-
-
-
-/// TryToSinkInstruction - Try to move the specified instruction from its
-/// current block into the beginning of DestBlock, which can only happen if it's
-/// safe to move the instruction past all of the instructions between it and the
-/// end of its block.
+/// Try to move the specified instruction from its current block into the
+/// beginning of DestBlock, which can only happen if it's safe to move the
+/// instruction past all of the instructions between it and the end of its
+/// block.
static bool TryToSinkInstruction(Instruction *I, BasicBlock *DestBlock) {
assert(I->hasOneUse() && "Invariants didn't hold!");
// Cannot move control-flow-involving, volatile loads, vaarg, etc.
- if (isa<PHINode>(I) || isa<LandingPadInst>(I) || I->mayHaveSideEffects() ||
+ if (isa<PHINode>(I) || I->isEHPad() || I->mayHaveSideEffects() ||
isa<TerminatorInst>(I))
return false;
&DestBlock->getParent()->getEntryBlock())
return false;
+ // Do not sink convergent call instructions.
+ if (auto *CI = dyn_cast<CallInst>(I)) {
+ if (CI->isConvergent())
+ return false;
+ }
+
// We can only sink load instructions if there is nothing between the load and
// the end of block that could change the value.
if (I->mayReadFromMemory()) {
- for (BasicBlock::iterator Scan = I, E = I->getParent()->end();
+ for (BasicBlock::iterator Scan = I->getIterator(),
+ E = I->getParent()->end();
Scan != E; ++Scan)
if (Scan->mayWriteToMemory())
return false;
}
BasicBlock::iterator InsertPos = DestBlock->getFirstInsertionPt();
- I->moveBefore(InsertPos);
+ I->moveBefore(&*InsertPos);
++NumSunkInst;
return true;
}
-
-/// AddReachableCodeToWorklist - Walk the function in depth-first order, adding
-/// all reachable code to the worklist.
-///
-/// This has a couple of tricks to make the code faster and more powerful. In
-/// particular, we constant fold and DCE instructions as we go, to avoid adding
-/// them to the worklist (this significantly speeds up instcombine on code where
-/// many instructions are dead or constant). Additionally, if we find a branch
-/// whose condition is a known constant, we only visit the reachable successors.
-///
-static bool AddReachableCodeToWorklist(BasicBlock *BB,
- SmallPtrSet<BasicBlock*, 64> &Visited,
- InstCombiner &IC,
- const DataLayout *TD,
- const TargetLibraryInfo *TLI) {
- bool MadeIRChange = false;
- SmallVector<BasicBlock*, 256> Worklist;
- Worklist.push_back(BB);
-
- SmallVector<Instruction*, 128> InstrsForInstCombineWorklist;
- DenseMap<ConstantExpr*, Constant*> FoldedConstants;
-
- do {
- BB = Worklist.pop_back_val();
-
- // We have now visited this block! If we've already been here, ignore it.
- if (!Visited.insert(BB)) continue;
-
- for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
- Instruction *Inst = BBI++;
-
- // DCE instruction if trivially dead.
- if (isInstructionTriviallyDead(Inst, TLI)) {
- ++NumDeadInst;
- DEBUG(errs() << "IC: DCE: " << *Inst << '\n');
- Inst->eraseFromParent();
- continue;
- }
-
- // ConstantProp instruction if trivially constant.
- if (!Inst->use_empty() && isa<Constant>(Inst->getOperand(0)))
- if (Constant *C = ConstantFoldInstruction(Inst, TD, TLI)) {
- DEBUG(errs() << "IC: ConstFold to: " << *C << " from: "
- << *Inst << '\n');
- Inst->replaceAllUsesWith(C);
- ++NumConstProp;
- Inst->eraseFromParent();
- continue;
- }
-
- if (TD) {
- // See if we can constant fold its operands.
- for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end();
- i != e; ++i) {
- ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
- if (CE == 0) continue;
-
- Constant*& FoldRes = FoldedConstants[CE];
- if (!FoldRes)
- FoldRes = ConstantFoldConstantExpression(CE, TD, TLI);
- if (!FoldRes)
- FoldRes = CE;
-
- if (FoldRes != CE) {
- *i = FoldRes;
- MadeIRChange = true;
- }
- }
- }
-
- InstrsForInstCombineWorklist.push_back(Inst);
- }
-
- // Recursively visit successors. If this is a branch or switch on a
- // constant, only visit the reachable successor.
- TerminatorInst *TI = BB->getTerminator();
- if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
- if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
- bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
- BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
- Worklist.push_back(ReachableBB);
- continue;
- }
- } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
- if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
- // See if this is an explicit destination.
- for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
- i != e; ++i)
- if (i.getCaseValue() == Cond) {
- BasicBlock *ReachableBB = i.getCaseSuccessor();
- Worklist.push_back(ReachableBB);
- continue;
- }
-
- // Otherwise it is the default destination.
- Worklist.push_back(SI->getDefaultDest());
- continue;
- }
- }
-
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
- Worklist.push_back(TI->getSuccessor(i));
- } while (!Worklist.empty());
-
- // Once we've found all of the instructions to add to instcombine's worklist,
- // add them in reverse order. This way instcombine will visit from the top
- // of the function down. This jives well with the way that it adds all uses
- // of instructions to the worklist after doing a transformation, thus avoiding
- // some N^2 behavior in pathological cases.
- IC.Worklist.AddInitialGroup(&InstrsForInstCombineWorklist[0],
- InstrsForInstCombineWorklist.size());
-
- return MadeIRChange;
-}
-
-bool InstCombiner::DoOneIteration(Function &F, unsigned Iteration) {
- MadeIRChange = false;
-
- DEBUG(errs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
- << F.getName() << "\n");
-
- {
- // Do a depth-first traversal of the function, populate the worklist with
- // the reachable instructions. Ignore blocks that are not reachable. Keep
- // track of which blocks we visit.
- SmallPtrSet<BasicBlock*, 64> Visited;
- MadeIRChange |= AddReachableCodeToWorklist(F.begin(), Visited, *this, TD,
- TLI);
-
- // Do a quick scan over the function. If we find any blocks that are
- // unreachable, remove any instructions inside of them. This prevents
- // the instcombine code from having to deal with some bad special cases.
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
- if (Visited.count(BB)) continue;
-
- // Delete the instructions backwards, as it has a reduced likelihood of
- // having to update as many def-use and use-def chains.
- Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
- while (EndInst != BB->begin()) {
- // Delete the next to last instruction.
- BasicBlock::iterator I = EndInst;
- Instruction *Inst = --I;
- if (!Inst->use_empty())
- Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
- if (isa<LandingPadInst>(Inst)) {
- EndInst = Inst;
- continue;
- }
- if (!isa<DbgInfoIntrinsic>(Inst)) {
- ++NumDeadInst;
- MadeIRChange = true;
- }
- Inst->eraseFromParent();
- }
- }
- }
-
+bool InstCombiner::run() {
while (!Worklist.isEmpty()) {
Instruction *I = Worklist.RemoveOne();
- if (I == 0) continue; // skip null values.
+ if (I == nullptr) continue; // skip null values.
// Check to see if we can DCE the instruction.
if (isInstructionTriviallyDead(I, TLI)) {
- DEBUG(errs() << "IC: DCE: " << *I << '\n');
+ DEBUG(dbgs() << "IC: DCE: " << *I << '\n');
EraseInstFromFunction(*I);
++NumDeadInst;
MadeIRChange = true;
}
// Instruction isn't dead, see if we can constant propagate it.
- if (!I->use_empty() && isa<Constant>(I->getOperand(0)))
- if (Constant *C = ConstantFoldInstruction(I, TD, TLI)) {
- DEBUG(errs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
+ if (!I->use_empty() &&
+ (I->getNumOperands() == 0 || isa<Constant>(I->getOperand(0)))) {
+ if (Constant *C = ConstantFoldInstruction(I, DL, TLI)) {
+ DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: " << *I << '\n');
+
+ // Add operands to the worklist.
+ ReplaceInstUsesWith(*I, C);
+ ++NumConstProp;
+ EraseInstFromFunction(*I);
+ MadeIRChange = true;
+ continue;
+ }
+ }
+
+ // In general, it is possible for computeKnownBits to determine all bits in a
+ // value even when the operands are not all constants.
+ if (!I->use_empty() && I->getType()->isIntegerTy()) {
+ unsigned BitWidth = I->getType()->getScalarSizeInBits();
+ APInt KnownZero(BitWidth, 0);
+ APInt KnownOne(BitWidth, 0);
+ computeKnownBits(I, KnownZero, KnownOne, /*Depth*/0, I);
+ if ((KnownZero | KnownOne).isAllOnesValue()) {
+ Constant *C = ConstantInt::get(I->getContext(), KnownOne);
+ DEBUG(dbgs() << "IC: ConstFold (all bits known) to: " << *C <<
+ " from: " << *I << '\n');
// Add operands to the worklist.
ReplaceInstUsesWith(*I, C);
MadeIRChange = true;
continue;
}
+ }
// See if we can trivially sink this instruction to a successor basic block.
if (I->hasOneUse()) {
BasicBlock *BB = I->getParent();
- Instruction *UserInst = cast<Instruction>(I->use_back());
+ Instruction *UserInst = cast<Instruction>(*I->user_begin());
BasicBlock *UserParent;
// Get the block the use occurs in.
if (PHINode *PN = dyn_cast<PHINode>(UserInst))
- UserParent = PN->getIncomingBlock(I->use_begin().getUse());
+ UserParent = PN->getIncomingBlock(*I->use_begin());
else
UserParent = UserInst->getParent();
// If the user is one of our immediate successors, and if that successor
// only has us as a predecessors (we'd have to split the critical edge
// otherwise), we can keep going.
- if (UserIsSuccessor && UserParent->getSinglePredecessor())
+ if (UserIsSuccessor && UserParent->getSinglePredecessor()) {
// Okay, the CFG is simple enough, try to sink this instruction.
- MadeIRChange |= TryToSinkInstruction(I, UserParent);
+ if (TryToSinkInstruction(I, UserParent)) {
+ MadeIRChange = true;
+ // We'll add uses of the sunk instruction below, but since sinking
+ // can expose opportunities for it's *operands* add them to the
+ // worklist
+ for (Use &U : I->operands())
+ if (Instruction *OpI = dyn_cast<Instruction>(U.get()))
+ Worklist.Add(OpI);
+ }
+ }
}
}
// Now that we have an instruction, try combining it to simplify it.
- Builder->SetInsertPoint(I->getParent(), I);
+ Builder->SetInsertPoint(I);
Builder->SetCurrentDebugLocation(I->getDebugLoc());
#ifndef NDEBUG
std::string OrigI;
#endif
DEBUG(raw_string_ostream SS(OrigI); I->print(SS); OrigI = SS.str(););
- DEBUG(errs() << "IC: Visiting: " << OrigI << '\n');
+ DEBUG(dbgs() << "IC: Visiting: " << OrigI << '\n');
if (Instruction *Result = visit(*I)) {
++NumCombined;
// Should we replace the old instruction with a new one?
if (Result != I) {
- DEBUG(errs() << "IC: Old = " << *I << '\n'
+ DEBUG(dbgs() << "IC: Old = " << *I << '\n'
<< " New = " << *Result << '\n');
- if (!I->getDebugLoc().isUnknown())
+ if (I->getDebugLoc())
Result->setDebugLoc(I->getDebugLoc());
// Everything uses the new instruction now.
I->replaceAllUsesWith(Result);
// Insert the new instruction into the basic block...
BasicBlock *InstParent = I->getParent();
- BasicBlock::iterator InsertPos = I;
+ BasicBlock::iterator InsertPos = I->getIterator();
// If we replace a PHI with something that isn't a PHI, fix up the
// insertion point.
EraseInstFromFunction(*I);
} else {
#ifndef NDEBUG
- DEBUG(errs() << "IC: Mod = " << OrigI << '\n'
+ DEBUG(dbgs() << "IC: Mod = " << OrigI << '\n'
<< " New = " << *I << '\n');
#endif
return MadeIRChange;
}
-namespace {
-class InstCombinerLibCallSimplifier : public LibCallSimplifier {
- InstCombiner *IC;
-public:
- InstCombinerLibCallSimplifier(const DataLayout *TD,
- const TargetLibraryInfo *TLI,
- InstCombiner *IC)
- : LibCallSimplifier(TD, TLI, UnsafeFPShrink) {
- this->IC = IC;
- }
+/// Walk the function in depth-first order, adding all reachable code to the
+/// worklist.
+///
+/// This has a couple of tricks to make the code faster and more powerful. In
+/// particular, we constant fold and DCE instructions as we go, to avoid adding
+/// them to the worklist (this significantly speeds up instcombine on code where
+/// many instructions are dead or constant). Additionally, if we find a branch
+/// whose condition is a known constant, we only visit the reachable successors.
+///
+static bool AddReachableCodeToWorklist(BasicBlock *BB, const DataLayout &DL,
+ SmallPtrSetImpl<BasicBlock *> &Visited,
+ InstCombineWorklist &ICWorklist,
+ const TargetLibraryInfo *TLI) {
+ bool MadeIRChange = false;
+ SmallVector<BasicBlock*, 256> Worklist;
+ Worklist.push_back(BB);
+
+ SmallVector<Instruction*, 128> InstrsForInstCombineWorklist;
+ DenseMap<ConstantExpr*, Constant*> FoldedConstants;
+
+ do {
+ BB = Worklist.pop_back_val();
+
+ // We have now visited this block! If we've already been here, ignore it.
+ if (!Visited.insert(BB).second)
+ continue;
+
+ for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E; ) {
+ Instruction *Inst = &*BBI++;
+
+ // DCE instruction if trivially dead.
+ if (isInstructionTriviallyDead(Inst, TLI)) {
+ ++NumDeadInst;
+ DEBUG(dbgs() << "IC: DCE: " << *Inst << '\n');
+ Inst->eraseFromParent();
+ continue;
+ }
+
+ // ConstantProp instruction if trivially constant.
+ if (!Inst->use_empty() &&
+ (Inst->getNumOperands() == 0 || isa<Constant>(Inst->getOperand(0))))
+ if (Constant *C = ConstantFoldInstruction(Inst, DL, TLI)) {
+ DEBUG(dbgs() << "IC: ConstFold to: " << *C << " from: "
+ << *Inst << '\n');
+ Inst->replaceAllUsesWith(C);
+ ++NumConstProp;
+ Inst->eraseFromParent();
+ continue;
+ }
+
+ // See if we can constant fold its operands.
+ for (User::op_iterator i = Inst->op_begin(), e = Inst->op_end(); i != e;
+ ++i) {
+ ConstantExpr *CE = dyn_cast<ConstantExpr>(i);
+ if (CE == nullptr)
+ continue;
+
+ Constant *&FoldRes = FoldedConstants[CE];
+ if (!FoldRes)
+ FoldRes = ConstantFoldConstantExpression(CE, DL, TLI);
+ if (!FoldRes)
+ FoldRes = CE;
+
+ if (FoldRes != CE) {
+ *i = FoldRes;
+ MadeIRChange = true;
+ }
+ }
+
+ InstrsForInstCombineWorklist.push_back(Inst);
+ }
+
+ // Recursively visit successors. If this is a branch or switch on a
+ // constant, only visit the reachable successor.
+ TerminatorInst *TI = BB->getTerminator();
+ if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
+ if (BI->isConditional() && isa<ConstantInt>(BI->getCondition())) {
+ bool CondVal = cast<ConstantInt>(BI->getCondition())->getZExtValue();
+ BasicBlock *ReachableBB = BI->getSuccessor(!CondVal);
+ Worklist.push_back(ReachableBB);
+ continue;
+ }
+ } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
+ if (ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition())) {
+ // See if this is an explicit destination.
+ for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end();
+ i != e; ++i)
+ if (i.getCaseValue() == Cond) {
+ BasicBlock *ReachableBB = i.getCaseSuccessor();
+ Worklist.push_back(ReachableBB);
+ continue;
+ }
+
+ // Otherwise it is the default destination.
+ Worklist.push_back(SI->getDefaultDest());
+ continue;
+ }
+ }
+
+ for (BasicBlock *SuccBB : TI->successors())
+ Worklist.push_back(SuccBB);
+ } while (!Worklist.empty());
+
+ // Once we've found all of the instructions to add to instcombine's worklist,
+ // add them in reverse order. This way instcombine will visit from the top
+ // of the function down. This jives well with the way that it adds all uses
+ // of instructions to the worklist after doing a transformation, thus avoiding
+ // some N^2 behavior in pathological cases.
+ ICWorklist.AddInitialGroup(InstrsForInstCombineWorklist);
- /// replaceAllUsesWith - override so that instruction replacement
- /// can be defined in terms of the instruction combiner framework.
- virtual void replaceAllUsesWith(Instruction *I, Value *With) const {
- IC->ReplaceInstUsesWith(*I, With);
+ return MadeIRChange;
+}
+
+/// \brief Populate the IC worklist from a function, and prune any dead basic
+/// blocks discovered in the process.
+///
+/// This also does basic constant propagation and other forward fixing to make
+/// the combiner itself run much faster.
+static bool prepareICWorklistFromFunction(Function &F, const DataLayout &DL,
+ TargetLibraryInfo *TLI,
+ InstCombineWorklist &ICWorklist) {
+ bool MadeIRChange = false;
+
+ // Do a depth-first traversal of the function, populate the worklist with
+ // the reachable instructions. Ignore blocks that are not reachable. Keep
+ // track of which blocks we visit.
+ SmallPtrSet<BasicBlock *, 64> Visited;
+ MadeIRChange |=
+ AddReachableCodeToWorklist(&F.front(), DL, Visited, ICWorklist, TLI);
+
+ // Do a quick scan over the function. If we find any blocks that are
+ // unreachable, remove any instructions inside of them. This prevents
+ // the instcombine code from having to deal with some bad special cases.
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ if (Visited.count(&*BB))
+ continue;
+
+ // Delete the instructions backwards, as it has a reduced likelihood of
+ // having to update as many def-use and use-def chains.
+ Instruction *EndInst = BB->getTerminator(); // Last not to be deleted.
+ while (EndInst != BB->begin()) {
+ // Delete the next to last instruction.
+ Instruction *Inst = &*--EndInst->getIterator();
+ if (!Inst->use_empty() && !Inst->getType()->isTokenTy())
+ Inst->replaceAllUsesWith(UndefValue::get(Inst->getType()));
+ if (Inst->isEHPad()) {
+ EndInst = Inst;
+ continue;
+ }
+ if (!isa<DbgInfoIntrinsic>(Inst)) {
+ ++NumDeadInst;
+ MadeIRChange = true;
+ }
+ if (!Inst->getType()->isTokenTy())
+ Inst->eraseFromParent();
+ }
}
-};
+
+ return MadeIRChange;
}
-bool InstCombiner::runOnFunction(Function &F) {
- TD = getAnalysisIfAvailable<DataLayout>();
- TLI = &getAnalysis<TargetLibraryInfo>();
- // Minimizing size?
- MinimizeSize = F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
- Attribute::MinSize);
+static bool
+combineInstructionsOverFunction(Function &F, InstCombineWorklist &Worklist,
+ AliasAnalysis *AA, AssumptionCache &AC,
+ TargetLibraryInfo &TLI, DominatorTree &DT,
+ LoopInfo *LI = nullptr) {
+ auto &DL = F.getParent()->getDataLayout();
/// Builder - This is an IRBuilder that automatically inserts new
/// instructions into the worklist when they are created.
- IRBuilder<true, TargetFolder, InstCombineIRInserter>
- TheBuilder(F.getContext(), TargetFolder(TD),
- InstCombineIRInserter(Worklist));
- Builder = &TheBuilder;
-
- InstCombinerLibCallSimplifier TheSimplifier(TD, TLI, this);
- Simplifier = &TheSimplifier;
-
- bool EverMadeChange = false;
+ IRBuilder<true, TargetFolder, InstCombineIRInserter> Builder(
+ F.getContext(), TargetFolder(DL), InstCombineIRInserter(Worklist, &AC));
// Lower dbg.declare intrinsics otherwise their value may be clobbered
// by instcombiner.
- EverMadeChange = LowerDbgDeclare(F);
+ bool DbgDeclaresChanged = LowerDbgDeclare(F);
// Iterate while there is work to do.
- unsigned Iteration = 0;
- while (DoOneIteration(F, Iteration++))
- EverMadeChange = true;
+ int Iteration = 0;
+ for (;;) {
+ ++Iteration;
+ DEBUG(dbgs() << "\n\nINSTCOMBINE ITERATION #" << Iteration << " on "
+ << F.getName() << "\n");
+
+ bool Changed = false;
+ if (prepareICWorklistFromFunction(F, DL, &TLI, Worklist))
+ Changed = true;
+
+ InstCombiner IC(Worklist, &Builder, F.optForMinSize(),
+ AA, &AC, &TLI, &DT, DL, LI);
+ if (IC.run())
+ Changed = true;
+
+ if (!Changed)
+ break;
+ }
+
+ return DbgDeclaresChanged || Iteration > 1;
+}
+
+PreservedAnalyses InstCombinePass::run(Function &F,
+ AnalysisManager<Function> *AM) {
+ auto &AC = AM->getResult<AssumptionAnalysis>(F);
+ auto &DT = AM->getResult<DominatorTreeAnalysis>(F);
+ auto &TLI = AM->getResult<TargetLibraryAnalysis>(F);
+
+ auto *LI = AM->getCachedResult<LoopAnalysis>(F);
+
+ // FIXME: The AliasAnalysis is not yet supported in the new pass manager
+ if (!combineInstructionsOverFunction(F, Worklist, nullptr, AC, TLI, DT, LI))
+ // No changes, all analyses are preserved.
+ return PreservedAnalyses::all();
- Builder = 0;
- return EverMadeChange;
+ // Mark all the analyses that instcombine updates as preserved.
+ // FIXME: Need a way to preserve CFG analyses here!
+ PreservedAnalyses PA;
+ PA.preserve<DominatorTreeAnalysis>();
+ return PA;
+}
+
+namespace {
+/// \brief The legacy pass manager's instcombine pass.
+///
+/// This is a basic whole-function wrapper around the instcombine utility. It
+/// will try to combine all instructions in the function.
+class InstructionCombiningPass : public FunctionPass {
+ InstCombineWorklist Worklist;
+
+public:
+ static char ID; // Pass identification, replacement for typeid
+
+ InstructionCombiningPass() : FunctionPass(ID) {
+ initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
+ }
+
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+ bool runOnFunction(Function &F) override;
+};
+}
+
+void InstructionCombiningPass::getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ AU.addRequired<AAResultsWrapperPass>();
+ AU.addRequired<AssumptionCacheTracker>();
+ AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addRequired<DominatorTreeWrapperPass>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
+ AU.addPreserved<GlobalsAAWrapperPass>();
+}
+
+bool InstructionCombiningPass::runOnFunction(Function &F) {
+ if (skipOptnoneFunction(F))
+ return false;
+
+ // Required analyses.
+ auto AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
+ auto &AC = getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
+ auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
+
+ // Optional analyses.
+ auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
+ auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
+
+ return combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, DT, LI);
+}
+
+char InstructionCombiningPass::ID = 0;
+INITIALIZE_PASS_BEGIN(InstructionCombiningPass, "instcombine",
+ "Combine redundant instructions", false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(GlobalsAAWrapperPass)
+INITIALIZE_PASS_END(InstructionCombiningPass, "instcombine",
+ "Combine redundant instructions", false, false)
+
+// Initialization Routines
+void llvm::initializeInstCombine(PassRegistry &Registry) {
+ initializeInstructionCombiningPassPass(Registry);
+}
+
+void LLVMInitializeInstCombine(LLVMPassRegistryRef R) {
+ initializeInstructionCombiningPassPass(*unwrap(R));
}
FunctionPass *llvm::createInstructionCombiningPass() {
- return new InstCombiner();
+ return new InstructionCombiningPass();
}
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