//===----------------------------------------------------------------------===//
//
// This file implements routines for folding instructions into simpler forms
-// that do not require creating new instructions. For example, this does
-// constant folding, and can handle identities like (X&0)->0.
+// that do not require creating new instructions. This does constant folding
+// ("add i32 1, 1" -> "2") but can also handle non-constant operands, either
+// returning a constant ("and i32 %x, 0" -> "0") or an already existing value
+// ("and i32 %x, %x" -> "%x"). All operands are assumed to have already been
+// simplified: This is usually true and assuming it simplifies the logic (if
+// they have not been simplified then results are correct but maybe suboptimal).
//
//===----------------------------------------------------------------------===//
+#define DEBUG_TYPE "instsimplify"
+#include "llvm/Operator.h"
+#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/Dominators.h"
+#include "llvm/Analysis/ValueTracking.h"
+#include "llvm/Support/ConstantRange.h"
#include "llvm/Support/PatternMatch.h"
#include "llvm/Support/ValueHandle.h"
+#include "llvm/Target/TargetData.h"
using namespace llvm;
using namespace llvm::PatternMatch;
-#define RecursionLimit 3
+enum { RecursionLimit = 3 };
+STATISTIC(NumExpand, "Number of expansions");
+STATISTIC(NumFactor , "Number of factorizations");
+STATISTIC(NumReassoc, "Number of reassociations");
+
+static Value *SimplifyAndInst(Value *, Value *, const TargetData *,
+ const DominatorTree *, unsigned);
static Value *SimplifyBinOp(unsigned, Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
static Value *SimplifyCmpInst(unsigned, Value *, Value *, const TargetData *,
const DominatorTree *, unsigned);
+static Value *SimplifyOrInst(Value *, Value *, const TargetData *,
+ const DominatorTree *, unsigned);
+static Value *SimplifyXorInst(Value *, Value *, const TargetData *,
+ const DominatorTree *, unsigned);
/// ValueDominatesPHI - Does the given value dominate the specified phi node?
static bool ValueDominatesPHI(Value *V, PHINode *P, const DominatorTree *DT) {
return false;
}
+/// ExpandBinOp - Simplify "A op (B op' C)" by distributing op over op', turning
+/// it into "(A op B) op' (A op C)". Here "op" is given by Opcode and "op'" is
+/// given by OpcodeToExpand, while "A" corresponds to LHS and "B op' C" to RHS.
+/// Also performs the transform "(A op' B) op C" -> "(A op C) op' (B op C)".
+/// Returns the simplified value, or null if no simplification was performed.
+static Value *ExpandBinOp(unsigned Opcode, Value *LHS, Value *RHS,
+ unsigned OpcToExpand, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ Instruction::BinaryOps OpcodeToExpand = (Instruction::BinaryOps)OpcToExpand;
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
+ // Check whether the expression has the form "(A op' B) op C".
+ if (BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS))
+ if (Op0->getOpcode() == OpcodeToExpand) {
+ // It does! Try turning it into "(A op C) op' (B op C)".
+ Value *A = Op0->getOperand(0), *B = Op0->getOperand(1), *C = RHS;
+ // Do "A op C" and "B op C" both simplify?
+ if (Value *L = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse))
+ if (Value *R = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
+ // They do! Return "L op' R" if it simplifies or is already available.
+ // If "L op' R" equals "A op' B" then "L op' R" is just the LHS.
+ if ((L == A && R == B) || (Instruction::isCommutative(OpcodeToExpand)
+ && L == B && R == A)) {
+ ++NumExpand;
+ return LHS;
+ }
+ // Otherwise return "L op' R" if it simplifies.
+ if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
+ MaxRecurse)) {
+ ++NumExpand;
+ return V;
+ }
+ }
+ }
+
+ // Check whether the expression has the form "A op (B op' C)".
+ if (BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS))
+ if (Op1->getOpcode() == OpcodeToExpand) {
+ // It does! Try turning it into "(A op B) op' (A op C)".
+ Value *A = LHS, *B = Op1->getOperand(0), *C = Op1->getOperand(1);
+ // Do "A op B" and "A op C" both simplify?
+ if (Value *L = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse))
+ if (Value *R = SimplifyBinOp(Opcode, A, C, TD, DT, MaxRecurse)) {
+ // They do! Return "L op' R" if it simplifies or is already available.
+ // If "L op' R" equals "B op' C" then "L op' R" is just the RHS.
+ if ((L == B && R == C) || (Instruction::isCommutative(OpcodeToExpand)
+ && L == C && R == B)) {
+ ++NumExpand;
+ return RHS;
+ }
+ // Otherwise return "L op' R" if it simplifies.
+ if (Value *V = SimplifyBinOp(OpcodeToExpand, L, R, TD, DT,
+ MaxRecurse)) {
+ ++NumExpand;
+ return V;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/// FactorizeBinOp - Simplify "LHS Opcode RHS" by factorizing out a common term
+/// using the operation OpCodeToExtract. For example, when Opcode is Add and
+/// OpCodeToExtract is Mul then this tries to turn "(A*B)+(A*C)" into "A*(B+C)".
+/// Returns the simplified value, or null if no simplification was performed.
+static Value *FactorizeBinOp(unsigned Opcode, Value *LHS, Value *RHS,
+ unsigned OpcToExtract, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ Instruction::BinaryOps OpcodeToExtract = (Instruction::BinaryOps)OpcToExtract;
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
+ BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
+ BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
+
+ if (!Op0 || Op0->getOpcode() != OpcodeToExtract ||
+ !Op1 || Op1->getOpcode() != OpcodeToExtract)
+ return 0;
+
+ // The expression has the form "(A op' B) op (C op' D)".
+ Value *A = Op0->getOperand(0), *B = Op0->getOperand(1);
+ Value *C = Op1->getOperand(0), *D = Op1->getOperand(1);
+
+ // Use left distributivity, i.e. "X op' (Y op Z) = (X op' Y) op (X op' Z)".
+ // 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 || (Instruction::isCommutative(OpcodeToExtract) && A == D)) {
+ Value *DD = A == C ? D : C;
+ // Form "A op' (B op DD)" if it simplifies completely.
+ // Does "B op DD" simplify?
+ if (Value *V = SimplifyBinOp(Opcode, B, DD, TD, DT, MaxRecurse)) {
+ // It does! Return "A op' V" if it simplifies or is already available.
+ // If V equals B then "A op' V" is just the LHS. If V equals DD then
+ // "A op' V" is just the RHS.
+ if (V == B || V == DD) {
+ ++NumFactor;
+ return V == B ? LHS : RHS;
+ }
+ // Otherwise return "A op' V" if it simplifies.
+ if (Value *W = SimplifyBinOp(OpcodeToExtract, A, V, TD, DT, MaxRecurse)) {
+ ++NumFactor;
+ return W;
+ }
+ }
+ }
+
+ // Use right distributivity, i.e. "(X op Y) op' Z = (X op' Z) op (Y op' Z)".
+ // 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 || (Instruction::isCommutative(OpcodeToExtract) && B == C)) {
+ Value *CC = B == D ? C : D;
+ // Form "(A op CC) op' B" if it simplifies completely..
+ // Does "A op CC" simplify?
+ if (Value *V = SimplifyBinOp(Opcode, A, CC, TD, DT, MaxRecurse)) {
+ // It does! Return "V op' B" if it simplifies or is already available.
+ // If V equals A then "V op' B" is just the LHS. If V equals CC then
+ // "V op' B" is just the RHS.
+ if (V == A || V == CC) {
+ ++NumFactor;
+ return V == A ? LHS : RHS;
+ }
+ // Otherwise return "V op' B" if it simplifies.
+ if (Value *W = SimplifyBinOp(OpcodeToExtract, V, B, TD, DT, MaxRecurse)) {
+ ++NumFactor;
+ return W;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/// SimplifyAssociativeBinOp - Generic simplifications for associative binary
+/// operations. Returns the simpler value, or null if none was found.
+static Value *SimplifyAssociativeBinOp(unsigned Opc, Value *LHS, Value *RHS,
+ const TargetData *TD,
+ const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ Instruction::BinaryOps Opcode = (Instruction::BinaryOps)Opc;
+ assert(Instruction::isAssociative(Opcode) && "Not an associative operation!");
+
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
+ BinaryOperator *Op0 = dyn_cast<BinaryOperator>(LHS);
+ BinaryOperator *Op1 = dyn_cast<BinaryOperator>(RHS);
+
+ // Transform: "(A op B) op C" ==> "A op (B op C)" if it simplifies completely.
+ if (Op0 && Op0->getOpcode() == Opcode) {
+ Value *A = Op0->getOperand(0);
+ Value *B = Op0->getOperand(1);
+ Value *C = RHS;
+
+ // Does "B op C" simplify?
+ if (Value *V = SimplifyBinOp(Opcode, B, C, TD, DT, MaxRecurse)) {
+ // It does! Return "A op V" if it simplifies or is already available.
+ // If V equals B then "A op V" is just the LHS.
+ if (V == B) return LHS;
+ // Otherwise return "A op V" if it simplifies.
+ if (Value *W = SimplifyBinOp(Opcode, A, V, TD, DT, MaxRecurse)) {
+ ++NumReassoc;
+ return W;
+ }
+ }
+ }
+
+ // Transform: "A op (B op C)" ==> "(A op B) op C" if it simplifies completely.
+ if (Op1 && Op1->getOpcode() == Opcode) {
+ Value *A = LHS;
+ Value *B = Op1->getOperand(0);
+ Value *C = Op1->getOperand(1);
+
+ // Does "A op B" simplify?
+ if (Value *V = SimplifyBinOp(Opcode, A, B, TD, DT, MaxRecurse)) {
+ // It does! Return "V op C" if it simplifies or is already available.
+ // If V equals B then "V op C" is just the RHS.
+ if (V == B) return RHS;
+ // Otherwise return "V op C" if it simplifies.
+ if (Value *W = SimplifyBinOp(Opcode, V, C, TD, DT, MaxRecurse)) {
+ ++NumReassoc;
+ return W;
+ }
+ }
+ }
+
+ // The remaining transforms require commutativity as well as associativity.
+ if (!Instruction::isCommutative(Opcode))
+ return 0;
+
+ // Transform: "(A op B) op C" ==> "(C op A) op B" if it simplifies completely.
+ if (Op0 && Op0->getOpcode() == Opcode) {
+ Value *A = Op0->getOperand(0);
+ Value *B = Op0->getOperand(1);
+ Value *C = RHS;
+
+ // Does "C op A" simplify?
+ if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
+ // It does! Return "V op B" if it simplifies or is already available.
+ // If V equals A then "V op B" is just the LHS.
+ if (V == A) return LHS;
+ // Otherwise return "V op B" if it simplifies.
+ if (Value *W = SimplifyBinOp(Opcode, V, B, TD, DT, MaxRecurse)) {
+ ++NumReassoc;
+ return W;
+ }
+ }
+ }
+
+ // Transform: "A op (B op C)" ==> "B op (C op A)" if it simplifies completely.
+ if (Op1 && Op1->getOpcode() == Opcode) {
+ Value *A = LHS;
+ Value *B = Op1->getOperand(0);
+ Value *C = Op1->getOperand(1);
+
+ // Does "C op A" simplify?
+ if (Value *V = SimplifyBinOp(Opcode, C, A, TD, DT, MaxRecurse)) {
+ // It does! Return "B op V" if it simplifies or is already available.
+ // If V equals C then "B op V" is just the RHS.
+ if (V == C) return RHS;
+ // Otherwise return "B op V" if it simplifies.
+ if (Value *W = SimplifyBinOp(Opcode, B, V, TD, DT, MaxRecurse)) {
+ ++NumReassoc;
+ return W;
+ }
+ }
+ }
+
+ return 0;
+}
+
/// ThreadBinOpOverSelect - In the case of a binary operation with a select
/// instruction as an operand, try to simplify the binop by seeing whether
/// evaluating it on both branches of the select results in the same value.
const TargetData *TD,
const DominatorTree *DT,
unsigned MaxRecurse) {
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
SelectInst *SI;
if (isa<SelectInst>(LHS)) {
SI = cast<SelectInst>(LHS);
Value *RHS, const TargetData *TD,
const DominatorTree *DT,
unsigned MaxRecurse) {
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
// Make sure the select is on the LHS.
if (!isa<SelectInst>(LHS)) {
std::swap(LHS, RHS);
assert(isa<SelectInst>(LHS) && "Not comparing with a select instruction!");
SelectInst *SI = cast<SelectInst>(LHS);
- // Now that we have "cmp select(cond, TV, FV), RHS", analyse it.
+ // Now that we have "cmp select(Cond, TV, FV), RHS", analyse it.
// Does "cmp TV, RHS" simplify?
if (Value *TCmp = SimplifyCmpInst(Pred, SI->getTrueValue(), RHS, TD, DT,
- MaxRecurse))
+ MaxRecurse)) {
// It does! Does "cmp FV, RHS" simplify?
if (Value *FCmp = SimplifyCmpInst(Pred, SI->getFalseValue(), RHS, TD, DT,
- MaxRecurse))
+ MaxRecurse)) {
// It does! If they simplified to the same value, then use it as the
// result of the original comparison.
if (TCmp == FCmp)
return TCmp;
+ Value *Cond = SI->getCondition();
+ // If the false value simplified to false, then the result of the compare
+ // is equal to "Cond && TCmp". This also catches the case when the false
+ // value simplified to false and the true value to true, returning "Cond".
+ if (match(FCmp, m_Zero()))
+ if (Value *V = SimplifyAndInst(Cond, TCmp, TD, DT, MaxRecurse))
+ return V;
+ // If the true value simplified to true, then the result of the compare
+ // is equal to "Cond || FCmp".
+ if (match(TCmp, m_One()))
+ if (Value *V = SimplifyOrInst(Cond, FCmp, TD, DT, MaxRecurse))
+ return V;
+ // Finally, if the false value simplified to true and the true value to
+ // false, then the result of the compare is equal to "!Cond".
+ if (match(FCmp, m_One()) && match(TCmp, m_Zero()))
+ if (Value *V =
+ SimplifyXorInst(Cond, Constant::getAllOnesValue(Cond->getType()),
+ TD, DT, MaxRecurse))
+ return V;
+ }
+ }
+
return 0;
}
static Value *ThreadBinOpOverPHI(unsigned Opcode, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
PHINode *PI;
if (isa<PHINode>(LHS)) {
PI = cast<PHINode>(LHS);
Value *CommonValue = 0;
for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
Value *Incoming = PI->getIncomingValue(i);
- // If the incoming value is the phi node itself, it can be safely skipped.
+ // If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
Value *V = PI == LHS ?
SimplifyBinOp(Opcode, Incoming, RHS, TD, DT, MaxRecurse) :
static Value *ThreadCmpOverPHI(CmpInst::Predicate Pred, Value *LHS, Value *RHS,
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
+ // Recursion is always used, so bail out at once if we already hit the limit.
+ if (!MaxRecurse--)
+ return 0;
+
// Make sure the phi is on the LHS.
if (!isa<PHINode>(LHS)) {
std::swap(LHS, RHS);
Value *CommonValue = 0;
for (unsigned i = 0, e = PI->getNumIncomingValues(); i != e; ++i) {
Value *Incoming = PI->getIncomingValue(i);
- // If the incoming value is the phi node itself, it can be safely skipped.
+ // If the incoming value is the phi node itself, it can safely be skipped.
if (Incoming == PI) continue;
Value *V = SimplifyCmpInst(Pred, Incoming, RHS, TD, DT, MaxRecurse);
// If the operation failed to simplify, or simplified to a different value
/// SimplifyAddInst - Given operands for an Add, see if we can
/// fold the result. If not, this returns null.
-Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
- const TargetData *TD, const DominatorTree *) {
+static Value *SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { CLHS, CRHS };
std::swap(Op0, Op1);
}
- if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
- // X + undef -> undef
- if (isa<UndefValue>(Op1C))
- return Op1C;
+ // X + undef -> undef
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ // X + 0 -> X
+ if (match(Op1, m_Zero()))
+ return Op0;
+
+ // X + (Y - X) -> Y
+ // (Y - X) + X -> Y
+ // Eg: X + -X -> 0
+ Value *Y = 0;
+ if (match(Op1, m_Sub(m_Value(Y), m_Specific(Op0))) ||
+ match(Op0, m_Sub(m_Value(Y), m_Specific(Op1))))
+ return Y;
+
+ // X + ~X -> -1 since ~X = -X-1
+ if (match(Op0, m_Not(m_Specific(Op1))) ||
+ match(Op1, m_Not(m_Specific(Op0))))
+ return Constant::getAllOnesValue(Op0->getType());
+
+ /// i1 add -> xor.
+ if (MaxRecurse && Op0->getType()->isIntegerTy(1))
+ if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
+ return V;
+
+ // Try some generic simplifications for associative operations.
+ if (Value *V = SimplifyAssociativeBinOp(Instruction::Add, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
+
+ // Mul distributes over Add. Try some generic simplifications based on this.
+ if (Value *V = FactorizeBinOp(Instruction::Add, Op0, Op1, Instruction::Mul,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // Threading Add over selects and phi nodes is pointless, so don't bother.
+ // Threading over the select in "A + select(cond, B, C)" means evaluating
+ // "A+B" and "A+C" and seeing if they are equal; but they are equal if and
+ // only if B and C are equal. If B and C are equal then (since we assume
+ // that operands have already been simplified) "select(cond, B, C)" should
+ // have been simplified to the common value of B and C already. Analysing
+ // "A+B" and "A+C" thus gains nothing, but costs compile time. Similarly
+ // for threading over phi nodes.
+
+ return 0;
+}
+
+Value *llvm::SimplifyAddInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyAddInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
+}
+
+/// SimplifySubInst - Given operands for a Sub, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0))
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Sub, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // X - undef -> undef
+ // undef - X -> undef
+ if (match(Op0, m_Undef()) || match(Op1, m_Undef()))
+ return UndefValue::get(Op0->getType());
+
+ // X - 0 -> X
+ if (match(Op1, m_Zero()))
+ return Op0;
+
+ // X - X -> 0
+ if (Op0 == Op1)
+ return Constant::getNullValue(Op0->getType());
+
+ // (X*2) - X -> X
+ // (X<<1) - X -> X
+ Value *X = 0;
+ if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
+ match(Op0, m_Shl(m_Specific(Op1), m_One())))
+ return Op1;
+
+ // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
+ // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
+ Value *Y = 0, *Z = Op1;
+ if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
+ // See if "V === Y - Z" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, DT, MaxRecurse-1))
+ // It does! Now see if "X + V" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ // See if "V === X - Z" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
+ // It does! Now see if "Y + V" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ }
+
+ // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
+ // For example, X - (X + 1) -> -1
+ X = Op0;
+ if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
+ // See if "V === X - Y" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, DT, MaxRecurse-1))
+ // It does! Now see if "V - Z" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ // See if "V === X - Z" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
+ // It does! Now see if "V - Y" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ }
+
+ // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
+ // For example, X - (X - Y) -> Y.
+ Z = Op0;
+ if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
+ // See if "V === Z - X" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, DT, MaxRecurse-1))
+ // It does! Now see if "V + Y" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+
+ // Mul distributes over Sub. Try some generic simplifications based on this.
+ if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // i1 sub -> xor.
+ if (MaxRecurse && Op0->getType()->isIntegerTy(1))
+ if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
+ return V;
+
+ // Threading Sub over selects and phi nodes is pointless, so don't bother.
+ // Threading over the select in "A - select(cond, B, C)" means evaluating
+ // "A-B" and "A-C" and seeing if they are equal; but they are equal if and
+ // only if B and C are equal. If B and C are equal then (since we assume
+ // that operands have already been simplified) "select(cond, B, C)" should
+ // have been simplified to the common value of B and C already. Analysing
+ // "A-B" and "A-C" thus gains nothing, but costs compile time. Similarly
+ // for threading over phi nodes.
+
+ return 0;
+}
+
+Value *llvm::SimplifySubInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifySubInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
+}
+
+/// SimplifyMulInst - Given operands for a Mul, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Mul, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ // X * undef -> 0
+ if (match(Op1, m_Undef()))
+ return Constant::getNullValue(Op0->getType());
+
+ // X * 0 -> 0
+ if (match(Op1, m_Zero()))
+ return Op1;
+
+ // X * 1 -> X
+ if (match(Op1, m_One()))
+ return Op0;
+
+ // (X / Y) * Y -> X if the division is exact.
+ Value *X = 0, *Y = 0;
+ if ((match(Op0, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y
+ (match(Op1, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y)
+ BinaryOperator *Div = cast<BinaryOperator>(Y == Op1 ? Op0 : Op1);
+ if (Div->isExact())
+ return X;
+ }
+
+ // i1 mul -> and.
+ if (MaxRecurse && Op0->getType()->isIntegerTy(1))
+ if (Value *V = SimplifyAndInst(Op0, Op1, TD, DT, MaxRecurse-1))
+ return V;
+
+ // Try some generic simplifications for associative operations.
+ if (Value *V = SimplifyAssociativeBinOp(Instruction::Mul, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
+
+ // Mul distributes over Add. Try some generic simplifications based on this.
+ if (Value *V = ExpandBinOp(Instruction::Mul, Op0, Op1, Instruction::Add,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // If the operation is with the result of a select instruction, check whether
+ // operating on either branch of the select always yields the same value.
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
+ if (Value *V = ThreadBinOpOverSelect(Instruction::Mul, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
+
+ // If the operation is with the result of a phi instruction, check whether
+ // operating on all incoming values of the phi always yields the same value.
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
+ if (Value *V = ThreadBinOpOverPHI(Instruction::Mul, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+/// SimplifyDiv - Given operands for an SDiv or UDiv, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyDiv(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Constant *C0 = dyn_cast<Constant>(Op0)) {
+ if (Constant *C1 = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { C0, C1 };
+ return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
+ }
+ }
+
+ bool isSigned = Opcode == Instruction::SDiv;
+
+ // X / undef -> undef
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ // undef / X -> 0
+ if (match(Op0, m_Undef()))
+ return Constant::getNullValue(Op0->getType());
+
+ // 0 / X -> 0, we don't need to preserve faults!
+ if (match(Op0, m_Zero()))
+ return Op0;
+
+ // X / 1 -> X
+ if (match(Op1, m_One()))
+ return Op0;
+
+ if (Op0->getType()->isIntegerTy(1))
+ // It can't be division by zero, hence it must be division by one.
+ return Op0;
+
+ // X / X -> 1
+ if (Op0 == Op1)
+ return ConstantInt::get(Op0->getType(), 1);
+
+ // (X * Y) / Y -> X if the multiplication does not overflow.
+ Value *X = 0, *Y = 0;
+ if (match(Op0, m_Mul(m_Value(X), m_Value(Y))) && (X == Op1 || Y == Op1)) {
+ if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
+ BinaryOperator *Mul = cast<BinaryOperator>(Op0);
+ // If the Mul knows it does not overflow, then we are good to go.
+ if ((isSigned && Mul->hasNoSignedWrap()) ||
+ (!isSigned && Mul->hasNoUnsignedWrap()))
+ return X;
+ // If X has the form X = A / Y then X * Y cannot overflow.
+ if (BinaryOperator *Div = dyn_cast<BinaryOperator>(X))
+ if (Div->getOpcode() == Opcode && Div->getOperand(1) == Y)
+ return X;
+ }
+
+ // (X rem Y) / Y -> 0
+ if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
+ (!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
+ return Constant::getNullValue(Op0->getType());
+
+ // If the operation is with the result of a select instruction, check whether
+ // operating on either branch of the select always yields the same value.
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
+ if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // If the operation is with the result of a phi instruction, check whether
+ // operating on all incoming values of the phi always yields the same value.
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
+ if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+/// SimplifySDivInst - Given operands for an SDiv, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifySDivInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+/// SimplifyUDivInst - Given operands for a UDiv, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyUDivInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+static Value *SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *,
+ const DominatorTree *, unsigned) {
+ // undef / X -> undef (the undef could be a snan).
+ if (match(Op0, m_Undef()))
+ return Op0;
+
+ // X / undef -> undef
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ return 0;
+}
+
+Value *llvm::SimplifyFDivInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyFDivInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+/// SimplifyRem - Given operands for an SRem or URem, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyRem(Instruction::BinaryOps Opcode, Value *Op0, Value *Op1,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Constant *C0 = dyn_cast<Constant>(Op0)) {
+ if (Constant *C1 = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { C0, C1 };
+ return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
+ }
+ }
+
+ bool isSigned = Opcode == Instruction::SRem;
+
+ // X % undef -> undef
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ // undef % X -> 0
+ if (match(Op0, m_Undef()))
+ return Constant::getNullValue(Op0->getType());
+
+ // 0 % X -> 0, we don't need to preserve faults!
+ if (match(Op0, m_Zero()))
+ return Op0;
+
+ // X % 0 -> undef, we don't need to preserve faults!
+ if (match(Op1, m_Zero()))
+ return UndefValue::get(Op0->getType());
+
+ // X % 1 -> 0
+ if (match(Op1, m_One()))
+ return Constant::getNullValue(Op0->getType());
+
+ if (Op0->getType()->isIntegerTy(1))
+ // It can't be remainder by zero, hence it must be remainder by one.
+ return Constant::getNullValue(Op0->getType());
+
+ // X % X -> 0
+ if (Op0 == Op1)
+ return Constant::getNullValue(Op0->getType());
+
+ // If the operation is with the result of a select instruction, check whether
+ // operating on either branch of the select always yields the same value.
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
+ if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // If the operation is with the result of a phi instruction, check whether
+ // operating on all incoming values of the phi always yields the same value.
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
+ if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+/// SimplifySRemInst - Given operands for an SRem, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Value *V = SimplifyRem(Instruction::SRem, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+Value *llvm::SimplifySRemInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifySRemInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+/// SimplifyURemInst - Given operands for a URem, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Value *V = SimplifyRem(Instruction::URem, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
- // X + 0 --> X
- if (Op1C->isNullValue())
- return Op0;
+ return 0;
+}
+
+Value *llvm::SimplifyURemInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyURemInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+static Value *SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *,
+ const DominatorTree *, unsigned) {
+ // undef % X -> undef (the undef could be a snan).
+ if (match(Op0, m_Undef()))
+ return Op0;
+
+ // X % undef -> undef
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ return 0;
+}
+
+Value *llvm::SimplifyFRemInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyFRemInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
+/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Constant *C0 = dyn_cast<Constant>(Op0)) {
+ if (Constant *C1 = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { C0, C1 };
+ return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
+ }
}
- // FIXME: Could pull several more out of instcombine.
+ // 0 shift by X -> 0
+ if (match(Op0, m_Zero()))
+ return Op0;
+
+ // X shift by 0 -> X
+ if (match(Op1, m_Zero()))
+ return Op0;
+
+ // X shift by undef -> undef because it may shift by the bitwidth.
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ // Shifting by the bitwidth or more is undefined.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
+ if (CI->getValue().getLimitedValue() >=
+ Op0->getType()->getScalarSizeInBits())
+ return UndefValue::get(Op0->getType());
+
+ // If the operation is with the result of a select instruction, check whether
+ // operating on either branch of the select always yields the same value.
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
+ if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // If the operation is with the result of a phi instruction, check whether
+ // operating on all incoming values of the phi always yields the same value.
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
+ if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+/// SimplifyShlInst - Given operands for an Shl, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // undef << X -> 0
+ if (match(Op0, m_Undef()))
+ return Constant::getNullValue(Op0->getType());
+
+ // (X >> A) << A -> X
+ Value *X;
+ if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1))) &&
+ cast<PossiblyExactOperator>(Op0)->isExact())
+ return X;
+ return 0;
+}
+
+Value *llvm::SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyShlInst(Op0, Op1, isNSW, isNUW, TD, DT, RecursionLimit);
+}
+
+/// SimplifyLShrInst - Given operands for an LShr, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // undef >>l X -> 0
+ if (match(Op0, m_Undef()))
+ return Constant::getNullValue(Op0->getType());
+
+ // (X << A) >> A -> X
+ Value *X;
+ if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
+ cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap())
+ return X;
+
return 0;
}
+Value *llvm::SimplifyLShrInst(Value *Op0, Value *Op1, bool isExact,
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyLShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit);
+}
+
+/// SimplifyAShrInst - Given operands for an AShr, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
+ if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // all ones >>a X -> all ones
+ if (match(Op0, m_AllOnes()))
+ return Op0;
+
+ // undef >>a X -> all ones
+ if (match(Op0, m_Undef()))
+ return Constant::getAllOnesValue(Op0->getType());
+
+ // (X << A) >> A -> X
+ Value *X;
+ if (match(Op0, m_Shl(m_Value(X), m_Specific(Op1))) &&
+ cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap())
+ return X;
+
+ return 0;
+}
+
+Value *llvm::SimplifyAShrInst(Value *Op0, Value *Op1, bool isExact,
+ const TargetData *TD, const DominatorTree *DT) {
+ return ::SimplifyAShrInst(Op0, Op1, isExact, TD, DT, RecursionLimit);
+}
+
/// SimplifyAndInst - Given operands for an And, see if we can
/// fold the result. If not, this returns null.
static Value *SimplifyAndInst(Value *Op0, Value *Op1, const TargetData *TD,
}
// X & undef -> 0
- if (isa<UndefValue>(Op1))
+ if (match(Op1, m_Undef()))
return Constant::getNullValue(Op0->getType());
// X & X = X
if (Op0 == Op1)
return Op0;
- // X & <0,0> = <0,0>
- if (isa<ConstantAggregateZero>(Op1))
+ // X & 0 = 0
+ if (match(Op1, m_Zero()))
return Op1;
- // X & <-1,-1> = X
- if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1))
- if (CP->isAllOnesValue())
- return Op0;
-
- if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) {
- // X & 0 = 0
- if (Op1CI->isZero())
- return Op1CI;
- // X & -1 = X
- if (Op1CI->isAllOnesValue())
- return Op0;
- }
+ // X & -1 = X
+ if (match(Op1, m_AllOnes()))
+ return Op0;
// A & ~A = ~A & A = 0
- Value *A, *B;
- if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
- (match(Op1, m_Not(m_Value(A))) && A == Op0))
+ if (match(Op0, m_Not(m_Specific(Op1))) ||
+ match(Op1, m_Not(m_Specific(Op0))))
return Constant::getNullValue(Op0->getType());
// (A | ?) & A = A
+ Value *A = 0, *B = 0;
if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1))
return Op1;
(A == Op0 || B == Op0))
return Op0;
- // (A & B) & A -> A & B
- if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
- (A == Op1 || B == Op1))
- return Op0;
+ // Try some generic simplifications for associative operations.
+ if (Value *V = SimplifyAssociativeBinOp(Instruction::And, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
- // A & (A & B) -> A & B
- if (match(Op1, m_And(m_Value(A), m_Value(B))) &&
- (A == Op0 || B == Op0))
- return Op1;
+ // And distributes over Or. Try some generic simplifications based on this.
+ if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Or,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // And distributes over Xor. Try some generic simplifications based on this.
+ if (Value *V = ExpandBinOp(Instruction::And, Op0, Op1, Instruction::Xor,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // Or distributes over And. Try some generic simplifications based on this.
+ if (Value *V = FactorizeBinOp(Instruction::And, Op0, Op1, Instruction::Or,
+ TD, DT, MaxRecurse))
+ return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
- if (MaxRecurse && (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)))
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::And, Op0, Op1, TD, DT,
- MaxRecurse-1))
+ MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
- if (MaxRecurse && (isa<PHINode>(Op0) || isa<PHINode>(Op1)))
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::And, Op0, Op1, TD, DT,
- MaxRecurse-1))
+ MaxRecurse))
return V;
return 0;
}
// X | undef -> -1
- if (isa<UndefValue>(Op1))
+ if (match(Op1, m_Undef()))
return Constant::getAllOnesValue(Op0->getType());
// X | X = X
if (Op0 == Op1)
return Op0;
- // X | <0,0> = X
- if (isa<ConstantAggregateZero>(Op1))
+ // X | 0 = X
+ if (match(Op1, m_Zero()))
return Op0;
- // X | <-1,-1> = <-1,-1>
- if (ConstantVector *CP = dyn_cast<ConstantVector>(Op1))
- if (CP->isAllOnesValue())
- return Op1;
-
- if (ConstantInt *Op1CI = dyn_cast<ConstantInt>(Op1)) {
- // X | 0 = X
- if (Op1CI->isZero())
- return Op0;
- // X | -1 = -1
- if (Op1CI->isAllOnesValue())
- return Op1CI;
- }
+ // X | -1 = -1
+ if (match(Op1, m_AllOnes()))
+ return Op1;
// A | ~A = ~A | A = -1
- Value *A, *B;
- if ((match(Op0, m_Not(m_Value(A))) && A == Op1) ||
- (match(Op1, m_Not(m_Value(A))) && A == Op0))
+ if (match(Op0, m_Not(m_Specific(Op1))) ||
+ match(Op1, m_Not(m_Specific(Op0))))
return Constant::getAllOnesValue(Op0->getType());
// (A & ?) | A = A
+ Value *A = 0, *B = 0;
if (match(Op0, m_And(m_Value(A), m_Value(B))) &&
(A == Op1 || B == Op1))
return Op1;
(A == Op0 || B == Op0))
return Op0;
- // (A | B) | A -> A | B
- if (match(Op0, m_Or(m_Value(A), m_Value(B))) &&
+ // ~(A & ?) | A = -1
+ if (match(Op0, m_Not(m_And(m_Value(A), m_Value(B)))) &&
(A == Op1 || B == Op1))
- return Op0;
+ return Constant::getAllOnesValue(Op1->getType());
- // A | (A | B) -> A | B
- if (match(Op1, m_Or(m_Value(A), m_Value(B))) &&
+ // A | ~(A & ?) = -1
+ if (match(Op1, m_Not(m_And(m_Value(A), m_Value(B)))) &&
(A == Op0 || B == Op0))
- return Op1;
+ return Constant::getAllOnesValue(Op0->getType());
+
+ // Try some generic simplifications for associative operations.
+ if (Value *V = SimplifyAssociativeBinOp(Instruction::Or, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
+
+ // Or distributes over And. Try some generic simplifications based on this.
+ if (Value *V = ExpandBinOp(Instruction::Or, Op0, Op1, Instruction::And,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // And distributes over Or. Try some generic simplifications based on this.
+ if (Value *V = FactorizeBinOp(Instruction::Or, Op0, Op1, Instruction::And,
+ TD, DT, MaxRecurse))
+ return V;
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
- if (MaxRecurse && (isa<SelectInst>(Op0) || isa<SelectInst>(Op1)))
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
if (Value *V = ThreadBinOpOverSelect(Instruction::Or, Op0, Op1, TD, DT,
- MaxRecurse-1))
+ MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
- if (MaxRecurse && (isa<PHINode>(Op0) || isa<PHINode>(Op1)))
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
if (Value *V = ThreadBinOpOverPHI(Instruction::Or, Op0, Op1, TD, DT,
- MaxRecurse-1))
+ MaxRecurse))
return V;
return 0;
return ::SimplifyOrInst(Op0, Op1, TD, DT, RecursionLimit);
}
+/// SimplifyXorInst - Given operands for a Xor, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Constant *CLHS = dyn_cast<Constant>(Op0)) {
+ if (Constant *CRHS = dyn_cast<Constant>(Op1)) {
+ Constant *Ops[] = { CLHS, CRHS };
+ return ConstantFoldInstOperands(Instruction::Xor, CLHS->getType(),
+ Ops, 2, TD);
+ }
+
+ // Canonicalize the constant to the RHS.
+ std::swap(Op0, Op1);
+ }
+
+ // A ^ undef -> undef
+ if (match(Op1, m_Undef()))
+ return Op1;
+
+ // A ^ 0 = A
+ if (match(Op1, m_Zero()))
+ return Op0;
+
+ // A ^ A = 0
+ if (Op0 == Op1)
+ return Constant::getNullValue(Op0->getType());
+
+ // A ^ ~A = ~A ^ A = -1
+ if (match(Op0, m_Not(m_Specific(Op1))) ||
+ match(Op1, m_Not(m_Specific(Op0))))
+ return Constant::getAllOnesValue(Op0->getType());
+
+ // Try some generic simplifications for associative operations.
+ if (Value *V = SimplifyAssociativeBinOp(Instruction::Xor, Op0, Op1, TD, DT,
+ MaxRecurse))
+ return V;
+
+ // And distributes over Xor. Try some generic simplifications based on this.
+ if (Value *V = FactorizeBinOp(Instruction::Xor, Op0, Op1, Instruction::And,
+ TD, DT, MaxRecurse))
+ return V;
+
+ // Threading Xor over selects and phi nodes is pointless, so don't bother.
+ // Threading over the select in "A ^ select(cond, B, C)" means evaluating
+ // "A^B" and "A^C" and seeing if they are equal; but they are equal if and
+ // only if B and C are equal. If B and C are equal then (since we assume
+ // that operands have already been simplified) "select(cond, B, C)" should
+ // have been simplified to the common value of B and C already. Analysing
+ // "A^B" and "A^C" thus gains nothing, but costs compile time. Similarly
+ // for threading over phi nodes.
+
+ return 0;
+}
+
+Value *llvm::SimplifyXorInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT) {
+ return ::SimplifyXorInst(Op0, Op1, TD, DT, RecursionLimit);
+}
+
static const Type *GetCompareTy(Value *Op) {
return CmpInst::makeCmpResultType(Op->getType());
}
Pred = CmpInst::getSwappedPredicate(Pred);
}
- // ITy - This is the return type of the compare we're considering.
- const Type *ITy = GetCompareTy(LHS);
+ const Type *ITy = GetCompareTy(LHS); // The return type.
+ const Type *OpTy = LHS->getType(); // The operand type.
// icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
- // icmp <global/alloca*/null>, <global/alloca*/null> - Global/Stack value
- // addresses never equal each other! We already know that Op0 != Op1.
- if ((isa<GlobalValue>(LHS) || isa<AllocaInst>(LHS) ||
- isa<ConstantPointerNull>(LHS)) &&
- (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
- isa<ConstantPointerNull>(RHS)))
+ // Special case logic when the operands have i1 type.
+ if (OpTy->isIntegerTy(1) || (OpTy->isVectorTy() &&
+ cast<VectorType>(OpTy)->getElementType()->isIntegerTy(1))) {
+ switch (Pred) {
+ default: break;
+ case ICmpInst::ICMP_EQ:
+ // X == 1 -> X
+ if (match(RHS, m_One()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_NE:
+ // X != 0 -> X
+ if (match(RHS, m_Zero()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_UGT:
+ // X >u 0 -> X
+ if (match(RHS, m_Zero()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_UGE:
+ // X >=u 1 -> X
+ if (match(RHS, m_One()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_SLT:
+ // X <s 0 -> X
+ if (match(RHS, m_Zero()))
+ return LHS;
+ break;
+ case ICmpInst::ICMP_SLE:
+ // X <=s -1 -> X
+ if (match(RHS, m_One()))
+ return LHS;
+ break;
+ }
+ }
+
+ // icmp <alloca*>, <global/alloca*/null> - Different stack variables have
+ // different addresses, and what's more the address of a stack variable is
+ // never null or equal to the address of a global. Note that generalizing
+ // to the case where LHS is a global variable address or null is pointless,
+ // since if both LHS and RHS are constants then we already constant folded
+ // the compare, and if only one of them is then we moved it to RHS already.
+ if (isa<AllocaInst>(LHS) && (isa<GlobalValue>(RHS) || isa<AllocaInst>(RHS) ||
+ isa<ConstantPointerNull>(RHS)))
+ // We already know that LHS != RHS.
return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
- // See if we are doing a comparison with a constant.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
- // If we have an icmp le or icmp ge instruction, turn it into the
- // appropriate icmp lt or icmp gt instruction. This allows us to rely on
- // them being folded in the code below.
+ // If we are comparing with zero then try hard since this is a common case.
+ if (match(RHS, m_Zero())) {
+ bool LHSKnownNonNegative, LHSKnownNegative;
switch (Pred) {
- default: break;
+ default:
+ assert(false && "Unknown ICmp predicate!");
+ case ICmpInst::ICMP_ULT:
+ return ConstantInt::getFalse(LHS->getContext());
+ case ICmpInst::ICMP_UGE:
+ return ConstantInt::getTrue(LHS->getContext());
+ case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULE:
- if (CI->isMaxValue(false)) // A <=u MAX -> TRUE
- return ConstantInt::getTrue(CI->getContext());
+ if (isKnownNonZero(LHS, TD))
+ return ConstantInt::getFalse(LHS->getContext());
+ break;
+ case ICmpInst::ICMP_NE:
+ case ICmpInst::ICMP_UGT:
+ if (isKnownNonZero(LHS, TD))
+ return ConstantInt::getTrue(LHS->getContext());
+ break;
+ case ICmpInst::ICMP_SLT:
+ ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
+ if (LHSKnownNegative)
+ return ConstantInt::getTrue(LHS->getContext());
+ if (LHSKnownNonNegative)
+ return ConstantInt::getFalse(LHS->getContext());
break;
case ICmpInst::ICMP_SLE:
- if (CI->isMaxValue(true)) // A <=s MAX -> TRUE
- return ConstantInt::getTrue(CI->getContext());
+ ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
+ if (LHSKnownNegative)
+ return ConstantInt::getTrue(LHS->getContext());
+ if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
+ return ConstantInt::getFalse(LHS->getContext());
+ break;
+ case ICmpInst::ICMP_SGE:
+ ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
+ if (LHSKnownNegative)
+ return ConstantInt::getFalse(LHS->getContext());
+ if (LHSKnownNonNegative)
+ return ConstantInt::getTrue(LHS->getContext());
break;
+ case ICmpInst::ICMP_SGT:
+ ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, TD);
+ if (LHSKnownNegative)
+ return ConstantInt::getFalse(LHS->getContext());
+ if (LHSKnownNonNegative && isKnownNonZero(LHS, TD))
+ return ConstantInt::getTrue(LHS->getContext());
+ break;
+ }
+ }
+
+ // See if we are doing a comparison with a constant integer.
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ // Rule out tautological comparisons (eg., ult 0 or uge 0).
+ ConstantRange RHS_CR = ICmpInst::makeConstantRange(Pred, CI->getValue());
+ if (RHS_CR.isEmptySet())
+ return ConstantInt::getFalse(CI->getContext());
+ if (RHS_CR.isFullSet())
+ return ConstantInt::getTrue(CI->getContext());
+
+ // Many binary operators with constant RHS have easy to compute constant
+ // range. Use them to check whether the comparison is a tautology.
+ uint32_t Width = CI->getBitWidth();
+ APInt Lower = APInt(Width, 0);
+ APInt Upper = APInt(Width, 0);
+ ConstantInt *CI2;
+ if (match(LHS, m_URem(m_Value(), m_ConstantInt(CI2)))) {
+ // 'urem x, CI2' produces [0, CI2).
+ Upper = CI2->getValue();
+ } else if (match(LHS, m_SRem(m_Value(), m_ConstantInt(CI2)))) {
+ // 'srem x, CI2' produces (-|CI2|, |CI2|).
+ Upper = CI2->getValue().abs();
+ Lower = (-Upper) + 1;
+ } else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
+ // 'udiv x, CI2' produces [0, UINT_MAX / CI2].
+ APInt NegOne = APInt::getAllOnesValue(Width);
+ if (!CI2->isZero())
+ Upper = NegOne.udiv(CI2->getValue()) + 1;
+ } else if (match(LHS, m_SDiv(m_Value(), m_ConstantInt(CI2)))) {
+ // 'sdiv x, CI2' produces [INT_MIN / CI2, INT_MAX / CI2].
+ APInt IntMin = APInt::getSignedMinValue(Width);
+ APInt IntMax = APInt::getSignedMaxValue(Width);
+ APInt Val = CI2->getValue().abs();
+ if (!Val.isMinValue()) {
+ Lower = IntMin.sdiv(Val);
+ Upper = IntMax.sdiv(Val) + 1;
+ }
+ } else if (match(LHS, m_LShr(m_Value(), m_ConstantInt(CI2)))) {
+ // 'lshr x, CI2' produces [0, UINT_MAX >> CI2].
+ APInt NegOne = APInt::getAllOnesValue(Width);
+ if (CI2->getValue().ult(Width))
+ Upper = NegOne.lshr(CI2->getValue()) + 1;
+ } else if (match(LHS, m_AShr(m_Value(), m_ConstantInt(CI2)))) {
+ // 'ashr x, CI2' produces [INT_MIN >> CI2, INT_MAX >> CI2].
+ APInt IntMin = APInt::getSignedMinValue(Width);
+ APInt IntMax = APInt::getSignedMaxValue(Width);
+ if (CI2->getValue().ult(Width)) {
+ Lower = IntMin.ashr(CI2->getValue());
+ Upper = IntMax.ashr(CI2->getValue()) + 1;
+ }
+ } else if (match(LHS, m_Or(m_Value(), m_ConstantInt(CI2)))) {
+ // 'or x, CI2' produces [CI2, UINT_MAX].
+ Lower = CI2->getValue();
+ } else if (match(LHS, m_And(m_Value(), m_ConstantInt(CI2)))) {
+ // 'and x, CI2' produces [0, CI2].
+ Upper = CI2->getValue() + 1;
+ }
+ if (Lower != Upper) {
+ ConstantRange LHS_CR = ConstantRange(Lower, Upper);
+ if (RHS_CR.contains(LHS_CR))
+ return ConstantInt::getTrue(RHS->getContext());
+ if (RHS_CR.inverse().contains(LHS_CR))
+ return ConstantInt::getFalse(RHS->getContext());
+ }
+ }
+
+ // Compare of cast, for example (zext X) != 0 -> X != 0
+ if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
+ Instruction *LI = cast<CastInst>(LHS);
+ Value *SrcOp = LI->getOperand(0);
+ const Type *SrcTy = SrcOp->getType();
+ const Type *DstTy = LI->getType();
+
+ // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
+ // if the integer type is the same size as the pointer type.
+ if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
+ TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // Transfer the cast to the constant.
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp,
+ ConstantExpr::getIntToPtr(RHSC, SrcTy),
+ TD, DT, MaxRecurse-1))
+ return V;
+ } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
+ if (RI->getOperand(0)->getType() == SrcTy)
+ // Compare without the cast.
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
+ TD, DT, MaxRecurse-1))
+ return V;
+ }
+ }
+
+ if (isa<ZExtInst>(LHS)) {
+ // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
+ // same type.
+ if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
+ if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
+ // Compare X and Y. Note that signed predicates become unsigned.
+ if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
+ SrcOp, RI->getOperand(0), TD, DT,
+ MaxRecurse-1))
+ return V;
+ }
+ // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
+ // too. If not, then try to deduce the result of the comparison.
+ else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DstTy.
+ Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
+
+ // If the re-extended constant didn't change then this is effectively
+ // also a case of comparing two zero-extended values.
+ if (RExt == CI && MaxRecurse)
+ if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
+ SrcOp, Trunc, TD, DT, MaxRecurse-1))
+ return V;
+
+ // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
+ // there. Use this to work out the result of the comparison.
+ if (RExt != CI) {
+ switch (Pred) {
+ default:
+ assert(false && "Unknown ICmp predicate!");
+ // LHS <u RHS.
+ case ICmpInst::ICMP_EQ:
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE:
+ return ConstantInt::getFalse(CI->getContext());
+
+ case ICmpInst::ICMP_NE:
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE:
+ return ConstantInt::getTrue(CI->getContext());
+
+ // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
+ // is non-negative then LHS <s RHS.
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getTrue(CI->getContext()) :
+ ConstantInt::getFalse(CI->getContext());
+
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getFalse(CI->getContext()) :
+ ConstantInt::getTrue(CI->getContext());
+ }
+ }
+ }
+ }
+
+ if (isa<SExtInst>(LHS)) {
+ // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
+ // same type.
+ if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
+ if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
+ // Compare X and Y. Note that the predicate does not change.
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
+ TD, DT, MaxRecurse-1))
+ return V;
+ }
+ // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
+ // too. If not, then try to deduce the result of the comparison.
+ else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DstTy.
+ Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
+
+ // If the re-extended constant didn't change then this is effectively
+ // also a case of comparing two sign-extended values.
+ if (RExt == CI && MaxRecurse)
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT,
+ MaxRecurse-1))
+ return V;
+
+ // Otherwise the upper bits of LHS are all equal, while RHS has varying
+ // bits there. Use this to work out the result of the comparison.
+ if (RExt != CI) {
+ switch (Pred) {
+ default:
+ assert(false && "Unknown ICmp predicate!");
+ case ICmpInst::ICMP_EQ:
+ return ConstantInt::getFalse(CI->getContext());
+ case ICmpInst::ICMP_NE:
+ return ConstantInt::getTrue(CI->getContext());
+
+ // If RHS is non-negative then LHS <s RHS. If RHS is negative then
+ // LHS >s RHS.
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getTrue(CI->getContext()) :
+ ConstantInt::getFalse(CI->getContext());
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getFalse(CI->getContext()) :
+ ConstantInt::getTrue(CI->getContext());
+
+ // If LHS is non-negative then LHS <u RHS. If LHS is negative then
+ // LHS >u RHS.
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE:
+ // Comparison is true iff the LHS <s 0.
+ if (MaxRecurse)
+ if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
+ Constant::getNullValue(SrcTy),
+ TD, DT, MaxRecurse-1))
+ return V;
+ break;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE:
+ // Comparison is true iff the LHS >=s 0.
+ if (MaxRecurse)
+ if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
+ Constant::getNullValue(SrcTy),
+ TD, DT, MaxRecurse-1))
+ return V;
+ break;
+ }
+ }
+ }
+ }
+ }
+
+ // Special logic for binary operators.
+ BinaryOperator *LBO = dyn_cast<BinaryOperator>(LHS);
+ BinaryOperator *RBO = dyn_cast<BinaryOperator>(RHS);
+ if (MaxRecurse && (LBO || RBO)) {
+ // Analyze the case when either LHS or RHS is an add instruction.
+ Value *A = 0, *B = 0, *C = 0, *D = 0;
+ // LHS = A + B (or A and B are null); RHS = C + D (or C and D are null).
+ bool NoLHSWrapProblem = false, NoRHSWrapProblem = false;
+ if (LBO && LBO->getOpcode() == Instruction::Add) {
+ A = LBO->getOperand(0); B = LBO->getOperand(1);
+ NoLHSWrapProblem = ICmpInst::isEquality(Pred) ||
+ (CmpInst::isUnsigned(Pred) && LBO->hasNoUnsignedWrap()) ||
+ (CmpInst::isSigned(Pred) && LBO->hasNoSignedWrap());
+ }
+ if (RBO && RBO->getOpcode() == Instruction::Add) {
+ C = RBO->getOperand(0); D = RBO->getOperand(1);
+ NoRHSWrapProblem = ICmpInst::isEquality(Pred) ||
+ (CmpInst::isUnsigned(Pred) && RBO->hasNoUnsignedWrap()) ||
+ (CmpInst::isSigned(Pred) && RBO->hasNoSignedWrap());
+ }
+
+ // icmp (X+Y), X -> icmp Y, 0 for equalities or if there is no overflow.
+ if ((A == RHS || B == RHS) && NoLHSWrapProblem)
+ if (Value *V = SimplifyICmpInst(Pred, A == RHS ? B : A,
+ Constant::getNullValue(RHS->getType()),
+ TD, DT, MaxRecurse-1))
+ return V;
+
+ // icmp X, (X+Y) -> icmp 0, Y for equalities or if there is no overflow.
+ if ((C == LHS || D == LHS) && NoRHSWrapProblem)
+ if (Value *V = SimplifyICmpInst(Pred,
+ Constant::getNullValue(LHS->getType()),
+ C == LHS ? D : C, TD, DT, MaxRecurse-1))
+ return V;
+
+ // icmp (X+Y), (X+Z) -> icmp Y,Z for equalities or if there is no overflow.
+ if (A && C && (A == C || A == D || B == C || B == D) &&
+ NoLHSWrapProblem && NoRHSWrapProblem) {
+ // Determine Y and Z in the form icmp (X+Y), (X+Z).
+ Value *Y = (A == C || A == D) ? B : A;
+ Value *Z = (C == A || C == B) ? D : C;
+ if (Value *V = SimplifyICmpInst(Pred, Y, Z, TD, DT, MaxRecurse-1))
+ return V;
+ }
+ }
+
+ if (LBO && match(LBO, m_URem(m_Value(), m_Specific(RHS)))) {
+ bool KnownNonNegative, KnownNegative;
+ switch (Pred) {
+ default:
+ break;
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE:
+ ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
+ if (!KnownNonNegative)
+ break;
+ // fall-through
+ case ICmpInst::ICMP_EQ:
+ case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_UGE:
- if (CI->isMinValue(false)) // A >=u MIN -> TRUE
- return ConstantInt::getTrue(CI->getContext());
+ return ConstantInt::getFalse(RHS->getContext());
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ ComputeSignBit(LHS, KnownNonNegative, KnownNegative, TD);
+ if (!KnownNonNegative)
+ break;
+ // fall-through
+ case ICmpInst::ICMP_NE:
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE:
+ return ConstantInt::getTrue(RHS->getContext());
+ }
+ }
+ if (RBO && match(RBO, m_URem(m_Value(), m_Specific(LHS)))) {
+ bool KnownNonNegative, KnownNegative;
+ switch (Pred) {
+ default:
break;
+ case ICmpInst::ICMP_SGT:
case ICmpInst::ICMP_SGE:
- if (CI->isMinValue(true)) // A >=s MIN -> TRUE
- return ConstantInt::getTrue(CI->getContext());
+ ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
+ if (!KnownNonNegative)
+ break;
+ // fall-through
+ case ICmpInst::ICMP_NE:
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE:
+ return ConstantInt::getTrue(RHS->getContext());
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ ComputeSignBit(RHS, KnownNonNegative, KnownNegative, TD);
+ if (!KnownNonNegative)
+ break;
+ // fall-through
+ case ICmpInst::ICMP_EQ:
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE:
+ return ConstantInt::getFalse(RHS->getContext());
+ }
+ }
+
+ if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
+ LBO->getOperand(1) == RBO->getOperand(1)) {
+ switch (LBO->getOpcode()) {
+ default: break;
+ case Instruction::UDiv:
+ case Instruction::LShr:
+ if (ICmpInst::isSigned(Pred))
+ break;
+ // fall-through
+ case Instruction::SDiv:
+ case Instruction::AShr:
+ if (!LBO->isExact() && !RBO->isExact())
+ break;
+ if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
+ RBO->getOperand(0), TD, DT, MaxRecurse-1))
+ return V;
+ break;
+ case Instruction::Shl: {
+ bool NUW = LBO->hasNoUnsignedWrap() && LBO->hasNoUnsignedWrap();
+ bool NSW = LBO->hasNoSignedWrap() && RBO->hasNoSignedWrap();
+ if (!NUW && !NSW)
+ break;
+ if (!NSW && ICmpInst::isSigned(Pred))
+ break;
+ if (Value *V = SimplifyICmpInst(Pred, LBO->getOperand(0),
+ RBO->getOperand(0), TD, DT, MaxRecurse-1))
+ return V;
break;
}
+ }
}
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
- if (MaxRecurse && (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)))
- if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
+ if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
+ if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
- if (MaxRecurse && (isa<PHINode>(LHS) || isa<PHINode>(RHS)))
- if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
+ if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
+ if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
return 0;
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
- if (MaxRecurse && (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)))
- if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
+ if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
+ if (Value *V = ThreadCmpOverSelect(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
// If the comparison is with the result of a phi instruction, check whether
// doing the compare with each incoming phi value yields a common result.
- if (MaxRecurse && (isa<PHINode>(LHS) || isa<PHINode>(RHS)))
- if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse-1))
+ if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
+ if (Value *V = ThreadCmpOverPHI(Pred, LHS, RHS, TD, DT, MaxRecurse))
return V;
return 0;
/// fold the result. If not, this returns null.
Value *llvm::SimplifyGEPInst(Value *const *Ops, unsigned NumOps,
const TargetData *TD, const DominatorTree *) {
+ // The type of the GEP pointer operand.
+ const PointerType *PtrTy = cast<PointerType>(Ops[0]->getType());
+
// getelementptr P -> P.
if (NumOps == 1)
return Ops[0];
- // TODO.
- //if (isa<UndefValue>(Ops[0]))
- // return UndefValue::get(GEP.getType());
+ if (isa<UndefValue>(Ops[0])) {
+ // Compute the (pointer) type returned by the GEP instruction.
+ const Type *LastType = GetElementPtrInst::getIndexedType(PtrTy, &Ops[1],
+ NumOps-1);
+ const Type *GEPTy = PointerType::get(LastType, PtrTy->getAddressSpace());
+ return UndefValue::get(GEPTy);
+ }
- // getelementptr P, 0 -> P.
- if (NumOps == 2)
+ if (NumOps == 2) {
+ // getelementptr P, 0 -> P.
if (ConstantInt *C = dyn_cast<ConstantInt>(Ops[1]))
if (C->isZero())
return Ops[0];
+ // getelementptr P, N -> P if P points to a type of zero size.
+ if (TD) {
+ const Type *Ty = PtrTy->getElementType();
+ if (Ty->isSized() && TD->getTypeAllocSize(Ty) == 0)
+ return Ops[0];
+ }
+ }
// Check to see if this is constant foldable.
for (unsigned i = 0; i != NumOps; ++i)
(Constant *const*)Ops+1, NumOps-1);
}
+/// SimplifyPHINode - See if we can fold the given phi. If not, returns null.
+static Value *SimplifyPHINode(PHINode *PN, const DominatorTree *DT) {
+ // If all of the PHI's incoming values are the same then replace the PHI node
+ // with the common value.
+ Value *CommonValue = 0;
+ bool HasUndefInput = false;
+ for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
+ Value *Incoming = PN->getIncomingValue(i);
+ // If the incoming value is the phi node itself, it can safely be skipped.
+ if (Incoming == PN) continue;
+ if (isa<UndefValue>(Incoming)) {
+ // Remember that we saw an undef value, but otherwise ignore them.
+ HasUndefInput = true;
+ continue;
+ }
+ if (CommonValue && Incoming != CommonValue)
+ return 0; // Not the same, bail out.
+ CommonValue = Incoming;
+ }
+
+ // If CommonValue is null then all of the incoming values were either undef or
+ // equal to the phi node itself.
+ if (!CommonValue)
+ return UndefValue::get(PN->getType());
+
+ // If we have a PHI node like phi(X, undef, X), where X is defined by some
+ // instruction, we cannot return X as the result of the PHI node unless it
+ // dominates the PHI block.
+ if (HasUndefInput)
+ return ValueDominatesPHI(CommonValue, PN, DT) ? CommonValue : 0;
+
+ return CommonValue;
+}
+
//=== Helper functions for higher up the class hierarchy.
const TargetData *TD, const DominatorTree *DT,
unsigned MaxRecurse) {
switch (Opcode) {
+ case Instruction::Add:
+ return SimplifyAddInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
+ TD, DT, MaxRecurse);
+ case Instruction::Sub:
+ return SimplifySubInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
+ TD, DT, MaxRecurse);
+ case Instruction::Mul: return SimplifyMulInst (LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::SDiv: return SimplifySDivInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::UDiv: return SimplifyUDivInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::FDiv: return SimplifyFDivInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::SRem: return SimplifySRemInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::URem: return SimplifyURemInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::FRem: return SimplifyFRemInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::Shl:
+ return SimplifyShlInst(LHS, RHS, /*isNSW*/false, /*isNUW*/false,
+ TD, DT, MaxRecurse);
+ case Instruction::LShr:
+ return SimplifyLShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse);
+ case Instruction::AShr:
+ return SimplifyAShrInst(LHS, RHS, /*isExact*/false, TD, DT, MaxRecurse);
case Instruction::And: return SimplifyAndInst(LHS, RHS, TD, DT, MaxRecurse);
- case Instruction::Or: return SimplifyOrInst(LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::Or: return SimplifyOrInst (LHS, RHS, TD, DT, MaxRecurse);
+ case Instruction::Xor: return SimplifyXorInst(LHS, RHS, TD, DT, MaxRecurse);
default:
if (Constant *CLHS = dyn_cast<Constant>(LHS))
if (Constant *CRHS = dyn_cast<Constant>(RHS)) {
return ConstantFoldInstOperands(Opcode, LHS->getType(), COps, 2, TD);
}
+ // If the operation is associative, try some generic simplifications.
+ if (Instruction::isAssociative(Opcode))
+ if (Value *V = SimplifyAssociativeBinOp(Opcode, LHS, RHS, TD, DT,
+ MaxRecurse))
+ return V;
+
// If the operation is with the result of a select instruction, check whether
// operating on either branch of the select always yields the same value.
- if (MaxRecurse && (isa<SelectInst>(LHS) || isa<SelectInst>(RHS)))
+ if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
if (Value *V = ThreadBinOpOverSelect(Opcode, LHS, RHS, TD, DT,
- MaxRecurse-1))
+ MaxRecurse))
return V;
// If the operation is with the result of a phi instruction, check whether
// operating on all incoming values of the phi always yields the same value.
- if (MaxRecurse && (isa<PHINode>(LHS) || isa<PHINode>(RHS)))
- if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse-1))
+ if (isa<PHINode>(LHS) || isa<PHINode>(RHS))
+ if (Value *V = ThreadBinOpOverPHI(Opcode, LHS, RHS, TD, DT, MaxRecurse))
return V;
return 0;
/// instruction. If not, this returns null.
Value *llvm::SimplifyInstruction(Instruction *I, const TargetData *TD,
const DominatorTree *DT) {
+ Value *Result;
+
switch (I->getOpcode()) {
default:
- return ConstantFoldInstruction(I, TD);
+ Result = ConstantFoldInstruction(I, TD);
+ break;
case Instruction::Add:
- return SimplifyAddInst(I->getOperand(0), I->getOperand(1),
- cast<BinaryOperator>(I)->hasNoSignedWrap(),
- cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
- TD, DT);
+ Result = SimplifyAddInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
+ TD, DT);
+ break;
+ case Instruction::Sub:
+ Result = SimplifySubInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
+ TD, DT);
+ break;
+ case Instruction::Mul:
+ Result = SimplifyMulInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::SDiv:
+ Result = SimplifySDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::UDiv:
+ Result = SimplifyUDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::FDiv:
+ Result = SimplifyFDivInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::SRem:
+ Result = SimplifySRemInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::URem:
+ Result = SimplifyURemInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::FRem:
+ Result = SimplifyFRemInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::Shl:
+ Result = SimplifyShlInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->hasNoSignedWrap(),
+ cast<BinaryOperator>(I)->hasNoUnsignedWrap(),
+ TD, DT);
+ break;
+ case Instruction::LShr:
+ Result = SimplifyLShrInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->isExact(),
+ TD, DT);
+ break;
+ case Instruction::AShr:
+ Result = SimplifyAShrInst(I->getOperand(0), I->getOperand(1),
+ cast<BinaryOperator>(I)->isExact(),
+ TD, DT);
+ break;
case Instruction::And:
- return SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ Result = SimplifyAndInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::Or:
- return SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ Result = SimplifyOrInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
+ case Instruction::Xor:
+ Result = SimplifyXorInst(I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::ICmp:
- return SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
- I->getOperand(0), I->getOperand(1), TD, DT);
+ Result = SimplifyICmpInst(cast<ICmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::FCmp:
- return SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
- I->getOperand(0), I->getOperand(1), TD, DT);
+ Result = SimplifyFCmpInst(cast<FCmpInst>(I)->getPredicate(),
+ I->getOperand(0), I->getOperand(1), TD, DT);
+ break;
case Instruction::Select:
- return SimplifySelectInst(I->getOperand(0), I->getOperand(1),
- I->getOperand(2), TD, DT);
+ Result = SimplifySelectInst(I->getOperand(0), I->getOperand(1),
+ I->getOperand(2), TD, DT);
+ break;
case Instruction::GetElementPtr: {
SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
- return SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
+ Result = SimplifyGEPInst(&Ops[0], Ops.size(), TD, DT);
+ break;
}
case Instruction::PHI:
- return cast<PHINode>(I)->hasConstantValue(DT);
+ Result = SimplifyPHINode(cast<PHINode>(I), DT);
+ break;
}
+
+ /// If called on unreachable code, the above logic may report that the
+ /// instruction simplified to itself. Make life easier for users by
+ /// detecting that case here, returning a safe value instead.
+ return Result == I ? UndefValue::get(I->getType()) : Result;
}
/// ReplaceAndSimplifyAllUses - Perform From->replaceAllUsesWith(To) and then
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