//===----------------------------------------------------------------------===//
#include "InstCombine.h"
+#include "llvm/Analysis/ConstantFolding.h"
+#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Support/PatternMatch.h"
using namespace llvm;
using namespace PatternMatch;
MatchSelectPattern(Value *V, Value *&LHS, Value *&RHS) {
SelectInst *SI = dyn_cast<SelectInst>(V);
if (SI == 0) return SPF_UNKNOWN;
-
+
ICmpInst *ICI = dyn_cast<ICmpInst>(SI->getCondition());
if (ICI == 0) return SPF_UNKNOWN;
-
+
LHS = ICI->getOperand(0);
RHS = ICI->getOperand(1);
-
- // (icmp X, Y) ? X : Y
+
+ // (icmp X, Y) ? X : Y
if (SI->getTrueValue() == ICI->getOperand(0) &&
SI->getFalseValue() == ICI->getOperand(1)) {
switch (ICI->getPredicate()) {
case ICmpInst::ICMP_SLE: return SPF_SMIN;
}
}
-
- // (icmp X, Y) ? Y : X
+
+ // (icmp X, Y) ? Y : X
if (SI->getTrueValue() == ICI->getOperand(1) &&
SI->getFalseValue() == ICI->getOperand(0)) {
switch (ICI->getPredicate()) {
case ICmpInst::ICMP_SLE: return SPF_SMAX;
}
}
-
+
// TODO: (X > 4) ? X : 5 --> (X >= 5) ? X : 5 --> MAX(X, 5)
-
+
return SPF_UNKNOWN;
}
if (TI->isCast()) {
if (TI->getOperand(0)->getType() != FI->getOperand(0)->getType())
return 0;
+ // The select condition may be a vector. We may only change the operand
+ // type if the vector width remains the same (and matches the condition).
+ Type *CondTy = SI.getCondition()->getType();
+ if (CondTy->isVectorTy() && CondTy->getVectorNumElements() !=
+ FI->getOperand(0)->getType()->getVectorNumElements())
+ return 0;
} else {
return 0; // unknown unary op.
}
// Fold this by inserting a select from the input values.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), TI->getOperand(0),
- FI->getOperand(0), SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
- return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
+ Value *NewSI = Builder->CreateSelect(SI.getCondition(), TI->getOperand(0),
+ FI->getOperand(0), SI.getName()+".v");
+ return CastInst::Create(Instruction::CastOps(TI->getOpcode()), NewSI,
TI->getType());
}
}
// If we reach here, they do have operations in common.
- SelectInst *NewSI = SelectInst::Create(SI.getCondition(), OtherOpT,
- OtherOpF, SI.getName()+".v");
- InsertNewInstBefore(NewSI, SI);
+ Value *NewSI = Builder->CreateSelect(SI.getCondition(), OtherOpT,
+ OtherOpF, SI.getName()+".v");
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TI)) {
if (MatchIsOpZero)
return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
}
llvm_unreachable("Shouldn't get here");
- return 0;
}
static bool isSelect01(Constant *C1, Constant *C2) {
ConstantInt *C2I = dyn_cast<ConstantInt>(C2);
if (!C2I)
return false;
- return (C1I->isZero() || C1I->isOne()) && (C2I->isZero() || C2I->isOne());
+ if (!C1I->isZero() && !C2I->isZero()) // One side must be zero.
+ return false;
+ return C1I->isOne() || C1I->isAllOnesValue() ||
+ C2I->isOne() || C2I->isAllOnesValue();
}
/// FoldSelectIntoOp - Try fold the select into one of the operands to
unsigned OpToFold = 0;
if ((SFO & 1) && FalseVal == TVI->getOperand(0)) {
OpToFold = 1;
- } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
+ } else if ((SFO & 2) && FalseVal == TVI->getOperand(1)) {
OpToFold = 2;
}
Constant *C = GetSelectFoldableConstant(TVI);
Value *OOp = TVI->getOperand(2-OpToFold);
// Avoid creating select between 2 constants unless it's selecting
- // between 0 and 1.
+ // between 0, 1 and -1.
if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), OOp, C);
- InsertNewInstBefore(NewSel, SI);
+ Value *NewSel = Builder->CreateSelect(SI.getCondition(), OOp, C);
NewSel->takeName(TVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(TVI))
- return BinaryOperator::Create(BO->getOpcode(), FalseVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
+ BinaryOperator *TVI_BO = cast<BinaryOperator>(TVI);
+ BinaryOperator *BO = BinaryOperator::Create(TVI_BO->getOpcode(),
+ FalseVal, NewSel);
+ if (isa<PossiblyExactOperator>(BO))
+ BO->setIsExact(TVI_BO->isExact());
+ if (isa<OverflowingBinaryOperator>(BO)) {
+ BO->setHasNoUnsignedWrap(TVI_BO->hasNoUnsignedWrap());
+ BO->setHasNoSignedWrap(TVI_BO->hasNoSignedWrap());
+ }
+ return BO;
}
}
}
unsigned OpToFold = 0;
if ((SFO & 1) && TrueVal == FVI->getOperand(0)) {
OpToFold = 1;
- } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
+ } else if ((SFO & 2) && TrueVal == FVI->getOperand(1)) {
OpToFold = 2;
}
Constant *C = GetSelectFoldableConstant(FVI);
Value *OOp = FVI->getOperand(2-OpToFold);
// Avoid creating select between 2 constants unless it's selecting
- // between 0 and 1.
+ // between 0, 1 and -1.
if (!isa<Constant>(OOp) || isSelect01(C, cast<Constant>(OOp))) {
- Instruction *NewSel = SelectInst::Create(SI.getCondition(), C, OOp);
- InsertNewInstBefore(NewSel, SI);
+ Value *NewSel = Builder->CreateSelect(SI.getCondition(), C, OOp);
NewSel->takeName(FVI);
- if (BinaryOperator *BO = dyn_cast<BinaryOperator>(FVI))
- return BinaryOperator::Create(BO->getOpcode(), TrueVal, NewSel);
- llvm_unreachable("Unknown instruction!!");
+ BinaryOperator *FVI_BO = cast<BinaryOperator>(FVI);
+ BinaryOperator *BO = BinaryOperator::Create(FVI_BO->getOpcode(),
+ TrueVal, NewSel);
+ if (isa<PossiblyExactOperator>(BO))
+ BO->setIsExact(FVI_BO->isExact());
+ if (isa<OverflowingBinaryOperator>(BO)) {
+ BO->setHasNoUnsignedWrap(FVI_BO->hasNoUnsignedWrap());
+ BO->setHasNoSignedWrap(FVI_BO->hasNoSignedWrap());
+ }
+ return BO;
}
}
}
return 0;
}
+/// SimplifyWithOpReplaced - See if V simplifies when its operand Op is
+/// replaced with RepOp.
+static Value *SimplifyWithOpReplaced(Value *V, Value *Op, Value *RepOp,
+ const DataLayout *TD,
+ const TargetLibraryInfo *TLI) {
+ // Trivial replacement.
+ if (V == Op)
+ return RepOp;
+
+ Instruction *I = dyn_cast<Instruction>(V);
+ if (!I)
+ return 0;
+
+ // If this is a binary operator, try to simplify it with the replaced op.
+ if (BinaryOperator *B = dyn_cast<BinaryOperator>(I)) {
+ if (B->getOperand(0) == Op)
+ return SimplifyBinOp(B->getOpcode(), RepOp, B->getOperand(1), TD, TLI);
+ if (B->getOperand(1) == Op)
+ return SimplifyBinOp(B->getOpcode(), B->getOperand(0), RepOp, TD, TLI);
+ }
+
+ // Same for CmpInsts.
+ if (CmpInst *C = dyn_cast<CmpInst>(I)) {
+ if (C->getOperand(0) == Op)
+ return SimplifyCmpInst(C->getPredicate(), RepOp, C->getOperand(1), TD,
+ TLI);
+ if (C->getOperand(1) == Op)
+ return SimplifyCmpInst(C->getPredicate(), C->getOperand(0), RepOp, TD,
+ TLI);
+ }
+
+ // TODO: We could hand off more cases to instsimplify here.
+
+ // If all operands are constant after substituting Op for RepOp then we can
+ // constant fold the instruction.
+ if (Constant *CRepOp = dyn_cast<Constant>(RepOp)) {
+ // Build a list of all constant operands.
+ SmallVector<Constant*, 8> ConstOps;
+ for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+ if (I->getOperand(i) == Op)
+ ConstOps.push_back(CRepOp);
+ else if (Constant *COp = dyn_cast<Constant>(I->getOperand(i)))
+ ConstOps.push_back(COp);
+ else
+ break;
+ }
+
+ // All operands were constants, fold it.
+ if (ConstOps.size() == I->getNumOperands()) {
+ if (CmpInst *C = dyn_cast<CmpInst>(I))
+ return ConstantFoldCompareInstOperands(C->getPredicate(), ConstOps[0],
+ ConstOps[1], TD, TLI);
+
+ if (LoadInst *LI = dyn_cast<LoadInst>(I))
+ if (!LI->isVolatile())
+ return ConstantFoldLoadFromConstPtr(ConstOps[0], TD);
+
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(),
+ ConstOps, TD, TLI);
+ }
+ }
+
+ return 0;
+}
+
/// visitSelectInstWithICmp - Visit a SelectInst that has an
/// ICmpInst as its first operand.
///
Value *FalseVal = SI.getFalseValue();
// Check cases where the comparison is with a constant that
- // can be adjusted to fit the min/max idiom. We may edit ICI in
- // place here, so make sure the select is the only user.
+ // can be adjusted to fit the min/max idiom. We may move or edit ICI
+ // here, so make sure the select is the only user.
if (ICI->hasOneUse())
if (ConstantInt *CI = dyn_cast<ConstantInt>(CmpRHS)) {
+ // X < MIN ? T : F --> F
+ if ((Pred == ICmpInst::ICMP_SLT || Pred == ICmpInst::ICMP_ULT)
+ && CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
+ return ReplaceInstUsesWith(SI, FalseVal);
+ // X > MAX ? T : F --> F
+ else if ((Pred == ICmpInst::ICMP_SGT || Pred == ICmpInst::ICMP_UGT)
+ && CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
+ return ReplaceInstUsesWith(SI, FalseVal);
switch (Pred) {
default: break;
case ICmpInst::ICMP_ULT:
- case ICmpInst::ICMP_SLT: {
- // X < MIN ? T : F --> F
- if (CI->isMinValue(Pred == ICmpInst::ICMP_SLT))
- return ReplaceInstUsesWith(SI, FalseVal);
- // X < C ? X : C-1 --> X > C-1 ? C-1 : X
- Constant *AdjustedRHS =
- ConstantInt::get(CI->getContext(), CI->getValue()-1);
- if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
- (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
- Pred = ICmpInst::getSwappedPredicate(Pred);
- CmpRHS = AdjustedRHS;
- std::swap(FalseVal, TrueVal);
- ICI->setPredicate(Pred);
- ICI->setOperand(1, CmpRHS);
- SI.setOperand(1, TrueVal);
- SI.setOperand(2, FalseVal);
- Changed = true;
- }
- break;
- }
+ case ICmpInst::ICMP_SLT:
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT: {
- // X > MAX ? T : F --> F
- if (CI->isMaxValue(Pred == ICmpInst::ICMP_SGT))
- return ReplaceInstUsesWith(SI, FalseVal);
+ // These transformations only work for selects over integers.
+ IntegerType *SelectTy = dyn_cast<IntegerType>(SI.getType());
+ if (!SelectTy)
+ break;
+
+ Constant *AdjustedRHS;
+ if (Pred == ICmpInst::ICMP_UGT || Pred == ICmpInst::ICMP_SGT)
+ AdjustedRHS = ConstantInt::get(CI->getContext(), CI->getValue() + 1);
+ else // (Pred == ICmpInst::ICMP_ULT || Pred == ICmpInst::ICMP_SLT)
+ AdjustedRHS = ConstantInt::get(CI->getContext(), CI->getValue() - 1);
+
// X > C ? X : C+1 --> X < C+1 ? C+1 : X
- Constant *AdjustedRHS =
- ConstantInt::get(CI->getContext(), CI->getValue()+1);
+ // X < C ? X : C-1 --> X > C-1 ? C-1 : X
if ((CmpLHS == TrueVal && AdjustedRHS == FalseVal) ||
- (CmpLHS == FalseVal && AdjustedRHS == TrueVal)) {
- Pred = ICmpInst::getSwappedPredicate(Pred);
- CmpRHS = AdjustedRHS;
- std::swap(FalseVal, TrueVal);
- ICI->setPredicate(Pred);
- ICI->setOperand(1, CmpRHS);
- SI.setOperand(1, TrueVal);
- SI.setOperand(2, FalseVal);
- Changed = true;
- }
+ (CmpLHS == FalseVal && AdjustedRHS == TrueVal))
+ ; // Nothing to do here. Values match without any sign/zero extension.
+
+ // Types do not match. Instead of calculating this with mixed types
+ // promote all to the larger type. This enables scalar evolution to
+ // analyze this expression.
+ else if (CmpRHS->getType()->getScalarSizeInBits()
+ < SelectTy->getBitWidth()) {
+ Constant *sextRHS = ConstantExpr::getSExt(AdjustedRHS, SelectTy);
+
+ // X = sext x; x >s c ? X : C+1 --> X = sext x; X <s C+1 ? C+1 : X
+ // X = sext x; x <s c ? X : C-1 --> X = sext x; X >s C-1 ? C-1 : X
+ // X = sext x; x >u c ? X : C+1 --> X = sext x; X <u C+1 ? C+1 : X
+ // X = sext x; x <u c ? X : C-1 --> X = sext x; X >u C-1 ? C-1 : X
+ if (match(TrueVal, m_SExt(m_Specific(CmpLHS))) &&
+ sextRHS == FalseVal) {
+ CmpLHS = TrueVal;
+ AdjustedRHS = sextRHS;
+ } else if (match(FalseVal, m_SExt(m_Specific(CmpLHS))) &&
+ sextRHS == TrueVal) {
+ CmpLHS = FalseVal;
+ AdjustedRHS = sextRHS;
+ } else if (ICI->isUnsigned()) {
+ Constant *zextRHS = ConstantExpr::getZExt(AdjustedRHS, SelectTy);
+ // X = zext x; x >u c ? X : C+1 --> X = zext x; X <u C+1 ? C+1 : X
+ // X = zext x; x <u c ? X : C-1 --> X = zext x; X >u C-1 ? C-1 : X
+ // zext + signed compare cannot be changed:
+ // 0xff <s 0x00, but 0x00ff >s 0x0000
+ if (match(TrueVal, m_ZExt(m_Specific(CmpLHS))) &&
+ zextRHS == FalseVal) {
+ CmpLHS = TrueVal;
+ AdjustedRHS = zextRHS;
+ } else if (match(FalseVal, m_ZExt(m_Specific(CmpLHS))) &&
+ zextRHS == TrueVal) {
+ CmpLHS = FalseVal;
+ AdjustedRHS = zextRHS;
+ } else
+ break;
+ } else
+ break;
+ } else
+ break;
+
+ Pred = ICmpInst::getSwappedPredicate(Pred);
+ CmpRHS = AdjustedRHS;
+ std::swap(FalseVal, TrueVal);
+ ICI->setPredicate(Pred);
+ ICI->setOperand(0, CmpLHS);
+ ICI->setOperand(1, CmpRHS);
+ SI.setOperand(1, TrueVal);
+ SI.setOperand(2, FalseVal);
+
+ // Move ICI instruction right before the select instruction. Otherwise
+ // the sext/zext value may be defined after the ICI instruction uses it.
+ ICI->moveBefore(&SI);
+
+ Changed = true;
break;
}
}
}
- if (CmpLHS == TrueVal && CmpRHS == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (Pred == ICmpInst::ICMP_EQ)
- return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? X : Y -> X
- if (Pred == ICmpInst::ICMP_NE)
- return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
+ // Transform (X >s -1) ? C1 : C2 --> ((X >>s 31) & (C2 - C1)) + C1
+ // and (X <s 0) ? C2 : C1 --> ((X >>s 31) & (C2 - C1)) + C1
+ // FIXME: Type and constness constraints could be lifted, but we have to
+ // watch code size carefully. We should consider xor instead of
+ // sub/add when we decide to do that.
+ if (IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
+ if (TrueVal->getType() == Ty) {
+ if (ConstantInt *Cmp = dyn_cast<ConstantInt>(CmpRHS)) {
+ ConstantInt *C1 = NULL, *C2 = NULL;
+ if (Pred == ICmpInst::ICMP_SGT && Cmp->isAllOnesValue()) {
+ C1 = dyn_cast<ConstantInt>(TrueVal);
+ C2 = dyn_cast<ConstantInt>(FalseVal);
+ } else if (Pred == ICmpInst::ICMP_SLT && Cmp->isNullValue()) {
+ C1 = dyn_cast<ConstantInt>(FalseVal);
+ C2 = dyn_cast<ConstantInt>(TrueVal);
+ }
+ if (C1 && C2) {
+ // This shift results in either -1 or 0.
+ Value *AShr = Builder->CreateAShr(CmpLHS, Ty->getBitWidth()-1);
- } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
- // Transform (X == Y) ? Y : X -> X
- if (Pred == ICmpInst::ICMP_EQ)
+ // Check if we can express the operation with a single or.
+ if (C2->isAllOnesValue())
+ return ReplaceInstUsesWith(SI, Builder->CreateOr(AShr, C1));
+
+ Value *And = Builder->CreateAnd(AShr, C2->getValue()-C1->getValue());
+ return ReplaceInstUsesWith(SI, Builder->CreateAdd(And, C1));
+ }
+ }
+ }
+ }
+
+ // If we have an equality comparison then we know the value in one of the
+ // arms of the select. See if substituting this value into the arm and
+ // simplifying the result yields the same value as the other arm.
+ if (Pred == ICmpInst::ICMP_EQ) {
+ if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, TD, TLI) == TrueVal ||
+ SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, TD, TLI) == TrueVal)
return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? Y : X -> Y
- if (Pred == ICmpInst::ICMP_NE)
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, TD, TLI) == FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, TD, TLI) == FalseVal)
+ return ReplaceInstUsesWith(SI, FalseVal);
+ } else if (Pred == ICmpInst::ICMP_NE) {
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, TD, TLI) == FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, TD, TLI) == FalseVal)
+ return ReplaceInstUsesWith(SI, TrueVal);
+ if (SimplifyWithOpReplaced(FalseVal, CmpLHS, CmpRHS, TD, TLI) == TrueVal ||
+ SimplifyWithOpReplaced(FalseVal, CmpRHS, CmpLHS, TD, TLI) == TrueVal)
return ReplaceInstUsesWith(SI, TrueVal);
- /// NOTE: if we wanted to, this is where to detect integer MIN/MAX
}
+
+ // NOTE: if we wanted to, this is where to detect integer MIN/MAX
+
+ if (CmpRHS != CmpLHS && isa<Constant>(CmpRHS)) {
+ if (CmpLHS == TrueVal && Pred == ICmpInst::ICMP_EQ) {
+ // Transform (X == C) ? X : Y -> (X == C) ? C : Y
+ SI.setOperand(1, CmpRHS);
+ Changed = true;
+ } else if (CmpLHS == FalseVal && Pred == ICmpInst::ICMP_NE) {
+ // Transform (X != C) ? Y : X -> (X != C) ? Y : C
+ SI.setOperand(2, CmpRHS);
+ Changed = true;
+ }
+ }
+
return Changed ? &SI : 0;
}
// can always be mapped.
const Instruction *I = dyn_cast<Instruction>(V);
if (I == 0) return true;
-
+
// If V is a PHI node defined in the same block as the condition PHI, we can
// map the arguments.
const PHINode *CondPHI = cast<PHINode>(SI.getCondition());
-
+
if (const PHINode *VP = dyn_cast<PHINode>(I))
if (VP->getParent() == CondPHI->getParent())
return true;
-
+
// Otherwise, if the PHI and select are defined in the same block and if V is
// defined in a different block, then we can transform it.
if (SI.getParent() == CondPHI->getParent() &&
I->getParent() != CondPHI->getParent())
return true;
-
+
// Otherwise we have a 'hard' case and we can't tell without doing more
// detailed dominator based analysis, punt.
return false;
}
/// FoldSPFofSPF - We have an SPF (e.g. a min or max) of an SPF of the form:
-/// SPF2(SPF1(A, B), C)
+/// SPF2(SPF1(A, B), C)
Instruction *InstCombiner::FoldSPFofSPF(Instruction *Inner,
SelectPatternFlavor SPF1,
Value *A, Value *B,
// MIN(MIN(a, b), a) -> MIN(a, b)
if (SPF1 == SPF2)
return ReplaceInstUsesWith(Outer, Inner);
-
+
// MAX(MIN(a, b), a) -> a
// MIN(MAX(a, b), a) -> a
if ((SPF1 == SPF_SMIN && SPF2 == SPF_SMAX) ||
(SPF1 == SPF_UMAX && SPF2 == SPF_UMIN))
return ReplaceInstUsesWith(Outer, C);
}
-
+
// TODO: MIN(MIN(A, 23), 97)
return 0;
}
+/// foldSelectICmpAnd - If one of the constants is zero (we know they can't
+/// both be) and we have an icmp instruction with zero, and we have an 'and'
+/// with the non-constant value and a power of two we can turn the select
+/// into a shift on the result of the 'and'.
+static Value *foldSelectICmpAnd(const SelectInst &SI, ConstantInt *TrueVal,
+ ConstantInt *FalseVal,
+ InstCombiner::BuilderTy *Builder) {
+ const ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition());
+ if (!IC || !IC->isEquality())
+ return 0;
+
+ if (!match(IC->getOperand(1), m_Zero()))
+ return 0;
+
+ ConstantInt *AndRHS;
+ Value *LHS = IC->getOperand(0);
+ if (LHS->getType() != SI.getType() ||
+ !match(LHS, m_And(m_Value(), m_ConstantInt(AndRHS))))
+ return 0;
+ // If both select arms are non-zero see if we have a select of the form
+ // 'x ? 2^n + C : C'. Then we can offset both arms by C, use the logic
+ // for 'x ? 2^n : 0' and fix the thing up at the end.
+ ConstantInt *Offset = 0;
+ if (!TrueVal->isZero() && !FalseVal->isZero()) {
+ if ((TrueVal->getValue() - FalseVal->getValue()).isPowerOf2())
+ Offset = FalseVal;
+ else if ((FalseVal->getValue() - TrueVal->getValue()).isPowerOf2())
+ Offset = TrueVal;
+ else
+ return 0;
+
+ // Adjust TrueVal and FalseVal to the offset.
+ TrueVal = ConstantInt::get(Builder->getContext(),
+ TrueVal->getValue() - Offset->getValue());
+ FalseVal = ConstantInt::get(Builder->getContext(),
+ FalseVal->getValue() - Offset->getValue());
+ }
+
+ // Make sure the mask in the 'and' and one of the select arms is a power of 2.
+ if (!AndRHS->getValue().isPowerOf2() ||
+ (!TrueVal->getValue().isPowerOf2() &&
+ !FalseVal->getValue().isPowerOf2()))
+ return 0;
+
+ // Determine which shift is needed to transform result of the 'and' into the
+ // desired result.
+ ConstantInt *ValC = !TrueVal->isZero() ? TrueVal : FalseVal;
+ unsigned ValZeros = ValC->getValue().logBase2();
+ unsigned AndZeros = AndRHS->getValue().logBase2();
+
+ Value *V = LHS;
+ if (ValZeros > AndZeros)
+ V = Builder->CreateShl(V, ValZeros - AndZeros);
+ else if (ValZeros < AndZeros)
+ V = Builder->CreateLShr(V, AndZeros - ValZeros);
+
+ // Okay, now we know that everything is set up, we just don't know whether we
+ // have a icmp_ne or icmp_eq and whether the true or false val is the zero.
+ bool ShouldNotVal = !TrueVal->isZero();
+ ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
+ if (ShouldNotVal)
+ V = Builder->CreateXor(V, ValC);
+
+ // Apply an offset if needed.
+ if (Offset)
+ V = Builder->CreateAdd(V, Offset);
+ return V;
+}
Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
Value *CondVal = SI.getCondition();
Value *TrueVal = SI.getTrueValue();
Value *FalseVal = SI.getFalseValue();
- // select true, X, Y -> X
- // select false, X, Y -> Y
- if (ConstantInt *C = dyn_cast<ConstantInt>(CondVal))
- return ReplaceInstUsesWith(SI, C->getZExtValue() ? TrueVal : FalseVal);
-
- // select C, X, X -> X
- if (TrueVal == FalseVal)
- return ReplaceInstUsesWith(SI, TrueVal);
-
- if (isa<UndefValue>(TrueVal)) // select C, undef, X -> X
- return ReplaceInstUsesWith(SI, FalseVal);
- if (isa<UndefValue>(FalseVal)) // select C, X, undef -> X
- return ReplaceInstUsesWith(SI, TrueVal);
- if (isa<UndefValue>(CondVal)) { // select undef, X, Y -> X or Y
- if (isa<Constant>(TrueVal))
- return ReplaceInstUsesWith(SI, TrueVal);
- else
- return ReplaceInstUsesWith(SI, FalseVal);
- }
+ if (Value *V = SimplifySelectInst(CondVal, TrueVal, FalseVal, TD))
+ return ReplaceInstUsesWith(SI, V);
if (SI.getType()->isIntegerTy(1)) {
if (ConstantInt *C = dyn_cast<ConstantInt>(TrueVal)) {
if (C->getZExtValue()) {
// Change: A = select B, true, C --> A = or B, C
return BinaryOperator::CreateOr(CondVal, FalseVal);
- } else {
- // Change: A = select B, false, C --> A = and !B, C
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
- return BinaryOperator::CreateAnd(NotCond, FalseVal);
}
+ // Change: A = select B, false, C --> A = and !B, C
+ Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName());
+ return BinaryOperator::CreateAnd(NotCond, FalseVal);
} else if (ConstantInt *C = dyn_cast<ConstantInt>(FalseVal)) {
if (C->getZExtValue() == false) {
// Change: A = select B, C, false --> A = and B, C
return BinaryOperator::CreateAnd(CondVal, TrueVal);
- } else {
- // Change: A = select B, C, true --> A = or !B, C
- Value *NotCond =
- InsertNewInstBefore(BinaryOperator::CreateNot(CondVal,
- "not."+CondVal->getName()), SI);
- return BinaryOperator::CreateOr(NotCond, TrueVal);
}
+ // Change: A = select B, C, true --> A = or !B, C
+ Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName());
+ return BinaryOperator::CreateOr(NotCond, TrueVal);
}
-
+
// select a, b, a -> a&b
// select a, a, b -> a|b
if (CondVal == TrueVal)
return BinaryOperator::CreateOr(CondVal, FalseVal);
else if (CondVal == FalseVal)
return BinaryOperator::CreateAnd(CondVal, TrueVal);
+
+ // select a, ~a, b -> (~a)&b
+ // select a, b, ~a -> (~a)|b
+ if (match(TrueVal, m_Not(m_Specific(CondVal))))
+ return BinaryOperator::CreateAnd(TrueVal, FalseVal);
+ else if (match(FalseVal, m_Not(m_Specific(CondVal))))
+ return BinaryOperator::CreateOr(TrueVal, FalseVal);
}
// Selecting between two integer constants?
// select C, -1, 0 -> sext C to int
if (FalseValC->isZero() && TrueValC->isAllOnesValue())
return new SExtInst(CondVal, SI.getType());
-
+
// select C, 0, 1 -> zext !C to int
if (TrueValC->isZero() && FalseValC->getValue() == 1) {
Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName());
Value *NotCond = Builder->CreateNot(CondVal, "not."+CondVal->getName());
return new SExtInst(NotCond, SI.getType());
}
-
- if (ICmpInst *IC = dyn_cast<ICmpInst>(SI.getCondition())) {
- // If one of the constants is zero (we know they can't both be) and we
- // have an icmp instruction with zero, and we have an 'and' with the
- // non-constant value, eliminate this whole mess. This corresponds to
- // cases like this: ((X & 27) ? 27 : 0)
- if (TrueValC->isZero() || FalseValC->isZero())
- if (IC->isEquality() && isa<ConstantInt>(IC->getOperand(1)) &&
- cast<Constant>(IC->getOperand(1))->isNullValue())
- if (Instruction *ICA = dyn_cast<Instruction>(IC->getOperand(0)))
- if (ICA->getOpcode() == Instruction::And &&
- isa<ConstantInt>(ICA->getOperand(1)) &&
- (ICA->getOperand(1) == TrueValC ||
- ICA->getOperand(1) == FalseValC) &&
- cast<ConstantInt>(ICA->getOperand(1))->getValue().isPowerOf2()) {
- // Okay, now we know that everything is set up, we just don't
- // know whether we have a icmp_ne or icmp_eq and whether the
- // true or false val is the zero.
- bool ShouldNotVal = !TrueValC->isZero();
- ShouldNotVal ^= IC->getPredicate() == ICmpInst::ICMP_NE;
- Value *V = ICA;
- if (ShouldNotVal)
- V = Builder->CreateXor(V, ICA->getOperand(1));
- return ReplaceInstUsesWith(SI, V);
- }
- }
+
+ if (Value *V = foldSelectICmpAnd(SI, TrueValC, FalseValC, Builder))
+ return ReplaceInstUsesWith(SI, V);
}
// See if we are selecting two values based on a comparison of the two values.
if (FCI->getOperand(0) == TrueVal && FCI->getOperand(1) == FalseVal) {
// Transform (X == Y) ? X : Y -> Y
if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
- // This is not safe in general for floating point:
+ // This is not safe in general for floating point:
// consider X== -0, Y== +0.
// It becomes safe if either operand is a nonzero constant.
ConstantFP *CFPt, *CFPf;
!CFPf->getValueAPF().isZero()))
return ReplaceInstUsesWith(SI, FalseVal);
}
- // Transform (X != Y) ? X : Y -> X
- if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
+ // Transform (X une Y) ? X : Y -> X
+ if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
+ // This is not safe in general for floating point:
+ // consider X== -0, Y== +0.
+ // It becomes safe if either operand is a nonzero constant.
+ ConstantFP *CFPt, *CFPf;
+ if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
+ !CFPt->getValueAPF().isZero()) ||
+ ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
+ !CFPf->getValueAPF().isZero()))
return ReplaceInstUsesWith(SI, TrueVal);
+ }
// NOTE: if we wanted to, this is where to detect MIN/MAX
} else if (FCI->getOperand(0) == FalseVal && FCI->getOperand(1) == TrueVal){
// Transform (X == Y) ? Y : X -> X
if (FCI->getPredicate() == FCmpInst::FCMP_OEQ) {
- // This is not safe in general for floating point:
+ // This is not safe in general for floating point:
// consider X== -0, Y== +0.
// It becomes safe if either operand is a nonzero constant.
ConstantFP *CFPt, *CFPf;
!CFPf->getValueAPF().isZero()))
return ReplaceInstUsesWith(SI, FalseVal);
}
- // Transform (X != Y) ? Y : X -> Y
- if (FCI->getPredicate() == FCmpInst::FCMP_ONE)
- return ReplaceInstUsesWith(SI, TrueVal);
+ // Transform (X une Y) ? Y : X -> Y
+ if (FCI->getPredicate() == FCmpInst::FCMP_UNE) {
+ // This is not safe in general for floating point:
+ // consider X== -0, Y== +0.
+ // It becomes safe if either operand is a nonzero constant.
+ ConstantFP *CFPt, *CFPf;
+ if (((CFPt = dyn_cast<ConstantFP>(TrueVal)) &&
+ !CFPt->getValueAPF().isZero()) ||
+ ((CFPf = dyn_cast<ConstantFP>(FalseVal)) &&
+ !CFPf->getValueAPF().isZero()))
+ return ReplaceInstUsesWith(SI, TrueVal);
+ }
// NOTE: if we wanted to, this is where to detect MIN/MAX
}
// NOTE: if we wanted to, this is where to detect ABS
// So at this point we know we have (Y -> OtherAddOp):
// select C, (add X, Y), (sub X, Z)
Value *NegVal; // Compute -Z
- if (Constant *C = dyn_cast<Constant>(SubOp->getOperand(1))) {
- NegVal = ConstantExpr::getNeg(C);
+ if (SI.getType()->isFPOrFPVectorTy()) {
+ NegVal = Builder->CreateFNeg(SubOp->getOperand(1));
} else {
- NegVal = InsertNewInstBefore(
- BinaryOperator::CreateNeg(SubOp->getOperand(1),
- "tmp"), SI);
+ NegVal = Builder->CreateNeg(SubOp->getOperand(1));
}
Value *NewTrueOp = OtherAddOp;
Value *NewFalseOp = NegVal;
if (AddOp != TI)
std::swap(NewTrueOp, NewFalseOp);
- Instruction *NewSel =
- SelectInst::Create(CondVal, NewTrueOp,
- NewFalseOp, SI.getName() + ".p");
-
- NewSel = InsertNewInstBefore(NewSel, SI);
- return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
+ Value *NewSel =
+ Builder->CreateSelect(CondVal, NewTrueOp,
+ NewFalseOp, SI.getName() + ".p");
+
+ if (SI.getType()->isFPOrFPVectorTy())
+ return BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
+ else
+ return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);
}
}
}
if (SI.getType()->isIntegerTy()) {
if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
return FoldI;
-
+
// MAX(MAX(a, b), a) -> MAX(a, b)
// MIN(MIN(a, b), a) -> MIN(a, b)
// MAX(MIN(a, b), a) -> a
}
// See if we can fold the select into a phi node if the condition is a select.
- if (isa<PHINode>(SI.getCondition()))
+ if (isa<PHINode>(SI.getCondition()))
// The true/false values have to be live in the PHI predecessor's blocks.
if (CanSelectOperandBeMappingIntoPredBlock(TrueVal, SI) &&
CanSelectOperandBeMappingIntoPredBlock(FalseVal, SI))
if (Instruction *NV = FoldOpIntoPhi(SI))
return NV;
+ if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
+ if (TrueSI->getCondition() == CondVal) {
+ if (SI.getTrueValue() == TrueSI->getTrueValue())
+ return 0;
+ SI.setOperand(1, TrueSI->getTrueValue());
+ return &SI;
+ }
+ }
+ if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
+ if (FalseSI->getCondition() == CondVal) {
+ if (SI.getFalseValue() == FalseSI->getFalseValue())
+ return 0;
+ SI.setOperand(2, FalseSI->getFalseValue());
+ return &SI;
+ }
+ }
+
if (BinaryOperator::isNot(CondVal)) {
SI.setOperand(0, BinaryOperator::getNotArgument(CondVal));
SI.setOperand(1, FalseVal);
return &SI;
}
+ if (VectorType *VecTy = dyn_cast<VectorType>(SI.getType())) {
+ unsigned VWidth = VecTy->getNumElements();
+ APInt UndefElts(VWidth, 0);
+ APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
+ if (Value *V = SimplifyDemandedVectorElts(&SI, AllOnesEltMask, UndefElts)) {
+ if (V != &SI)
+ return ReplaceInstUsesWith(SI, V);
+ return &SI;
+ }
+
+ if (ConstantVector *CV = dyn_cast<ConstantVector>(CondVal)) {
+ // Form a shufflevector instruction.
+ SmallVector<Constant *, 8> Mask(VWidth);
+ Type *Int32Ty = Type::getInt32Ty(CV->getContext());
+ for (unsigned i = 0; i != VWidth; ++i) {
+ Constant *Elem = cast<Constant>(CV->getOperand(i));
+ if (ConstantInt *E = dyn_cast<ConstantInt>(Elem))
+ Mask[i] = ConstantInt::get(Int32Ty, i + (E->isZero() ? VWidth : 0));
+ else if (isa<UndefValue>(Elem))
+ Mask[i] = UndefValue::get(Int32Ty);
+ else
+ return 0;
+ }
+ Constant *MaskVal = ConstantVector::get(Mask);
+ Value *V = Builder->CreateShuffleVector(TrueVal, FalseVal, MaskVal);
+ return ReplaceInstUsesWith(SI, V);
+ }
+
+ if (isa<ConstantAggregateZero>(CondVal)) {
+ return ReplaceInstUsesWith(SI, FalseVal);
+ }
+ }
+
return 0;
}
projects / oota-llvm.git / blobdiff