#include "InstCombine.h"
#include "llvm/Support/PatternMatch.h"
+#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
using namespace llvm;
using namespace PatternMatch;
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.
}
return BinaryOperator::Create(BO->getOpcode(), NewSI, MatchOp);
}
llvm_unreachable("Shouldn't get here");
- return 0;
}
static bool isSelect01(Constant *C1, Constant *C2) {
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 TargetData *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 (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.
///
case ICmpInst::ICMP_UGT:
case ICmpInst::ICMP_SGT: {
// These transformations only work for selects over integers.
- const IntegerType *SelectTy = dyn_cast<IntegerType>(SI.getType());
+ IntegerType *SelectTy = dyn_cast<IntegerType>(SI.getType());
if (!SelectTy)
break;
// 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 (const IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
+ 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 (CmpLHS == TrueVal && CmpRHS == FalseVal) {
- // Transform (X == Y) ? X : Y -> Y
- if (Pred == ICmpInst::ICMP_EQ)
+ // 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) ? 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
-
- } else if (CmpLHS == FalseVal && CmpRHS == TrueVal) {
- // Transform (X == Y) ? Y : X -> X
- if (Pred == ICmpInst::ICMP_EQ)
+ if (SimplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, TD, TLI) == FalseVal ||
+ SimplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, TD, TLI) == FalseVal)
return ReplaceInstUsesWith(SI, FalseVal);
- // Transform (X != Y) ? Y : X -> Y
- if (Pred == ICmpInst::ICMP_NE)
+ } 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
}
- if (isa<Constant>(CmpRHS)) {
+ // 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);
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?
// So at this point we know we have (Y -> OtherAddOp):
// select C, (add X, Y), (sub X, Z)
Value *NegVal; // Compute -Z
- if (SI.getType()->isFloatingPointTy()) {
+ if (SI.getType()->isFPOrFPVectorTy()) {
NegVal = Builder->CreateFNeg(SubOp->getOperand(1));
} else {
NegVal = Builder->CreateNeg(SubOp->getOperand(1));
Builder->CreateSelect(CondVal, NewTrueOp,
NewFalseOp, SI.getName() + ".p");
- if (SI.getType()->isFloatingPointTy())
+ if (SI.getType()->isFPOrFPVectorTy())
return BinaryOperator::CreateFAdd(SubOp->getOperand(0), NewSel);
else
return BinaryOperator::CreateAdd(SubOp->getOperand(0), NewSel);