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- InstCombine (cast (xor A, B) to bool) ==> (setne A, B)

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- InstCombine (cast (and X, (1 << size(X)-1)) to bool) ==> x < 0


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7241 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2003-07-22 21:46:59 +00:00
parent a73fede714
commit 1ba5bcd1ae
1 changed files with 44 additions and 5 deletions
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49
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -291,6 +291,13 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
return Changed ? &I : 0;
}
// isSignBit - Return true if the value represented by the constant only has the
// highest order bit set.
static bool isSignBit(ConstantInt *CI) {
unsigned NumBits = CI->getType()->getPrimitiveSize()*8;
return (CI->getRawValue() & ~(-1LL << NumBits)) == (1ULL << (NumBits-1));
}
Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@ -959,13 +966,15 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Src)) {
Value *Op0 = BO->getOperand(0), *Op1 = BO->getOperand(1);
// Replace (cast (sub A, B) to bool) with (setne A, B)
if (BO->getOpcode() == Instruction::Sub)
switch (BO->getOpcode()) {
case Instruction::Sub:
case Instruction::Xor:
// Replace (cast ([sub|xor] A, B) to bool) with (setne A, B)
return new SetCondInst(Instruction::SetNE, Op0, Op1);
// Replace (cast (add A, B) to bool) with (setne A, -B) if B is
// efficiently invertible, or if the add has just this one use.
if (BO->getOpcode() == Instruction::Add)
case Instruction::Add:
if (Value *NegVal = dyn_castNegVal(Op1))
return new SetCondInst(Instruction::SetNE, Op0, NegVal);
else if (Value *NegVal = dyn_castNegVal(Op0))
@ -976,6 +985,36 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
InsertNewInstBefore(Neg, CI);
return new SetCondInst(Instruction::SetNE, Op0, Neg);
}
break;
case Instruction::And:
// Replace (cast (and X, (1 << size(X)-1)) to bool) with x < 0,
// converting X to be a signed value as appropriate. Don't worry about
// bool values, as they will be optimized other ways if they occur in
// this configuration.
if (ConstantInt *CInt = dyn_cast<ConstantInt>(Op1))
if (isSignBit(CInt)) {
// If 'X' is not signed, insert a cast now...
if (!CInt->getType()->isSigned()) {
const Type *DestTy;
switch (CInt->getType()->getPrimitiveID()) {
case Type::UByteTyID: DestTy = Type::SByteTy; break;
case Type::UShortTyID: DestTy = Type::ShortTy; break;
case Type::UIntTyID: DestTy = Type::IntTy; break;
case Type::ULongTyID: DestTy = Type::LongTy; break;
default: assert(0 && "Invalid unsigned integer type!"); abort();
}
CastInst *NewCI = new CastInst(Op0, DestTy,
Op0->getName()+".signed");
InsertNewInstBefore(NewCI, CI);
Op0 = NewCI;
}
return new SetCondInst(Instruction::SetLT, Op0,
Constant::getNullValue(Op0->getType()));
}
break;
default: break;
}
}
}
@ -1294,7 +1333,7 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
// Instcombine load (constant global) into the value loaded...
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Op))
if ((GV->isConstant()) && (!(GV->isExternal())))
if (GV->isConstant() && !GV->isExternal())
return ReplaceInstUsesWith(LI, GV->getInitializer());
// Instcombine load (constantexpr_GEP global, 0, ...) into the value loaded...
@ -1302,7 +1341,7 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
if (CE->getOpcode() == Instruction::GetElementPtr)
if (ConstantPointerRef *G=dyn_cast<ConstantPointerRef>(CE->getOperand(0)))
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getValue()))
if ((GV->isConstant()) && (!(GV->isExternal())))
if (GV->isConstant() && !GV->isExternal())
if (Constant *V = GetGEPGlobalInitializer(GV->getInitializer(), CE))
return ReplaceInstUsesWith(LI, V);
return 0;