mirror of
https://github.com/RPCS3/llvm-mirror.git
synced 2024-12-24 04:25:22 +00:00
Clean up previous cast optimization a bit. Also make zext elimination a bit more aggressive: if it's not necessary to emit an AND (i.e. high bits are already zero), it's profitable to evaluate the operand at a different type.
llvm-svn: 62297
This commit is contained in:
parent
1810c6366d
commit
e7c9310d1b
@ -394,8 +394,7 @@ namespace {
|
||||
Value *EvaluateInDifferentType(Value *V, const Type *Ty, bool isSigned);
|
||||
|
||||
bool CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
unsigned CastOpc,
|
||||
int &NumCastsRemoved, bool &SeenTrunc);
|
||||
unsigned CastOpc, int &NumCastsRemoved);
|
||||
unsigned GetOrEnforceKnownAlignment(Value *V,
|
||||
unsigned PrefAlign = 0);
|
||||
|
||||
@ -7497,10 +7496,9 @@ Instruction *InstCombiner::PromoteCastOfAllocation(BitCastInst &CI,
|
||||
/// If CastOpc is a sext or zext, we are asking if the low bits of the value can
|
||||
/// bit computed in a larger type, which is then and'd or sext_in_reg'd to get
|
||||
/// the final result.
|
||||
bool
|
||||
InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
unsigned CastOpc,
|
||||
int &NumCastsRemoved, bool &SeenTrunc){
|
||||
bool InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
unsigned CastOpc,
|
||||
int &NumCastsRemoved){
|
||||
// We can always evaluate constants in another type.
|
||||
if (isa<ConstantInt>(V))
|
||||
return true;
|
||||
@ -7520,8 +7518,6 @@ InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
// casts first.
|
||||
if (!isa<CastInst>(I->getOperand(0)) && I->hasOneUse())
|
||||
++NumCastsRemoved;
|
||||
if (isa<TruncInst>(I))
|
||||
SeenTrunc = true;
|
||||
return true;
|
||||
}
|
||||
}
|
||||
@ -7540,9 +7536,9 @@ InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
case Instruction::Xor:
|
||||
// These operators can all arbitrarily be extended or truncated.
|
||||
return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc) &&
|
||||
NumCastsRemoved) &&
|
||||
CanEvaluateInDifferentType(I->getOperand(1), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc);
|
||||
NumCastsRemoved);
|
||||
|
||||
case Instruction::Shl:
|
||||
// If we are truncating the result of this SHL, and if it's a shift of a
|
||||
@ -7552,7 +7548,7 @@ InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
if (BitWidth < OrigTy->getBitWidth() &&
|
||||
CI->getLimitedValue(BitWidth) < BitWidth)
|
||||
return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc);
|
||||
NumCastsRemoved);
|
||||
}
|
||||
break;
|
||||
case Instruction::LShr:
|
||||
@ -7567,7 +7563,7 @@ InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
APInt::getHighBitsSet(OrigBitWidth, OrigBitWidth-BitWidth)) &&
|
||||
CI->getLimitedValue(BitWidth) < BitWidth) {
|
||||
return CanEvaluateInDifferentType(I->getOperand(0), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc);
|
||||
NumCastsRemoved);
|
||||
}
|
||||
}
|
||||
break;
|
||||
@ -7587,16 +7583,16 @@ InstCombiner::CanEvaluateInDifferentType(Value *V, const IntegerType *Ty,
|
||||
case Instruction::Select: {
|
||||
SelectInst *SI = cast<SelectInst>(I);
|
||||
return CanEvaluateInDifferentType(SI->getTrueValue(), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc) &&
|
||||
NumCastsRemoved) &&
|
||||
CanEvaluateInDifferentType(SI->getFalseValue(), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc);
|
||||
NumCastsRemoved);
|
||||
}
|
||||
case Instruction::PHI: {
|
||||
// We can change a phi if we can change all operands.
|
||||
PHINode *PN = cast<PHINode>(I);
|
||||
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
|
||||
if (!CanEvaluateInDifferentType(PN->getIncomingValue(i), Ty, CastOpc,
|
||||
NumCastsRemoved, SeenTrunc))
|
||||
NumCastsRemoved))
|
||||
return false;
|
||||
return true;
|
||||
}
|
||||
@ -7845,10 +7841,9 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
||||
|
||||
// Attempt to propagate the cast into the instruction for int->int casts.
|
||||
int NumCastsRemoved = 0;
|
||||
bool SeenTrunc = false;
|
||||
if (!isa<BitCastInst>(CI) &&
|
||||
CanEvaluateInDifferentType(SrcI, cast<IntegerType>(DestTy),
|
||||
CI.getOpcode(), NumCastsRemoved, SeenTrunc)) {
|
||||
CI.getOpcode(), NumCastsRemoved)) {
|
||||
// If this cast is a truncate, evaluting in a different type always
|
||||
// eliminates the cast, so it is always a win. If this is a zero-extension,
|
||||
// we need to do an AND to maintain the clear top-part of the computation,
|
||||
@ -7865,14 +7860,27 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
||||
case Instruction::Trunc:
|
||||
DoXForm = true;
|
||||
break;
|
||||
case Instruction::ZExt:
|
||||
case Instruction::ZExt: {
|
||||
DoXForm = NumCastsRemoved >= 1;
|
||||
// TODO: Check if we need to insert an AND.
|
||||
if (!DoXForm) {
|
||||
// If it's unnecessary to issue an AND to clear the high bits, it's
|
||||
// always profitable to do this xform.
|
||||
Value *TryRes = EvaluateInDifferentType(SrcI, DestTy,
|
||||
CI.getOpcode() == Instruction::SExt);
|
||||
APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
|
||||
if (MaskedValueIsZero(TryRes, Mask))
|
||||
return ReplaceInstUsesWith(CI, TryRes);
|
||||
else if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
|
||||
if (TryI->use_empty())
|
||||
EraseInstFromFunction(*TryI);
|
||||
}
|
||||
break;
|
||||
}
|
||||
case Instruction::SExt: {
|
||||
DoXForm = NumCastsRemoved >= 2;
|
||||
if (!SeenTrunc) {
|
||||
// Do we have to emit a truncate to SrcBitSize followed by a sext?
|
||||
if (!DoXForm && !isa<TruncInst>(SrcI)) {
|
||||
// If we do not have to emit the truncate + sext pair, then it's always
|
||||
// profitable to do this xform.
|
||||
//
|
||||
// It's not safe to eliminate the trunc + sext pair if one of the
|
||||
// eliminated cast is a truncate. e.g.
|
||||
@ -7880,11 +7888,14 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
||||
// t3 = sext i16 t2 to i32
|
||||
// !=
|
||||
// i32 t1
|
||||
unsigned NumSignBits = ComputeNumSignBits(&CI);
|
||||
if (NumSignBits > (DestBitSize - SrcBitSize)) {
|
||||
DoXForm = true;
|
||||
JustReplace = true;
|
||||
}
|
||||
Value *TryRes = EvaluateInDifferentType(SrcI, DestTy,
|
||||
CI.getOpcode() == Instruction::SExt);
|
||||
unsigned NumSignBits = ComputeNumSignBits(TryRes);
|
||||
if (NumSignBits > (DestBitSize - SrcBitSize))
|
||||
return ReplaceInstUsesWith(CI, TryRes);
|
||||
else if (Instruction *TryI = dyn_cast<Instruction>(TryRes))
|
||||
if (TryI->use_empty())
|
||||
EraseInstFromFunction(*TryI);
|
||||
}
|
||||
break;
|
||||
}
|
||||
@ -7893,6 +7904,10 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
||||
if (DoXForm) {
|
||||
Value *Res = EvaluateInDifferentType(SrcI, DestTy,
|
||||
CI.getOpcode() == Instruction::SExt);
|
||||
if (JustReplace)
|
||||
// Just replace this cast with the result.
|
||||
return ReplaceInstUsesWith(CI, Res);
|
||||
|
||||
assert(Res->getType() == DestTy);
|
||||
switch (CI.getOpcode()) {
|
||||
default: assert(0 && "Unknown cast type!");
|
||||
@ -7901,15 +7916,24 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
||||
// Just replace this cast with the result.
|
||||
return ReplaceInstUsesWith(CI, Res);
|
||||
case Instruction::ZExt: {
|
||||
// We need to emit an AND to clear the high bits.
|
||||
assert(SrcBitSize < DestBitSize && "Not a zext?");
|
||||
|
||||
// If the high bits are already zero, just replace this cast with the
|
||||
// result.
|
||||
APInt Mask(APInt::getBitsSet(DestBitSize, SrcBitSize, DestBitSize));
|
||||
if (MaskedValueIsZero(Res, Mask))
|
||||
return ReplaceInstUsesWith(CI, Res);
|
||||
|
||||
// We need to emit an AND to clear the high bits.
|
||||
Constant *C = ConstantInt::get(APInt::getLowBitsSet(DestBitSize,
|
||||
SrcBitSize));
|
||||
return BinaryOperator::CreateAnd(Res, C);
|
||||
}
|
||||
case Instruction::SExt:
|
||||
if (JustReplace)
|
||||
// Just replace this cast with the result.
|
||||
case Instruction::SExt: {
|
||||
// If the high bits are already filled with sign bit, just replace this
|
||||
// cast with the result.
|
||||
unsigned NumSignBits = ComputeNumSignBits(Res);
|
||||
if (NumSignBits > (DestBitSize - SrcBitSize))
|
||||
return ReplaceInstUsesWith(CI, Res);
|
||||
|
||||
// We need to emit a cast to truncate, then a cast to sext.
|
||||
@ -7917,6 +7941,7 @@ Instruction *InstCombiner::commonIntCastTransforms(CastInst &CI) {
|
||||
InsertCastBefore(Instruction::Trunc, Res, Src->getType(),
|
||||
CI), DestTy);
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -254,3 +254,10 @@ define i1 @test37(i32 %a) {
|
||||
ret i1 %e
|
||||
}
|
||||
|
||||
define i64 @test38(i32 %a) {
|
||||
%1 = icmp eq i32 %a, -2
|
||||
%2 = zext i1 %1 to i8
|
||||
%3 = xor i8 %2, 1
|
||||
%4 = zext i8 %3 to i64
|
||||
ret i64 %4
|
||||
}
|
||||
|
Loading…
Reference in New Issue
Block a user