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Eliminate zext over (iv & const) or ((iv+const)&const) 

if a longer iv is available.  These subscript forms are
not common; they're a bottleneck in OpenSSL.

llvm-svn: 69215
This commit is contained in:
Dale Johannesen 2009-04-15 20:41:02 +00:00
parent 76784d70bc
commit 82230b5b17
1 changed files with 89 additions and 31 deletions
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120
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -798,48 +798,106 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
if (PN == OrigControllingPHI && PN->getType() != LargestType)
for (Value::use_iterator UI = PN->use_begin(), UE = PN->use_end();
UI != UE; ++UI) {
if (isa<SExtInst>(UI) && NoSignedWrap) {
Instruction *UInst = dyn_cast<Instruction>(*UI);
if (UInst && isa<SExtInst>(UInst) && NoSignedWrap) {
Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, L,
UI->getType(), Rewriter, InsertPt);
UI->replaceAllUsesWith(TruncIndVar);
if (Instruction *DeadUse = dyn_cast<Instruction>(*UI))
DeadInsts.insert(DeadUse);
UInst->getType(), Rewriter, InsertPt);
UInst->replaceAllUsesWith(TruncIndVar);
DeadInsts.insert(UInst);
}
// See if we can figure out sext(i+constant) doesn't wrap, so we can
// use a larger add. This is common in subscripting.
Instruction *UInst = dyn_cast<Instruction>(*UI);
if (UInst && UInst->getOpcode()==Instruction::Add &&
UInst->hasOneUse() &&
isa<ConstantInt>(UInst->getOperand(1)) &&
isa<SExtInst>(UInst->use_begin()) && NoSignedWrap && LimitVal) {
uint64_t numBits = LimitVal->getValue().getBitWidth();
ConstantInt* RHS = dyn_cast<ConstantInt>(UInst->getOperand(1));
if (((APInt::getSignedMaxValue(numBits) - IncrVal->getValue()) -
RHS->getValue()).sgt(LimitVal->getValue())) {
SExtInst* oldSext = dyn_cast<SExtInst>(UInst->use_begin());
Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType, L,
oldSext->getType(), Rewriter,
InsertPt);
APInt APcopy = APInt(RHS->getValue());
ConstantInt* newRHS =
ConstantInt::get(APcopy.sext(oldSext->getType()->
getPrimitiveSizeInBits()));
Value *NewAdd = BinaryOperator::CreateAdd(TruncIndVar, newRHS,
UInst->getName()+".nosex",
UInst);
oldSext->replaceAllUsesWith(NewAdd);
if (Instruction *DeadUse = dyn_cast<Instruction>(oldSext))
DeadInsts.insert(DeadUse);
if (Instruction *DeadUse = dyn_cast<Instruction>(UInst))
DeadInsts.insert(DeadUse);
NoSignedWrap && LimitVal) {
uint64_t oldBitSize = LimitVal->getValue().getBitWidth();
uint64_t newBitSize = LargestType->getPrimitiveSizeInBits();
ConstantInt* AddRHS = dyn_cast<ConstantInt>(UInst->getOperand(1));
if (((APInt::getSignedMaxValue(oldBitSize) - IncrVal->getValue()) -
AddRHS->getValue()).sgt(LimitVal->getValue())) {
// We've determined this is (i+constant) and it won't overflow.
if (isa<SExtInst>(UInst->use_begin())) {
SExtInst* oldSext = dyn_cast<SExtInst>(UInst->use_begin());
Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType,
L, oldSext->getType(), Rewriter,
InsertPt);
APInt APcopy = APInt(AddRHS->getValue());
ConstantInt* newAddRHS =ConstantInt::get(APcopy.sext(newBitSize));
Value *NewAdd =
BinaryOperator::CreateAdd(TruncIndVar, newAddRHS,
UInst->getName()+".nosex", UInst);
oldSext->replaceAllUsesWith(NewAdd);
if (Instruction *DeadUse = dyn_cast<Instruction>(oldSext))
DeadInsts.insert(DeadUse);
DeadInsts.insert(UInst);
}
}
}
if (isa<ZExtInst>(UI) && NoUnsignedWrap) {
if (UInst && isa<ZExtInst>(UInst) && NoUnsignedWrap) {
Value *TruncIndVar = getZeroExtendedTruncVar(AR, SE, LargestType, L,
UI->getType(), Rewriter, InsertPt);
UI->replaceAllUsesWith(TruncIndVar);
if (Instruction *DeadUse = dyn_cast<Instruction>(*UI))
UInst->getType(), Rewriter, InsertPt);
UInst->replaceAllUsesWith(TruncIndVar);
DeadInsts.insert(UInst);
}
// If we have zext(i&constant), we can use the larger variable. This
// is not common but is a bottleneck in Openssl.
// (RHS doesn't have to be constant. There should be a better approach
// than bottom-up pattern matching for this...)
if (UInst && UInst->getOpcode()==Instruction::And &&
UInst->hasOneUse() &&
isa<ConstantInt>(UInst->getOperand(1)) &&
isa<ZExtInst>(UInst->use_begin())) {
uint64_t newBitSize = LargestType->getPrimitiveSizeInBits();
ConstantInt* AndRHS = dyn_cast<ConstantInt>(UInst->getOperand(1));
ZExtInst* oldZext = dyn_cast<ZExtInst>(UInst->use_begin());
Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType,
L, oldZext->getType(), Rewriter, InsertPt);
APInt APcopy = APInt(AndRHS->getValue());
ConstantInt* newAndRHS = ConstantInt::get(APcopy.zext(newBitSize));
Value *NewAnd =
BinaryOperator::CreateAnd(TruncIndVar, newAndRHS,
UInst->getName()+".nozex", UInst);
oldZext->replaceAllUsesWith(NewAnd);
if (Instruction *DeadUse = dyn_cast<Instruction>(oldZext))
DeadInsts.insert(DeadUse);
DeadInsts.insert(UInst);
}
// If we have zext((i+constant)&constant), we can use the larger
// variable even if the add does overflow. This works whenever the
// constant being ANDed is the same size as i, which it presumably is.
// We don't need to restrict the expression being and'ed to i+const,
// but we have to promote everything in it, so it's convenient.
if (UInst && UInst->getOpcode()==Instruction::Add &&
UInst->hasOneUse() &&
isa<ConstantInt>(UInst->getOperand(1))) {
uint64_t newBitSize = LargestType->getPrimitiveSizeInBits();
ConstantInt* AddRHS = dyn_cast<ConstantInt>(UInst->getOperand(1));
Instruction *UInst2 = dyn_cast<Instruction>(UInst->use_begin());
if (UInst2 && UInst2->getOpcode() == Instruction::And &&
UInst2->hasOneUse() &&
isa<ConstantInt>(UInst2->getOperand(1)) &&
isa<ZExtInst>(UInst2->use_begin())) {
ZExtInst* oldZext = dyn_cast<ZExtInst>(UInst2->use_begin());
Value *TruncIndVar = getSignExtendedTruncVar(AR, SE, LargestType,
L, oldZext->getType(), Rewriter, InsertPt);
ConstantInt* AndRHS = dyn_cast<ConstantInt>(UInst2->getOperand(1));
APInt APcopy = APInt(AddRHS->getValue());
ConstantInt* newAddRHS = ConstantInt::get(APcopy.zext(newBitSize));
Value *NewAdd =
BinaryOperator::CreateAdd(TruncIndVar, newAddRHS,
UInst->getName()+".nozex", UInst2);
APInt APcopy2 = APInt(AndRHS->getValue());
ConstantInt* newAndRHS = ConstantInt::get(APcopy2.zext(newBitSize));
Value *NewAnd =
BinaryOperator::CreateAnd(NewAdd, newAndRHS,
UInst->getName()+".nozex", UInst2);
oldZext->replaceAllUsesWith(NewAnd);
if (Instruction *DeadUse = dyn_cast<Instruction>(oldZext))
DeadInsts.insert(DeadUse);
DeadInsts.insert(UInst);
DeadInsts.insert(UInst2);
}
}
}