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Eliminate zext over (iv | const) or (signed iv),

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and sext over (iv | const), if a longer iv is
available.  Allow expressions to have more than
one zext/sext parent.  All from OpenSSL.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@69241 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2009-04-15 23:31:51 +00:00
parent a0ed8ca233
commit c671d892ab
1 changed files with 77 additions and 22 deletions
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99
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -663,6 +663,23 @@ static Value *getZeroExtendedTruncVar(const SCEVAddRecExpr *AR,
return Rewriter.expandCodeFor(ExtendedAddRec, InsertPt);
}
/// allUsesAreSameTyped - See whether all Uses of I are instructions
/// with the same Opcode and the same type.
static bool allUsesAreSameTyped(unsigned int Opcode, Instruction *I) {
const Type* firstType = NULL;
for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
UI != UE; ++UI) {
Instruction *II = dyn_cast<Instruction>(*UI);
if (!II || II->getOpcode() != Opcode)
return false;
if (!firstType)
firstType = II->getType();
else if (firstType != II->getType())
return false;
}
return true;
}
bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
LI = &getAnalysis<LoopInfo>();
SE = &getAnalysis<ScalarEvolution>();
@ -808,7 +825,7 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
// See if we can figure out sext(i+constant) doesn't wrap, so we can
// use a larger add. This is common in subscripting.
if (UInst && UInst->getOpcode()==Instruction::Add &&
UInst->hasOneUse() &&
allUsesAreSameTyped(Instruction::SExt, UInst) &&
isa<ConstantInt>(UInst->getOperand(1)) &&
NoSignedWrap && LimitVal) {
uint64_t oldBitSize = LimitVal->getValue().getBitWidth();
@ -827,27 +844,56 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
Value *NewAdd =
BinaryOperator::CreateAdd(TruncIndVar, newAddRHS,
UInst->getName()+".nosex", UInst);
oldSext->replaceAllUsesWith(NewAdd);
if (Instruction *DeadUse = dyn_cast<Instruction>(oldSext))
DeadInsts.insert(DeadUse);
for (Value::use_iterator UI2 = UInst->use_begin(),
UE2 = UInst->use_end(); UI2 != UE2; ++UI2) {
Instruction *II = dyn_cast<Instruction>(UI2);
II->replaceAllUsesWith(NewAdd);
DeadInsts.insert(II);
}
DeadInsts.insert(UInst);
}
}
}
if (UInst && isa<ZExtInst>(UInst) && NoUnsignedWrap) {
// Try for sext(i | constant). This is safe as long as the
// high bit of the constant is not set.
if (UInst && UInst->getOpcode()==Instruction::Or &&
allUsesAreSameTyped(Instruction::SExt, UInst) && NoSignedWrap &&
isa<ConstantInt>(UInst->getOperand(1))) {
ConstantInt* RHS = dyn_cast<ConstantInt>(UInst->getOperand(1));
if (!RHS->getValue().isNegative()) {
uint64_t newBitSize = LargestType->getPrimitiveSizeInBits();
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(newBitSize));
Value *NewAdd =
BinaryOperator::CreateOr(TruncIndVar, newRHS,
UInst->getName()+".nosex", UInst);
for (Value::use_iterator UI2 = UInst->use_begin(),
UE2 = UInst->use_end(); UI2 != UE2; ++UI2) {
Instruction *II = dyn_cast<Instruction>(UI2);
II->replaceAllUsesWith(NewAdd);
DeadInsts.insert(II);
}
DeadInsts.insert(UInst);
}
}
// A zext of a signed variable known not to overflow is still safe.
if (UInst && isa<ZExtInst>(UInst) && (NoUnsignedWrap || NoSignedWrap)) {
Value *TruncIndVar = getZeroExtendedTruncVar(AR, SE, LargestType, L,
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.
// If we have zext(i&constant), it's always safe to 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())) {
allUsesAreSameTyped(Instruction::ZExt, UInst) &&
isa<ConstantInt>(UInst->getOperand(1))) {
uint64_t newBitSize = LargestType->getPrimitiveSizeInBits();
ConstantInt* AndRHS = dyn_cast<ConstantInt>(UInst->getOperand(1));
ZExtInst* oldZext = dyn_cast<ZExtInst>(UInst->use_begin());
@ -858,9 +904,12 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
Value *NewAnd =
BinaryOperator::CreateAnd(TruncIndVar, newAndRHS,
UInst->getName()+".nozex", UInst);
oldZext->replaceAllUsesWith(NewAnd);
if (Instruction *DeadUse = dyn_cast<Instruction>(oldZext))
DeadInsts.insert(DeadUse);
for (Value::use_iterator UI2 = UInst->use_begin(),
UE2 = UInst->use_end(); UI2 != UE2; ++UI2) {
Instruction *II = dyn_cast<Instruction>(UI2);
II->replaceAllUsesWith(NewAnd);
DeadInsts.insert(II);
}
DeadInsts.insert(UInst);
}
// If we have zext((i+constant)&constant), we can use the larger
@ -868,33 +917,39 @@ bool IndVarSimplify::runOnLoop(Loop *L, LPPassManager &LPM) {
// 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 &&
// zext((i | constant)&constant) is also valid and accepted here.
if (UInst && (UInst->getOpcode()==Instruction::Add ||
UInst->getOpcode()==Instruction::Or) &&
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())) {
allUsesAreSameTyped(Instruction::ZExt, UInst2) &&
isa<ConstantInt>(UInst2->getOperand(1))) {
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 =
Value *NewAdd = ((UInst->getOpcode()==Instruction::Add) ?
BinaryOperator::CreateAdd(TruncIndVar, newAddRHS,
UInst->getName()+".nozex", UInst2);
UInst->getName()+".nozex", UInst2) :
BinaryOperator::CreateOr(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);
for (Value::use_iterator UI2 = UInst2->use_begin(),
UE2 = UInst2->use_end(); UI2 != UE2; ++UI2) {
Instruction *II = dyn_cast<Instruction>(UI2);
II->replaceAllUsesWith(NewAnd);
DeadInsts.insert(II);
}
DeadInsts.insert(UInst);
DeadInsts.insert(UInst2);
}