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Remove the code from IVUsers that attempted to handle

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casted induction variables in cases where the cast
isn't foldable. It ended up being a pessimization in
many cases. This could be fixed, but it would require
a bunch of complicated code in IVUsers' clients. The
advantages of this approach aren't visible enough to
justify it at this time.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73706 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
2009-06-18 16:54:06 +00:00
parent fd3daa74c2
commit 4e8a98519e
6 changed files with 20 additions and 68 deletions
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30
lib/Analysis/IVUsers.cpp
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@@ -82,11 +82,8 @@ static bool containsAddRecFromDifferentLoop(SCEVHandle S, Loop *L) {
/// outer loop of the current loop.
static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
SCEVHandle &Start, SCEVHandle &Stride,
bool &isSigned,
ScalarEvolution *SE, DominatorTree *DT) {
SCEVHandle TheAddRec = Start; // Initialize to zero.
bool isSExt = false;
bool isZExt = false;
// If the outer level is an AddExpr, the operands are all start values except
// for a nested AddRecExpr.
@@ -101,13 +98,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
} else {
Start = SE->getAddExpr(Start, AE->getOperand(i));
}
} else if (const SCEVZeroExtendExpr *Z = dyn_cast<SCEVZeroExtendExpr>(SH)) {
TheAddRec = Z->getOperand();
isZExt = true;
} else if (const SCEVSignExtendExpr *S = dyn_cast<SCEVSignExtendExpr>(SH)) {
TheAddRec = S->getOperand();
isSExt = true;
} else if (isa<SCEVAddRecExpr>(SH)) {
TheAddRec = SH;
} else {
@@ -131,9 +121,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
if (containsAddRecFromDifferentLoop(AddRecStart, L))
return false;
if (isSExt || isZExt)
Start = SE->getTruncateExpr(Start, AddRec->getType());
Start = SE->getAddExpr(Start, AddRecStart);
// If stride is an instruction, make sure it dominates the loop preheader.
@@ -148,7 +135,6 @@ static bool getSCEVStartAndStride(const SCEVHandle &SH, Loop *L, Loop *UseLoop,
}
Stride = AddRecStride;
isSigned = isSExt;
return true;
}
@@ -218,9 +204,8 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
Loop *UseLoop = LI->getLoopFor(I->getParent());
SCEVHandle Start = SE->getIntegerSCEV(0, ISE->getType());
SCEVHandle Stride = Start;
bool isSigned = false; // Arbitrary initial value - pacifies compiler.
if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, isSigned, SE, DT))
if (!getSCEVStartAndStride(ISE, L, UseLoop, Start, Stride, SE, DT))
return false; // Non-reducible symbolic expression, bail out.
SmallPtrSet<Instruction *, 4> UniqueUsers;
@@ -271,11 +256,11 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
// The value used will be incremented by the stride more than we are
// expecting, so subtract this off.
SCEVHandle NewStart = SE->getMinusSCEV(Start, Stride);
StrideUses->addUser(NewStart, User, I, isSigned);
StrideUses->addUser(NewStart, User, I);
StrideUses->Users.back().setIsUseOfPostIncrementedValue(true);
DOUT << " USING POSTINC SCEV, START=" << *NewStart<< "\n";
} else {
StrideUses->addUser(Start, User, I, isSigned);
StrideUses->addUser(Start, User, I);
}
}
}
@@ -312,7 +297,6 @@ bool IVUsers::runOnLoop(Loop *l, LPPassManager &LPM) {
/// getReplacementExpr - Return a SCEV expression which computes the
/// value of the OperandValToReplace of the given IVStrideUse.
SCEVHandle IVUsers::getReplacementExpr(const IVStrideUse &U) const {
const Type *UseTy = U.getOperandValToReplace()->getType();
// Start with zero.
SCEVHandle RetVal = SE->getIntegerSCEV(0, U.getParent()->Stride->getType());
// Create the basic add recurrence.
@@ -329,14 +313,6 @@ SCEVHandle IVUsers::getReplacementExpr(const IVStrideUse &U) const {
if (ExitVal->isLoopInvariant(L))
RetVal = ExitVal;
}
// Promote the result to the type of the use.
if (SE->getTypeSizeInBits(RetVal->getType()) !=
SE->getTypeSizeInBits(UseTy)) {
if (U.isSigned())
RetVal = SE->getSignExtendExpr(RetVal, UseTy);
else
RetVal = SE->getZeroExtendExpr(RetVal, UseTy);
}
return RetVal;
}