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Allow indvar simplify to canonicalize ANY affine IV, not just affine IVs with

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constant stride.  This implements Transforms/IndVarsSimplify/variable-stride-ivs.ll


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22744 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-10 01:12:06 +00:00
parent a12489e34f
commit cda9ca5a4f
1 changed files with 8 additions and 8 deletions
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16
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -128,9 +128,9 @@ void IndVarSimplify::EliminatePointerRecurrence(PHINode *PN,
unsigned PreheaderIdx = PN->getBasicBlockIndex(Preheader);
unsigned BackedgeIdx = PreheaderIdx^1;
if (GetElementPtrInst *GEPI =
dyn_cast<GetElementPtrInst>(PN->getIncomingValue(BackedgeIdx)))
dyn_cast<GetElementPtrInst>(PN->getIncomingValue(BackedgeIdx)))
if (GEPI->getOperand(0) == PN) {
assert(GEPI->getNumOperands() == 2 && "GEP types must mismatch!");
assert(GEPI->getNumOperands() == 2 && "GEP types must match!");
// Okay, we found a pointer recurrence. Transform this pointer
// recurrence into an integer recurrence. Compute the value that gets
@ -407,13 +407,13 @@ void IndVarSimplify::runOnLoop(Loop *L) {
if (PN->getType()->isInteger()) { // FIXME: when we have fast-math, enable!
SCEVHandle SCEV = SE->getSCEV(PN);
if (SCEV->hasComputableLoopEvolution(L))
// FIXME: Without a strength reduction pass, it is an extremely bad idea
// to indvar substitute anything more complex than a linear induction
// variable. Doing so will put expensive multiply instructions inside
// of the loop. For now just disable indvar subst on anything more
// complex than a linear addrec.
// FIXME: It is an extremely bad idea to indvar substitute anything more
// complex than affine induction variables. Doing so will put expensive
// polynomial evaluations inside of the loop, and the str reduction pass
// currently can only reduce affine polynomials. For now just disable
// indvar subst on anything more complex than an affine addrec.
if (SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(SCEV))
if (AR->getNumOperands() == 2 && isa<SCEVConstant>(AR->getOperand(1)))
if (AR->isAffine())
IndVars.push_back(std::make_pair(PN, SCEV));
}
}