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Two fixes. First, stop using the ugly shouldSubstituteIndVar method. 

Second, disable substitution of quadratic addrec expressions to avoid putting
multiplies in loops!

llvm-svn: 14358
This commit is contained in:
Chris Lattner 2004-06-24 06:49:18 +00:00
parent 8863de761d
commit 7a002d6010
1 changed files with 7 additions and 1 deletions
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8
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -602,7 +602,13 @@ 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))
if (SE->shouldSubstituteIndVar(SCEV)) // HACK!
// 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.
if (!isa<SCEVAddRecExpr>(SCEV) ||
cast<SCEVAddRecExpr>(SCEV)->getNumOperands() < 3)
IndVars.push_back(std::make_pair(PN, SCEV));
}