diff options
| author | Chris Lattner <sabre@nondot.org> | 2004-06-24 06:49:18 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2004-06-24 06:49:18 +0000 |
| commit | a25502acd7c0d56cbd20da37f25830d81be834c5 (patch) | |
| tree | d1a290ab384dc1ab622d0c99cb80df58244a5052 /lib/Transforms | |
| parent | 7548a540f74be48b3d900134e7220155aab1703a (diff) | |
Two fixes. First, stop using the ugly shouldSubstituteIndVar method.
Second, disable substitution of quadratic addrec expressions to avoid putting
multiplies in loops!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@14358 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/IndVarSimplify.cpp | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp index 56f021334b..5c4c63be5b 100644 --- a/lib/Transforms/Scalar/IndVarSimplify.cpp +++ b/lib/Transforms/Scalar/IndVarSimplify.cpp @@ -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)); } |