From c5f22a78151eddef7848e09c9cb1b32017901d6e Mon Sep 17 00:00:00 2001 From: Eli Friedman Date: Thu, 7 Apr 2011 01:35:06 +0000 Subject: PR9634: Don't unconditionally tell the AliasSetTracker that the PreheaderLoad is equivalent to any other relevant value; it isn't true in general. If it is equivalent, the LoopPromoter will tell the AST the equivalence. Also, delete the PreheaderLoad if it is unused. Chris, since you were the last one to make major changes here, can you check that this is sane? llvm-svn: 129049 --- llvm/lib/Transforms/Scalar/LICM.cpp | 25 ++++--------------------- 1 file changed, 4 insertions(+), 21 deletions(-) (limited to 'llvm/lib/Transforms') diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp index 6cf1bd3deb5..93de9cf002e 100644 --- a/llvm/lib/Transforms/Scalar/LICM.cpp +++ b/llvm/lib/Transforms/Scalar/LICM.cpp @@ -743,30 +743,13 @@ void LICM::PromoteAliasSet(AliasSet &AS) { Preheader->getTerminator()); SSA.AddAvailableValue(Preheader, PreheaderLoad); - // Copy any value stored to or loaded from a must-alias of the pointer. - if (PreheaderLoad->getType()->isPointerTy()) { - Value *SomeValue; - if (LoadInst *LI = dyn_cast(LoopUses[0])) - SomeValue = LI; - else - SomeValue = cast(LoopUses[0])->getValueOperand(); - - CurAST->copyValue(SomeValue, PreheaderLoad); - } - // Rewrite all the loads in the loop and remember all the definitions from // stores in the loop. Promoter.run(LoopUses); - - // If the preheader load is itself a pointer, we need to tell alias analysis - // about the new pointer we created in the preheader block and about any PHI - // nodes that just got inserted. - if (PreheaderLoad->getType()->isPointerTy()) { - for (unsigned i = 0, e = NewPHIs.size(); i != e; ++i) - CurAST->copyValue(PreheaderLoad, NewPHIs[i]); - } - - // fwew, we're done! + + // If the SSAUpdater didn't use the load in the preheader, just zap it now. + if (PreheaderLoad->use_empty()) + PreheaderLoad->eraseFromParent(); } -- cgit v1.2.3