From 1dcad96dc68c8a4565f10759bcabc634f61243e0 Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Sat, 2 May 2009 05:36:01 +0000 Subject: [PATCH] Don't split critical edges during the AddUsersIfInteresting phase of LSR. This makes the AddUsersIfInteresting phase of LSR a pure analysis instead of a phase that potentially does CFG modifications. The conditions where this code would actually perform a split are rare, and in the cases where it actually would do a split the split is usually undone by CodeGenPrepare, and in cases where splits actually survive into codegen, they appear to hurt more often than they help. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70625 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/LoopStrengthReduce.cpp | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-) diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp index 29acfe8506e..e5502002713 100644 --- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp +++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp @@ -406,20 +406,7 @@ static bool IVUseShouldUsePostIncValue(Instruction *User, Instruction *IV, } // Okay, all uses of IV by PN are in predecessor blocks that really are - // dominated by the latch block. Split the critical edges and use the - // post-incremented value. - for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) - if (PN->getIncomingValue(i) == IV) { - SplitCriticalEdge(PN->getIncomingBlock(i), PN->getParent(), P, false); - // Splitting the critical edge can reduce the number of entries in this - // PHI. - e = PN->getNumIncomingValues(); - if (--NumUses == 0) break; - } - - // PHI node might have become a constant value after SplitCriticalEdge. - DeadInsts.push_back(User); - + // dominated by the latch block. Use the post-incremented value. return true; }