From 66b282014cff346ab20c6c8aed774ca2c6bfefd1 Mon Sep 17 00:00:00 2001 From: David Sherwood Date: Mon, 7 Oct 2024 07:58:27 +0100 Subject: [PATCH] [LoopVectorize] Remove redundant code in emitSCEVChecks (#111132) There was some code in emitSCEVChecks to update the dominator tree if LoopBypassBlocks is empty, however there are no tests that fail when replacing this code with an assert. I built both SPEC2017 and the LLVM test suite and also didn't see any build failures. I've removed the code for now and added an assert to guard this in case anything changes, since it seems pointless to have code that's impossible to defend. --- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 14 ++------------ 1 file changed, 2 insertions(+), 12 deletions(-) diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp index 447656b2a9950f..001c8987667df8 100644 --- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp +++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp @@ -2486,18 +2486,8 @@ BasicBlock *InnerLoopVectorizer::emitSCEVChecks(BasicBlock *Bypass) { (OptForSizeBasedOnProfile && Cost->Hints->getForce() != LoopVectorizeHints::FK_Enabled)) && "Cannot SCEV check stride or overflow when optimizing for size"); - - - // Update dominator only if this is first RT check. - if (LoopBypassBlocks.empty()) { - DT->changeImmediateDominator(Bypass, SCEVCheckBlock); - if (!Cost->requiresScalarEpilogue(VF.isVector())) - // If there is an epilogue which must run, there's no edge from the - // middle block to exit blocks and thus no need to update the immediate - // dominator of the exit blocks. - DT->changeImmediateDominator(LoopExitBlock, SCEVCheckBlock); - } - + assert(!LoopBypassBlocks.empty() && + "Should already be a bypass block due to iteration count check"); LoopBypassBlocks.push_back(SCEVCheckBlock); AddedSafetyChecks = true; return SCEVCheckBlock;