From 858cd1c33c6ba47cf3401b1e00862aa22302af10 Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Sat, 24 Mar 2012 23:03:27 +0000 Subject: [PATCH] Don't form a WeakVH around the sentinel node in the instructions BB list. This is a bad idea. ;] I'm hopeful this is the bug that's showing up with the MSVC bots, but we'll see. It is definitely unnecessary. InstSimplify won't do anything to a terminator instruction, we don't need to even include it in the iteration range. We can also skip the now dead terminator check, although I've made it an assert to help document that this is an important invariant. I'm still a bit queasy about this because there is an implicit assumption that the terminator instruction cannot be RAUW'ed by the simplification code. While that appears to be true at the moment, I see no guarantee that would ensure it remains true in the future. I'm looking at the cleanest way to solve that... git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@153399 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Utils/Local.cpp | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp index e65e5675acd..96c69337333 100644 --- a/lib/Transforms/Utils/Local.cpp +++ b/lib/Transforms/Utils/Local.cpp @@ -355,7 +355,8 @@ bool llvm::RecursivelyDeleteDeadPHINode(PHINode *PN) { /// instructions in other blocks as well in this block. bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD) { bool MadeChange = false; - for (BasicBlock::iterator BI = BB->begin(), E = BB->end(); BI != E; ) { + for (BasicBlock::iterator BI = BB->begin(), E = --BB->end(); BI != E; ) { + assert(!BI->isTerminator()); Instruction *Inst = BI++; WeakVH BIHandle(BI); @@ -366,9 +367,6 @@ bool llvm::SimplifyInstructionsInBlock(BasicBlock *BB, const TargetData *TD) { continue; } - if (Inst->isTerminator()) - break; - MadeChange |= RecursivelyDeleteTriviallyDeadInstructions(Inst); if (BIHandle != BI) BI = BB->begin();