From 98df4f9cf2dea81af1cc2e68f23b285d22cebc6a Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Thu, 11 Feb 2010 05:11:54 +0000 Subject: [PATCH] Make DSE only scan blocks that are reachable from the entry block. Other blocks may have pointer cycles that will crash basicaa and other alias analyses. In any case, there is no point wasting cycles optimizing dead blocks. This fixes rdar://7635088 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95852 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Transforms/Scalar/DeadStoreElimination.cpp | 8 +++++++- test/Transforms/DeadStoreElimination/crash.ll | 14 ++++++++++++++ 2 files changed, 21 insertions(+), 1 deletion(-) diff --git a/lib/Transforms/Scalar/DeadStoreElimination.cpp b/lib/Transforms/Scalar/DeadStoreElimination.cpp index 320afa19d5f..09c01d31412 100644 --- a/lib/Transforms/Scalar/DeadStoreElimination.cpp +++ b/lib/Transforms/Scalar/DeadStoreElimination.cpp @@ -44,8 +44,14 @@ namespace { virtual bool runOnFunction(Function &F) { bool Changed = false; + + DominatorTree &DT = getAnalysis(); + for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) - Changed |= runOnBasicBlock(*I); + // Only check non-dead blocks. Dead blocks may have strange pointer + // cycles that will confuse alias analysis. + if (DT.isReachableFromEntry(I)) + Changed |= runOnBasicBlock(*I); return Changed; } diff --git a/test/Transforms/DeadStoreElimination/crash.ll b/test/Transforms/DeadStoreElimination/crash.ll index f89f8f5185c..6d8ba71b209 100644 --- a/test/Transforms/DeadStoreElimination/crash.ll +++ b/test/Transforms/DeadStoreElimination/crash.ll @@ -41,3 +41,17 @@ bb14: ; preds = %bb4 } declare void @llvm.memcpy.i64(i8* nocapture, i8* nocapture, i64, i32) nounwind + + +; rdar://7635088 +define i32 @test3() { +entry: + ret i32 0 + +dead: + %P2 = getelementptr i32 *%P2, i32 52 + %Q2 = getelementptr i32 *%Q2, i32 52 + store i32 4, i32* %P2 + store i32 4, i32* %Q2 + br label %dead +} \ No newline at end of file -- 2.34.1