From a823e3d42c48ceeb2f5011f7402031bf02fa0fe1 Mon Sep 17 00:00:00 2001 From: Bill Wendling Date: Wed, 26 Oct 2011 01:10:25 +0000 Subject: [PATCH] Reapply r142920 with fix: An MBB which branches to an EH landing pad shouldn't be considered for tail merging. In SjLj EH, the jump to the landing pad is not done explicitly through a branch statement. The EH landing pad is added as a successor to the throwing BB. Because of that however, the branch folding pass could mistakenly think that it could merge the throwing BB with another BB. This isn't safe to do. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143001 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/BranchFolding.cpp | 3 +++ 1 file changed, 3 insertions(+) diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp index 75288b0934c..5dec3681127 100644 --- a/lib/CodeGen/BranchFolding.cpp +++ b/lib/CodeGen/BranchFolding.cpp @@ -870,6 +870,9 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) { // Visit each predecessor only once. if (!UniquePreds.insert(PBB)) continue; + // Skip blocks which may jump to a landing pad. Can't tail merge these. + if (PBB->getLandingPadSuccessor()) + continue; MachineBasicBlock *TBB = 0, *FBB = 0; SmallVector Cond; if (!TII->AnalyzeBranch(*PBB, TBB, FBB, Cond, true)) {