From c3b3aa277acaccf85a49d8d74dde3f1e03a38041 Mon Sep 17 00:00:00 2001 From: Philip Reames Date: Wed, 1 Sep 2021 16:58:04 -0700 Subject: [PATCH] Fix a missing MemorySSA update in breakLoopBackedge This is a case I'd missed in 6a8237. The odd bit here is that missing the edge removal update seems to produce MemorySSA which verifies, but is still corrupt in a way which bothers following passes. I wasn't able to reduce a single pass test case, which is why the reported test case is taken as is. Differential Revision: https://reviews.llvm.org/D109068 --- llvm/lib/Transforms/Utils/LoopUtils.cpp | 7 +++++-- llvm/test/Transforms/LoopDeletion/bbi-59728.ll | 27 ++++++++++++++++++++++++++ 2 files changed, 32 insertions(+), 2 deletions(-) create mode 100644 llvm/test/Transforms/LoopDeletion/bbi-59728.ll diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp index 36d8bc5..b8f8ad5 100644 --- a/llvm/lib/Transforms/Utils/LoopUtils.cpp +++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp @@ -729,8 +729,9 @@ void llvm::breakLoopBackedge(Loop *L, DominatorTree &DT, ScalarEvolution &SE, // and outer loop so the other target doesn't need to an exit if (L->isLoopExiting(Latch)) { // TODO: Generalize ConstantFoldTerminator so that it can be used - // here without invalidating LCSSA. (Tricky case: header is an exit - // block of a preceeding sibling loop w/o dedicated exits.) + // here without invalidating LCSSA or MemorySSA. (Tricky case for + // LCSSA: header is an exit block of a preceeding sibling loop w/o + // dedicated exits.) const unsigned ExitIdx = L->contains(BI->getSuccessor(0)) ? 1 : 0; BasicBlock *ExitBB = BI->getSuccessor(ExitIdx); @@ -746,6 +747,8 @@ void llvm::breakLoopBackedge(Loop *L, DominatorTree &DT, ScalarEvolution &SE, BI->eraseFromParent(); DTU.applyUpdates({{DominatorTree::Delete, Latch, Header}}); + if (MSSA) + MSSAU->applyUpdates({{DominatorTree::Delete, Latch, Header}}, DT); return; } } diff --git a/llvm/test/Transforms/LoopDeletion/bbi-59728.ll b/llvm/test/Transforms/LoopDeletion/bbi-59728.ll new file mode 100644 index 0000000..7f7426f --- /dev/null +++ b/llvm/test/Transforms/LoopDeletion/bbi-59728.ll @@ -0,0 +1,27 @@ +; NOTE: Assertions have been autogenerated by utils/update_test_checks.py +; RUN: opt %s -verify-memoryssa -passes='loop-mssa(loop-deletion,loop-simplifycfg)' -S | FileCheck %s + +; This is a case where we failed to update memory SSA correctly in +; loop-deletion which escapes local verification, but causes a crash +; in loop-simplifycfg. +define void @func_45() { +; CHECK-LABEL: @func_45( +; CHECK-NEXT: entry: +; CHECK-NEXT: br label [[FOR_BODY45:%.*]] +; CHECK: for.body45: +; CHECK-NEXT: store i32 433429641, i32* undef, align 1 +; CHECK-NEXT: br label [[FOR_BODY45]] +; +entry: + br label %for.body45 + +for.body45: ; preds = %for.end72, %entry + br label %for.body48 + +for.body48: ; preds = %for.body48, %for.body45 + store i32 433429641, i32* undef, align 1 + br i1 undef, label %for.body48, label %for.end72 + +for.end72: ; preds = %for.body48 + br label %for.body45 +} -- 2.7.4