[llvm] 37aa16e - [DA] Don't propagate from unreachable blocks
Austin Kerbow via llvm-commits
llvm-commits at lists.llvm.org
Fri Jan 24 10:29:19 PST 2020
Author: Austin Kerbow
Date: 2020-01-24T10:28:11-08:00
New Revision: 37aa16ebb713c1d76d93f7d29419fd6ea88ac72c
URL: https://github.com/llvm/llvm-project/commit/37aa16ebb713c1d76d93f7d29419fd6ea88ac72c
DIFF: https://github.com/llvm/llvm-project/commit/37aa16ebb713c1d76d93f7d29419fd6ea88ac72c.diff
LOG: [DA] Don't propagate from unreachable blocks
Summary: Fixes crash that could occur when a divergent terminator has an unreachable parent.
Reviewers: rampitec, nhaehnle, arsenm
Subscribers: jvesely, wdng, hiraditya, jfb, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73323
Added:
llvm/test/Analysis/DivergenceAnalysis/AMDGPU/unreachable-loop-block.ll
Modified:
llvm/lib/Analysis/DivergenceAnalysis.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Analysis/DivergenceAnalysis.cpp b/llvm/lib/Analysis/DivergenceAnalysis.cpp
index 3d1be1e1cce0..402ec5f3a25e 100644
--- a/llvm/lib/Analysis/DivergenceAnalysis.cpp
+++ b/llvm/lib/Analysis/DivergenceAnalysis.cpp
@@ -301,6 +301,10 @@ void DivergenceAnalysis::propagateBranchDivergence(const Instruction &Term) {
markDivergent(Term);
+ // Don't propagate divergence from unreachable blocks.
+ if (!DT.isReachableFromEntry(Term.getParent()))
+ return;
+
const auto *BranchLoop = LI.getLoopFor(Term.getParent());
// whether there is a divergent loop exit from BranchLoop (if any)
diff --git a/llvm/test/Analysis/DivergenceAnalysis/AMDGPU/unreachable-loop-block.ll b/llvm/test/Analysis/DivergenceAnalysis/AMDGPU/unreachable-loop-block.ll
new file mode 100644
index 000000000000..af3db4c88815
--- /dev/null
+++ b/llvm/test/Analysis/DivergenceAnalysis/AMDGPU/unreachable-loop-block.ll
@@ -0,0 +1,17 @@
+; RUN: opt %s -mtriple amdgcn-- -analyze -divergence -use-gpu-divergence-analysis | FileCheck %s
+
+; CHECK: DIVERGENT: %tmp = cmpxchg volatile
+define amdgpu_kernel void @unreachable_loop(i32 %tidx) #0 {
+entry:
+ unreachable
+
+unreachable_loop: ; preds = %do.body.i, %if.then11
+ %tmp = cmpxchg volatile i32 addrspace(1)* null, i32 0, i32 0 seq_cst seq_cst
+ %cmp.i = extractvalue { i32, i1 } %tmp, 1
+ br i1 %cmp.i, label %unreachable_loop, label %end
+
+end: ; preds = %do.body.i51, %atomicAdd_g_f.exit
+ unreachable
+}
+
+attributes #0 = { norecurse nounwind }
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