[PATCH] D73323: [DA] Don't propagate from unreachable blocks
Austin Kerbow via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Thu Jan 23 19:56:14 PST 2020
kerbowa created this revision.
kerbowa added reviewers: rampitec, nhaehnle, arsenm.
Herald added subscribers: llvm-commits, jfb, hiraditya, wdng, jvesely.
Herald added a project: LLVM.
Fixes crash that could occur when a divergent terminator has an unreachable parent.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D73323
Files:
llvm/lib/Analysis/DivergenceAnalysis.cpp
llvm/test/Analysis/DivergenceAnalysis/AMDGPU/unreachable-loop-block.ll
Index: llvm/test/Analysis/DivergenceAnalysis/AMDGPU/unreachable-loop-block.ll
===================================================================
--- /dev/null
+++ 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 }
Index: llvm/lib/Analysis/DivergenceAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/DivergenceAnalysis.cpp
+++ llvm/lib/Analysis/DivergenceAnalysis.cpp
@@ -301,6 +301,10 @@
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)
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