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DivergenceAnalysis: Fix crash with no return blocks 

The post dominator tree does not have a root node in this case.

llvm-svn: 268933
This commit is contained in:
Matt Arsenault 2016-05-09 16:57:08 +00:00
parent 91592568f9
commit 1af53a91c0
2 changed files with 37 additions and 1 deletions
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8
llvm/lib/Analysis/DivergenceAnalysis.cpp
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@ -143,7 +143,13 @@ void DivergencePropagator::exploreSyncDependency(TerminatorInst *TI) {
if (!DT.isReachableFromEntry(ThisBB))
return;
BasicBlock *IPostDom = PDT.getNode(ThisBB)->getIDom()->getBlock();
// If the function has no exit blocks or doesn't reach any exit blocks, the
// post dominator may be null.
DomTreeNode *ThisNode = PDT.getNode(ThisBB);
if (!ThisNode)
return;
BasicBlock *IPostDom = ThisNode->getIDom()->getBlock();
if (IPostDom == nullptr)
return;

30
llvm/test/Analysis/DivergenceAnalysis/AMDGPU/no-return-blocks.ll Normal file
View File

@ -0,0 +1,30 @@
; RUN: opt %s -mtriple amdgcn-- -analyze -divergence | FileCheck %s
; CHECK: DIVERGENT: %tmp5 = getelementptr inbounds float, float addrspace(1)* %arg, i64 %tmp2
; CHECK: DIVERGENT: %tmp10 = load volatile float, float addrspace(1)* %tmp5, align 4
; CHECK: DIVERGENT: %tmp11 = load volatile float, float addrspace(1)* %tmp5, align 4
; The post dominator tree does not have a root node in this case
define void @no_return_blocks(float addrspace(1)* noalias nocapture readonly %arg, float addrspace(1)* noalias nocapture readonly %arg1) #0 {
bb0:
%tmp = tail call i32 @llvm.amdgcn.workitem.id.x() #0
%tmp2 = sext i32 %tmp to i64
%tmp5 = getelementptr inbounds float, float addrspace(1)* %arg, i64 %tmp2
%tmp6 = load volatile float, float addrspace(1)* %tmp5, align 4
%tmp8 = fcmp olt float %tmp6, 0.000000e+00
br i1 %tmp8, label %bb1, label %bb2
bb1:
%tmp10 = load volatile float, float addrspace(1)* %tmp5, align 4
br label %bb2
bb2:
%tmp11 = load volatile float, float addrspace(1)* %tmp5, align 4
br label %bb1
}
; Function Attrs: nounwind readnone
declare i32 @llvm.amdgcn.workitem.id.x() #1
attributes #0 = { nounwind }
attributes #1 = { nounwind readnone }