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[MemorySSA] Check for unreachable blocks when getting last definition.

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If a single predecessor is found, still check if the block is
unreachable. The test that found this had a self loop unreachable block.
Resolves PR43493.

llvm-svn: 373383
This commit is contained in:
Alina Sbirlea 2019-10-01 19:09:50 +00:00
parent e73903e8d2
commit df5f9ba943
2 changed files with 30 additions and 0 deletions
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3
lib/Analysis/MemorySSAUpdater.cpp
View File

@ -839,6 +839,9 @@ void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
} else {
// Single predecessor, BB cannot be dead. GetLastDef of Pred.
assert(Count == 1 && Pred && "Single predecessor expected.");
// BB can be unreachable though, return LoE if that is the case.
if (!DT.getNode(BB))
return MSSA->getLiveOnEntryDef();
BB = Pred;
}
};

27
test/Analysis/MemorySSA/pr43493.ll Normal file
View File

@ -0,0 +1,27 @@
; RUN: opt -enable-mssa-loop-dependency=true -loop-rotate -verify-memoryssa -S %s | FileCheck %s
; REQUIRES: asserts
; CHECK-LABEL: @func_35()
define void @func_35() {
entry:
br i1 undef, label %for.cond1704.preheader, label %return
for.cond1704.preheader: ; preds = %entry
br label %for.cond1704
for.cond1704: ; preds = %for.cond1704.preheader, %for.body1707
br i1 false, label %for.body1707, label %return.loopexit
for.body1707: ; preds = %for.cond1704
store i32 1712, i32* undef, align 1
br label %for.cond1704
for.body1102: ; preds = %for.body1102
br i1 undef, label %for.body1102, label %return
return.loopexit: ; preds = %for.cond1704
br label %return
return: ; preds = %return.loopexit, %for.body1102, %entry
ret void
}