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author | Bill Wendling <isanbard@gmail.com> | 2012-10-23 18:37:11 +0000 |
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committer | Bill Wendling <isanbard@gmail.com> | 2012-10-23 18:37:11 +0000 |
commit | b846719663fb7f7847dacf956696ef257ab88d8e (patch) | |
tree | 30a2ef186a192fc5b9f64b0d23ed8df81f895b24 | |
parent | 5a719fcb5ea91ec4e7af6fc2e48ec31774a859dd (diff) | |
download | llvm-b846719663fb7f7847dacf956696ef257ab88d8e.tar.gz llvm-b846719663fb7f7847dacf956696ef257ab88d8e.tar.bz2 llvm-b846719663fb7f7847dacf956696ef257ab88d8e.tar.xz |
Ignore unreachable blocks when doing memory dependence analysis on non-local
loads. It's not really profitable and may result in GVN going into an infinite
loop when it hits constructs like this:
%x = gep %some.type %x, ...
Found via an LTO build of LLVM.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166490 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | lib/Analysis/MemoryDependenceAnalysis.cpp | 4 | ||||
-rw-r--r-- | test/Transforms/GVN/crash.ll | 36 |
2 files changed, 38 insertions, 2 deletions
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index 9316df6fbf..9872890494 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -983,7 +983,7 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer, for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end(); I != E; ++I) { Visited.insert(std::make_pair(I->getBB(), Addr)); - if (!I->getResult().isNonLocal()) + if (!I->getResult().isNonLocal() && DT->isReachableFromEntry(I->getBB())) Result.push_back(NonLocalDepResult(I->getBB(), I->getResult(), Addr)); } ++NumCacheCompleteNonLocalPtr; @@ -1029,7 +1029,7 @@ getNonLocalPointerDepFromBB(const PHITransAddr &Pointer, NumSortedEntries); // If we got a Def or Clobber, add this to the list of results. - if (!Dep.isNonLocal()) { + if (!Dep.isNonLocal() && DT->isReachableFromEntry(BB)) { Result.push_back(NonLocalDepResult(BB, Dep, Pointer.getAddr())); continue; } diff --git a/test/Transforms/GVN/crash.ll b/test/Transforms/GVN/crash.ll index 31eae256c6..4a8c8e4589 100644 --- a/test/Transforms/GVN/crash.ll +++ b/test/Transforms/GVN/crash.ll @@ -163,3 +163,39 @@ entry: ret i8 %1 } + +; Test that a GEP in an unreachable block with the following form doesn't crash +; GVN: +; +; %x = gep %some.type %x, ... + +%struct.type = type { i64, i32, i32 } + +define fastcc void @func() nounwind uwtable ssp align 2 { +entry: + br label %reachable.bb + +;; Unreachable code. + +unreachable.bb: + %gep.val = getelementptr inbounds %struct.type* %gep.val, i64 1 + br i1 undef, label %u2.bb, label %u1.bb + +u1.bb: + %tmp1 = getelementptr inbounds %struct.type* %gep.val, i64 0, i32 0 + store i64 -1, i64* %tmp1, align 8 + br label %unreachable.bb + +u2.bb: + %0 = load i32* undef, align 4 + %conv.i.i.i.i.i = zext i32 %0 to i64 + br label %u2.bb + +;; Reachable code. + +reachable.bb: + br label %r1.bb + +r1.bb: + br label %u2.bb +} |