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fix PR3217: fully cached queries need to be verified against the

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visited set before they are used.  If used, their blocks need to be
added to the visited set so that subsequent queries don't use conflicting
pointer values in the cache result blocks.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61080 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2008-12-16 07:10:09 +00:00
parent 812d7506d0
commit f478951b0e
2 changed files with 49 additions and 1 deletions
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22
lib/Analysis/MemoryDependenceAnalysis.cpp
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@ -601,10 +601,30 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize,
// If we have valid cached information for exactly the block we are
// investigating, just return it with no recomputation.
if (CacheInfo->first == BBSkipFirstBlockPair(StartBB, SkipFirstBlock)) {
// We have a fully cached result for this query then we can just return the
// cached results and populate the visited set. However, we have to verify
// that we don't already have conflicting results for these blocks. Check
// to ensure that if a block in the results set is in the visited set that
// it was for the same pointer query.
if (!Visited.empty()) {
for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
I != E; ++I) {
DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->first);
if (VI == Visited.end() || VI->second == Pointer) continue;
// We have a pointer mismatch in a block. Just return clobber, saying
// that something was clobbered in this result. We could also do a
// non-fully cached query, but there is little point in doing this.
return true;
}
}
for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end();
I != E; ++I)
I != E; ++I) {
Visited.insert(std::make_pair(I->first, Pointer));
if (!I->second.isNonLocal())
Result.push_back(*I);
}
++NumCacheCompleteNonLocalPtr;
return false;
}

28
test/Transforms/GVN/2008-12-15-CacheVisited.ll Normal file
View File

@ -0,0 +1,28 @@
; RUN: llvm-as < %s | opt -gvn | llvm-dis
; Cached results must be added to and verified against the visited sets.
; PR3217
define fastcc void @gen_field_die(i32* %decl) nounwind {
entry:
br i1 false, label %bb203, label %bb202
bb202: ; preds = %entry
unreachable
bb203: ; preds = %entry
%tmp = getelementptr i32* %decl, i32 1 ; <i32*> [#uses=1]
%tmp1 = load i32* %tmp, align 4 ; <i32> [#uses=0]
br i1 false, label %bb207, label %bb204
bb204: ; preds = %bb203
%tmp2 = getelementptr i32* %decl, i32 1 ; <i32*> [#uses=1]
br label %bb208
bb207: ; preds = %bb203
br label %bb208
bb208: ; preds = %bb207, %bb204
%iftmp.1374.0.in = phi i32* [ null, %bb207 ], [ %tmp2, %bb204 ] ; <i32*> [#uses=1]
%iftmp.1374.0 = load i32* %iftmp.1374.0.in ; <i32> [#uses=0]
unreachable
}