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author | Bill Wendling <isanbard@gmail.com> | 2013-01-17 21:28:46 +0000 |
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committer | Bill Wendling <isanbard@gmail.com> | 2013-01-17 21:28:46 +0000 |
commit | 167ede898a6105e05fcd9d2ae5679fbf1744018f (patch) | |
tree | 254dc04cdef9c9bb1e019ed1a9df88f5e5c7a402 /lib/Analysis | |
parent | cb4830cc99e790e0a76e1a9b1414e4b7e6e06134 (diff) | |
download | external_llvm-167ede898a6105e05fcd9d2ae5679fbf1744018f.zip external_llvm-167ede898a6105e05fcd9d2ae5679fbf1744018f.tar.gz external_llvm-167ede898a6105e05fcd9d2ae5679fbf1744018f.tar.bz2 |
Reverting r171325 & r172363. This was causing a mis-compile on the self-hosted LTO build bots.
Okay, here's how to reproduce the problem:
1) Build a Release (or Release+Asserts) version of clang in the normal way.
2) Using the clang & clang++ binaries from (1), build a Release (or
Release+Asserts) version of the same sources, but this time enable LTO ---
specify the `-flto' flag on the command line.
3) Run the ARC migrator tests:
$ arcmt-test --args -triple x86_64-apple-darwin10 -fsyntax-only -x objective-c++ ./src/tools/clang/test/ARCMT/cxx-rewrite.mm
You'll see that the output isn't correct (the whitespace is off).
The mis-compile is in the function `RewriteBuffer::RemoveText' in the
clang/lib/Rewrite/Core/Rewriter.cpp file. When that function and RewriteRope.cpp
are compiled with LTO and the `arcmt-test' executable is regenerated, you'll see
the error. When those files are not LTO'ed, then the output of the `arcmt-test'
is fine.
It is *really* hard to get a testcase out of this. I'll file a PR with what I
have currently.
--- Reverse-merging r172363 into '.':
U include/llvm/Analysis/MemoryBuiltins.h
U lib/Analysis/MemoryBuiltins.cpp
--- Reverse-merging r171325 into '.':
U test/Transforms/InstCombine/objsize.ll
G include/llvm/Analysis/MemoryBuiltins.h
G lib/Analysis/MemoryBuiltins.cpp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172756 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis')
-rw-r--r-- | lib/Analysis/MemoryBuiltins.cpp | 41 |
1 files changed, 12 insertions, 29 deletions
diff --git a/lib/Analysis/MemoryBuiltins.cpp b/lib/Analysis/MemoryBuiltins.cpp index 1d27a83..0fc0550 100644 --- a/lib/Analysis/MemoryBuiltins.cpp +++ b/lib/Analysis/MemoryBuiltins.cpp @@ -385,23 +385,16 @@ ObjectSizeOffsetVisitor::ObjectSizeOffsetVisitor(const DataLayout *TD, SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) { V = V->stripPointerCasts(); + if (Instruction *I = dyn_cast<Instruction>(V)) { + // If we have already seen this instruction, bail out. Cycles can happen in + // unreachable code after constant propagation. + if (!SeenInsts.insert(I)) + return unknown(); - if (isa<Instruction>(V) || isa<GEPOperator>(V)) { - // return cached value or insert unknown in cache if size of V was not - // computed yet in order to avoid recursions in PHis - std::pair<CacheMapTy::iterator, bool> CacheVal = - CacheMap.insert(std::make_pair(V, unknown())); - if (!CacheVal.second) - return CacheVal.first->second; - - SizeOffsetType Result; if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) - Result = visitGEPOperator(*GEP); - else - Result = visit(cast<Instruction>(*V)); - return CacheMap[V] = Result; + return visitGEPOperator(*GEP); + return visit(*I); } - if (Argument *A = dyn_cast<Argument>(V)) return visitArgument(*A); if (ConstantPointerNull *P = dyn_cast<ConstantPointerNull>(V)) @@ -415,6 +408,8 @@ SizeOffsetType ObjectSizeOffsetVisitor::compute(Value *V) { if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) { if (CE->getOpcode() == Instruction::IntToPtr) return unknown(); // clueless + if (CE->getOpcode() == Instruction::GetElementPtr) + return visitGEPOperator(cast<GEPOperator>(*CE)); } DEBUG(dbgs() << "ObjectSizeOffsetVisitor::compute() unhandled value: " << *V @@ -548,21 +543,9 @@ SizeOffsetType ObjectSizeOffsetVisitor::visitLoadInst(LoadInst&) { return unknown(); } -SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode &PHI) { - if (PHI.getNumIncomingValues() == 0) - return unknown(); - - SizeOffsetType Ret = compute(PHI.getIncomingValue(0)); - if (!bothKnown(Ret)) - return unknown(); - - // verify that all PHI incoming pointers have the same size and offset - for (unsigned i = 1, e = PHI.getNumIncomingValues(); i != e; ++i) { - SizeOffsetType EdgeData = compute(PHI.getIncomingValue(i)); - if (!bothKnown(EdgeData) || EdgeData != Ret) - return unknown(); - } - return Ret; +SizeOffsetType ObjectSizeOffsetVisitor::visitPHINode(PHINode&) { + // too complex to analyze statically. + return unknown(); } SizeOffsetType ObjectSizeOffsetVisitor::visitSelectInst(SelectInst &I) { |