diff options
| -rw-r--r-- | llvm/lib/Bitcode/Writer/ValueEnumerator.cpp | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp index f2be18e0378..c14591acc8a 100644 --- a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp +++ b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp @@ -495,29 +495,31 @@ void ValueEnumerator::EnumerateMDNodeOperands(const MDNode *N) { void ValueEnumerator::EnumerateMetadata(const Value *MD) { assert((isa<MDNode>(MD) || isa<MDString>(MD)) && "Invalid metadata kind"); - // Enumerate the type of this value. - EnumerateType(MD->getType()); - + // Skip function-local nodes themselves, but walk their operands. const MDNode *N = dyn_cast<MDNode>(MD); - - // In the module-level pass, skip function-local nodes themselves, but - // do walk their operands. if (N && N->isFunctionLocal() && N->getFunction()) { EnumerateMDNodeOperands(N); return; } - // Check to see if it's already in! - unsigned &MDValueID = MDValueMap[MD]; - if (MDValueID) + // Insert a dummy ID to block the co-recursive call to + // EnumerateMDNodeOperands() from re-visiting MD in a cyclic graph. + // + // Return early if there's already an ID. + if (!MDValueMap.insert(std::make_pair(MD, 0)).second) return; - MDValues.push_back(MD); - MDValueID = MDValues.size(); + // Enumerate the type of this value. + EnumerateType(MD->getType()); - // Enumerate all non-function-local operands. + // Visit operands first to minimize RAUW. if (N) EnumerateMDNodeOperands(N); + + // Replace the dummy ID inserted above with the correct one. MDValueMap may + // have changed by inserting operands, so we need a fresh lookup here. + MDValues.push_back(MD); + MDValueMap[MD] = MDValues.size(); } /// EnumerateFunctionLocalMetadataa - Incorporate function-local metadata |
