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IR: Metadata: Detect an RAUW recursion

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Speculatively handle a recursion in
`GenericMDNode::handleChangedOperand()`.  I'm hoping this fixes the
failing hexagon bot [1].

[1]: http://lab.llvm.org:8011/builders/llvm-hexagon-elf/builds/13434

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223849 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan P. N. Exon Smith 2014-12-09 23:04:59 +00:00
parent c9f47d8821
commit ae5224d468
2 changed files with 12 additions and 2 deletions
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5
include/llvm/IR/Metadata.h
View File

@ -49,6 +49,7 @@ class Metadata {
protected:
/// \brief Storage flag for non-uniqued, otherwise unowned, metadata.
bool IsDistinctInContext : 1;
bool InRAUW : 1;
// TODO: expose remaining bits to subclasses.
unsigned short SubclassData16;
@ -65,8 +66,8 @@ public:
protected:
Metadata(unsigned ID)
: SubclassID(ID), IsDistinctInContext(false), SubclassData16(0),
SubclassData32(0) {}
: SubclassID(ID), IsDistinctInContext(false), InRAUW(false),
SubclassData16(0), SubclassData32(0) {}
~Metadata() {}
/// \brief Store this in a big non-uniqued untyped bucket.

9
lib/IR/Metadata.cpp
View File

@ -495,6 +495,14 @@ void GenericMDNode::handleChangedOperand(void *Ref, Metadata *New) {
setOperand(Op, New);
return;
}
if (InRAUW) {
// We just hit a recursion due to RAUW. Set the operand and move on, since
// we're about to be deleted.
//
// FIXME: Can this cycle really happen?
setOperand(Op, New);
return;
}
auto &Store = getContext().pImpl->MDNodeSet;
Store.erase(this);
@ -550,6 +558,7 @@ void GenericMDNode::handleChangedOperand(void *Ref, Metadata *New) {
// Collision.
if (!isResolved()) {
// Still unresolved, so RAUW.
InRAUW = true;
ReplaceableUses->replaceAllUsesWith(*I);
delete this;
return;