Reviewers: Kevin Millikin,
Description:
Adjust pointer maps for branches when connecting live ranges.
Please review this at http://codereview.chromium.org/6541024/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files:
M src/lithium-allocator.cc
Index: src/lithium-allocator.cc
diff --git a/src/lithium-allocator.cc b/src/lithium-allocator.cc
index
9f5f1b97d8d60b0c5a084963224e4d98303f3401..d745b0c8d4f9a34fcfd878e6808b838494a16de2
100644
--- a/src/lithium-allocator.cc
+++ b/src/lithium-allocator.cc
@@ -1098,6 +1098,21 @@ void LAllocator::ResolveControlFlow(LiveRange* range,
} else {
ASSERT(pred->end()->SecondSuccessor() == NULL);
gap = GetLastGap(pred);
+
+ // We are going to insert mov from one live-range to another
before the
+ // branch instruction. Some branch instructions (e.g. loops' back
edges)
+ // can potentially cause a GC so they have a pointer map.
+ // By insterting a move we essentially create a copy of a
+ // value which is invisible to PopulatePointerMaps(), because we
store
+ // it into a location different from the operand of a live range
+ // covering a branch instruction.
+ // Thus we need to manually record a pointer.
+ if (HasTaggedValue(range->id())) {
+ LInstruction* branch =
InstructionAt(pred->last_instruction_index());
+ if (branch->HasPointerMap()) {
+ branch->pointer_map()->RecordPointer(cur_op);
+ }
+ }
}
gap->GetOrCreateParallelMove(LGap::START)->AddMove(pred_op, cur_op);
}
--
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