Revision: 6858
Author: [email protected]
Date: Fri Feb 18 08:29:41 2011
Log: Adjust pointer maps for branches when connecting live ranges.
Review URL: http://codereview.chromium.org/6541024
http://code.google.com/p/v8/source/detail?r=6858
Modified:
/branches/bleeding_edge/src/lithium-allocator.cc
=======================================
--- /branches/bleeding_edge/src/lithium-allocator.cc Fri Feb 4 05:28:23
2011
+++ /branches/bleeding_edge/src/lithium-allocator.cc Fri Feb 18 08:29:41
2011
@@ -1098,6 +1098,21 @@
} else {
ASSERT(pred->end()->SecondSuccessor() == NULL);
gap = GetLastGap(pred);
+
+ // We are going to insert a move 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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