Fix escape analysis for redefining operators.

src/hydrogen-escape-analysis.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 13 matching lines @@
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include "hydrogen-escape-analysis.h"
 
 namespace v8 {
 namespace internal {
 
 
-void HEscapeAnalysisPhase::CollectIfNoEscapingUses(HInstruction* instr) {
-  for (HUseIterator it(instr->uses()); !it.Done(); it.Advance()) {
+bool HEscapeAnalysisPhase::HasNoEscapingUses(HValue* value) {
+  for (HUseIterator it(value->uses()); !it.Done(); it.Advance()) {
     HValue* use = it.value();
     if (use->HasEscapingOperandAt(it.index())) {
       if (FLAG_trace_escape_analysis) {
-        PrintF("#%d (%s) escapes through #%d (%s) @%d\n", instr->id(),
-               instr->Mnemonic(), use->id(), use->Mnemonic(), it.index());
+        PrintF("#%d (%s) escapes through #%d (%s) @%d\n", value->id(),
+               value->Mnemonic(), use->id(), use->Mnemonic(), it.index());
       }
-      return;
+      return false;
+    }
+    if (use->RedefinedOperandIndex() == it.index() && !HasNoEscapingUses(use)) {
+      if (FLAG_trace_escape_analysis) {
+        PrintF("#%d (%s) escapes redefinition #%d (%s) @%d\n", value->id(),
+               value->Mnemonic(), use->id(), use->Mnemonic(), it.index());
+      }
+      return false;
     }
   }
-  if (FLAG_trace_escape_analysis) {
-    PrintF("#%d (%s) is being captured\n", instr->id(), instr->Mnemonic());
-  }
-  captured_.Add(instr, zone());
+  return true;
 }
 
 
 void HEscapeAnalysisPhase::CollectCapturedValues() {
   int block_count = graph()->blocks()->length();
   for (int i = 0; i < block_count; ++i) {
     HBasicBlock* block = graph()->blocks()->at(i);
     for (HInstructionIterator it(block); !it.Done(); it.Advance()) {
       HInstruction* instr = it.Current();
-      if (instr->IsAllocate()) {
-        CollectIfNoEscapingUses(instr);
+      if (instr->IsAllocate() && HasNoEscapingUses(instr)) {
+        if (FLAG_trace_escape_analysis) {
+          PrintF("#%d (%s) is being captured\n", instr->id(),

[Hannes Payer (out of office), 2013/08/29 11:53:29]

may fit into one line

[Michael Starzinger, 2013/08/29 11:54:39]

Nope, exactly 81 characters, hate-o-rade.

+                 instr->Mnemonic());
+        }
+        captured_.Add(instr, zone());
       }
     }
   }
 }
 
 
 HCapturedObject* HEscapeAnalysisPhase::NewState(HInstruction* previous) {
   Zone* zone = graph()->zone();
   HCapturedObject* state =
       new(zone) HCapturedObject(number_of_values_, number_of_objects_, zone);
@@ skipping 222 matching lines @@
     AnalyzeDataFlow(allocate);
 
     cumulative_values_ += number_of_values_;
     ASSERT(allocate->HasNoUses());
     ASSERT(!allocate->IsLinked());
   }
 }
 
 
 } }  // namespace v8::internal