Reviewers: Vyacheslav Egorov,
Description:
Don't use environment values at certain deoptimize-instructions.
If a HDeoptimize does not cut away parts of the control-flow-graph
we don't need to insert uses to correctly elimiate dead phis since
the full function is visible to the optimizing compiler.
This is a small improvement of the change r7221 which fixed a problem
when deoptimizing on never executed case-clauses.
Please review this at http://codereview.chromium.org/7012010/
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
Affected files:
M src/hydrogen.h
M src/hydrogen.cc
Index: src/hydrogen.cc
===================================================================
--- src/hydrogen.cc (revision 7872)
+++ src/hydrogen.cc (working copy)
@@ -115,12 +115,12 @@
}
-HDeoptimize* HBasicBlock::CreateDeoptimize() {
+HDeoptimize* HBasicBlock::CreateDeoptimize(bool use_environment) {
ASSERT(HasEnvironment());
+ if (!use_environment) return new(zone()) HDeoptimize(0);
+
HEnvironment* environment = last_environment();
-
HDeoptimize* instr = new(zone()) HDeoptimize(environment->length());
-
for (int i = 0; i < environment->length(); i++) {
HValue* val = environment->values()->at(i);
instr->AddEnvironmentValue(val);
@@ -2490,7 +2490,9 @@
// Unconditionally deoptimize on the first non-smi compare.
clause->RecordTypeFeedback(oracle());
if (!clause->IsSmiCompare()) {
- current_block()->FinishExitWithDeoptimization();
+ // Finish with deoptimize and add uses of enviroment values to
+ // account for invisible uses.
+ current_block()->FinishExitWithDeoptimization(true);
set_current_block(NULL);
break;
}
@@ -3237,7 +3239,7 @@
// know about and do not want to handle ones we've never seen. Otherwise
// use a generic IC.
if (count == types->length() && FLAG_deoptimize_uncommon_cases) {
- current_block()->FinishExitWithDeoptimization();
+ current_block()->FinishExitWithDeoptimization(false);
} else {
HInstruction* instr = BuildStoreNamedGeneric(object, name, value);
instr->set_position(expr->position());
@@ -3916,7 +3918,7 @@
// know about and do not want to handle ones we've never seen. Otherwise
// use a generic IC.
if (count == types->length() && FLAG_deoptimize_uncommon_cases) {
- current_block()->FinishExitWithDeoptimization();
+ current_block()->FinishExitWithDeoptimization(false);
} else {
HValue* context = environment()->LookupContext();
HCallNamed* call = new(zone()) HCallNamed(context, name,
argument_count);
Index: src/hydrogen.h
===================================================================
--- src/hydrogen.h (revision 7872)
+++ src/hydrogen.h (working copy)
@@ -125,8 +125,8 @@
void AddSimulate(int id) { AddInstruction(CreateSimulate(id)); }
void AssignCommonDominator(HBasicBlock* other);
- void FinishExitWithDeoptimization() {
- FinishExit(CreateDeoptimize());
+ void FinishExitWithDeoptimization(bool use_environment) {
+ FinishExit(CreateDeoptimize(use_environment));
}
// Add the inlined function exit sequence, adding an HLeaveInlined
@@ -153,7 +153,7 @@
void AddDominatedBlock(HBasicBlock* block);
HSimulate* CreateSimulate(int id);
- HDeoptimize* CreateDeoptimize();
+ HDeoptimize* CreateDeoptimize(bool use_environment);
int block_id_;
HGraph* graph_;
--
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