Revision: 6037
Author: [email protected]
Date: Wed Dec 15 09:11:11 2010
Log: Deoptimize non-smi switch cases if they are reached.
This way if the type oracle says an unreachable clause has a non-smi
type, we can still emit optimized code instead of doing an early
bailout.
This change depends of Florian's r5970.
Review URL: http://codereview.chromium.org/5812005
http://code.google.com/p/v8/source/detail?r=6037
Modified:
/branches/bleeding_edge/src/hydrogen.cc
/branches/bleeding_edge/src/ia32/full-codegen-ia32.cc
/branches/bleeding_edge/src/runtime.cc
=======================================
--- /branches/bleeding_edge/src/hydrogen.cc Wed Dec 15 08:12:55 2010
+++ /branches/bleeding_edge/src/hydrogen.cc Wed Dec 15 09:11:11 2010
@@ -2574,6 +2574,8 @@
void HGraphBuilder::VisitSwitchStatement(SwitchStatement* stmt) {
VISIT_FOR_VALUE(stmt->tag());
+ // TODO(3168478): simulate added for tag should be enough.
+ AddSimulate(stmt->EntryId());
HValue* switch_value = Pop();
ZoneList<CaseClause*>* clauses = stmt->cases();
@@ -2581,11 +2583,17 @@
if (num_clauses == 0) return;
if (num_clauses > 128) BAILOUT("SwitchStatement: too many clauses");
+ int num_smi_clauses = num_clauses;
for (int i = 0; i < num_clauses; i++) {
CaseClause* clause = clauses->at(i);
if (clause->is_default()) continue;
clause->RecordTypeFeedback(oracle());
- if (!clause->IsSmiCompare()) BAILOUT("SwitchStatement: non-smi
compare");
+ if (!clause->IsSmiCompare()) {
+ if (i == 0) BAILOUT("SwitchStatement: no smi compares");
+ // We will deoptimize if the first non-smi compare is reached.
+ num_smi_clauses = i;
+ break;
+ }
if (!clause->label()->IsSmiLiteral()) {
BAILOUT("SwitchStatement: non-literal switch label");
}
@@ -2596,17 +2604,18 @@
// Build a series of empty subgraphs for the comparisons.
// The default clause does not have a comparison subgraph.
- ZoneList<HSubgraph*> compare_graphs(num_clauses);
- for (int i = 0; i < num_clauses; i++) {
- HSubgraph* subgraph = !clauses->at(i)->is_default()
- ? CreateEmptySubgraph()
- : NULL;
- compare_graphs.Add(subgraph);
+ ZoneList<HSubgraph*> compare_graphs(num_smi_clauses);
+ for (int i = 0; i < num_smi_clauses; i++) {
+ if (clauses->at(i)->is_default()) {
+ compare_graphs.Add(NULL);
+ } else {
+ compare_graphs.Add(CreateEmptySubgraph());
+ }
}
HSubgraph* prev_graph = current_subgraph_;
HCompare* prev_compare_inst = NULL;
- for (int i = 0; i < num_clauses; i++) {
+ for (int i = 0; i < num_smi_clauses; i++) {
CaseClause* clause = clauses->at(i);
if (clause->is_default()) continue;
@@ -2623,6 +2632,7 @@
}
// Build instructions for current subgraph.
+ ASSERT(clause->IsSmiCompare());
prev_compare_inst = BuildSwitchCompare(subgraph, switch_value, clause);
if (HasStackOverflow()) return;
@@ -2641,34 +2651,53 @@
last_false_block,
prev_compare_inst));
}
+
+ // If we have a non-smi compare clause, we deoptimize after trying
+ // all the previous compares.
+ if (num_smi_clauses < num_clauses) {
+ last_false_block->Finish(new HDeoptimize);
+ }
// Build statement blocks, connect them to their comparison block and
// to the previous statement block, if there is a fall-through.
HSubgraph* previous_subgraph = NULL;
for (int i = 0; i < num_clauses; i++) {
CaseClause* clause = clauses->at(i);
- HSubgraph* subgraph = CreateEmptySubgraph();
-
- if (clause->is_default()) {
- // Default clause: Connect it to the last false block.
- last_false_block->Finish(new HGoto(subgraph->entry_block()));
- } else {
- // Connect with the corresponding comparison.
- HBasicBlock* empty =
- compare_graphs.at(i)->exit_block()->end()->FirstSuccessor();
- empty->Finish(new HGoto(subgraph->entry_block()));
+ // Subgraph for the statements of the clause is only created when
+ // it's reachable either from the corresponding compare or as a
+ // fall-through from previous statements.
+ HSubgraph* subgraph = NULL;
+
+ if (i < num_smi_clauses) {
+ if (clause->is_default()) {
+ if (!last_false_block->IsFinished()) {
+ // Default clause: Connect it to the last false block.
+ subgraph = CreateEmptySubgraph();
+ last_false_block->Finish(new HGoto(subgraph->entry_block()));
+ }
+ } else {
+ ASSERT(clause->IsSmiCompare());
+ // Connect with the corresponding comparison.
+ subgraph = CreateEmptySubgraph();
+ HBasicBlock* empty =
+ compare_graphs.at(i)->exit_block()->end()->FirstSuccessor();
+ empty->Finish(new HGoto(subgraph->entry_block()));
+ }
}
// Check for fall-through from previous statement block.
if (previous_subgraph != NULL && previous_subgraph->HasExit()) {
+ if (subgraph == NULL) subgraph = CreateEmptySubgraph();
previous_subgraph->exit_block()->
Finish(new HGoto(subgraph->entry_block()));
}
- ADD_TO_SUBGRAPH(subgraph, clause->statements());
- HBasicBlock* break_block = subgraph->BundleBreak(stmt);
- if (break_block != NULL) {
- break_block->Finish(new HGoto(single_exit_block));
+ if (subgraph != NULL) {
+ ADD_TO_SUBGRAPH(subgraph, clause->statements());
+ HBasicBlock* break_block = subgraph->BundleBreak(stmt);
+ if (break_block != NULL) {
+ break_block->Finish(new HGoto(single_exit_block));
+ }
}
previous_subgraph = subgraph;
@@ -2676,7 +2705,7 @@
// If the last statement block has a fall-through, connect it to the
// single exit block.
- if (previous_subgraph->HasExit()) {
+ if (previous_subgraph != NULL && previous_subgraph->HasExit()) {
previous_subgraph->exit_block()->Finish(new HGoto(single_exit_block));
}
=======================================
--- /branches/bleeding_edge/src/ia32/full-codegen-ia32.cc Wed Dec 15
08:14:29 2010
+++ /branches/bleeding_edge/src/ia32/full-codegen-ia32.cc Wed Dec 15
09:11:11 2010
@@ -745,10 +745,9 @@
Breakable nested_statement(this, stmt);
SetStatementPosition(stmt);
- PrepareForBailoutForId(stmt->EntryId(), NO_REGISTERS);
-
// Keep the switch value on the stack until a case matches.
VisitForStackValue(stmt->tag());
+ PrepareForBailoutForId(stmt->EntryId(), NO_REGISTERS);
ZoneList<CaseClause*>* clauses = stmt->cases();
CaseClause* default_clause = NULL; // Can occur anywhere in the list.
=======================================
--- /branches/bleeding_edge/src/runtime.cc Tue Dec 14 10:53:48 2010
+++ /branches/bleeding_edge/src/runtime.cc Wed Dec 15 09:11:11 2010
@@ -6876,12 +6876,17 @@
if (CompileOptimized(function, ast_id) && function->IsOptimized()) {
DeoptimizationInputData* data = DeoptimizationInputData::cast(
function->code()->deoptimization_data());
- if (FLAG_trace_osr) {
- PrintF("[on-stack replacement offset %d in optimized code]\n",
+ if (data->OsrPcOffset()->value() >= 0) {
+ if (FLAG_trace_osr) {
+ PrintF("[on-stack replacement offset %d in optimized code]\n",
data->OsrPcOffset()->value());
- }
- ASSERT(data->OsrAstId()->value() == ast_id);
- ASSERT(data->OsrPcOffset()->value() >= 0);
+ }
+ ASSERT(data->OsrAstId()->value() == ast_id);
+ } else {
+ // We may never generate the desired OSR entry if we emit an
+ // early deoptimize.
+ succeeded = false;
+ }
} else {
succeeded = false;
}
--
v8-dev mailing list
[email protected]
http://groups.google.com/group/v8-dev
