VM(RegExp): Allow OSR optimization of RegExp :matcher functions.

runtime/vm/regexp_assembler_ir.cc

Index: runtime/vm/regexp_assembler_ir.cc
diff --git a/runtime/vm/regexp_assembler_ir.cc b/runtime/vm/regexp_assembler_ir.cc
index 2bdc701b8315cd222701a57599d7709d829dae86..fe7c4827b446dddf0bed4595f4091f4389db08c7 100644
--- a/runtime/vm/regexp_assembler_ir.cc
+++ b/runtime/vm/regexp_assembler_ir.cc
@@ -78,6 +78,7 @@ IRRegExpMacroAssembler::IRRegExpMacroAssembler(
     intptr_t capture_count,
     const ParsedFunction* parsed_function,
     const ZoneGrowableArray<const ICData*>& ic_data_array,
+    intptr_t osr_id,
     Zone* zone)
     : RegExpMacroAssembler(zone),
       thread_(Thread::Current()),
@@ -125,7 +126,7 @@ IRRegExpMacroAssembler::IRRegExpMacroAssembler(
       *parsed_function_,
       new (zone) TargetEntryInstr(block_id_.Alloc(), kInvalidTryIndex,
                                   GetNextDeoptId()),
-      Compiler::kNoOSRDeoptId);
+      osr_id);
   start_block_ = new (zone)
       JoinEntryInstr(block_id_.Alloc(), kInvalidTryIndex, GetNextDeoptId());
   success_block_ = new (zone)
@@ -223,7 +224,7 @@ void IRRegExpMacroAssembler::GenerateEntryBlock() {
 void IRRegExpMacroAssembler::GenerateBacktrackBlock() {
   set_current_instruction(backtrack_block_);
   TAG();
-  CheckPreemption();
+  CheckPreemption(/*is_backtrack=*/true);
 
   const intptr_t entries_count = entry_block_->indirect_entries().length();
 
@@ -1767,10 +1768,16 @@ IndirectEntryInstr* IRRegExpMacroAssembler::IndirectWithJoinGoto(
 }
 
 
-void IRRegExpMacroAssembler::CheckPreemption() {
+void IRRegExpMacroAssembler::CheckPreemption(bool is_backtrack) {
   TAG();
-  AppendInstruction(new (Z) CheckStackOverflowInstr(TokenPosition::kNoSource, 0,
-                                                    GetNextDeoptId()));
+
+  // Setting non-zero loop_depth turns this CheckStackOverflow into

[erikcorry, 2017/06/21 07:54:07]

This is confusing.  "Turns it into an OSR entry" sounds like it affects the
'kind' flag which can be either kOsrEntry or kFull.  Perhaps:

Perhaps it's clearer to rename kFull to kOsrAndPreemption?  And/or  write:

// We don't have the loop_depth available when compiling regexps, but
// we set loop_depth to a non-zero value because this instruction does
// not emit OSR entry information outside loops.

[Vyacheslav Egorov (Google), 2017/06/21 11:42:04]

Done.

+  // an OSR entry.
+  AppendInstruction(new (Z) CheckStackOverflowInstr(
+      TokenPosition::kNoSource,
+      /*loop_depth=*/1, GetNextDeoptId(),
+      is_backtrack ? CheckStackOverflowInstr::kFull
+                   : CheckStackOverflowInstr::kOsrEntry));
 }