Explicitly clear out the IC-data register in ExecuteMatch.

runtime/vm/intrinsifier_ia32.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 //
 // The intrinsic code below is executed before a method has built its frame.
 // The return address is on the stack and the arguments below it.
 // Registers EDX (arguments descriptor) and ECX (function) must be preserved.
 // Each intrinsification method returns true if the corresponding
 // Dart method was intrinsified.
 
@@ skipping 2042 matching lines @@
 void Intrinsifier::JSRegExp_ExecuteMatch(Assembler* assembler) {
   if (FLAG_use_jscre) {
     return;
   }
   static const intptr_t kRegExpParamOffset = 3 * kWordSize;
   static const intptr_t kStringParamOffset = 2 * kWordSize;
   // start_index smi is located at offset 1.
 
   // Incoming registers:
   // EAX: Function. (Will be loaded with the specialized matcher function.)
-  // ECX: IC-Data. (Will be preserved.)
+  // ECX: Unknown. (Must be GC safe on tail call.)
   // EDX: Arguments descriptor. (Will be preserved.)
 
   // Load the specialized function pointer into EAX. Leverage the fact the
   // string CIDs as well as stored function pointers are in sequence.
   __ movl(EBX, Address(ESP, kRegExpParamOffset));
   __ movl(EDI, Address(ESP, kStringParamOffset));
   __ LoadClassId(EDI, EDI);
   __ SubImmediate(EDI, Immediate(kOneByteStringCid));
   __ movl(EAX, FieldAddress(EBX, EDI, TIMES_4,
                             JSRegExp::function_offset(kOneByteStringCid)));
 
   // Registers are now set up for the lazy compile stub. It expects the function
   // in EAX, the argument descriptor in EDX, and IC-Data in ECX.
   static const intptr_t arg_count = RegExpMacroAssembler::kParamCount;
   __ LoadObject(EDX, Array::Handle(ArgumentsDescriptor::New(arg_count)));
+  __ xorl(ECX, ECX);
 
   // Tail-call the function.
   __ movl(EDI, FieldAddress(EAX, Function::instructions_offset()));
   __ addl(EDI, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ jmp(EDI);
 }
 
 
 // On stack: user tag (+1), return-address (+0).
 void Intrinsifier::UserTag_makeCurrent(Assembler* assembler) {
@@ skipping 36 matching lines @@
                         Isolate::current_tag_offset());
   // Set return value to Isolate::current_tag_.
   __ movl(EAX, current_tag_addr);
   __ ret();
 }
 
 #undef __
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32