ARM/ARM64: Fix smashed CODE_REG in intrinsics with InvokeMathCFunctionInstrs.

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 23 matching lines @@
 // The EBP register should not be modified, because it is used by the profiler.
 // The THR register (see constants_ia32.h) must be preserved.
 
 #define __ assembler->
 
 
 intptr_t Intrinsifier::ParameterSlotFromSp() { return 0; }
 
 
 void Intrinsifier::IntrinsicCallPrologue(Assembler* assembler) {
+  COMPILE_ASSERT(CALLEE_SAVED_TEMP != ARGS_DESC_REG);
+
   assembler->Comment("IntrinsicCallPrologue");
-  assembler->movl(CALLEE_SAVED_TEMP, ICREG);

[Vyacheslav Egorov (Google), 2016/05/25 11:15:31]

I wonder why this was preserved in the first place. I can't find any uses in the
prologue.

[rmacnak, 2016/05/25 16:58:51]

I suspect it was for something in the past. I previously removed it from
ParallelMoveResolver when adding support for the iOS ARM ABI.

-  assembler->movl(CALLEE_SAVED_TEMP2, ARGS_DESC_REG);
+  assembler->movl(CALLEE_SAVED_TEMP, ARGS_DESC_REG);
 }
 
 
 void Intrinsifier::IntrinsicCallEpilogue(Assembler* assembler) {
   assembler->Comment("IntrinsicCallEpilogue");
-  assembler->movl(ICREG, CALLEE_SAVED_TEMP);
-  assembler->movl(ARGS_DESC_REG, CALLEE_SAVED_TEMP2);
+  assembler->movl(ARGS_DESC_REG, CALLEE_SAVED_TEMP);
 }
 
 
 static intptr_t ComputeObjectArrayTypeArgumentsOffset() {
   const Library& core_lib = Library::Handle(Library::CoreLibrary());
   const Class& cls = Class::Handle(
       core_lib.LookupClassAllowPrivate(Symbols::_List()));
   ASSERT(!cls.IsNull());
   ASSERT(cls.NumTypeArguments() == 1);
   const intptr_t field_offset = cls.type_arguments_field_offset();
@@ skipping 2089 matching lines @@
   __ Bind(&true_label);
   __ LoadObject(EAX, Bool::True());
   __ ret();
 }
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_IA32