A64: Move integer exponent into correct register before calling MathPowStub.

src/a64/lithium-codegen-a64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3767 matching lines @@
   } else if (exponent_type.IsTagged()) {
     Label no_deopt;
     __ JumpIfSmi(x11, &no_deopt);
     __ Ldr(x0, FieldMemOperand(x11, HeapObject::kMapOffset));
     DeoptimizeIfNotRoot(x0, Heap::kHeapNumberMapRootIndex,
                         instr->environment());
     __ Bind(&no_deopt);
     MathPowStub stub(MathPowStub::TAGGED);
     __ CallStub(&stub);
   } else if (exponent_type.IsInteger32()) {
+    __ Mov(x12, x11);

[ulan, 2014/01/29 15:13:41]

MathPowStub expects integer exponent in x12

[baptiste.afsa1, 2014/01/29 15:23:48]

Isn't it possible to modify register constraints in lithium-a64.cc to avoid
doing this move explicitly?

[ulan, 2014/01/29 15:33:14]

Agreed. Done.

On 2014/01/29 15:23:48, baptiste.afsa1 wrote:

     MathPowStub stub(MathPowStub::INTEGER);
     __ CallStub(&stub);
   } else {
     ASSERT(exponent_type.IsDouble());
     MathPowStub stub(MathPowStub::DOUBLE);
     __ CallStub(&stub);
   }
 }
 
 
@@ skipping 1661 matching lines @@
   __ Bind(&out_of_object);
   __ Ldr(result, FieldMemOperand(object, JSObject::kPropertiesOffset));
   // Index is equal to negated out of object property index plus 1.
   __ Sub(result, result, Operand::UntagSmiAndScale(index, kPointerSizeLog2));
   __ Ldr(result, FieldMemOperand(result,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ Bind(&done);
 }
 
 } }  // namespace v8::internal