Port intrisification of setIndexed on Uint8 and Int8 arrays from ia32 to x64.

runtime/vm/intrinsifier_x64.cc

 // Copyright (c) 2012, 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.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 453 matching lines @@
                               Int8Array::data_offset()));
   __ SmiTag(RAX);
   __ ret();
   __ Bind(&fall_through);
   return false;
 }
 
 
 bool Intrinsifier::Int8Array_setIndexed(Assembler* assembler) {
   Label fall_through;
+  // Verify that the array index is valid.
+  TestByteArraySetIndex(assembler, &fall_through);
+  // After TestByteArraySetIndex:
+  // * RAX has the base address of the byte array.
+  // * R12 has the index into the array.
+  // R12 contains the SMI index which is shifted by 1.
+  __ SmiUntag(R12);
+  // Move R12 into RDI.

[Florian Schneider, 2012/11/22 14:35:53]

This comment is not very useful. I suggest removing all trivial comments to make
the code more readable and maintainable.

+  __ movq(RDI, R12);
+  // Load the value into R12.
+  __ movq(R12, Address(RSP, + 1 * kWordSize));  // Value.

[Florian Schneider, 2012/11/22 14:35:53]

Maybe use a different register than R12 vor the value, so that you don't need to
copy the index first.

+  // If R12 is not an Smi, jump to fall through.
+  __ testq(R12, Immediate(kSmiTagMask));
+  __ j(NOT_ZERO, &fall_through, Assembler::kNearJump);
+  __ SmiUntag(R12);
+  // Add 128 to R12 to bring it into the range 0..FF.
+  __ addq(R12, Immediate(128));
+  // If R12 is too large for an Int8, jump to fall through.
+  __ cmpq(R12, Immediate(0xFF));
+  __ j(ABOVE, &fall_through, Assembler::kNearJump);
+  // Undo addition.
+  __ subq(R12, Immediate(128));
+  // Store byte from RBX into array RAX[RDI].
+  __ movb(FieldAddress(RAX, RDI, TIMES_1, Uint8Array::data_offset()), R12);
+  __ ret();
   __ Bind(&fall_through);
   return false;
 }
 
 
 bool Intrinsifier::Uint8Array_setIndexed(Assembler* assembler) {
   Label fall_through;
+  // Verify that the array index is valid.
+  TestByteArraySetIndex(assembler, &fall_through);
+  // After TestByteArraySetIndex:
+  // * RAX has the base address of the byte array.
+  // * R12 has the index into the array.
+  // R12 contains the SMI index which is shifted by 1.
+  __ SmiUntag(R12);
+  // Move R12 into RDI.

[Florian Schneider, 2012/11/22 14:35:53]

Same comments as for Int8Array.

+  __ movq(RDI, R12);
+  // Load the value into R12.
+  __ movq(R12, Address(RSP, + 1 * kWordSize));  // Value.
+  // If R12 is not an Smi, jump to fall through.
+  __ testq(R12, Immediate(kSmiTagMask));
+  __ j(NOT_ZERO, &fall_through, Assembler::kNearJump);
+  __ SmiUntag(R12);
+  // If R12 is too large for an Uint8, jump to fall through.
+  __ cmpq(R12, Immediate(0xFF));
+  __ j(ABOVE, &fall_through, Assembler::kNearJump);
+  // Store byte from RBX into array RAX[RDI].
+  __ movb(FieldAddress(RAX, RDI, TIMES_1, Uint8Array::data_offset()), R12);
+  __ ret();
   __ Bind(&fall_through);
   return false;
 }
 
 
 bool Intrinsifier::Uint8Array_getIndexed(Assembler* assembler) {
   Label fall_through;
   TestByteArrayIndex(assembler, &fall_through);
   __ SmiUntag(R12);
   __ movzxb(RAX, FieldAddress(RAX,
@@ skipping 1080 matching lines @@
   __ LoadObject(RAX, bool_true);
   __ ret();
   return true;
 }
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64