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

runtime/vm/intrinsifier_x64.cc

Index: runtime/vm/intrinsifier_x64.cc
diff --git a/runtime/vm/intrinsifier_x64.cc b/runtime/vm/intrinsifier_x64.cc
index e5dd2b404a8b3a05d09cea8633227cf100ecabae..b3722466b0c4e605f51b462d4de33520d6357d36 100644
--- a/runtime/vm/intrinsifier_x64.cc
+++ b/runtime/vm/intrinsifier_x64.cc
@@ -471,6 +471,31 @@ bool Intrinsifier::Int8Array_getIndexed(Assembler* assembler) {
 
 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;
 }
@@ -478,6 +503,27 @@ bool Intrinsifier::Int8Array_setIndexed(Assembler* assembler) {
 
 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;
 }