Intrinsify writing to Uint8 and Int8 arrays on IA32.

runtime/vm/intrinsifier_ia32.cc

Index: runtime/vm/intrinsifier_ia32.cc
diff --git a/runtime/vm/intrinsifier_ia32.cc b/runtime/vm/intrinsifier_ia32.cc
index 6f4eb81fbeb7ea4e50b764c8deb6a839529bc9fa..90c8e7099e951e51e9501c4426db17a97aeeaa5d 100644
--- a/runtime/vm/intrinsifier_ia32.cc
+++ b/runtime/vm/intrinsifier_ia32.cc
@@ -520,6 +520,30 @@ 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);

[srdjan, 2012/10/08 21:45:53]

Please add comments about register content.

+  __ SmiUntag(EBX);
+  // Move EBX into EDI.
+  __ movl(EDI, EBX);
+  // Move the value into EBX.
+  __ movl(EBX, Address(ESP, + 1 * kWordSize));  // Value.
+  // If EBX is not an Smi, jump to fall through.
+  __ testl(EBX, Immediate(kSmiTagMask));
+  __ j(NOT_ZERO, &fall_through, Assembler::kNearJump);
+  __ SmiUntag(EBX);
+  // If EBX is too large an Int8, jump to fall through.
+  __ cmpl(EBX, Immediate(0xFF));

[cshapiro, 2012/10/08 21:40:41]

We need to add 128 to EBX for this compare to be semantically correct.

It would be great to add a test for this condition, trying values on either side
of the range to ensure the boundary conditions are correctly accommodated.

+  __ j(GREATER, &fall_through, Assembler::kNearJump);
+  // Store EBX into array EAX[EDI] = EBX.
+  __ movb(FieldAddress(EAX, EDI, TIMES_1, Int8Array::data_offset()), BL);
+  __ ret();
+  __ Bind(&fall_through);
+  return false;
+}
+
+
 bool Intrinsifier::Uint8Array_getIndexed(Assembler* assembler) {
   Label fall_through;
   TestByteArrayIndex(assembler, &fall_through);
@@ -535,6 +559,30 @@ bool Intrinsifier::Uint8Array_getIndexed(Assembler* assembler) {
 }
 
 
+bool Intrinsifier::Uint8Array_setIndexed(Assembler* assembler) {
+  Label fall_through;
+  // Verify that the array index is valid.
+  TestByteArraySetIndex(assembler, &fall_through);

[srdjan, 2012/10/08 21:45:53]

ditto

+  __ SmiUntag(EBX);
+  // Move EBX into EDI.
+  __ movl(EDI, EBX);
+  // Move the value into EBX.
+  __ movl(EBX, Address(ESP, + 1 * kWordSize));  // Value.
+  // If EBX is not an Smi, jump to fall through.
+  __ testl(EBX, Immediate(kSmiTagMask));
+  __ j(NOT_ZERO, &fall_through, Assembler::kNearJump);
+  __ SmiUntag(EBX);
+  // If EBX is too large an Uint8, jump to fall through.
+  __ cmpl(EBX, Immediate(0xFF));
+  __ j(GREATER, &fall_through, Assembler::kNearJump);
+  // Store EBX into array EAX[EDI] = EBX.
+  __ movb(FieldAddress(EAX, EDI, TIMES_1, Uint8Array::data_offset()), BL);
+  __ ret();
+  __ Bind(&fall_through);
+  return false;
+}
+
+
 bool Intrinsifier::Int16Array_getIndexed(Assembler* assembler) {
   Label fall_through;
   TestByteArrayIndex(assembler, &fall_through);