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..4b72367d0677b49469294bfff5a9869e3ab05c81 100644
--- a/runtime/vm/intrinsifier_ia32.cc
+++ b/runtime/vm/intrinsifier_ia32.cc
@@ -520,6 +520,38 @@ 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:
+  // * EAX has the base address of the byte array.
+  // * EBX has the index into the array.
+  // EBX contains the SMI index which is shifted by 1.
+  __ SmiUntag(EBX);
+  // Move EBX into EDI.
+  __ movl(EDI, EBX);
+  // Load 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);
+  // Add 128 to EBX to bring it into 0..FF.
+  __ addl(EBX, Immediate(128));

[cshapiro, 2012/10/12 23:05:21]

It would be great if we could put these magic numbers somewhere in the
RawInt8Array or Int8Array classes.  I think this is fine for now, but something
we should certainly address when we have the 16 and 32 bit cases.

+  __ cmpl(EBX, Immediate(0xFF));
+  // If EBX is too large an Int8, jump to fall through.
+  __ j(ABOVE, &fall_through, Assembler::kNearJump);
+  // Remove addition.
+  __ subl(EBX, Immediate(128));
+  // Store BL into array EAX[EDI] = BL.
+  __ 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 +567,34 @@ 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);
+  // After TestByteArraySetIndex:
+  // * EAX has the base address of the byte array.
+  // * EBX has the index into the array.
+  // EBX contains the SMI index which is shifted by 1.
+  __ SmiUntag(EBX);
+  // Move EBX into EDI.
+  __ movl(EDI, EBX);
+  // Load 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(ABOVE, &fall_through, Assembler::kNearJump);
+  // Store BL into array EAX[EDI] = BL.
+  __ 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);