Support conversion of clamped double values for pixel arrays in Crankshaft.

src/arm/lithium-arm.cc

 // Copyright 2011 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 1733 matching lines @@
 }
 
 
 LInstruction* LChunkBuilder::DoCheckMap(HCheckMap* instr) {
   LOperand* value = UseRegisterAtStart(instr->value());
   LInstruction* result = new LCheckMap(value);
   return AssignEnvironment(result);
 }
 
 
+LInstruction* LChunkBuilder::DoClampToUint8(HClampToUint8* instr) {
+  HValue* value = instr->value();
+  Representation rep = value->representation();

[Kevin Millikin (Chromium), 2011/05/16 07:06:35]

Can we rename this to input_rep and assert that instr->representation is int32?

[danno, 2011/05/16 14:13:43]

Done.

+  LOperand* reg = UseRegister(value);
+  if (rep.IsDouble()) {
+    return DefineAsRegister(new LClampDoubleToUint8(reg, FixedTemp(d1)));

[Kevin Millikin (Chromium), 2011/05/16 07:06:35]

Probably needs a comment that the fixed register is because register allocator
does not (yet) support allocation of double temporaries.  I'd be puzzled if I
read this code again in a month.

[danno, 2011/05/16 14:13:43]

Done.

+  } else if (rep.IsInteger32()) {
+    return DefineAsRegister(new LClampIToUint8(reg));
+  } else {
+    ASSERT(rep.IsTagged());
+    LClampTaggedToUint8* result = new LClampTaggedToUint8(reg, FixedTemp(d1));
+    return AssignEnvironment(DefineAsRegister(result));
+  }
+}
+
+
 LInstruction* LChunkBuilder::DoReturn(HReturn* instr) {
   return new LReturn(UseFixed(instr->value(), r0));
 }
 
 
 LInstruction* LChunkBuilder::DoConstant(HConstant* instr) {
   Representation r = instr->representation();
   if (r.IsInteger32()) {
     return DefineAsRegister(new LConstantI);
   } else if (r.IsDouble()) {
@@ skipping 416 matching lines @@
 
 LInstruction* LChunkBuilder::DoIn(HIn* instr) {
   LOperand* key = UseRegisterAtStart(instr->key());
   LOperand* object = UseRegisterAtStart(instr->object());
   LIn* result = new LIn(key, object);
   return MarkAsCall(DefineFixed(result, r0), instr);
 }
 
 
 } }  // namespace v8::internal