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

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index af01c296b12895ebe4f91d205f47f4b1f51aa501..e3b512afbaa0f368e3fcff5ac07c3240f6cf22cd 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -1751,6 +1751,22 @@ LInstruction* LChunkBuilder::DoCheckMap(HCheckMap* instr) {
 }
 
 
+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));
 }