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

src/ia32/macro-assembler-ia32.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 59 matching lines @@
   // Compute number of region covering addr. See Page::GetRegionNumberForAddress
   // method for more details.
   and_(addr, Page::kPageAlignmentMask);
   shr(addr, Page::kRegionSizeLog2);
 
   // Set dirty mark for region.
   bts(Operand(object, Page::kDirtyFlagOffset), addr);
 }
 
 
+void MacroAssembler::ClampDoubleToUint8(XMMRegister input_reg,
+                                        XMMRegister scratch_reg,
+                                        Register result_reg) {
+  Label done;
+  ExternalReference zero_ref = ExternalReference::address_of_zero();
+  movdbl(scratch_reg, Operand::StaticVariable(zero_ref));
+  Set(result_reg, Immediate(0));
+  ucomisd(input_reg, scratch_reg);
+  j(below, &done, Label::kNear);
+  ExternalReference half_ref = ExternalReference::address_of_one_half();
+  movdbl(scratch_reg, Operand::StaticVariable(half_ref));
+  addsd(scratch_reg, input_reg);
+  cvttsd2si(result_reg, Operand(scratch_reg));
+  test(result_reg, Immediate(0xFFFFFF00));
+  j(zero, &done, Label::kNear);
+  Set(result_reg, Immediate(255));
+  bind(&done);
+}
+
+
+void MacroAssembler::ClampUint8(Register reg) {
+  Label done;
+  test(reg, Immediate(0xFFFFFF00));
+  j(zero, &done, Label::kNear);
+  setcc(negative, reg);  // 1 if negative, 0 if positive.
+  dec_b(reg);  // 0 if negative, 255 if positive.
+  bind(&done);
+}
+
+
 void MacroAssembler::InNewSpace(Register object,
                                 Register scratch,
                                 Condition cc,
                                 Label* branch,
                                 Label::Distance branch_near) {
   ASSERT(cc == equal || cc == not_equal);
   if (Serializer::enabled()) {
     // Can't do arithmetic on external references if it might get serialized.
     mov(scratch, Operand(object));
     // The mask isn't really an address.  We load it as an external reference in
@@ skipping 1949 matching lines @@
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32