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

src/arm/macro-assembler-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 3010 matching lines @@
     // Result was clobbered. Restore it.
     ldr(result, MemOperand(ldr_location));
   }
   // Get the address of the constant.
   and_(result, result, Operand(kLdrOffsetMask));
   add(result, ldr_location, Operand(result));
   add(result, result, Operand(kPCRegOffset));
 }
 
 
+void MacroAssembler::ClampUint8(Register output_reg, Register input_reg) {
+  Usat(output_reg, 8, Operand(input_reg));
+}
+
+
+void MacroAssembler::ClampDoubleToUint8(Register result_reg,
+                                        DoubleRegister input_reg,
+                                        DoubleRegister temp_double_reg) {
+  Label above_zero;
+  Label done;
+  Label in_bounds;
+
+  vmov(temp_double_reg, 0.0);
+  VFPCompareAndSetFlags(input_reg, temp_double_reg);
+  b(gt, &above_zero);
+
+  // Double value is less than zero, NaN or Inf, return 0.
+  mov(result_reg, Operand(0));
+  b(al, &done);
+
+  // Double value is >= 255, return 255.
+  bind(&above_zero);
+  vmov(temp_double_reg, 255.0);
+  VFPCompareAndSetFlags(input_reg, temp_double_reg);
+  b(le, &in_bounds);
+  mov(result_reg, Operand(255));
+  b(al, &done);
+
+  // In 0-255 range, round and truncate.
+  bind(&in_bounds);
+  vmov(temp_double_reg, 0.5);
+  vadd(temp_double_reg, input_reg, temp_double_reg);
+  vcvt_u32_f64(s0, temp_double_reg);
+  vmov(result_reg, s0);
+  bind(&done);
+}
+
+
 CodePatcher::CodePatcher(byte* address, int instructions)
     : address_(address),
       instructions_(instructions),
       size_(instructions * Assembler::kInstrSize),
       masm_(Isolate::Current(), address, size_ + Assembler::kGap) {
   // Create a new macro assembler pointing to the address of the code to patch.
   // The size is adjusted with kGap on order for the assembler to generate size
   // bytes of instructions without failing with buffer size constraints.
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
@@ skipping 22 matching lines @@
 void CodePatcher::EmitCondition(Condition cond) {
   Instr instr = Assembler::instr_at(masm_.pc_);
   instr = (instr & ~kCondMask) | cond;
   masm_.emit(instr);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM