Fix rounding in Uint8ClampedArray setter.

src/arm/macro-assembler-arm.cc

 // Copyright 2012 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 3666 matching lines @@
   // 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(temp_double_reg.low(), temp_double_reg);
-  vmov(result_reg, temp_double_reg.low());
+  // Save FPSCR.
+  vmrs(ip);
+  // Set rounding mode to round to the nearest integer by clearing bits[23:22].
+  bic(result_reg, ip, Operand(kVFPRoundingModeMask));
+  vmsr(result_reg);
+  vcvt_s32_f64(input_reg.low(), input_reg, kFPSCRRounding);
+  vmov(result_reg, input_reg.low());
+  // Restore FPSCR.
+  vmsr(ip);
   bind(&done);
 }
 
 
 void MacroAssembler::LoadInstanceDescriptors(Register map,
                                              Register descriptors,
                                              Register scratch) {
   Register temp = descriptors;
   ldr(temp, FieldMemOperand(map, Map::kTransitionsOrBackPointerOffset));
 
@@ skipping 123 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