[v8-dev] ARM: Improve double to integer truncation on ARM.

src/arm/macro-assembler-arm.h

 // 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 941 matching lines @@
   // dest. If the HeapNumber does not fit into a 32bits signed integer branch
   // to not_int32 label. If VFP3 is available double_scratch is used but not
   // scratch2.
   void ConvertToInt32(Register source,
                       Register dest,
                       Register scratch,
                       Register scratch2,
                       DwVfpRegister double_scratch,
                       Label *not_int32);
 
+  // Try to convert a double to a signed 32-bit integer. If the double value
+  // can be exactly represented as an integer the code jump to 'done' and
+  // 'result' contains the integer value. Otherwise the code fall trough.

[ulan, 2012/12/05 15:43:15]

Minor nit: should be ", the code jumps" and ", the code falls through".

+  void TryFastDoubleToInt32(Register result,
+                            DwVfpRegister double_input,
+                            DwVfpRegister double_scratch,
+                            Label* done);
+
   // Truncates a double using a specific rounding mode, and writes the value
   // to the result register.
   // Clears the z flag (ne condition) if an overflow occurs.
   // If kCheckForInexactConversion is passed, the z flag is also cleared if the
   // conversion was inexact, i.e. if the double value could not be converted
   // exactly to a 32-bit integer.
   void EmitVFPTruncate(VFPRoundingMode rounding_mode,
                        Register result,
                        DwVfpRegister double_input,
                        Register scratch,
@@ skipping 10 matching lines @@
   void EmitOutOfInt32RangeTruncate(Register result,
                                    Register input_high,
                                    Register input_low,
                                    Register scratch);
 
   // Performs a truncating conversion of a floating point number as used by
   // the JS bitwise operations. See ECMA-262 9.5: ToInt32.
   // Exits with 'result' holding the answer and all other registers clobbered.
   void EmitECMATruncate(Register result,
                         DwVfpRegister double_input,
-                        SwVfpRegister single_scratch,
+                        DwVfpRegister double_scratch,
                         Register scratch,
                         Register scratch2,
                         Register scratch3);
 
   // Count leading zeros in a 32 bit word.  On ARM5 and later it uses the clz
   // instruction.  On pre-ARM5 hardware this routine gives the wrong answer
   // for 0 (31 instead of 32).  Source and scratch can be the same in which case
   // the source is clobbered.  Source and zeros can also be the same in which
   // case scratch should be a different register.
   void CountLeadingZeros(Register zeros,
@@ skipping 418 matching lines @@
 #define __FILE_LINE__ __FILE__ ":" CODE_COVERAGE_TOSTRING(__LINE__)
 #define ACCESS_MASM(masm) masm->stop(__FILE_LINE__); masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_MACRO_ASSEMBLER_ARM_H_