ARM: Optimsisation of ECMA ToInt32.

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 915 matching lines @@
       ObjectToDoubleFlags flags = NO_OBJECT_TO_DOUBLE_FLAGS);
 
   // Load the value of a smi object into a VFP double register. The register
   // scratch1 can be the same register as smi in which case smi will hold the
   // untagged value afterwards.
   void SmiToDoubleVFPRegister(Register smi,
                               DwVfpRegister value,
                               Register scratch1,
                               SwVfpRegister scratch2);
 
-  // Convert the HeapNumber pointed to by source to a 32bits signed integer
-  // 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);
-
   // Check if a double can be exactly represented as a signed 32-bit integer.
   // Z flag set to one if true.
   void TestDoubleIsInt32(DwVfpRegister double_input,
                          DwVfpRegister double_scratch);
 
   // Try to convert a double to a signed 32-bit integer.
   // Z flag set to one and result assigned if the conversion is exact.
   void TryDoubleToInt32Exact(Register result,
                              DwVfpRegister double_input,
                              DwVfpRegister double_scratch);
 
   // Floor a double and writes the value to the result register.
   // Go to exact if the conversion is exact (to be able to test -0),
   // fall through calling code if an overflow occurred, else go to done.
   void TryInt32Floor(Register result,
                      DwVfpRegister double_input,
                      Register input_high,
                      DwVfpRegister double_scratch,
                      Label* done,
                      Label* exact);
 
-  // Helper for EmitECMATruncate.
-  // This will truncate a floating-point value outside of the signed 32bit
-  // integer range to a 32bit signed integer.
-  // Expects the double value loaded in input_high and input_low.
-  // Exits with the answer in 'result'.
-  // Note that this code does not work for values in the 32bit range!
-  void EmitOutOfInt32RangeTruncate(Register result,
-                                   Register input_high,
-                                   Register input_low,
-                                   Register scratch);
+  // Performs a truncating conversion of a heap floating point number as used by
+  // the JS bitwise operations. See ECMA-262 9.5: ToInt32.
+  // Exits with 'result' holding the answer.
+  void ECMAConvertNumberToInt32(Register source,
+                                Register result,
+                                Register scratch,
+                                Register input_high,
+                                Register input_low,
+                                DwVfpRegister double_scratch1,
+                                DwVfpRegister double_scratch2);
 
   // 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,
-                        DwVfpRegister double_scratch,
+  void ECMAToInt32VFP(Register result,
+                      DwVfpRegister double_input,
+                      DwVfpRegister double_scratch,
+                      Register scratch,
+                      Register input_high,
+                      Register input_low);
+
+  // 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.
+  void ECMAToInt32NoVFP(Register result,
                         Register scratch,
-                        Register scratch2,
-                        Register scratch3);
+                        Register input_high,
+                        Register input_low);
 
   // 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,
                          Register source,
                          Register scratch);
 
@@ skipping 360 matching lines @@
   // bitmap register points at the word with the mark bits and the mask
   // the position of the first bit.  Leaves addr_reg unchanged.
   inline void GetMarkBits(Register addr_reg,
                           Register bitmap_reg,
                           Register mask_reg);
 
   // Helper for throwing exceptions.  Compute a handler address and jump to
   // it.  See the implementation for register usage.
   void JumpToHandlerEntry();
 
+  // Helper for ECMAToInt32VFP and ECMAToInt32NoVFP.

[ulan, 2013/03/11 15:11:03]

Description of preconditions for inputs would be helpful, like scratch contains
exponent - 1, 21 <= exponent <= 83

[Rodolph Perfetta, 2013/03/12 11:24:45]

Done.

+  void ECMAToInt32Tail(Register result,
+                       Register scratch,
+                       Register input_high,
+                       Register input_low,
+                       Label* out_of_range,
+                       Label* negate,
+                       Label* done);
+
   // Compute memory operands for safepoint stack slots.
   static int SafepointRegisterStackIndex(int reg_code);
   MemOperand SafepointRegisterSlot(Register reg);
   MemOperand SafepointRegistersAndDoublesSlot(Register reg);
 
   bool generating_stub_;
   bool allow_stub_calls_;
   bool has_frame_;
   // This handle will be patched with the code object on installation.
   Handle<Object> code_object_;
@@ skipping 53 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_