Re: [PATCH,bionic] Add -foptimize-sincos

[Alexander Ivchenko <aivchenk at gmail dot com>]

Richard, the target hook (libc_has_function) for what you described is
waiting for a review:
http://gcc.gnu.org/ml/gcc-patches/2013-03/msg01201.html

However, it doesn't have command line options support.

Alexander


2013/5/24 Richard Biener <richard.guenther@gmail.com>:
> On Fri, May 24, 2013 at 12:53 PM, Andrew Hsieh <andrewhsieh@google.com> wrote:
>> Bionic prior to Gingerbread doesn't support sincos*, but upstream GCC
>> enables sincos optimization for OPTION_BIONIC unconditionally since
>> 4.6.  I'd like to propose a new flag -foptimize-sincos for NDK to
>> maintain backward compatibility.
>>
>> 1. For BIONIC: sincos optimization is disabled by default.  Apps built
>> for Gingerbread+ or AOSP platform build which uses the same compiler
>> as NDK, can add -foptimize-sincos to enhance performance.  (although
>> it's likely that only benchmarks may benefit)
>>
>> 2. Other C libs aren't affected.  sincos optimization is enabled for
>> GLIBC and disabled for othres, regardless of this flag.
>
> That's a pretty awful option name for one that makes us assume the target
> C library has a sincos function.
>
> I'd rather think about a way to specify, for all known builtins, whether GCC
> should generate calls to such function where they are not in the source
> program.  That is, similar to how we have -f[no-]builtin-FOO introduce
> -f[no-]libc-FOO (with a better name for 'libc'?).  That way there would be
> a way to specify that -floop-distribute-patterns should not produce calls
> to memset () for example.
>
> Richard.
>
>> ====
>> Index: gcc/common.opt
>> ===================================================================
>> --- gcc/common.opt (revision 199277)
>> +++ gcc/common.opt (working copy)
>> @@ -1591,6 +1591,10 @@
>>  Common Report Var(flag_optimize_sibling_calls) Optimization
>>  Optimize sibling and tail recursive calls
>>
>> +foptimize-sincos
>> +Common Report Var(flag_optimize_sincos) Optimization
>> +Optimize calls to sin() and cos() with the same argument to sincos()
>> +
>>  fpartial-inlining
>>  Common Report Var(flag_partial_inlining)
>>  Perform partial inlining
>> Index: gcc/doc/invoke.texi
>> ===================================================================
>> --- gcc/doc/invoke.texi (revision 199277)
>> +++ gcc/doc/invoke.texi (working copy)
>> @@ -388,7 +388,7 @@
>>  -fno-sched-interblock -fno-sched-spec -fno-signed-zeros @gol
>>  -fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
>>  -fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls @gol
>> --fpartial-inlining -fpeel-loops -fpredictive-commoning @gol
>> +-foptimize-sincos -fpartial-inlining -fpeel-loops -fpredictive-commoning @gol
>>  -fprefetch-loop-arrays -fprofile-report @gol
>>  -fprofile-correction -fprofile-dir=@var{path} -fprofile-generate @gol
>>  -fprofile-generate=@var{path} @gol
>> @@ -6586,6 +6586,7 @@
>>  -fipa-profile @gol
>>  -fipa-reference @gol
>>  -fmerge-constants
>> +-foptimize-sincos @gol
>>  -fsplit-wide-types @gol
>>  -ftree-bit-ccp @gol
>>  -ftree-builtin-call-dce @gol
>> @@ -6772,6 +6773,12 @@
>>
>>  Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
>>
>> +@item -foptimize-sincos
>> +@opindex foptimize-sincos
>> +Optimize calls to sin() and cos() with the same argument to sincos()
>> +
>> +Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
>> +
>>  @item -fno-inline
>>  @opindex fno-inline
>>  Do not expand any functions inline apart from those marked with
>> Index: gcc/config/linux.h
>> ===================================================================
>> --- gcc/config/linux.h (revision 199277)
>> +++ gcc/config/linux.h (working copy)
>> @@ -102,7 +102,7 @@
>>
>>  /* Whether we have sincos that follows the GNU extension.  */
>>  #undef TARGET_HAS_SINCOS
>> -#define TARGET_HAS_SINCOS (OPTION_GLIBC || OPTION_BIONIC)
>> +#define TARGET_HAS_SINCOS (OPTION_GLIBC || (OPTION_BIONIC &&
>> flag_optimize_sincos))
>>
>>  /* Whether we have Bionic libc runtime */
>>  #undef TARGET_HAS_BIONIC