On Fri, May 24, 2013 at 12:53 PM, Andrew Hsieh <andrewhs...@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
