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.
====
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
