diff options
Diffstat (limited to 'pm_config.in.h')
| -rw-r--r-- | pm_config.in.h | 43 |
1 files changed, 20 insertions, 23 deletions
diff --git a/pm_config.in.h b/pm_config.in.h index 9459be02..fd651e3a 100644 --- a/pm_config.in.h +++ b/pm_config.in.h @@ -187,22 +187,14 @@ /* CONFIGURE: GNU Compiler extensions are used in performance critical places when available. Test whether they exist. - Turn off by defining NO_GCC_BUILTINS. - - Note that though these influence the resulting Netpbm machine code, the - compiler setting ultimately decides what instruction set the compiler uses. - If you want a generic build, check the manual and adjust CFLAGS in - config.mk accordingly. - - For example, if you want binaries that run on all Intel x86-32 - family CPUs back to 80386, adding "-march=i386" to CFLAGS in - config.mk is much better than setting NO_GCC_BUILTINS to 1. - If you want to be extra sure use: - "-march=i386 -mno-mmx -mno-sse -DNO_GCC_BUILTINS" - - Gcc uses SSE and SSE2 instructions by default for AMD/Intel x86-64. - Tinkering with "-mno-sse" is not recommended for these machines. If you - don't want SSE code, set NO_GCC_BUILTINS to 1. + Prevent the build from exploiting these extensions by defining + NO_GCC_UNIQUE. + + Before Netpbm 10.65 (December 2013), Netpbm used GCC compiler extensions + to generate SSE code in Pamflip. Starting in 10.65, Netpbm instead uses + the more standard operators defined in <emmtrins.h>. To prevent Netpbm + from explicitly using any SSE instructions, set WANT_SSE to N in + config.mk. */ /* @@ -214,7 +206,7 @@ > cc --version Apple clang version 4.0 (tags/Apple/clang-421.0.60) (based on LLVM 3.1svn) - which masquerades as GCC 4.2.1, but it does not have SSE2 function + which masquerades as GCC 4.2.1, but it does not have SSE2 operator __builtin_ia32_pcmpeqb128 . On the other hand, research by Prophet of the Way in September 2012 @@ -222,18 +214,24 @@ compiled successfully with SSE exploitation), but 3.1 does not. He did not find any mention in documentation of that change. + At least some versions of Clang that do not have __builtin_ia32_pcmpeqb128 + nonetheless have other GCC SSE2 operators, such as __builtin_ia32_pcmpgtb128. + We did not detect a pattern. + See below on compilers other than GCC that set __GNUC__: http://sourceforge.net/apps/mediawiki/predef/index.php?title=Compilers */ -#if defined(__GNUC__) && !defined(__clang__) && !defined(NO_GCC_BUILTINS) +#if defined(__GNUC__) && !defined(__clang__) && !defined(NO_GCC_UNIQUE) #define GCCVERSION __GNUC__*100 + __GNUC_MINOR__ #else #define GCCVERSION 0 #endif -/* HAVE_GCC_SSE2 means the compiler has GCC builtins to directly access - SSE/SSE2 features. This is different from whether the compiler generates - code that uses these features at all. +/* HAVE_GCC_SSE2 means the compiler has all of the GCC-specific builtins to + directly access SSE/SSE2 features. This is different from whether the + compiler generates code that uses these features at all. It is also + different from whether the compiler has the more standard operators defined + in <emmintrins.h>. */ #ifndef HAVE_GCC_SSE2 @@ -260,10 +258,9 @@ #endif #ifndef HAVE_GCC_BSWAP -#if GCCVERSION >=403 +#if GCCVERSION >=403 || defined(__clang__) #define HAVE_GCC_BSWAP 1 /* Use __builtin_bswap32(), __builtin_bswap64() for endian conversion. - Available from GCC v 4.3 onward. NOTE: On intel CPUs this may produce the bswap operand which is not available on 80386. */ #else |