Add configure test to verify SSE2 code compiles.
Make sure that emmintrin.h can be #include'd without causing a
compilation error, rather than blindly defining HAVE_SSE2 based on
architecture. Attempts to force SSE2 compilation on a 32-bit Ubuntu
13.10 system running as a VMware guest resulted in a no-win choice
without any obvious explanation besides toolchain misconfiguration/bug:
- Suffer compilation failure due to __MMX__, __SSE__, and __SSE2__ not
being defined, even if -mmmx, -msse, and -msse2 are manually
specified (note that they appear to be enabled by default).
- Manually define __MMX__, __SSE__, and __SSE2__, and suffer compiler
warnings that they are already automatically defined. This results in
successful compilation and execution, but the noise is intolerable.
diff --git a/configure.ac b/configure.ac
index 938c019..3837a78 100644
--- a/configure.ac
+++ b/configure.ac
@@ -198,21 +198,21 @@
case "${host_cpu}" in
i[[345]]86)
;;
- i686)
- JE_COMPILABLE([__asm__], [], [[__asm__ volatile("pause"); return 0;]],
- [je_cv_asm])
- if test "x${je_cv_asm}" = "xyes" ; then
+ i686|x86_64)
+ JE_COMPILABLE([pause instruction], [],
+ [[__asm__ volatile("pause"); return 0;]],
+ [je_cv_pause])
+ if test "x${je_cv_pause}" = "xyes" ; then
CPU_SPINWAIT='__asm__ volatile("pause")'
fi
- AC_DEFINE_UNQUOTED([HAVE_SSE2], [ ])
- ;;
- x86_64)
- JE_COMPILABLE([__asm__ syntax], [],
- [[__asm__ volatile("pause"); return 0;]], [je_cv_asm])
- if test "x${je_cv_asm}" = "xyes" ; then
- CPU_SPINWAIT='__asm__ volatile("pause")'
+ dnl emmintrin.h fails to compile unless MMX, SSE, and SSE2 are
+ dnl supported.
+ JE_COMPILABLE([SSE2 intrinsics], [
+#include <emmintrin.h>
+], [], [je_cv_sse2])
+ if test "x${je_cv_sse2}" = "xyes" ; then
+ AC_DEFINE_UNQUOTED([HAVE_SSE2], [ ])
fi
- AC_DEFINE_UNQUOTED([HAVE_SSE2], [ ])
;;
powerpc)
AC_DEFINE_UNQUOTED([HAVE_ALTIVEC], [ ])