Encapsulate the test for which flags are needed to get a compiler to
support certain features. Along with this, give various options to try
for AVX and AVX2 support. Ideally we want to use specific instruction
set feature flags, like -mavx2 for instance instead of -march=haswell,
but the flags required for certain compilers are different. This
allows, for AVX2 for instance, GCC to use -mavx2 -mfma -mbmi2 -mf16c
while the Intel compiler which doesn't support those flags can fall
back to using -march=core-avx2.
This addresses a bug where the Intel compiler will silently ignore the
AVX2 instruction feature flags and then potentially fail to build.
v2: Pass preprocessor-check argument as true-state instead of
false-state for clarity.
Cc: Tim Rowley <timothy.o.row...@intel.com>
Signed-off-by: Chuck Atkins <chuck.atk...@kitware.com>
---
configure.ac | 86 +++++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 62 insertions(+), 24 deletions(-)
diff --git a/configure.ac b/configure.ac
index cc9bc47..6082778 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2330,6 +2330,39 @@ swr_llvm_check() {
fi
}
+swr_cxx_feature_flags_check() {
+ preprocessor_test="$1"
+ option_list="$2"
+ unset SWR_CXX_FEATURE_FLAGS
+ AC_LANG_PUSH([C++])
+ save_CXXFLAGS="$CXXFLAGS"
+ save_IFS="$IFS"
+ IFS=","
+ found=0
+ for opts in $option_list
+ do
+ unset IFS
+ CXXFLAGS="$opts $save_CXXFLAGS"
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM(
+ [ #if !($preprocessor_test)
+ #error
+ #endif
+ ])],
+ [found=1; break],
+ [])
+ IFS=","
+ done
+ IFS="$save_IFS"
+ CXXFLAGS="$save_CXXFLAGS"
+ AC_LANG_POP([C++])
+ if test $found -eq 1; then
+ SWR_CXX_FEATURE_FLAGS="$opts"
+ return 0
+ fi
+ return 1
+}
+
dnl Duplicates in GALLIUM_DRIVERS_DIRS are removed by sorting it after this
block
if test -n "$with_gallium_drivers"; then
gallium_drivers=`IFS=', '; echo $with_gallium_drivers`
@@ -2399,31 +2432,36 @@ if test -n "$with_gallium_drivers"; then
xswr)
swr_llvm_check "swr"
- AC_MSG_CHECKING([whether $CXX supports c++11/AVX/AVX2])
- SWR_AVX_CXXFLAGS="-mavx"
- SWR_AVX2_CXXFLAGS="-mavx2 -mfma -mbmi2 -mf16c"
-
- AC_LANG_PUSH([C++])
- save_CXXFLAGS="$CXXFLAGS"
- CXXFLAGS="-std=c++11 $CXXFLAGS"
- AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],[],
- [AC_MSG_ERROR([c++11 compiler support not
detected])])
- CXXFLAGS="$save_CXXFLAGS"
-
- save_CXXFLAGS="$CXXFLAGS"
- CXXFLAGS="$SWR_AVX_CXXFLAGS $CXXFLAGS"
- AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],[],
- [AC_MSG_ERROR([AVX compiler support not
detected])])
- CXXFLAGS="$save_CXXFLAGS"
-
- save_CFLAGS="$CXXFLAGS"
- CXXFLAGS="$SWR_AVX2_CXXFLAGS $CXXFLAGS"
- AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],[],
- [AC_MSG_ERROR([AVX2 compiler support not
detected])])
- CXXFLAGS="$save_CXXFLAGS"
- AC_LANG_POP([C++])
-
+ AC_MSG_CHECKING([whether $CXX supports c++11])
+ if ! swr_cxx_feature_flags_check \
+ "__cplusplus >= 201103L" \
+ ",-std=c++11"; then
+ AC_MSG_RESULT([no])
+ AC_MSG_ERROR([swr requires C++11 support])
+ fi
+ AC_MSG_RESULT([$SWR_CXX_FEATURE_FLAGS])
+ CXXFLAGS="$SWR_CXX_FEATURE_FLAGS $CXXFLAGS"
+
+ AC_MSG_CHECKING([whether $CXX supports AVX])
+ if ! swr_cxx_feature_flags_check \
+ "defined(__AVX__)" \
+ ",-mavx,-march=core-avx"; then
+ AC_MSG_RESULT([no])
+ AC_MSG_ERROR([swr requires AVX compiler support])
+ fi
+ AC_MSG_RESULT([$SWR_CXX_FEATURE_FLAGS])
+ SWR_AVX_CXXFLAGS="$SWR_CXX_FEATURE_FLAGS"
AC_SUBST([SWR_AVX_CXXFLAGS])
+
+ AC_MSG_CHECKING([whether $CXX supports AVX2])
+ if ! swr_cxx_feature_flags_check \
+
"defined(__AVX2__)&&defined(__FMA__)&&defined(__BMI2__)&&defined(__F16C__)" \
+ ",-mavx2 -mfma -mbmi2 -mf16c,-march=core-avx2"; then
+ AC_MSG_RESULT([no])
+ AC_MSG_ERROR([swr requires AVX2 compiler support])
+ fi
+ AC_MSG_RESULT([$SWR_CXX_FEATURE_FLAGS])
+ SWR_AVX2_CXXFLAGS="$SWR_CXX_FEATURE_FLAGS"
AC_SUBST([SWR_AVX2_CXXFLAGS])
HAVE_GALLIUM_SWR=yes
--
2.5.5
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