mesa: use build flag to ensure stack is realigned on x86
Nowadays GCC assumes stack pointer is 16-byte aligned even on 32-bits, but that is an assumption OpenGL drivers (or any dynamic library for that matter) can't afford to make as there are many closed- and open- source application binaries out there that only assume 4-byte stack alignment.
V4: fix comment and indentation
V3: move all sse4.1 build flag config to the same location
and add comment as to why we need to do the realign
V2: use $target_cpu rather than $host_cpu
and setup build flags in config rather than makefile
https://bugs.freedesktop.org/show_bug.cgi?id=86788
Signed-off-by: Timothy Arceri <t_arceri@yahoo.com.au>
Reviewed-by: Matt Turner <mattst88@gmail.com>
CC: "10.4" <mesa-stable@lists.freedesktop.org>
diff --git a/configure.ac b/configure.ac
index b0df1bb..4bdf75d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -253,8 +253,16 @@
dnl
dnl Optional flags, check for compiler support
dnl
+SSE41_CFLAGS="-msse4.1"
+dnl Code compiled by GCC with -msse* assumes a 16 byte aligned
+dnl stack, but on x86-32 such alignment is not guaranteed.
+case "$target_cpu" in
+i?86)
+ SSE41_CFLAGS="$SSE41_CFLAGS -mstackrealign"
+ ;;
+esac
save_CFLAGS="$CFLAGS"
-CFLAGS="-msse4.1 $CFLAGS"
+CFLAGS="$SSE41_CFLAGS $CFLAGS"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
#include <smmintrin.h>
int main () {
@@ -267,6 +275,7 @@
DEFINES="$DEFINES -DUSE_SSE41"
fi
AM_CONDITIONAL([SSE41_SUPPORTED], [test x$SSE41_SUPPORTED = x1])
+AC_SUBST([SSE41_CFLAGS], $SSE41_CFLAGS)
dnl Can't have static and shared libraries, default to static if user
dnl explicitly requested. If both disabled, set to static since shared