[Mesa-dev] [PATCH V2] mesa: use build flag to ensure stack is realigned on x86

[Timothy Arceri]

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.

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 at yahoo.com.au>
---
 Tested by cross compiling and running 32-bit version of
 UrbanTerror.

 Please note if this patch is ok it should also be applied to 10.4 with
 the last hunk removed.

 configure.ac               | 11 ++++++++++-
 src/mesa/Makefile.am       |  2 +-
 src/mesa/main/sse_minmax.c |  3 ---
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/configure.ac b/configure.ac
index b0df1bb..7dc435a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -253,8 +253,9 @@ AC_SUBST([VISIBILITY_CXXFLAGS])
 dnl
 dnl Optional flags, check for compiler support
 dnl
+SSE41_CFLAGS="-msse4.1"
 save_CFLAGS="$CFLAGS"
-CFLAGS="-msse4.1 $CFLAGS"
+CFLAGS="$SSE41_CFLAGS $CFLAGS"
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
 #include <smmintrin.h>
 int main () {
@@ -474,6 +475,12 @@ fi
 dnl
 dnl Arch/platform-specific settings
 dnl
+case "$target_cpu" in
+    i?86)
+        SSE41_CFLAGS="$SSE41_CFLAGS -mstackrealign"
+;;
+esac
+
 AC_ARG_ENABLE([asm],
     [AS_HELP_STRING([--disable-asm],
         [disable assembly usage @<:@default=enabled on supported plaforms@:>@])],
@@ -2091,6 +2098,8 @@ AM_CONDITIONAL(HAVE_X86_ASM, test "x$asm_arch" = xx86 -o "x$asm_arch" = xx86_64)
 AM_CONDITIONAL(HAVE_X86_64_ASM, test "x$asm_arch" = xx86_64)
 AM_CONDITIONAL(HAVE_SPARC_ASM, test "x$asm_arch" = xsparc)
 
+AC_SUBST([SSE41_CFLAGS], $SSE41_CFLAGS)
+
 AC_SUBST([NINE_MAJOR], 1)
 AC_SUBST([NINE_MINOR], 0)
 AC_SUBST([NINE_TINY], 0)
diff --git a/src/mesa/Makefile.am b/src/mesa/Makefile.am
index 932db4f..3b68573 100644
--- a/src/mesa/Makefile.am
+++ b/src/mesa/Makefile.am
@@ -153,7 +153,7 @@ libmesagallium_la_LIBADD = \
 libmesa_sse41_la_SOURCES = \
 	main/streaming-load-memcpy.c \
 	main/sse_minmax.c
-libmesa_sse41_la_CFLAGS = $(AM_CFLAGS) -msse4.1
+libmesa_sse41_la_CFLAGS = $(AM_CFLAGS) $(SSE41_CFLAGS)
 
 pkgconfigdir = $(libdir)/pkgconfig
 pkgconfig_DATA = gl.pc
diff --git a/src/mesa/main/sse_minmax.c b/src/mesa/main/sse_minmax.c
index 93cf2a6..222ac14 100644
--- a/src/mesa/main/sse_minmax.c
+++ b/src/mesa/main/sse_minmax.c
@@ -31,9 +31,6 @@
 #include <stdint.h>
 
 void
-#if !defined(__x86_64__)
-   __attribute__((force_align_arg_pointer))
-#endif
 _mesa_uint_array_min_max(const unsigned *ui_indices, unsigned *min_index,
                          unsigned *max_index, const unsigned count)
 {
-- 
1.9.3