Compile x86/swscale_template with -mno-red-zone.

Replaces a very hackish hack to fix the same issue (call instruction
overwriting stack variables).

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
(cherry picked from commit 424bcc46b5)

configure

@@ -3073,6 +3073,10 @@ else
 fi
 check_cflags -fno-math-errno
 check_cflags -fno-signed-zeros
+check_cc -mno-red-zone <<EOF && noredzone_flags="-mno-red-zone"
+int x;
+EOF
+
 
 if enabled icc; then
     # Just warnings, no remarks
@@ -3383,6 +3387,7 @@ SLIB_EXTRA_CMD=${SLIB_EXTRA_CMD}
 SLIB_INSTALL_EXTRA_CMD=${SLIB_INSTALL_EXTRA_CMD}
 SLIB_UNINSTALL_EXTRA_CMD=${SLIB_UNINSTALL_EXTRA_CMD}
 SAMPLES:=${samples:-\$(FATE_SAMPLES)}
+NOREDZONE_FLAGS=$noredzone_flags
 EOF
 
 get_version(){

libswscale/Makefile

@@ -20,6 +20,8 @@ OBJS-$(HAVE_MMX)           +=  x86/rgb2rgb.o            \
                                x86/yuv2rgb_mmx.o
 OBJS-$(HAVE_VIS)           +=  sparc/yuv2rgb_vis.o
 
+$(SUBDIR)x86/swscale_mmx.o: CFLAGS += $(NOREDZONE_FLAGS)
+
 TESTPROGS = colorspace swscale
 
 DIRS = bfin mlib ppc sparc x86

libswscale/x86/swscale_template.c

@@ -2240,10 +2240,6 @@ static void RENAME(hyscale_fast)(SwsContext *c, int16_t *dst,
 #if defined(PIC)
     DECLARE_ALIGNED(8, uint64_t, ebxsave);
 #endif
-    // HACK: gcc 4.6 no longer decrements esp,
-    // use this to make it reserve space for the call
-    // return address
-    void *dummy;
 
     __asm__ volatile(
 #if defined(PIC)
@@ -2295,7 +2291,6 @@ static void RENAME(hyscale_fast)(SwsContext *c, int16_t *dst,
 #if defined(PIC)
           ,"m" (ebxsave)
 #endif
-          ,"m" (dummy)
         : "%"REG_a, "%"REG_c, "%"REG_d, "%"REG_S, "%"REG_D
 #if !defined(PIC)
          ,"%"REG_b
@@ -2317,10 +2312,6 @@ static void RENAME(hcscale_fast)(SwsContext *c, int16_t *dst1, int16_t *dst2,
 #if defined(PIC)
     DECLARE_ALIGNED(8, uint64_t, ebxsave);
 #endif
-    // HACK: gcc 4.6 no longer decrements esp,
-    // use this to make it reserve space for the call
-    // return address
-    void *dummy;
 
     __asm__ volatile(
 #if defined(PIC)
@@ -2360,7 +2351,6 @@ static void RENAME(hcscale_fast)(SwsContext *c, int16_t *dst1, int16_t *dst2,
 #if defined(PIC)
           ,"m" (ebxsave)
 #endif
-          ,"m" (dummy)
         : "%"REG_a, "%"REG_c, "%"REG_d, "%"REG_S, "%"REG_D
 #if !defined(PIC)
          ,"%"REG_b