[FFmpeg-devel] [PATCH 3/5] x86 inline assembly compliance

[FRÉDÉRIC RECOULES]

[inline assembly] prepares for mmx clobbers akin to xmm 

--- 
configure | 4 ++++ 
libavutil/x86/asm.h | 20 ++++++++++++++++++++ 
2 files changed, 24 insertions(+) 

diff --git a/configure b/configure 
index 5fe9950e20..4062ca095a 100755 
--- a/configure 
+++ b/configure 
@@ -2275,6 +2275,7 @@ TOOLCHAIN_FEATURES=" 
symver_gnu_asm 
vfp_args 
xform_asm 
+ mmx_clobbers 
xmm_clobbers 
" 

@@ -5907,6 +5908,9 @@ EOF 
check_inline_asm ebx_available '""::"b"(0)' && 
check_inline_asm ebx_available '"":::"%ebx"' 

+ # check whether mmx clobbers are supported 
+ check_inline_asm mmx_clobbers '"":::"%mm0"' 
+ 
# check whether xmm clobbers are supported 
check_inline_asm xmm_clobbers '"":::"%xmm0"' 

diff --git a/libavutil/x86/asm.h b/libavutil/x86/asm.h 
index 9bff42d628..bb3c13f5c1 100644 
--- a/libavutil/x86/asm.h 
+++ b/libavutil/x86/asm.h 
@@ -79,6 +79,26 @@ typedef int x86_reg; 
# define BROKEN_RELOCATIONS 1 
#endif 

+/* 
+ * If gcc is not set to support mmx (-mmmx) it will not accept mmx registers 
+ * in the clobber list for inline asm. MMX_CLOBBERS takes a list of mmx 
+ * registers to be marked as clobbered and evaluates to nothing if they are 
+ * not supported, or to the list itself if they are supported. Since a clobber 
+ * list may not be empty, XMM_CLOBBERS_ONLY should be used if the mmx 
+ * registers are the only in the clobber list. 
+ * For example a list with "eax" and "mm0" as clobbers should become: 
+ * : MMX_CLOBBERS("mm0",) "eax" 
+ * and a list with only "mm0" should become: 
+ * MMX_CLOBBERS_ONLY("mm0") 
+ */ 
+#if HAVE_MMX_CLOBBERS 
+# define MMX_CLOBBERS(...) __VA_ARGS__ 
+# define MMX_CLOBBERS_ONLY(...) : __VA_ARGS__ 
+#else 
+# define MMX_CLOBBERS(...) 
+# define MMX_CLOBBERS_ONLY(...) 
+#endif 
+ 
/* 
* If gcc is not set to support sse (-msse) it will not accept xmm registers 
* in the clobber list for inline asm. XMM_CLOBBERS takes a list of xmm 
-- 
2.17.1