[FFmpeg-devel] [PATCH v2] lsws/ppc/yuv2rgb_altivec: Fix build in non-VSX environments with Clang

[FFmpeg-devel] [PATCH v2] lsws/ppc/yuv2rgb_altivec: Fix build in non-VSX environments with Clang

[Brad Smith]

lsws/ppc/yuv2rgb_altivec: Fix build in non-VSX environments with Clang

Add a check for the existence of the vec_xl() function. Clang provides
the function even with VSX not enabled.

v2: test for function if AltiVec is enabled instead of with AltiVec and without VSX
---
 configure                        | 8 ++++++++
 libswscale/ppc/yuv2rgb_altivec.c | 4 ++--
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index ff6a5c3600..637034e87d 100755
--- a/configure
+++ b/configure
@@ -2154,6 +2154,7 @@ ARCH_EXT_LIST_PPC="
     ldbrx
     power8
     ppc4xx
+    vec_xl
     vsx
 "
 
@@ -2679,6 +2680,7 @@ altivec_deps="ppc"
 dcbzl_deps="ppc"
 ldbrx_deps="ppc"
 ppc4xx_deps="ppc"
+vec_xl_deps="altivec"
 vsx_deps="altivec"
 power8_deps="vsx"
 
@@ -6221,6 +6223,11 @@ elif enabled ppc; then
         check_cpp_condition power8 "altivec.h" "defined(_ARCH_PWR8)"
     fi
 
+    if enabled altivec; then
+        check_cc vec_xl altivec.h "const unsigned char *y1i = { 0 };
+                                vector unsigned char y0 = vec_xl(0, y1i);"
+    fi
+
 elif enabled riscv; then
 
     enabled rvv && check_inline_asm rvv '".option arch, +v\nvsetivli zero, 0, e8, m1, ta, ma"'
@@ -7731,6 +7738,7 @@ if enabled ppc; then
     echo "POWER8 enabled            ${power8-no}"
     echo "PPC 4xx optimizations     ${ppc4xx-no}"
     echo "dcbzl available           ${dcbzl-no}"
+    echo "vec_xl available          ${vec_xl-no}"
 fi
 if enabled loongarch; then
     echo "LSX enabled               ${lsx-no}"
diff --git a/libswscale/ppc/yuv2rgb_altivec.c b/libswscale/ppc/yuv2rgb_altivec.c
index 5e1033a973..8b0a93796f 100644
--- a/libswscale/ppc/yuv2rgb_altivec.c
+++ b/libswscale/ppc/yuv2rgb_altivec.c
@@ -284,7 +284,7 @@ static inline void cvtyuvtoRGB(SwsContext *c, vector signed short Y,
  * ------------------------------------------------------------------------------
  */
 
-#if !HAVE_VSX
+#if !HAVE_VEC_XL
 static inline vector unsigned char vec_xl(signed long long offset, const ubyte *addr)
 {
     const vector unsigned char *v_addr = (const vector unsigned char *) (addr + offset);
@@ -292,7 +292,7 @@ static inline vector unsigned char vec_xl(signed long long offset, const ubyte *
 
     return (vector unsigned char) vec_perm(v_addr[0], v_addr[1], align_perm);
 }
-#endif /* !HAVE_VSX */
+#endif /* !HAVE_VEC_XL */
 
 #define DEFCSP420_CVT(name, out_pixels)                                       \
 static int altivec_ ## name(SwsContext *c, const unsigned char **in,          \
-- 
2.41.0

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Re: [FFmpeg-devel] [PATCH v2] lsws/ppc/yuv2rgb_altivec: Fix build in non-VSX environments with Clang

[Michael Niedermayer]

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On Fri, Aug 18, 2023 at 10:14:04PM -0400, Brad Smith wrote:
> lsws/ppc/yuv2rgb_altivec: Fix build in non-VSX environments with Clang
> 
> Add a check for the existence of the vec_xl() function. Clang provides
> the function even with VSX not enabled.
> 
> v2: test for function if AltiVec is enabled instead of with AltiVec and without VSX
> ---
>  configure                        | 8 ++++++++
>  libswscale/ppc/yuv2rgb_altivec.c | 4 ++--
>  2 files changed, 10 insertions(+), 2 deletions(-)

Has this been tested on an affected platform ?
I mean the function is provided but does it also work ?

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes

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