[FFmpeg-cvslog] swscale: save ebx register when it is not available

[Andreas Cadhalpun]

ffmpeg | branch: release/3.2 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Fri Dec 16 02:29:56 2016 +0100| [884cd3caa5cc111daaa4ff2ca05c99e05a713e47] | committer: Andreas Cadhalpun

swscale: save ebx register when it is not available

Configure checks if the ebx register can be used for asm and it has to
be saved if and only if this is not the case.
Without this the build fails when configuring with --toolchain=hardened
--disable-pic on i386 using gcc 4.8:
error: PIC register clobbered by '%ebx' in 'asm'

In that case gcc 4.8 reserves the ebx register for the GOT needed for
PIE, so it can't be used in asm directly.

Reviewed-by: Michael Niedermayer <michael at niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit 319438e2f206036ee0cddf401dd50f3b2a3ae117)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=884cd3caa5cc111daaa4ff2ca05c99e05a713e47
---

 libswscale/x86/hscale_fast_bilinear_simd.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/libswscale/x86/hscale_fast_bilinear_simd.c b/libswscale/x86/hscale_fast_bilinear_simd.c
index 2cba5f0..60a2cbf 100644
--- a/libswscale/x86/hscale_fast_bilinear_simd.c
+++ b/libswscale/x86/hscale_fast_bilinear_simd.c
@@ -199,7 +199,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
 #if ARCH_X86_64
     uint64_t retsave;
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
     uint64_t ebxsave;
 #endif
 #endif
@@ -209,7 +209,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
         "mov               -8(%%rsp), %%"FF_REG_a"    \n\t"
         "mov            %%"FF_REG_a", %5              \n\t"  // retsave
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
         "mov            %%"FF_REG_b", %5              \n\t"  // ebxsave
 #endif
 #endif
@@ -255,7 +255,7 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
         "mov                      %5, %%"FF_REG_a" \n\t"
         "mov            %%"FF_REG_a", -8(%%rsp)    \n\t"
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
         "mov                      %5, %%"FF_REG_b" \n\t"
 #endif
 #endif
@@ -264,12 +264,12 @@ void ff_hyscale_fast_mmxext(SwsContext *c, int16_t *dst,
 #if ARCH_X86_64
           ,"m"(retsave)
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
           ,"m" (ebxsave)
 #endif
 #endif
         : "%"FF_REG_a, "%"FF_REG_c, "%"FF_REG_d, "%"FF_REG_S, "%"FF_REG_D
-#if ARCH_X86_64 || !defined(PIC)
+#if ARCH_X86_64 || HAVE_EBX_AVAILABLE
          ,"%"FF_REG_b
 #endif
     );
@@ -289,7 +289,7 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
 #if ARCH_X86_64
     DECLARE_ALIGNED(8, uint64_t, retsave);
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
     DECLARE_ALIGNED(8, uint64_t, ebxsave);
 #endif
 #endif
@@ -298,7 +298,7 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
         "mov          -8(%%rsp), %%"FF_REG_a"    \n\t"
         "mov       %%"FF_REG_a", %7              \n\t"  // retsave
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
         "mov       %%"FF_REG_b", %7              \n\t"  // ebxsave
 #endif
 #endif
@@ -332,7 +332,7 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
         "mov                    %7, %%"FF_REG_a" \n\t"
         "mov          %%"FF_REG_a", -8(%%rsp)    \n\t"
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
         "mov %7, %%"FF_REG_b"    \n\t"
 #endif
 #endif
@@ -341,12 +341,12 @@ void ff_hcscale_fast_mmxext(SwsContext *c, int16_t *dst1, int16_t *dst2,
 #if ARCH_X86_64
           ,"m"(retsave)
 #else
-#if defined(PIC)
+#if !HAVE_EBX_AVAILABLE
           ,"m" (ebxsave)
 #endif
 #endif
         : "%"FF_REG_a, "%"FF_REG_c, "%"FF_REG_d, "%"FF_REG_S, "%"FF_REG_D
-#if ARCH_X86_64 || !defined(PIC)
+#if ARCH_X86_64 || HAVE_EBX_AVAILABLE
          ,"%"FF_REG_b
 #endif
     );