Prevents the selection of the slowest code path on non-Intel CPU's.
Taken from x264 and adapted for use with libav.
---
libavutil/x86/cpu.c | 46 +++++++++++++++++++++++++++++++++++++++++++++
libavutil/x86/cpu.h | 1 +
libavutil/x86/cpuid.asm | 50 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 97 insertions(+)
diff --git a/libavutil/x86/cpu.c b/libavutil/x86/cpu.c
index 3b36fd0..718301e 100644
--- a/libavutil/x86/cpu.c
+++ b/libavutil/x86/cpu.c
@@ -199,3 +199,49 @@ int ff_get_cpu_flags_x86(void)
return rval;
}
+
+#if HAVE_MMX
+#ifdef __INTEL_COMPILER
+/* Agner's patch to Intel's CPU dispatcher from pages 131-132 of
+ * http://agner.org/optimize/optimizing_cpp.pdf (2011-01-30)
+ * adapted to libav's cpu schema. Copied from x264 and adapted for libav. */
+
+/* Global variable indicating cpu */
+int __intel_cpu_indicator = 0;
+
+/* CPU dispatcher function */
+void ff_intel_cpu_indicator_init(void)
+{
+ unsigned int cpu = ff_get_cpu_flags_x86();
+ if (cpu & AV_CPU_FLAG_AVX)
+ __intel_cpu_indicator = 0x20000;
+ else if (cpu & AV_CPU_FLAG_SSE42)
+ __intel_cpu_indicator = 0x8000;
+ else if (cpu & AV_CPU_FLAG_SSE4)
+ __intel_cpu_indicator = 0x2000;
+ else if (cpu & AV_CPU_FLAG_SSSE3)
+ __intel_cpu_indicator = 0x1000;
+ else if (cpu & AV_CPU_FLAG_SSE3)
+ __intel_cpu_indicator = 0x800;
+ else if (cpu & AV_CPU_FLAG_SSE2 && !(cpu & AV_CPU_FLAG_SSE2SLOW))
+ __intel_cpu_indicator = 0x200;
+ else if (cpu & AV_CPU_FLAG_SSE)
+ __intel_cpu_indicator = 0x80;
+ else if (cpu & AV_CPU_FLAG_MMXEXT)
+ __intel_cpu_indicator = 8;
+ else
+ __intel_cpu_indicator = 1;
+}
+
+/* __intel_cpu_indicator_init appears to have a non-standard calling
convention that
+ * assumes certain registers aren't preserved, so we'll route it through a
function
+ * that backs up all the registers. */
+void __intel_cpu_indicator_init(void)
+{
+ ff_safe_intel_cpu_indicator_init();
+}
+#else
+void ff_intel_cpu_indicator_init(void)
+{}
+#endif
+#endif
diff --git a/libavutil/x86/cpu.h b/libavutil/x86/cpu.h
index e4f6f0b..62122f4 100644
--- a/libavutil/x86/cpu.h
+++ b/libavutil/x86/cpu.h
@@ -57,5 +57,6 @@
void ff_cpu_cpuid(int index, int *eax, int *ebx, int *ecx, int *edx);
void ff_cpu_xgetbv(int op, int *eax, int *edx);
int ff_cpu_cpuid_test(void);
+void ff_safe_intel_cpu_indicator_init(void);
#endif /* AVUTIL_X86_CPU_H */
diff --git a/libavutil/x86/cpuid.asm b/libavutil/x86/cpuid.asm
index e739ebe..0f84a92 100644
--- a/libavutil/x86/cpuid.asm
+++ b/libavutil/x86/cpuid.asm
@@ -89,3 +89,53 @@ cglobal cpu_cpuid_test
popfd
ret
%endif
+
+cextern intel_cpu_indicator_init
+
+;-----------------------------------------------------------------------------
+; void ff_safe_intel_cpu_indicator_init(void)
+;-----------------------------------------------------------------------------
+cglobal safe_intel_cpu_indicator_init
+ push r0
+ push r1
+ push r2
+ push r3
+ push r4
+ push r5
+ push r6
+%if ARCH_X86_64
+ push r7
+ push r8
+ push r9
+ push r10
+ push r11
+ push r12
+ push r13
+ push r14
+%endif
+ push rbp
+ mov rbp, rsp
+%if WIN64
+ sub rsp, 32 ; shadow space
+%endif
+ and rsp, ~31
+ call intel_cpu_indicator_init
+ leave
+%if ARCH_X86_64
+ pop r14
+ pop r13
+ pop r12
+ pop r11
+ pop r10
+ pop r9
+ pop r8
+ pop r7
+%endif
+ pop r6
+ pop r5
+ pop r4
+ pop r3
+ pop r2
+ pop r1
+ pop r0
+ ret
--
1.8.1.msysgit.1
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