ffmpeg | branch: master | Henrik Gramner <hen...@gramner.com> | Tue Dec 20 21:33:12 2016 +0100| [cd09e3b34903db7b7e37fdb4d3e10549bf8b2e82] | committer: Henrik Gramner
x86inc: Avoid using eax/rax for storing the stack pointer When allocating stack space with an alignment requirement that is larger than the current stack alignment we need to store a copy of the original stack pointer in order to be able to restore it later. If we chose to use another register for this purpose we should not pick eax/rax since it can be overwritten as a return value. > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=cd09e3b34903db7b7e37fdb4d3e10549bf8b2e82 --- libavutil/x86/x86inc.asm | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/libavutil/x86/x86inc.asm b/libavutil/x86/x86inc.asm index b2e9c60..128ddc1 100644 --- a/libavutil/x86/x86inc.asm +++ b/libavutil/x86/x86inc.asm @@ -385,7 +385,14 @@ DECLARE_REG_TMP_SIZE 0,1,2,3,4,5,6,7,8,9,10,11,12,13,14 %ifnum %1 %if %1 != 0 && required_stack_alignment > STACK_ALIGNMENT %if %1 > 0 + ; Reserve an additional register for storing the original stack pointer, but avoid using + ; eax/rax for this purpose since it can potentially get overwritten as a return value. %assign regs_used (regs_used + 1) + %if ARCH_X86_64 && regs_used == 7 + %assign regs_used 8 + %elif ARCH_X86_64 == 0 && regs_used == 1 + %assign regs_used 2 + %endif %endif %if ARCH_X86_64 && regs_used < 5 + UNIX64 * 3 ; Ensure that we don't clobber any registers containing arguments. For UNIX64 we also preserve r6 (rax) _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog
