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Hack around gcc 4.6 breaking asm using call.

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gcc 4.6 no longer decrements esp to account for local variables.
Thus using call will end up overwriting some local variable.
So add an extra one it can safely clobber.
This is a huge hack because it's basically pure chance it works,
no idea how this is supposed to be done.

Fixes trac ticket #397.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
(cherry picked from commit c928e91729)
This commit is contained in:
Reimar Döffinger 2011-08-28 21:14:13 +02:00 committed by Carl Eugen Hoyos
parent bf7dc6b29d
commit f36cea2673
1 changed files with 10 additions and 0 deletions
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10
libswscale/x86/swscale_template.c
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@ -2240,6 +2240,10 @@ static void RENAME(hyscale_fast)(SwsContext *c, int16_t *dst,
#if defined(PIC)
DECLARE_ALIGNED(8, uint64_t, ebxsave);
#endif
// HACK: gcc 4.6 no longer decrements esp,
// use this to make it reserve space for the call
// return address
void *dummy;
__asm__ volatile(
#if defined(PIC)
@ -2291,6 +2295,7 @@ static void RENAME(hyscale_fast)(SwsContext *c, int16_t *dst,
#if defined(PIC)
,"m" (ebxsave)
#endif
,"m" (dummy)
: "%"REG_a, "%"REG_c, "%"REG_d, "%"REG_S, "%"REG_D
#if !defined(PIC)
,"%"REG_b
@ -2312,6 +2317,10 @@ static void RENAME(hcscale_fast)(SwsContext *c, int16_t *dst1, int16_t *dst2,
#if defined(PIC)
DECLARE_ALIGNED(8, uint64_t, ebxsave);
#endif
// HACK: gcc 4.6 no longer decrements esp,
// use this to make it reserve space for the call
// return address
void *dummy;
__asm__ volatile(
#if defined(PIC)
@ -2351,6 +2360,7 @@ static void RENAME(hcscale_fast)(SwsContext *c, int16_t *dst1, int16_t *dst2,
#if defined(PIC)
,"m" (ebxsave)
#endif
,"m" (dummy)
: "%"REG_a, "%"REG_c, "%"REG_d, "%"REG_S, "%"REG_D
#if !defined(PIC)
,"%"REG_b