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sparc: Prevent stfsr from directly following floating-point instruction

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On LEON, if the stfsr instruction is immediately following a floating-point
operation instruction in a running program, with no other instruction in
between the two, the stfsr might behave as if the order was reversed
between the two instructions and the stfsr occurred before the
floating-point operation.

Add a nop instruction before the stfsr to prevent this from happening.

Signed-off-by: Daniel Cederman <cederman@gaisler.com>
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Daniel Cederman 2024-01-15 15:53:45 +01:00 committed by Adhemerval Zanella
parent 3bb1350c36
commit 82a35070ec
1 changed files with 6 additions and 1 deletions
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7
sysdeps/sparc/fpu/fpu_control.h
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@ -61,7 +61,12 @@ typedef unsigned long int fpu_control_t;
# define _FPU_GETCW(cw) __asm__ __volatile__ ("stx %%fsr,%0" : "=m" (*&cw))
# define _FPU_SETCW(cw) __asm__ __volatile__ ("ldx %0,%%fsr" : : "m" (*&cw))
#else
# define _FPU_GETCW(cw) __asm__ __volatile__ ("st %%fsr,%0" : "=m" (*&cw))
# ifdef __leon__
/* Prevent stfsr from being placed directly after other fp instruction. */
# define _FPU_GETCW(cw) __asm__ __volatile__ ("nop; st %%fsr,%0" : "=m" (*&cw))
# else
# define _FPU_GETCW(cw) __asm__ __volatile__ ("st %%fsr,%0" : "=m" (*&cw))
# endif
# define _FPU_SETCW(cw) __asm__ __volatile__ ("ld %0,%%fsr" : : "m" (*&cw))
#endif