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hppa: Fix undefined behaviour in feclearexcept (BZ 30983)

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The expression

  (excepts & FE_ALL_EXCEPT) << 27

produces a signed integer overflow when 'excepts' is specified as
FE_INVALID (= 0x10), because
  - excepts is of type 'int',
  - FE_ALL_EXCEPT is of type 'int',
  - thus (excepts & FE_ALL_EXCEPT) is (int) 0x10,
  - 'int' is 32 bits wide.

The patched code produces the same instruction sequence as
previosuly.

Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Bruno Haible 2023-11-02 16:19:44 -03:00 committed by Adhemerval Zanella
parent 80a40a9e14
commit d082930272
1 changed files with 1 additions and 1 deletions
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sysdeps/hppa/fpu/fclrexcpt.c
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@ -26,7 +26,7 @@ feclearexcept (int excepts)
/* Get the current status word. */
__asm__ ("fstd %%fr0,0(%1)" : "=m" (s.l) : "r" (&s.l) : "%r0");
/* Clear all the relevant bits. */
s.sw[0] &= ~((excepts & FE_ALL_EXCEPT) << 27);
s.sw[0] &= ~(((unsigned int) excepts & FE_ALL_EXCEPT) << 27);
__asm__ ("fldd 0(%0),%%fr0" : : "r" (&s.l), "m" (s.l) : "%r0");
/* Success. */