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[libc][fenv] Add missing FE_* definitions for some environment. #91519

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merged 2 commits into from
May 8, 2024
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[libc][fenv] Add missing FE_* definitions for some environment. #91519

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[libc][fenv] Add missing FE_* definitions for some environment.
lntue May 8, 2024
68c2fd3
Also check for rounding mode macros.
lntue May 8, 2024
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41 changes: 41 additions & 0 deletions libc/hdr/fenv_macros.h
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Original file line number Diff line number Diff line change
Expand Up @@ -17,10 +17,51 @@

#include <fenv.h>

// In some environment, FE_ALL_EXCEPT is set to 0 and the remaining exceptions
// FE_* are missing.
#if (FE_ALL_EXCEPT == 0)
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This is not a valid preprocessor constant expression. On z/OS this caused hard error as the following:

cat t.C && clang++ -c t.C

#define FE_ALL_EXCEPT   ((unsigned int) 0x000000F8)

#if (FE_ALL_EXCEPT == 0)
#ifndef FE_DIVBYZERO
#define FE_DIVBYZERO 0
#endif // FE_DIVBYZERO
#endif
t.C:3:6: error: token is not a valid binary operator in a preprocessor subexpression
    3 | #if (FE_ALL_EXCEPT == 0)
      |      ^~~~~~~~~~~~~
t.C:1:36: note: expanded from macro 'FE_ALL_EXCEPT'
    1 | #define FE_ALL_EXCEPT   ((unsigned int) 0x000000F8)
      |                           ~~~~~~~~ ^
1 error generated.

We are currently using #ifndef FE_ALL_EXCEPT as hack.

Will you be able to provide a proper fix?

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I think we can remove the outer #if (FE_ALL_EXCEPT == 0) entirely, just directly check for exception macros individually and set them to 0 if not defined, WDYT ? @nickdesaulniers

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Yeah, seems like we can just remove this outer conditional.

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@zibi2 #114446

#ifndef FE_DIVBYZERO
#define FE_DIVBYZERO 0
#endif // FE_DIVBYZERO

#ifndef FE_INEXACT
#define FE_INEXACT 0
#endif // FE_INEXACT

#ifndef FE_INVALID
#define FE_INVALID 0
#endif // FE_INVALID

#ifndef FE_OVERFLOW
#define FE_OVERFLOW 0
#endif // FE_OVERFLOW

#ifndef FE_UNDERFLOW
#define FE_UNDERFLOW 0
#endif // FE_UNDERFLOW
#else
// If this is not provided by the system, define it for use internally.
#ifndef __FE_DENORM
#define __FE_DENORM (1 << 6)
#endif
#endif

// Rounding mode macros might be missing.
#ifndef FE_DOWNWARD
#define FE_DOWNWARD 0x400
#endif // FE_DOWNWARD

#ifndef FE_TONEAREST
#define FE_TONEAREST 0
#endif // FE_TONEAREST

#ifndef FE_TOWARDZERO
#define FE_TOWARDZERO 0xC00
#endif // FE_TOWARDZERO

#ifndef FE_UPWARD
#define FE_UPWARD 0x800
#endif // FE_UPWARD

#endif // LLVM_LIBC_FULL_BUILD

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