glibc/fesetenv.c at df7e29e2a4aadc7e19669eaf953cee1bcf8b156f - glibc - Gitea: Git with a cup of tea

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Joseph Myers 506d7fb1d4 Do not define various fenv.h macros for MIPS soft-float (bug 23479).

MIPS soft-float glibc does not support floating-point exceptions and
rounding modes, and uses a different ABI from hard-float so a
soft-float compilation cannot use a glibc that does support
floating-point exceptions and rounding modes.  Thus, bits/fenv.h
should not, when compiling for soft-float, define macros for the
unsupported features.

This patch changes it accordingly to define those macros only for
hard-float.  None of the exception macros are defined for soft-float,
with FE_ALL_EXCEPT defined to 0 in that case, and only FE_TONEAREST is
defined of the rounding-mode macros, and FE_NOMASK_ENV is not defined;
this is consistent with how architectures lacking exception and
rounding mode support generally define things in this header.  As well
as making the header more correct for this case, this also means the
generic math_private.h optimizations for this case automatically apply
(inlining libm-internal fenv.h function calls that are trivial when
exceptions and rounding modes are not supported).

The mips64 sfp-machine.h then needs similar changes to disable more of
the exception and rounding mode handling for soft-float.  (The mips32
sfp-machine.h is already used only for soft-float, has no integration
with hardware exceptions or rounding modes and so needs no changes.)

Existing binaries might use the old FE_NOMASK_ENV value as an argument
to fesetenv / feupdateenv and expect an error for it (given that it
was defined in a header that also defined FE_ALL_EXCEPT to a nonzero
value).  To preserve that error, wrappers for the fallback fesetenv
and feupdateenv are created in sysdeps/mips/nofpu/.

Tested for mips64 (hard-float and soft-float, all three ABIs).

	[BZ #23479]
	* sysdeps/mips/bits/fenv.h (FE_INEXACT): Define only if
	[__mips_hard_float].
	(FE_UNDERFLOW): Likewise.
	(FE_OVERFLOW): Likewise.
	(FE_DIVBYZERO): Likewise.
	(FE_INVALID): Likewise.
	(FE_ALL_EXCEPT): Define to 0 if [!__mips_hard_float].
	(FE_TOWARDZERO): Define only if [__mips_hard_float].
	(FE_UPWARD): Likewise.
	(FE_DOWNWARD): Likewise.
	(__FE_UNDEFINED): Define if [!__mips_hard_float]
	(FE_NOMASK_ENV): Define only if [__mips_hard_float].
	* sysdeps/mips/mips64/sfp-machine.h (_FP_DECL_EX): Define only if
	[__mips_hard_float].
	(FP_ROUNDMODE): Likewise.
	(FP_RND_NEAREST): Likewise.
	(FP_RND_ZERO): Likewise.
	(FP_RND_PINF): Likewise.
	(FP_RND_MINF): Likewise.
	(FP_EX_INVALID): Likewise.
	(FP_EX_OVERFLOW): Likewise.
	(FP_EX_UNDERFLOW): Likewise.
	(FP_EX_DIVZERO): Likewise.
	(FP_EX_INEXACT): Likewise.
	(FP_INIT_ROUNDMODE): Likewise.
	* sysdeps/mips/nofpu/fesetenv.c: New file.
	* sysdeps/mips/nofpu/feupdateenv.c: Likewise.

2018-08-02 15:53:29 +00:00

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 /* MIPS bits/fenv.h used to define exception macros for soft-float
    despite that not supporting exceptions.  Ensure use of the old
    FE_NOMASK_ENV value still produces errors (see bug 17088).  */
 #include <fenv.h>
 #undef FE_ALL_EXCEPT
 #define FE_ALL_EXCEPT 0x7c
 #define FE_NOMASK_ENV ((const fenv_t *) -2)
 #include <math/fesetenv.c>