On Tue, Nov 11, 2014 at 9:37 PM, Joseph Myers <jos...@codesourcery.com> wrote:
> This patch adds a predefined macro __NO_MATH_ERRNO__ for when
> -fno-math-errno is passed or implied. This allows math.h to provide a
> more accurate definition of the C99 math_errhandling macro that takes
> this option into account, and allows for choice of libm functions to
> be optimized at compile time based on this option.
>
> (There may be a case for such interfaces for -fno-rounding-math
> (default) and -fno-trapping-math as well, but as C99 standard pragmas
> would allow those to vary on a per-block basis, predefined macros
> would be problematic as the interface; you can't select a
> -fno-trapping-math or -fno-rounding-math version of a function in a
> standard header if a conforming program could then use "#pragma STDC
> FENV_ACCESS ON" to require a -ftrapping-math -frounding-math version
> in a particular block. So built-in functions might be a better way of
> providing access to information about those options.)
>
> Bootstrapped with no regressions on x86_64-unknown-linux-gnu. OK to
> commit (the cppbuiltin.c changes)?
Ok.
Thanks,
Richard.
> 2014-11-11 Joseph Myers <jos...@codesourcery.com>
>
> * cppbuiltin.c (define_builtin_macros_for_compilation_flags):
> Define __NO_MATH_ERRNO__ if -fno-math-errno.
> * doc/cpp.texi (__NO_MATH_ERRNO__): Document predefined macro.
>
> c-family:
> 2014-11-11 Joseph Myers <jos...@codesourcery.com>
>
> * c-cppbuiltin.c (c_cpp_builtins_optimize_pragma): Define and
> undefine __NO_MATH_ERRNO__ based on changes to -fmath-errno state.
>
> testsuite:
> 2014-11-11 Joseph Myers <jos...@codesourcery.com>
>
> * gcc.dg/no-math-errno-1.c, gcc.dg/no-math-errno-2.c,
> gcc.dg/no-math-errno-3.c, gcc.dg/no-math-errno-4.c: New tests.
>
> Index: gcc/c-family/c-cppbuiltin.c
> ===================================================================
> --- gcc/c-family/c-cppbuiltin.c (revision 217347)
> +++ gcc/c-family/c-cppbuiltin.c (working copy)
> @@ -549,6 +549,11 @@ c_cpp_builtins_optimize_pragma (cpp_reader *pfile,
> else if (prev->x_flag_signaling_nans && !cur->x_flag_signaling_nans)
> cpp_undef (pfile, "__SUPPORT_SNAN__");
>
> + if (!prev->x_flag_errno_math && cur->x_flag_errno_math)
> + cpp_undef (pfile, "__NO_MATH_ERRNO__");
> + else if (prev->x_flag_errno_math && !cur->x_flag_errno_math)
> + cpp_define (pfile, "__NO_MATH_ERRNO__");
> +
> if (!prev->x_flag_finite_math_only && cur->x_flag_finite_math_only)
> {
> cpp_undef (pfile, "__FINITE_MATH_ONLY__");
> Index: gcc/cppbuiltin.c
> ===================================================================
> --- gcc/cppbuiltin.c (revision 217347)
> +++ gcc/cppbuiltin.c (working copy)
> @@ -102,6 +102,8 @@ define_builtin_macros_for_compilation_flags (cpp_r
> cpp_define (pfile, "__FAST_MATH__");
> if (flag_signaling_nans)
> cpp_define (pfile, "__SUPPORT_SNAN__");
> + if (!flag_errno_math)
> + cpp_define (pfile, "__NO_MATH_ERRNO__");
>
> cpp_define_formatted (pfile, "__FINITE_MATH_ONLY__=%d",
> flag_finite_math_only);
> Index: gcc/doc/cpp.texi
> ===================================================================
> --- gcc/doc/cpp.texi (revision 217347)
> +++ gcc/doc/cpp.texi (working copy)
> @@ -2421,6 +2421,10 @@ Annex G requirements (for example, because @option
> was used). If 1 or more, it indicates that it is intended to support
> those requirements; this does not mean that all relevant language
> features are supported by GCC.
> +
> +@item __NO_MATH_ERRNO__
> +This macro is defined if @option{-fno-math-errno} is used, or enabled
> +by another option such as @option{-ffast-math} or by default.
> @end table
>
> @node System-specific Predefined Macros
> Index: gcc/testsuite/gcc.dg/no-math-errno-1.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/no-math-errno-1.c (revision 0)
> +++ gcc/testsuite/gcc.dg/no-math-errno-1.c (working copy)
> @@ -0,0 +1,7 @@
> +/* Test __NO_MATH_ERRNO__ is defined with -fno-math-errno. */
> +/* { dg-do compile } */
> +/* { dg-options "-fno-math-errno" } */
> +
> +#ifndef __NO_MATH_ERRNO__
> +#error "__NO_MATH_ERRNO__ not defined"
> +#endif
> Index: gcc/testsuite/gcc.dg/no-math-errno-2.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/no-math-errno-2.c (revision 0)
> +++ gcc/testsuite/gcc.dg/no-math-errno-2.c (working copy)
> @@ -0,0 +1,7 @@
> +/* Test __NO_MATH_ERRNO__ is defined with -ffast-math. */
> +/* { dg-do compile } */
> +/* { dg-options "-ffast-math" } */
> +
> +#ifndef __NO_MATH_ERRNO__
> +#error "__NO_MATH_ERRNO__ not defined"
> +#endif
> Index: gcc/testsuite/gcc.dg/no-math-errno-3.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/no-math-errno-3.c (revision 0)
> +++ gcc/testsuite/gcc.dg/no-math-errno-3.c (working copy)
> @@ -0,0 +1,7 @@
> +/* Test __NO_MATH_ERRNO__ is not defined with -fmath-errno. */
> +/* { dg-do compile } */
> +/* { dg-options "-fmath-errno" } */
> +
> +#ifdef __NO_MATH_ERRNO__
> +#error "__NO_MATH_ERRNO__ defined"
> +#endif
> Index: gcc/testsuite/gcc.dg/no-math-errno-4.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/no-math-errno-4.c (revision 0)
> +++ gcc/testsuite/gcc.dg/no-math-errno-4.c (working copy)
> @@ -0,0 +1,17 @@
> +/* Test __NO_MATH_ERRNO__ is defined and undefined by pragmas. */
> +/* { dg-do compile } */
> +/* { dg-options "-fmath-errno" } */
> +
> +#ifdef __NO_MATH_ERRNO__
> +#error "__NO_MATH_ERRNO__ defined"
> +#endif
> +
> +#pragma GCC optimize "-fno-math-errno"
> +#ifndef __NO_MATH_ERRNO__
> +#error "__NO_MATH_ERRNO__ not defined"
> +#endif
> +
> +#pragma GCC optimize "-fmath-errno"
> +#ifdef __NO_MATH_ERRNO__
> +#error "__NO_MATH_ERRNO__ defined"
> +#endif
>
> --
> Joseph S. Myers
> jos...@codesourcery.com
