# fmaf.m4 serial 4 dnl Copyright (C) 2011-2019 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_FUNC_FMAF], [ AC_REQUIRE([gl_MATH_H_DEFAULTS]) dnl Persuade glibc to declare fmaf(). AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) dnl Determine FMAF_LIBM. gl_MATHFUNC([fmaf], [float], [(float, float, float)], [extern #ifdef __cplusplus "C" #endif float fmaf (float, float, float); ]) if test $gl_cv_func_fmaf_no_libm = yes \ || test $gl_cv_func_fmaf_in_libm = yes; then dnl Also check whether it's declared. dnl IRIX 6.5 has fmaf() in libm but doesn't declare it in , dnl and the function is likely buggy. AC_CHECK_DECL([fmaf], , [REPLACE_FMAF=1], [[#include ]]) if test $REPLACE_FMAF = 0; then gl_FUNC_FMAF_WORKS case "$gl_cv_func_fmaf_works" in *no) REPLACE_FMAF=1 ;; esac fi else HAVE_FMAF=0 fi if test $HAVE_FMAF = 0 || test $REPLACE_FMAF = 1; then dnl Find libraries needed to link lib/fmaf.c. AC_REQUIRE([gl_FUNC_FREXPF]) AC_REQUIRE([gl_FUNC_LDEXPF]) AC_REQUIRE([gl_FUNC_FEGETROUND]) FMAF_LIBM= dnl Append $FREXPF_LIBM to FMAF_LIBM, avoiding gratuitous duplicates. case " $FMAF_LIBM " in *" $FREXPF_LIBM "*) ;; *) FMAF_LIBM="$FMAF_LIBM $FREXPF_LIBM" ;; esac dnl Append $LDEXPF_LIBM to FMAF_LIBM, avoiding gratuitous duplicates. case " $FMAF_LIBM " in *" $LDEXPF_LIBM "*) ;; *) FMAF_LIBM="$FMAF_LIBM $LDEXPF_LIBM" ;; esac dnl Append $FEGETROUND_LIBM to FMAF_LIBM, avoiding gratuitous duplicates. case " $FMAF_LIBM " in *" $FEGETROUND_LIBM "*) ;; *) FMAF_LIBM="$FMAF_LIBM $FEGETROUND_LIBM" ;; esac fi AC_SUBST([FMAF_LIBM]) ]) dnl Test whether fmaf() has any of the 7 known bugs of glibc 2.11.3 on x86_64. AC_DEFUN([gl_FUNC_FMAF_WORKS], [ AC_REQUIRE([AC_PROG_CC]) AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_REQUIRE([gl_FUNC_LDEXPF]) save_LIBS="$LIBS" LIBS="$LIBS $FMAF_LIBM $LDEXPF_LIBM" AC_CACHE_CHECK([whether fmaf works], [gl_cv_func_fmaf_works], [ AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #include #include float p0 = 0.0f; int main() { int failed_tests = 0; /* These tests fail with glibc 2.11.3 on x86_64. */ { volatile float x = 1.5f; /* 3 * 2^-1 */ volatile float y = x; volatile float z = ldexpf (1.0f, FLT_MANT_DIG + 1); /* 2^25 */ /* x * y + z with infinite precision: 2^25 + 9 * 2^-2. Lies between (2^23 + 0) * 2^2 and (2^23 + 1) * 2^2 and is closer to (2^23 + 1) * 2^2, therefore the rounding must round up and produce (2^23 + 1) * 2^2. */ volatile float expected = z + 4.0f; volatile float result = fmaf (x, y, z); if (result != expected) failed_tests |= 1; } { volatile float x = 1.25f; /* 2^0 + 2^-2 */ volatile float y = - x; volatile float z = ldexpf (1.0f, FLT_MANT_DIG + 1); /* 2^25 */ /* x * y + z with infinite precision: 2^25 - 2^0 - 2^-1 - 2^-4. Lies between (2^24 - 1) * 2^1 and 2^24 * 2^1 and is closer to (2^24 - 1) * 2^1, therefore the rounding must round down and produce (2^24 - 1) * 2^1. */ volatile float expected = (ldexpf (1.0f, FLT_MANT_DIG) - 1.0f) * 2.0f; volatile float result = fmaf (x, y, z); if (result != expected) failed_tests |= 2; } { volatile float x = 1.0f + ldexpf (1.0f, 1 - FLT_MANT_DIG); /* 2^0 + 2^-23 */ volatile float y = x; volatile float z = 4.0f; /* 2^2 */ /* x * y + z with infinite precision: 2^2 + 2^0 + 2^-22 + 2^-46. Lies between (2^23 + 2^21) * 2^-21 and (2^23 + 2^21 + 1) * 2^-21 and is closer to (2^23 + 2^21 + 1) * 2^-21, therefore the rounding must round up and produce (2^23 + 2^21 + 1) * 2^-21. */ volatile float expected = 4.0f + 1.0f + ldexpf (1.0f, 3 - FLT_MANT_DIG); volatile float result = fmaf (x, y, z); if (result != expected) failed_tests |= 4; } { volatile float x = 1.0f + ldexpf (1.0f, 1 - FLT_MANT_DIG); /* 2^0 + 2^-23 */ volatile float y = - x; volatile float z = 8.0f; /* 2^3 */ /* x * y + z with infinite precision: 2^2 + 2^1 + 2^0 - 2^-22 - 2^-46. Lies between (2^23 + 2^22 + 2^21 - 1) * 2^-21 and (2^23 + 2^22 + 2^21) * 2^-21 and is closer to (2^23 + 2^22 + 2^21 - 1) * 2^-21, therefore the rounding must round down and produce (2^23 + 2^22 + 2^21 - 1) * 2^-21. */ volatile float expected = 7.0f - ldexpf (1.0f, 3 - FLT_MANT_DIG); volatile float result = fmaf (x, y, z); if (result != expected) failed_tests |= 8; } { volatile float x = 1.25f; /* 2^0 + 2^-2 */ volatile float y = - 0.75f; /* - 2^0 + 2^-2 */ volatile float z = ldexpf (1.0f, FLT_MANT_DIG); /* 2^24 */ /* x * y + z with infinite precision: 2^24 - 2^0 + 2^-4. Lies between (2^24 - 2^0) and 2^24 and is closer to (2^24 - 2^0), therefore the rounding must round down and produce (2^24 - 2^0). */ volatile float expected = ldexpf (1.0f, FLT_MANT_DIG) - 1.0f; volatile float result = fmaf (x, y, z); if (result != expected) failed_tests |= 16; } if ((FLT_MANT_DIG % 2) == 0) { volatile float x = 1.0f + ldexpf (1.0f, - FLT_MANT_DIG / 2); /* 2^0 + 2^-12 */ volatile float y = x; volatile float z = ldexpf (1.0f, FLT_MIN_EXP - FLT_MANT_DIG); /* 2^-149 */ /* x * y + z with infinite precision: 2^0 + 2^-11 + 2^-24 + 2^-149. Lies between (2^23 + 2^12 + 0) * 2^-23 and (2^23 + 2^12 + 1) * 2^-23 and is closer to (2^23 + 2^12 + 1) * 2^-23, therefore the rounding must round up and produce (2^23 + 2^12 + 1) * 2^-23. */ volatile float expected = 1.0f + ldexpf (1.0f, 1 - FLT_MANT_DIG / 2) + ldexpf (1.0f, 1 - FLT_MANT_DIG); volatile float result = fmaf (x, y, z); if (result != expected) failed_tests |= 32; } { float minus_inf = -1.0f / p0; volatile float x = ldexpf (1.0f, FLT_MAX_EXP - 1); volatile float y = ldexpf (1.0f, FLT_MAX_EXP - 1); volatile float z = minus_inf; volatile float result = fmaf (x, y, z); if (!(result == minus_inf)) failed_tests |= 64; } return failed_tests; }]])], [gl_cv_func_fmaf_works=yes], [gl_cv_func_fmaf_works=no], [dnl Guess yes on native Windows with MSVC. dnl Otherwise guess no, even on glibc systems. gl_cv_func_fmaf_works="guessing no" case "$host_os" in mingw*) AC_EGREP_CPP([Known], [ #ifdef _MSC_VER Known #endif ], [gl_cv_func_fmaf_works="guessing yes"]) ;; esac ]) ]) LIBS="$save_LIBS" ]) # Prerequisites of lib/fmaf.c. AC_DEFUN([gl_PREREQ_FMAF], [:])