Piotr Caban : msvcrt: Import fmaf implementation from musl.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: 7fdb78e80bf3a8ea6d165d320c0db76192325069
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=7fdb78e80bf3a8ea6d165d320c0db76192325069

Author: Piotr Caban <piotr at codeweavers.com>
Date:   Tue Jun  8 21:19:39 2021 +0200

msvcrt: Import fmaf implementation from musl.

Signed-off-by: Piotr Caban <piotr at codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard at winehq.org>

---

 configure             |  3 +--
 configure.ac          |  3 +--
 dlls/msvcrt/math.c    | 39 ++++++++++++++++++++++++++++++++++-----
 dlls/msvcrt/unixlib.c | 13 -------------
 dlls/msvcrt/unixlib.h |  1 -
 include/config.h.in   |  3 ---
 6 files changed, 36 insertions(+), 26 deletions(-)

diff --git a/configure b/configure
index 6a250f3728e..06f18a9efe0 100755
--- a/configure
+++ b/configure
@@ -19621,8 +19621,7 @@ fi
 
 for ac_func in \
 	exp2 \
-	exp2f \
-	fmaf
+	exp2f
 
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
diff --git a/configure.ac b/configure.ac
index d4c1896fa96..98404b666d5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2660,8 +2660,7 @@ fi
 
 AC_CHECK_FUNCS(\
 	exp2 \
-	exp2f \
-	fmaf
+	exp2f
 )
 LIBS="$ac_save_LIBS"
 
diff --git a/dlls/msvcrt/math.c b/dlls/msvcrt/math.c
index a054f561a63..4d7cc6ab727 100644
--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -4127,14 +4127,43 @@ double CDECL fma( double x, double y, double z )
 
 /*********************************************************************
  *      fmaf (MSVCRT.@)
+ *
+ * Copied from musl: src/math/fmaf.c
  */
 float CDECL fmaf( float x, float y, float z )
 {
-  float w = unix_funcs->fmaf(x, y, z);
-  if ((isinf(x) && y == 0) || (x == 0 && isinf(y))) *_errno() = EDOM;
-  else if (isinf(x) && isinf(z) && x != z) *_errno() = EDOM;
-  else if (isinf(y) && isinf(z) && y != z) *_errno() = EDOM;
-  return w;
+    union { double f; UINT64 i; } u;
+    double xy, adjust;
+    int e;
+
+    xy = (double)x * y;
+    u.f = xy + z;
+    e = u.i>>52 & 0x7ff;
+    /* Common case: The double precision result is fine. */
+    if ((u.i & 0x1fffffff) != 0x10000000 || /* not a halfway case */
+            e == 0x7ff || /* NaN */
+            (u.f - xy == z && u.f - z == xy) || /* exact */
+            (_controlfp(0, 0) & _MCW_RC) != _RC_NEAR) /* not round-to-nearest */
+    {
+        if (!isnan(x) && !isnan(y) && !isnan(z) && isnan(u.f)) *_errno() = EDOM;
+
+        /* underflow may not be raised correctly, example:
+           fmaf(0x1p-120f, 0x1p-120f, 0x1p-149f) */
+        if (e < 0x3ff-126 && e >= 0x3ff-149 && _statusfp() & _SW_INEXACT)
+            fp_barrierf((float)u.f * (float)u.f);
+        return u.f;
+    }
+
+    /*
+     * If result is inexact, and exactly halfway between two float values,
+     * we need to adjust the low-order bit in the direction of the error.
+     */
+    _controlfp(_RC_CHOP, _MCW_RC);
+    adjust = fp_barrier(xy + z);
+    _controlfp(_RC_NEAR, _MCW_RC);
+    if (u.f == adjust)
+        u.i++;
+    return u.f;
 }
 
 /*********************************************************************
diff --git a/dlls/msvcrt/unixlib.c b/dlls/msvcrt/unixlib.c
index a01b227e428..91c6bc4c2f0 100644
--- a/dlls/msvcrt/unixlib.c
+++ b/dlls/msvcrt/unixlib.c
@@ -82,18 +82,6 @@ static float CDECL unix_exp2f( float x )
 #endif
 }
 
-/*********************************************************************
- *      fmaf
- */
-static float CDECL unix_fmaf( float x, float y, float z )
-{
-#ifdef HAVE_FMAF
-    return fmaf(x, y, z);
-#else
-    return x * y + z;
-#endif
-}
-
 /*********************************************************************
  *      pow
  */
@@ -116,7 +104,6 @@ static const struct unix_funcs funcs =
     unix_expf,
     unix_exp2,
     unix_exp2f,
-    unix_fmaf,
     unix_pow,
     unix_powf,
 };
diff --git a/dlls/msvcrt/unixlib.h b/dlls/msvcrt/unixlib.h
index b39f56c31cc..b7afa6cdf8b 100644
--- a/dlls/msvcrt/unixlib.h
+++ b/dlls/msvcrt/unixlib.h
@@ -27,7 +27,6 @@ struct unix_funcs
     float           (CDECL *expf)(float x);
     double          (CDECL *exp2)(double x);
     float           (CDECL *exp2f)(float x);
-    float           (CDECL *fmaf)(float x, float y, float z);
     double          (CDECL *pow)(double x, double y);
     float           (CDECL *powf)(float x, float y);
 };
diff --git a/include/config.h.in b/include/config.h.in
index be6dfb35ab3..09bcdd70983 100644
--- a/include/config.h.in
+++ b/include/config.h.in
@@ -120,9 +120,6 @@
 /* Define to 1 if you have the <float.h> header file. */
 #undef HAVE_FLOAT_H
 
-/* Define to 1 if you have the `fmaf' function. */
-#undef HAVE_FMAF
-
 /* Define to 1 if you have the `fnmatch' function. */
 #undef HAVE_FNMATCH