diff mbox series

[v4,08/12] math: Add math-use-builtinds-fmax.h

Message ID 20211203000103.737833-9-adhemerval.zanella@linaro.org
State Superseded
Headers show
Series Improve hypot | expand

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Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent

Commit Message

Adhemerval Zanella Dec. 3, 2021, midnight UTC
It allows the architecture to use the builtin instead of generic
implementation.
---
 math/s_fmax_template.c                   | 27 ++++++++++++++++++++++++
 sysdeps/generic/math-use-builtins-fmax.h |  4 ++++
 sysdeps/generic/math-use-builtins.h      |  1 +
 3 files changed, 32 insertions(+)
 create mode 100644 sysdeps/generic/math-use-builtins-fmax.h

Comments

Wilco Dijkstra Dec. 6, 2021, 11:52 a.m. UTC | #1
Hi Adhemerval,

 math/s_fmax_template.c                   | 27 ++++++++++++++++++++++++
 sysdeps/generic/math-use-builtins-fmax.h |  4 ++++
 sysdeps/generic/math-use-builtins.h      |  1 +
 3 files changed, 32 insertions(+)
 create mode 100644 sysdeps/generic/math-use-builtins-fmax.h

Looks good.

Wilco
Joseph Myers Dec. 6, 2021, 9:11 p.m. UTC | #2
On Thu, 2 Dec 2021, Adhemerval Zanella via Libc-alpha wrote:

> +#if __HAVE_FLOAT128
> +# define USE_BUILTIN_F128 , _Float128 : USE_FMAXF128_BUILTIN
> +# define BUILTIN_F128     , _Float128 :__builtin_fmaxf128
> +#else
> +# define USE_BUILTIN_F128
> +# define BUILTIN_F128
> +#endif
> +
> +#define USE_BUILTIN(X, Y)                   \
> +  _Generic((X),                             \
> +	   float       : USE_FMAXF_BUILTIN, \
> +	   double      : USE_FMAX_BUILTIN,  \
> +	   long double : USE_FMAXL_BUILTIN  \
> +	   USE_BUILTIN_F128)
> +
> +#define BUILTIN(X, Y)                       \
> +  _Generic((X),                             \
> +	   float       : __builtin_fmaxf,   \
> +	   double      : __builtin_fmax,    \
> +	   long double : __builtin_fmaxl    \
> +	   BUILTIN_F128)                    \
> +  (X, Y)

You should not hardcode cases for different types in type-generic 
templates.  This would fail if we add support for _Float16 functions in 
future, for example.

Use M_SUF to call built-in functions (possibly via defining M_FMAX in 
math-type-macros.h, similar to the other M_* macros there.

Do something similar for USE_*_BUILTIN (I suggest defining M_USE_BUILTIN 
in the per-type headers used by math-type-macros.h, so you can then call 
M_USE_BUILTIN (FMAX).

You'll probably need to use #if with the M_USE_BUILTIN call (which should 
be OK after the above changes), because GCC only added __builtin_fmaxfN 
functions in commit ee5fd23a481f510528e00f4c988ed0e6a71218c2 (GCC 8 and 
later) but older GCC versions are supported for building for some 
architectures with _Float128 support, and if __builtin_fmaxf128 gets 
referenced inside if (0) with older GCC it would be an undeclared 
identifier.
Adhemerval Zanella Dec. 7, 2021, 1:21 p.m. UTC | #3
On 06/12/2021 18:11, Joseph Myers wrote:
> On Thu, 2 Dec 2021, Adhemerval Zanella via Libc-alpha wrote:
> 
>> +#if __HAVE_FLOAT128
>> +# define USE_BUILTIN_F128 , _Float128 : USE_FMAXF128_BUILTIN
>> +# define BUILTIN_F128     , _Float128 :__builtin_fmaxf128
>> +#else
>> +# define USE_BUILTIN_F128
>> +# define BUILTIN_F128
>> +#endif
>> +
>> +#define USE_BUILTIN(X, Y)                   \
>> +  _Generic((X),                             \
>> +	   float       : USE_FMAXF_BUILTIN, \
>> +	   double      : USE_FMAX_BUILTIN,  \
>> +	   long double : USE_FMAXL_BUILTIN  \
>> +	   USE_BUILTIN_F128)
>> +
>> +#define BUILTIN(X, Y)                       \
>> +  _Generic((X),                             \
>> +	   float       : __builtin_fmaxf,   \
>> +	   double      : __builtin_fmax,    \
>> +	   long double : __builtin_fmaxl    \
>> +	   BUILTIN_F128)                    \
>> +  (X, Y)
> 
> You should not hardcode cases for different types in type-generic 
> templates.  This would fail if we add support for _Float16 functions in 
> future, for example.
> 
> Use M_SUF to call built-in functions (possibly via defining M_FMAX in 
> math-type-macros.h, similar to the other M_* macros there.
> 
> Do something similar for USE_*_BUILTIN (I suggest defining M_USE_BUILTIN 
> in the per-type headers used by math-type-macros.h, so you can then call 
> M_USE_BUILTIN (FMAX).

Indeed it is cleaner, I don't see the need of just M_FMAX.

> 
> You'll probably need to use #if with the M_USE_BUILTIN call (which should 
> be OK after the above changes), because GCC only added __builtin_fmaxfN 
> functions in commit ee5fd23a481f510528e00f4c988ed0e6a71218c2 (GCC 8 and 
> later) but older GCC versions are supported for building for some 
> architectures with _Float128 support, and if __builtin_fmaxf128 gets 
> referenced inside if (0) with older GCC it would be an undeclared 
> identifier.
>

Right, but currently we use declare_mgen_alias for fmax/fmin, so I am not
sure it we really need to take care if __builtin_fmaxfN support.

For _Float128 I will need to check if this does incur in any issue, I 
am currently building some older gcc toolchain to check it.
diff mbox series

Patch

diff --git a/math/s_fmax_template.c b/math/s_fmax_template.c
index d817406f04..4417fdb283 100644
--- a/math/s_fmax_template.c
+++ b/math/s_fmax_template.c
@@ -17,10 +17,37 @@ 
    <https://www.gnu.org/licenses/>.  */
 
 #include <math.h>
+#include <math-use-builtins.h>
+
+#if __HAVE_FLOAT128
+# define USE_BUILTIN_F128 , _Float128 : USE_FMAXF128_BUILTIN
+# define BUILTIN_F128     , _Float128 :__builtin_fmaxf128
+#else
+# define USE_BUILTIN_F128
+# define BUILTIN_F128
+#endif
+
+#define USE_BUILTIN(X, Y)                   \
+  _Generic((X),                             \
+	   float       : USE_FMAXF_BUILTIN, \
+	   double      : USE_FMAX_BUILTIN,  \
+	   long double : USE_FMAXL_BUILTIN  \
+	   USE_BUILTIN_F128)
+
+#define BUILTIN(X, Y)                       \
+  _Generic((X),                             \
+	   float       : __builtin_fmaxf,   \
+	   double      : __builtin_fmax,    \
+	   long double : __builtin_fmaxl    \
+	   BUILTIN_F128)                    \
+  (X, Y)
 
 FLOAT
 M_DECL_FUNC (__fmax) (FLOAT x, FLOAT y)
 {
+  if (USE_BUILTIN (x, y))
+    return BUILTIN (x, y);
+
   if (isgreaterequal (x, y))
     return x;
   else if (isless (x, y))
diff --git a/sysdeps/generic/math-use-builtins-fmax.h b/sysdeps/generic/math-use-builtins-fmax.h
new file mode 100644
index 0000000000..8fc4efca6a
--- /dev/null
+++ b/sysdeps/generic/math-use-builtins-fmax.h
@@ -0,0 +1,4 @@ 
+#define USE_FMAX_BUILTIN 0
+#define USE_FMAXF_BUILTIN 0
+#define USE_FMAXL_BUILTIN 0
+#define USE_FMAXF128_BUILTIN 0
diff --git a/sysdeps/generic/math-use-builtins.h b/sysdeps/generic/math-use-builtins.h
index 19d2d1cf3c..e07bba242f 100644
--- a/sysdeps/generic/math-use-builtins.h
+++ b/sysdeps/generic/math-use-builtins.h
@@ -34,5 +34,6 @@ 
 #include <math-use-builtins-copysign.h>
 #include <math-use-builtins-sqrt.h>
 #include <math-use-builtins-fma.h>
+#include <math-use-builtins-fmax.h>
 
 #endif /* MATH_USE_BUILTINS_H  */