replace tgammaf by the CORE-MATH implementation

The CORE-MATH implementation is correctly rounded (for any rounding mode).
This can be checked by exhaustive tests in a few minutes since there are
less than 2^32 values to check against for example GNU MPFR.
This patch also adds some bench values for tgammaf.

Tested on x86_64 and x86 (cfarm26).

With the initial GNU libc code it gave on an Intel(R) Core(TM) i7-8700:

      "tgammaf": {
       "": {
        "duration": 3.50188e+09,
        "iterations": 2e+07,
        "max": 602.891,
        "min": 65.1415,
        "mean": 175.094
       }
      }

With the new code:

      "tgammaf": {
       "": {
        "duration": 3.30825e+09,
        "iterations": 5e+07,
        "max": 211.592,
        "min": 32.0325,
        "mean": 66.1649
       }
      }

With the initial GNU libc code it gave on cfarm26 (i686):

  "tgammaf": {
   "": {
    "duration": 3.70505e+09,
    "iterations": 6e+06,
    "max": 2420.23,
    "min": 243.154,
    "mean": 617.509
   }
  }

With the new code:

  "tgammaf": {
   "": {
    "duration": 3.24497e+09,
    "iterations": 1.8e+07,
    "max": 1238.15,
    "min": 101.155,
    "mean": 180.276
   }
  }

Signed-off-by: Alexei Sibidanov <sibid@uvic.ca>
Signed-off-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>

Changes in v2:
    - include <math.h> (fix the linknamespace failures)
    - restored original benchtests/strcoll-inputs/filelist#en_US.UTF-8 file
    - restored original wrapper code (math/w_tgammaf_compat.c),
      except for the dealing with the sign
    - removed the tgammaf/float entries in all libm-test-ulps files
    - address other comments from Joseph Myers
      (https://sourceware.org/pipermail/libc-alpha/2024-July/158736.html)

Changes in v3:
    - pass NULL argument for signgam from w_tgammaf_compat.c
    - use of math_narrow_eval
    - added more comments

Changes in v4:
    - initialize local_signgam to 0 in math/w_tgamma_template.c
    - replace sysdeps/ieee754/dbl-64/gamma_productf.c by dummy file

Changes in v5:
    - do not mention local_signgam any more in math/w_tgammaf_compat.c
    - initialize local_signgam to 1 instead of 0 in w_tgamma_template.c
      and added comment

Changes in v6:
    - pass NULL as 2nd argument of __ieee754_gammaf_r in
      w_tgammaf_compat.c, and check for NULL in e_gammaf_r.c

Changes in v7:
    - added Signed-off-by line for Alexei Sibidanov (author of the code)

Changes in v8:
    - added Signed-off-by line for Paul Zimmermann (submitted of the patch)

Changes in v9:
    - address comments from review by Adhemerval Zanella
Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/SHARED-FILES b/SHARED-FILES
index d84e8e9..2aefac8 100644
--- a/SHARED-FILES
+++ b/SHARED-FILES
@@ -219,3 +219,15 @@ tzdata:
   timezone/leapseconds
   # This is yearistype.sh in the parent project
   timezone/yearistype
+
+# The following files are shared with the CORE-MATH project
+sysdeps/ieee754/flt-32/e_gammaf_r.c
+  (file src/binary32/tgamma/tgammaf.c in CORE-MATH)
+  Instructions to merge new versions:
+  - change the function name from cr_tgammaf to __ieee754_gammaf_r
+  - add "int *signgamp" as 2nd argument and add at the beginning:
+    if (signgamp != NULL) *signgamp = 1;
+  - remove the errno stuff (this is done by the wrapper)
+  - replace 0x1p127f * 0x1p127f by math_narrow_eval (x * 0x1p127f)
+  - replace 0x1p-127f * sgn[k&1] by math_narrow_eval (0x1p-127f * sgn[k&1])
+  - add libm_alias_finite (__ieee754_gammaf_r, __gammaf_r) at the end