[gcc r12-1332] [PATCH] PR middle-end/53267: Constant fold BUILT_IN_FMOD.

[Jeff Law <law@gcc.gnu.org>]

https://gcc.gnu.org/g:2c17b5f8cca82d1957242055991a2c23184a1af1

commit r12-1332-g2c17b5f8cca82d1957242055991a2c23184a1af1
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Wed Jun 9 11:23:41 2021 -0400

    [PATCH] PR middle-end/53267: Constant fold BUILT_IN_FMOD.
    
    gcc/ChangeLog
            PR middle-end/53267
            * fold-const-call.c (fold_const_call_sss) [CASE_CFN_FMOD]:
            Support evaluation of fmod/fmodf/fmodl at compile-time.
    
    gcc/testsuite/ChangeLog
            * gcc.dg/builtins-70.c: New test.

Diff:
---
 gcc/fold-const-call.c              |  3 +++
 gcc/testsuite/gcc.dg/builtins-70.c | 46 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/gcc/fold-const-call.c b/gcc/fold-const-call.c
index a1d70b62c31..d6cb9b11a31 100644
--- a/gcc/fold-const-call.c
+++ b/gcc/fold-const-call.c
@@ -1375,6 +1375,9 @@ fold_const_call_sss (real_value *result, combined_fn fn,
     CASE_CFN_FDIM:
       return do_mpfr_arg2 (result, mpfr_dim, arg0, arg1, format);
 
+    CASE_CFN_FMOD:
+      return do_mpfr_arg2 (result, mpfr_fmod, arg0, arg1, format);
+
     CASE_CFN_HYPOT:
       return do_mpfr_arg2 (result, mpfr_hypot, arg0, arg1, format);
 
diff --git a/gcc/testsuite/gcc.dg/builtins-70.c b/gcc/testsuite/gcc.dg/builtins-70.c
new file mode 100644
index 00000000000..a0c2dc9e9e5
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtins-70.c
@@ -0,0 +1,46 @@
+/* Copyright (C) 2021 Free Software Foundation.
+
+   Check that constant folding of built-in fmod functions doesn't
+   break anything and produces the expected results.
+
+/* { dg-do link } */
+/* { dg-options "-O2 -ffast-math" } */
+
+extern void link_error(void);
+
+extern double fmod(double,double);
+extern float fmodf(float,float);
+extern long double fmodl(long double,long double);
+
+int main()
+{
+  if (fmod (6.5, 2.3) < 1.8999 || fmod (6.5, 2.3) > 1.9001)
+    link_error ();
+  if (fmod (-6.5, 2.3) < -1.9001 || fmod (-6.5, 2.3) > -1.8999)
+    link_error ();
+  if (fmod (6.5, -2.3) < 1.8999 || fmod (6.5, -2.3) > 1.9001)
+    link_error ();
+  if (fmod (-6.5, -2.3) < -1.9001 || fmod (-6.5, -2.3) > -1.8999)
+    link_error ();
+
+  if (fmodf (6.5f, 2.3f) < 1.8999f || fmodf (6.5f, 2.3f) > 1.9001f)
+    link_error ();
+  if (fmodf (-6.5f, 2.3f) < -1.9001f || fmodf (-6.5f, 2.3f) > -1.8999f)
+    link_error ();
+  if (fmodf (6.5f, -2.3f) < 1.8999f || fmodf (6.5f, -2.3f) > 1.9001f)
+    link_error ();
+  if (fmodf (-6.5f, -2.3f) < -1.9001f || fmodf (-6.5f, -2.3f) > -1.8999f)
+    link_error ();
+
+  if (fmodl (6.5l, 2.3l) < 1.8999l || fmod (6.5l, 2.3l) > 1.9001l)
+    link_error ();
+  if (fmodl (-6.5l, 2.3l) < -1.9001l || fmod (-6.5l, 2.3l) > -1.8999l)
+    link_error ();
+  if (fmodl (6.5l, -2.3l) < 1.8999l || fmod (6.5l, -2.3l) > 1.9001l)
+    link_error ();
+  if (fmodl (-6.5l, -2.3l) < -1.9001l || fmod (-6.5l, -2.3l) > -1.8999l)
+    link_error ();
+
+  return 0;
+}
+