[gcc r17-2924] range-op-float: Remove inappropriate frange_drop_infs call [PR126549]

[Jakub Jelinek]

https://gcc.gnu.org/g:217df27883c450f3f098bd0d1dc1ea7d5dbe8ff8

commit r17-2924-g217df27883c450f3f098bd0d1dc1ea7d5dbe8ff8
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Aug 4 10:34:01 2026 +0200

    range-op-float: Remove inappropriate frange_drop_infs call [PR126549]
    
    For integer to floating conversions I've added frange_drop_infs
    call into the handler.  Supposedly I thought that integers converted
    to floating point are never +-inf, but that is clearly not the case
    as the testcases show.  For _Float16 it can be +-inf very easily,
    as the finite range is just [-65504.0f16,65504.0f16], for others
    all one needs is a large enough _BitInt.
    
    The following patch just drops that call.  In the common cases,
    +-inf will not appear in the range anyway, lb and ub will be usually
    finite.
    
    2026-08-04  Jakub Jelinek  <jakub@redhat.com>
    
            PR tree-optimization/126549
            * range-op-float.cc (operator_cast::fold_range): Don't call
            frange_drop_infs.
    
            * gcc.dg/torture/pr126549.c: New test.
            * gcc.dg/torture/bitint-107.c: New test.
    
    Reviewed-by: Aldy Hernandez <aldy@quesejoda.com>

Diff:
---
 gcc/range-op-float.cc                     |  1 -
 gcc/testsuite/gcc.dg/torture/bitint-107.c | 18 ++++++++++++++++++
 gcc/testsuite/gcc.dg/torture/pr126549.c   | 18 ++++++++++++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
index a625202f5312..c0283a687756 100644
--- a/gcc/range-op-float.cc
+++ b/gcc/range-op-float.cc
@@ -3148,7 +3148,6 @@ operator_cast::fold_range (frange &r, tree type, const irange &op1,
 	frange_nextafter (mode, ub, dconstinf);
     }
   r.set (type, lb, ub, nan_state (false));
-  frange_drop_infs (r, type);
   if (r.undefined_p ())
     r.set_varying (type);
   return true;
diff --git a/gcc/testsuite/gcc.dg/torture/bitint-107.c b/gcc/testsuite/gcc.dg/torture/bitint-107.c
new file mode 100644
index 000000000000..93a37bafe316
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/bitint-107.c
@@ -0,0 +1,18 @@
+/* PR tree-optimization/126549 */
+/* { dg-do run { target { float32 && bitint575 } } } */
+/* { dg-add-options float32 } */
+
+[[gnu::noipa]] int
+foo (unsigned _BitInt(133) a)
+{
+  unsigned _BitInt(133) u = a % 5444517870735015415413993718908291383300uwb;
+  _Float32 h = (_Float32) u;
+  return h > __FLT32_MAX__;
+}
+
+int
+main ()
+{
+  if (foo (5444517870735015415413993718908291383295uwb) != 1)
+    __builtin_abort ();
+}
diff --git a/gcc/testsuite/gcc.dg/torture/pr126549.c b/gcc/testsuite/gcc.dg/torture/pr126549.c
new file mode 100644
index 000000000000..e87610a17179
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr126549.c
@@ -0,0 +1,18 @@
+/* PR tree-optimization/126549 */
+/* { dg-do run { target float16 } } */
+/* { dg-add-options float16 } */
+
+[[gnu::noipa]] int
+foo (unsigned a)
+{
+  unsigned u = a % 100001U;
+  _Float16 h = (_Float16) u;
+  return h > 65504.0f16;
+}
+
+int
+main ()
+{
+  if (foo (70000U) != 1)
+    __builtin_abort ();
+}