[gcc r14-6264] tree-ssa-dce: Fix up maybe_optimize_arith_overflow for BITINT_TYPE [PR112880]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:f74939bd539c87f669e35042f7bc7aa47f0c29eb

commit r14-6264-gf74939bd539c87f669e35042f7bc7aa47f0c29eb
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Dec 7 09:46:38 2023 +0100

    tree-ssa-dce: Fix up maybe_optimize_arith_overflow for BITINT_TYPE [PR112880]
    
    The following testcase ICEs because maybe_optimize_arith_overflow
    uses build_nonstandard_integer_type, which is inappropriate if
    type is large BITINT_TYPE.
    
    2023-12-07  Jakub Jelinek  <jakub@redhat.com>
    
            PR tree-optimization/112880
            * tree-ssa-dce.cc (maybe_optimize_arith_overflow): Use
            unsigned_type_for instead of conditionally calling
            build_nonstandard_integer_type.
    
            * gcc.dg/bitint-49.c: New test.

Diff:
---
 gcc/testsuite/gcc.dg/bitint-49.c | 37 +++++++++++++++++++++++++++++++++++++
 gcc/tree-ssa-dce.cc              |  4 +---
 2 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/bitint-49.c b/gcc/testsuite/gcc.dg/bitint-49.c
new file mode 100644
index 00000000000..74d9bde7e15
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-49.c
@@ -0,0 +1,37 @@
+/* PR tree-optimization/112880 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-std=c23 -O2" } */
+
+#if __BITINT_MAXWIDTH__ >= 1024
+_BitInt(1024) a, b, c, d, e, f;
+
+void
+foo (void)
+{
+  __builtin_add_overflow (a, b, &a);
+  __builtin_sub_overflow (c, d, &c);
+  __builtin_mul_overflow (e, f, &e);
+}
+#endif
+
+#if __BITINT_MAXWIDTH__ >= 512
+_BitInt(512) g, h, i, j, k, l;
+
+void
+bar (void)
+{
+  __builtin_add_overflow (g, h, &g);
+  __builtin_sub_overflow (i, j, &i);
+  __builtin_mul_overflow (k, l, &k);
+}
+#endif
+
+_BitInt(32) m, n, o, p, q, r;
+
+void
+baz (void)
+{
+  __builtin_add_overflow (m, n, &m);
+  __builtin_sub_overflow (o, p, &o);
+  __builtin_mul_overflow (q, r, &q);
+}
diff --git a/gcc/tree-ssa-dce.cc b/gcc/tree-ssa-dce.cc
index 4e371b21a90..fbf4773eb9d 100644
--- a/gcc/tree-ssa-dce.cc
+++ b/gcc/tree-ssa-dce.cc
@@ -1241,9 +1241,7 @@ maybe_optimize_arith_overflow (gimple_stmt_iterator *gsi,
   tree arg1 = gimple_call_arg (stmt, 1);
   location_t loc = gimple_location (stmt);
   tree type = TREE_TYPE (TREE_TYPE (lhs));
-  tree utype = type;
-  if (!TYPE_UNSIGNED (type))
-    utype = build_nonstandard_integer_type (TYPE_PRECISION (type), 1);
+  tree utype = unsigned_type_for (type);
   tree result = fold_build2_loc (loc, subcode, utype,
 				 fold_convert_loc (loc, utype, arg0),
 				 fold_convert_loc (loc, utype, arg1));