[PATCH] lower-bitint: Handle casts from large/huge _BitInt to pointer/reference types [PR113692]

[Jakub Jelinek]

Hi!

I thought one needs to cast first to pointer-sized integer before casting to
pointer, but apparently that is not the case.
So the following patch arranges for the large/huge _BitInt to
pointer/reference conversions to use the same code as for conversions
of them to small integral types.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2024-02-02  Jakub Jelinek  <ja...@redhat.com>

        PR tree-optimization/113692
        * gimple-lower-bitint.cc (bitint_large_huge::lower_stmt): Handle casts
        from large/huge BITINT_TYPEs to POINTER_TYPE/REFERENCE_TYPE as
        final_cast_p.

        * gcc.dg/bitint-82.c: New test.

--- gcc/gimple-lower-bitint.cc.jj       2024-02-01 10:36:08.408867602 +0100
+++ gcc/gimple-lower-bitint.cc  2024-02-01 11:47:21.233840956 +0100
@@ -5264,7 +5264,8 @@ bitint_large_huge::lower_stmt (gimple *s
        mergeable_cast_p = true;
       else if (TREE_CODE (TREE_TYPE (rhs1)) == BITINT_TYPE
               && bitint_precision_kind (TREE_TYPE (rhs1)) >= bitint_prec_large
-              && INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
+              && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
+                  || POINTER_TYPE_P (TREE_TYPE (lhs))))
        {
          final_cast_p = true;
          if (TREE_CODE (rhs1) == SSA_NAME
@@ -5393,8 +5394,9 @@ bitint_large_huge::lower_stmt (gimple *s
         be needed.  */
       gcc_assert (TYPE_PRECISION (lhs_type) <= 2 * limb_prec);
       gimple *g;
-      if (TREE_CODE (lhs_type) == BITINT_TYPE
-         && bitint_precision_kind (lhs_type) == bitint_prec_middle)
+      if ((TREE_CODE (lhs_type) == BITINT_TYPE
+          && bitint_precision_kind (lhs_type) == bitint_prec_middle)
+         || POINTER_TYPE_P (lhs_type))
        lhs_type = build_nonstandard_integer_type (TYPE_PRECISION (lhs_type),
                                                   TYPE_UNSIGNED (lhs_type));
       m_data_cnt = 0;
--- gcc/testsuite/gcc.dg/bitint-82.c.jj 2024-02-01 11:55:37.995866642 +0100
+++ gcc/testsuite/gcc.dg/bitint-82.c    2024-02-01 11:54:16.998003815 +0100
@@ -0,0 +1,18 @@
+/* PR tree-optimization/113692 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2 -std=c23" } */
+
+#if __BITINT_MAXWIDTH__ >= 135
+_BitInt(135) i;
+#else
+_BitInt(63) i;
+#endif
+
+void *
+foo (void)
+{
+  void *ret = 0;
+  if (i & 1)
+    ret = (void *) 1;
+  return ret;
+}

        Jakub