lower-bitint: Encode address space qualifiers in VIEW_CONVERT_EXPRs [PR113736]

As discussed in the PR, e.g. build_fold_addr_expr needs TYPE_ADDR_SPACE
on the outermost reference rather than just on the base, so the
following patch makes sure to propagate the address space from
the accessed var to the MEM_REFs and/or VIEW_CONVERT_EXPRs used to
access those.

2024-02-06  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/113736
	* gimple-lower-bitint.cc (bitint_large_huge::limb_access): Use
	var's address space for MEM_REF or VIEW_CONVERT_EXPRs.

	* gcc.dg/bitint-86.c: New test.

2 files changed, 49 insertions, 4 deletions

diff --git a/gcc/gimple-lower-bitint.cc b/gcc/gimple-lower-bitint.cc
index e92f573..41484a0 100644
--- a/gcc/gimple-lower-bitint.cc
+++ b/gcc/gimple-lower-bitint.cc
@@ -601,12 +601,17 @@ bitint_large_huge::limb_access (tree type, tree var, tree idx, bool write_p)
 {
   tree atype = (tree_fits_uhwi_p (idx)
 		? limb_access_type (type, idx) : m_limb_type);
+  tree ltype = m_limb_type;
+  addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (var));
+  if (as != TYPE_ADDR_SPACE (ltype))
+    ltype = build_qualified_type (ltype, TYPE_QUALS (ltype)
+					 | ENCODE_QUAL_ADDR_SPACE (as));
   tree ret;
   if (DECL_P (var) && tree_fits_uhwi_p (idx))
     {
       tree ptype = build_pointer_type (strip_array_types (TREE_TYPE (var)));
       unsigned HOST_WIDE_INT off = tree_to_uhwi (idx) * m_limb_size;
-      ret = build2 (MEM_REF, m_limb_type,
+      ret = build2 (MEM_REF, ltype,
 		    build_fold_addr_expr (var),
 		    build_int_cst (ptype, off));
       TREE_THIS_VOLATILE (ret) = TREE_THIS_VOLATILE (var);
@@ -615,7 +620,7 @@ bitint_large_huge::limb_access (tree type, tree var, tree idx, bool write_p)
   else if (TREE_CODE (var) == MEM_REF && tree_fits_uhwi_p (idx))
     {
       ret
-	= build2 (MEM_REF, m_limb_type, TREE_OPERAND (var, 0),
+	= build2 (MEM_REF, ltype, TREE_OPERAND (var, 0),
 		  size_binop (PLUS_EXPR, TREE_OPERAND (var, 1),
 			      build_int_cst (TREE_TYPE (TREE_OPERAND (var, 1)),
 					     tree_to_uhwi (idx)
@@ -633,10 +638,10 @@ bitint_large_huge::limb_access (tree type, tree var, tree idx, bool write_p)
 	{
 	  unsigned HOST_WIDE_INT nelts
 	    = CEIL (tree_to_uhwi (TYPE_SIZE (type)), limb_prec);
-	  tree atype = build_array_type_nelts (m_limb_type, nelts);
+	  tree atype = build_array_type_nelts (ltype, nelts);
 	  var = build1 (VIEW_CONVERT_EXPR, atype, var);
 	}
-      ret = build4 (ARRAY_REF, m_limb_type, var, idx, NULL_TREE, NULL_TREE);
+      ret = build4 (ARRAY_REF, ltype, var, idx, NULL_TREE, NULL_TREE);
     }
   if (!write_p && !useless_type_conversion_p (atype, m_limb_type))
     {
diff --git a/gcc/testsuite/gcc.dg/bitint-86.c b/gcc/testsuite/gcc.dg/bitint-86.c
new file mode 100644
index 0000000..4e5761a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-86.c
@@ -0,0 +1,40 @@
+/* PR tree-optimization/113736 */
+/* { dg-do compile { target bitint } } */
+/* { dg-options "-O2 -std=gnu23 -w" } */
+
+#if __BITINT_MAXWIDTH__ >= 710
+struct S { _BitInt(710) a; };
+struct T { struct S b[4]; };
+
+#ifdef __x86_64__
+#define SEG __seg_gs
+#elif defined __i386__
+#define SEG __seg_fs
+#else
+#define SEG
+#endif
+
+void
+foo (__seg_gs struct T *p)
+{
+  struct S s;
+  p->b[0] = s;
+}
+
+void
+bar (__seg_gs struct T *p, _BitInt(710) x, int y, double z)
+{
+  p->b[0].a = x + 42;
+  p->b[1].a = x << y;
+  p->b[2].a = x >> y;
+  p->b[3].a = z;
+}
+
+int
+baz (__seg_gs struct T *p, _BitInt(710) x, _BitInt(710) y)
+{
+  return __builtin_add_overflow (x, y, &p->b[1].a);
+}
+#else
+int i;
+#endif