symtab-thunks: Use aggregate_value_p even on is_gimple_reg_type returns [PR112941]

Large/huge _BitInt types are returned in memory and the bitint lowering
pass right now relies on that.
The gimplification etc. use aggregate_value_p to see if it should be
returned in memory or not and use
  <retval> = _123;
  return <retval>;
rather than
  return _123;
But expand_thunk used e.g. by IPA-ICF was performing an optimization,
assuming is_gimple_reg_type is always passed in registers and not calling
aggregate_value_p in that case.  The following patch changes it to match
what the gimplification etc. are doing.

2023-12-22  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/112941
	* symtab-thunks.cc (expand_thunk): Check aggregate_value_p regardless
	of whether is_gimple_reg_type (restype) or not.

	* gcc.dg/bitint-60.c: New test.

diff --git a/gcc/symtab-thunks.cc b/gcc/symtab-thunks.cc
index 23ead0d2138d2a01bb5d2137bfee4650c62e3b0b..0e5fc4f90d2302c2d39cef0e3e9a0fba6f38db98 100644 (file)
--- a/gcc/symtab-thunks.cc
+++ b/gcc/symtab-thunks.cc
@@ -479,21 +479,15 @@ expand_thunk (cgraph_node *node, bool output_asm_thunks,
                                 resdecl,
                                 build_int_cst (TREE_TYPE (resdecl), 0));
            }
-         else if (!is_gimple_reg_type (restype))
+         else if (aggregate_value_p (resdecl, TREE_TYPE (thunk_fndecl)))
            {
-             if (aggregate_value_p (resdecl, TREE_TYPE (thunk_fndecl)))
+             restmp = resdecl;
+
+             if (VAR_P (restmp))
                {
-                 restmp = resdecl;
-
-                 if (VAR_P (restmp))
-                   {
-                     add_local_decl (cfun, restmp);
-                     BLOCK_VARS (DECL_INITIAL (current_function_decl))
-                       = restmp;
-                   }
+                 add_local_decl (cfun, restmp);
+                 BLOCK_VARS (DECL_INITIAL (current_function_decl)) = restmp;
                }
-             else
-               restmp = create_tmp_var (restype, "retval");
            }
          else
            restmp = create_tmp_reg (restype, "retval");

diff --git a/gcc/testsuite/gcc.dg/bitint-60.c b/gcc/testsuite/gcc.dg/bitint-60.c
new file mode 100644 (file)
index 0000000..d1916a0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-60.c
@@ -0,0 +1,20 @@
+/* PR tree-optimization/112941 */
+/* { dg-do compile { target bitint575 } } */
+/* { dg-options "-O2 -std=c23" } */
+
+unsigned _BitInt(495) f1 (signed _BitInt(381) x) { unsigned _BitInt(539) y = x; return y; }
+unsigned _BitInt(495) f2 (unsigned _BitInt(381) x) { unsigned _BitInt(539) y = x; return y; }
+unsigned _BitInt(495) f3 (signed _BitInt(381) x) { _BitInt(539) y = x; return y; }
+unsigned _BitInt(495) f4 (unsigned _BitInt(381) x) { _BitInt(539) y = x; return y; }
+_BitInt(495) f5 (signed _BitInt(381) x) { unsigned _BitInt(539) y = x; return y; }
+_BitInt(495) f6 (unsigned _BitInt(381) x) { unsigned _BitInt(539) y = x; return y; }
+_BitInt(495) f7 (signed _BitInt(381) x) { _BitInt(539) y = x; return y; }
+_BitInt(495) f8 (unsigned _BitInt(381) x) { _BitInt(539) y = x; return y; }
+unsigned _BitInt(495) f9 (signed _BitInt(381) x) { return (unsigned _BitInt(539)) x; }
+unsigned _BitInt(495) f10 (unsigned _BitInt(381) x) { return (unsigned _BitInt(539)) x; }
+unsigned _BitInt(495) f11 (signed _BitInt(381) x) { return (_BitInt(539)) x; }
+unsigned _BitInt(495) f12 (unsigned _BitInt(381) x) { return (_BitInt(539)) x; }
+_BitInt(495) f13 (signed _BitInt(381) x) { return (unsigned _BitInt(539)) x; }
+_BitInt(495) f14 (unsigned _BitInt(381) x) { return (unsigned _BitInt(539)) x; }
+_BitInt(495) f15 (signed _BitInt(381) x) { return (_BitInt(539)) x; }
+_BitInt(495) f16 (unsigned _BitInt(381) x) { return (_BitInt(539)) x; }