[gcc r12-7148] c: Fix up __builtin_assoc_barrier handling in the C FE [PR104427]

[gcc r12-7148] c: Fix up __builtin_assoc_barrier handling in the C FE [PR104427]

[Jakub Jelinek]

https://gcc.gnu.org/g:499f8d4c2bc585b985882b4716f35b4c1553ce32

commit r12-7148-g499f8d4c2bc585b985882b4716f35b4c1553ce32
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Feb 9 20:45:31 2022 +0100

    c: Fix up __builtin_assoc_barrier handling in the C FE [PR104427]
    
    The following testcase ICEs, because when creating PAREN_EXPR for
    __builtin_assoc_barrier the FE doesn't do the usual tweaks for
    EXCESS_PRECISION_EXPR or C_MAYBE_CONST_EXPR.  I believe that the
    declared effect of the builtin is just association barrier, so
    e.g. excess precision should be still handled like if it wasn't
    there.
    
    The following patch uses build_unary_op to handle those.
    
    2022-02-09  Jakub Jelinek  <jakub@redhat.com>
    
            PR c/104427
            * c-parser.cc (c_parser_postfix_expression)
            <case RID_BUILTIN_ASSOC_BARRIER>: Use parser_build_unary_op
            instead of build1_loc to build PAREN_EXPR.
            * c-typeck.cc (build_unary_op): Handle PAREN_EXPR.
            * c-fold.cc (c_fully_fold_internal): Likewise.
    
            * gcc.dg/pr104427.c: New test.

Diff:
---
 gcc/c/c-fold.cc                 |  1 +
 gcc/c/c-parser.cc               |  3 +--
 gcc/c/c-typeck.cc               |  4 ++++
 gcc/testsuite/gcc.dg/pr104427.c | 13 +++++++++++++
 4 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/gcc/c/c-fold.cc b/gcc/c/c-fold.cc
index fc593753c1b..76ea25b3d7f 100644
--- a/gcc/c/c-fold.cc
+++ b/gcc/c/c-fold.cc
@@ -465,6 +465,7 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
     case BIT_NOT_EXPR:
     case TRUTH_NOT_EXPR:
     case CONJ_EXPR:
+    case PAREN_EXPR:
     unary:
       /* Unary operations.  */
       orig_op0 = op0 = TREE_OPERAND (expr, 0);
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index e9086c58524..7e81c33de11 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -10128,8 +10128,7 @@ c_parser_postfix_expression (c_parser *parser)
 	    mark_exp_read (e1.value);
 	    location_t end_loc = c_parser_peek_token (parser)->get_finish ();
 	    parens.skip_until_found_close (parser);
-	    expr.value = build1_loc (loc, PAREN_EXPR, TREE_TYPE (e1.value),
-				     e1.value);
+	    expr = parser_build_unary_op (loc, PAREN_EXPR, e1);
 	    set_c_expr_source_range (&expr, start_loc, end_loc);
 	  }
 	  break;
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index b06f0787476..39094cc6f50 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -4921,6 +4921,10 @@ build_unary_op (location_t location, enum tree_code code, tree xarg,
       ret = val;
       goto return_build_unary_op;
 
+    case PAREN_EXPR:
+      ret = build1 (code, TREE_TYPE (arg), arg);
+      goto return_build_unary_op;
+
     default:
       gcc_unreachable ();
     }
diff --git a/gcc/testsuite/gcc.dg/pr104427.c b/gcc/testsuite/gcc.dg/pr104427.c
new file mode 100644
index 00000000000..397cb13b669
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr104427.c
@@ -0,0 +1,13 @@
+/* PR c/104427 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+/* { dg-add-options float16 } */
+/* { dg-require-effective-target float16 } */
+
+_Float16 x, y;
+
+int
+foo ()
+{
+  return __builtin_assoc_barrier (x + y) - y;
+}