gimplify: Small RAW_DATA_CST gimplification fix

I've noticed the following testcase hangs during gimplification.

While it is gimplifying an assignment from a VAR_DECL .LCNNN to MEM_REF,
because the VAR_DECL is TREE_READONLY, it will happily pick its initializer
and try to gimplify that, which means recursing to the exact same code.

The following patch fixes that by just gimplifying the lhs and building
assignment, because the code decided that it should use copying from
a static var.

2024-10-16  Jakub Jelinek  <jakub@redhat.com>

	* gimplify.cc (gimplify_init_ctor_eval): For larger RAW_DATA_CST,
	just gimplify cref as lvalue and add gimple assignment of rctor
	to cref instead of going through gimplification of INIT_EXPR, as
	the latter can suffer from infinite recursion.

	* c-c++-common/cpp/embed-24.c: New test.

diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 9284fffe137f0013a7d995de8bf44973763a6259..769b880cce58631ba6f7d0dadea3301c29e43bcd 100644 (file)
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -5419,9 +5419,10 @@ gimplify_init_ctor_eval (tree object, vec<constructor_elt, va_gc> *elts,
              cref = build2 (MEM_REF, rtype, addr,
                             build_int_cst (ptr_type_node, 0));
              rctor = tree_output_constant_def (rctor);
-             tree init = build2 (INIT_EXPR, rtype, cref, rctor);
-             gimplify_and_add (init, pre_p);
-             ggc_free (init);
+             if (gimplify_expr (&cref, pre_p, NULL, is_gimple_lvalue,
+                                fb_lvalue) != GS_ERROR)
+               gimplify_seq_add_stmt (pre_p,
+                                      gimple_build_assign (cref, rctor));
            }
        }
       else

diff --git a/gcc/testsuite/c-c++-common/cpp/embed-24.c b/gcc/testsuite/c-c++-common/cpp/embed-24.c
new file mode 100644 (file)
index 0000000..d59a7e5
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/cpp/embed-24.c
@@ -0,0 +1,52 @@
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+/* { dg-additional-options "-std=c23" { target c } } */
+
+static unsigned char a[] = {
+#embed __FILE__ limit (125)
+};
+
+void
+foo (unsigned char *p)
+{
+  for (int i = 0; i < 128; ++i)
+    if (p[i] != ((i < 64 || i == 127) ? (unsigned char) -1 : i - 64 + 33))
+      __builtin_abort ();
+  if (__builtin_memcmp (p + 128, a, 125))
+    __builtin_abort ();
+  for (int i = 253; i < 256; ++i)
+    if (p[i] != (unsigned char) -1)
+      __builtin_abort ();
+}
+
+#ifdef __cplusplus
+#define M1 (unsigned char) -1
+#else
+#define M1 -1
+#endif
+
+int
+main ()
+{
+  unsigned char res[256] = {
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    M1, M1, M1, M1, M1, M1, M1, M1, 
+    33, 34, 35, 36, 37, 38, 39, 40, 
+    41, 42, 43, 44, 45, 46, 47, 48, 
+    49, 50, 51, 52, 53, 54, 55, 56, 
+    57, 58, 59, 60, 61, 62, 63, 64, 
+    65, 66, 67, 68, 69, 70, 71, 72, 
+    73, 74, 75, 76, 77, 78, 79, 80, 
+    81, 82, 83, 84, 85, 86, 87, 88, 
+    89, 90, 91, 92, 93, 94, 95, M1,
+  #embed __FILE__ limit (125) suffix (,)
+    M1, M1, M1
+  };
+  foo (res);
+}