1 files changed, 81 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/memcmp-4.c b/gcc/testsuite/gcc.dg/memcmp-4.c
new file mode 100644
index 0000000..bbac719
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/memcmp-4.c
@@ -0,0 +1,81 @@
+/* PR middle-end/78257 - missing memcmp optimization with constant arrays
+   { dg-do compile }
+   { dg-options "-O -Wall -fdump-tree-optimized" } */
+
+typedef __INT8_TYPE__  int8_t;
+typedef __INT16_TYPE__ int16_t;
+typedef __INT32_TYPE__ int32_t;
+typedef __SIZE_TYPE__  size_t;
+
+extern int memcmp (const void*, const void*, size_t);
+
+/* Verify that initializers for flexible array members are handled
+   correctly.  */
+
+struct Si16_x
+{
+  int16_t n, a[];
+};
+
+const struct Si16_x si16_4 =
+  {
+   0x1112, { 0x2122, 0x3132, 0x4142 }
+  };
+
+const char si16_4_rep[] =
+  {
+   0x12, 0x11, 0x22, 0x21, 0x32, 0x31, 0x42, 0x41
+  };
+
+void eq_si16_x (void)
+{
+  int n = 0, b = sizeof si16_4_rep;
+  const char *p = (const char*)&si16_4, *q = si16_4_rep;
+
+  n += memcmp (p,      q,      b);
+  n += memcmp (p + 1,  q + 1,  b - 1);
+  n += memcmp (p + 2,  q + 2,  b - 2);
+  n += memcmp (p + 3,  q + 3,  b - 3);
+  n += memcmp (p + 4,  q + 4,  b - 4);
+  n += memcmp (p + 5,  q + 5,  b - 5);
+  n += memcmp (p + 6,  q + 6,  b - 6);
+  n += memcmp (p + 7,  q + 7,  b - 7);
+  n += memcmp (p + 8,  q + 8,  b - 8);
+
+  p = (const char*)&si16_4.n;
+
+  n += memcmp (p,      q,          b);
+  n += memcmp (p + 1,  q + 1,  b - 1);
+  n += memcmp (p + 2,  q + 2,  b - 2);
+  n += memcmp (p + 3,  q + 3,  b - 3);
+  n += memcmp (p + 4,  q + 4,  b - 4);
+  n += memcmp (p + 5,  q + 5,  b - 5);
+  n += memcmp (p + 6,  q + 6,  b - 6);
+  n += memcmp (p + 7,  q + 7,  b - 7);
+  n += memcmp (p + 8,  q + 8,  b - 8);
+
+  p = (const char*)si16_4.a;
+  q = si16_4_rep + 2;
+
+  n += memcmp (p,      q,      b - 2);
+  n += memcmp (p + 1,  q + 1,  b - 3);
+  n += memcmp (p + 2,  q + 2,  b - 4);
+  n += memcmp (p + 3,  q + 3,  b - 5);
+  n += memcmp (p + 4,  q + 4,  b - 6);
+  n += memcmp (p + 5,  q + 5,  b - 7);
+  n += memcmp (p + 6,  q + 6,  b - 8);
+
+  p = (const char*)&si16_4.a[1];
+  q = si16_4_rep + 4;
+
+  n += memcmp (p,      q,      b - 4);
+  n += memcmp (p + 1,  q + 1,  b - 5);
+  n += memcmp (p + 2,  q + 2,  b - 6);
+  n += memcmp (p + 3,  q + 3,  b - 7);
+  n += memcmp (p + 4,  q + 4,  b - 8);
+
+  if (n != 0)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "abort" "optimized" } } */