[PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685]

[Jakub Jelinek via Gcc-patches]

Hi!

In the following testcase, we predict baz to have cold
entry regardless of the user supplied attribute (as it call
unconditionally a cold function), but still issue
a -Wsuggest-attribute=cold warning despite it having that attribute
already.

The following patch avoids that.

Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?

2023-03-25  Jakub Jelinek  <ja...@redhat.com>

        PR ipa/105685
        * predict.cc (compute_function_frequency): Don't call
        warn_function_cold if function already has cold attribute.

        * c-c++-common/cold-2.c: New test.

--- gcc/predict.cc.jj   2023-01-02 09:32:38.273055726 +0100
+++ gcc/predict.cc      2023-03-24 16:54:13.658606215 +0100
@@ -4033,7 +4033,9 @@ compute_function_frequency (void)
     }
 
   node->frequency = NODE_FREQUENCY_UNLIKELY_EXECUTED;
-  warn_function_cold (current_function_decl);
+  if (lookup_attribute ("cold", DECL_ATTRIBUTES (current_function_decl))
+      == NULL)
+    warn_function_cold (current_function_decl);
   if (ENTRY_BLOCK_PTR_FOR_FN (cfun)->count.ipa() == profile_count::zero ())
     return;
   FOR_EACH_BB_FN (bb, cfun)
--- gcc/testsuite/c-c++-common/cold-2.c.jj      2023-03-24 16:56:07.344000973 
+0100
+++ gcc/testsuite/c-c++-common/cold-2.c 2023-03-24 16:55:58.985119001 +0100
@@ -0,0 +1,19 @@
+/* PR ipa/105685 */
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wsuggest-attribute=cold" } */
+
+extern void foo (char *, char const *, int);
+
+__attribute__((cold)) char *
+bar (int x)
+{
+  static char b[42];
+  foo (b, "foo", x);
+  return b;
+}
+
+__attribute__((cold)) char *
+baz (int x)            /* { dg-bogus "function might be candidate for 
attribute 'cold'" } */
+{
+  return bar (x);
+}

        Jakub