* [PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685]
@ 2023-03-25 9:53 Jakub Jelinek
2023-03-26 17:57 ` Jeff Law
2023-03-26 20:01 ` Jan Hubicka
0 siblings, 2 replies; 3+ messages in thread
From: Jakub Jelinek @ 2023-03-25 9:53 UTC (permalink / raw)
To: Richard Biener, Jan Hubicka; +Cc: 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 <jakub@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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685]
2023-03-25 9:53 [PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685] Jakub Jelinek
@ 2023-03-26 17:57 ` Jeff Law
2023-03-26 20:01 ` Jan Hubicka
1 sibling, 0 replies; 3+ messages in thread
From: Jeff Law @ 2023-03-26 17:57 UTC (permalink / raw)
To: Jakub Jelinek, Richard Biener, Jan Hubicka; +Cc: gcc-patches
On 3/25/23 03:53, Jakub Jelinek via Gcc-patches wrote:
> 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 <jakub@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.
OK
jeff
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685]
2023-03-25 9:53 [PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685] Jakub Jelinek
2023-03-26 17:57 ` Jeff Law
@ 2023-03-26 20:01 ` Jan Hubicka
1 sibling, 0 replies; 3+ messages in thread
From: Jan Hubicka @ 2023-03-26 20:01 UTC (permalink / raw)
To: Jakub Jelinek; +Cc: Richard Biener, 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 <jakub@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);
OK, tanks!
In general we probably want to walk aliases and suggest warning on
aliases attached to the function, but we get this wrong with other
attributes too, so I will add it to TODo for next stage1.
Honza
> 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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-03-25 9:53 [PATCH] predict: Don't emit -Wsuggest-attribute=cold warning for functions which already have that attribute [PR105685] Jakub Jelinek
2023-03-26 17:57 ` Jeff Law
2023-03-26 20:01 ` Jan Hubicka
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