[PATCH] IBM Z: fix `section type conflict` with -mindirect-branch-table

[PATCH] IBM Z: fix `section type conflict` with -mindirect-branch-table

[Ilya Leoshkevich]

Bootstrapped and regtested on s390x-redhat-linux.  Ok for master?


s390_code_end () puts indirect branch tables into separate sections and
tries to switch back to wherever it was in the beginning by calling
switch_to_section (current_function_section ()).

First of all, this is unnecessary - the other backends don't do it.

Furthermore, at this time there is no current function, but if the
last processed function was cold, in_cold_section_p remains set.  This
causes targetm.asm_out.function_section () to call
targetm.section_type_flags (), which in absence of current function
decl classifies the section as SECTION_WRITE.  This causes a section
type conflict with the existing SECTION_CODE.

gcc/ChangeLog:

	* config/s390/s390.cc (s390_code_end): Do not switch back to
	code section.

gcc/testsuite/ChangeLog:

	* gcc.target/s390/nobp-section-type-conflict.c: New test.
---
 gcc/config/s390/s390.cc                       |  1 -
 .../s390/nobp-section-type-conflict.c         | 22 +++++++++++++++++++
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c

diff --git a/gcc/config/s390/s390.cc b/gcc/config/s390/s390.cc
index 43c5c72554a..2db12d4ba4b 100644
--- a/gcc/config/s390/s390.cc
+++ b/gcc/config/s390/s390.cc
@@ -16809,7 +16809,6 @@ s390_code_end (void)
 	      assemble_name_raw (asm_out_file, label_start);
 	      fputs ("-.\n", asm_out_file);
 	    }
-	  switch_to_section (current_function_section ());
 	}
     }
 }
diff --git a/gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c b/gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c
new file mode 100644
index 00000000000..5d78bc99bb5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c
@@ -0,0 +1,22 @@
+/* Checks that we don't get error: section type conflict with ‘put_page’.  */
+
+/* { dg-do compile } */
+/* { dg-options "-mindirect-branch=thunk-extern -mfunction-return=thunk-extern -mindirect-branch-table -O2" } */
+
+int a;
+int b (void);
+void c (int);
+
+static void
+put_page (void)
+{
+  if (b ())
+    c (a);
+}
+
+__attribute__ ((__section__ (".init.text"), __cold__)) void
+d (void)
+{
+  put_page ();
+  put_page ();
+}
-- 
2.34.1

Re: [PATCH] IBM Z: fix `section type conflict` with -mindirect-branch-table

[Andreas Krebbel]

On 2/1/22 21:49, Ilya Leoshkevich wrote:
> Bootstrapped and regtested on s390x-redhat-linux.  Ok for master?
> 
> 
> s390_code_end () puts indirect branch tables into separate sections and
> tries to switch back to wherever it was in the beginning by calling
> switch_to_section (current_function_section ()).
> 
> First of all, this is unnecessary - the other backends don't do it.
> 
> Furthermore, at this time there is no current function, but if the
> last processed function was cold, in_cold_section_p remains set.  This
> causes targetm.asm_out.function_section () to call
> targetm.section_type_flags (), which in absence of current function
> decl classifies the section as SECTION_WRITE.  This causes a section
> type conflict with the existing SECTION_CODE.
> 
> gcc/ChangeLog:
> 
> 	* config/s390/s390.cc (s390_code_end): Do not switch back to
> 	code section.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* gcc.target/s390/nobp-section-type-conflict.c: New test.

Ok. Thanks!

Andreas


> ---
>  gcc/config/s390/s390.cc                       |  1 -
>  .../s390/nobp-section-type-conflict.c         | 22 +++++++++++++++++++
>  2 files changed, 22 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c
> 
> diff --git a/gcc/config/s390/s390.cc b/gcc/config/s390/s390.cc
> index 43c5c72554a..2db12d4ba4b 100644
> --- a/gcc/config/s390/s390.cc
> +++ b/gcc/config/s390/s390.cc
> @@ -16809,7 +16809,6 @@ s390_code_end (void)
>  	      assemble_name_raw (asm_out_file, label_start);
>  	      fputs ("-.\n", asm_out_file);
>  	    }
> -	  switch_to_section (current_function_section ());
>  	}
>      }
>  }
> diff --git a/gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c b/gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c
> new file mode 100644
> index 00000000000..5d78bc99bb5
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/s390/nobp-section-type-conflict.c
> @@ -0,0 +1,22 @@
> +/* Checks that we don't get error: section type conflict with ‘put_page’.  */
> +
> +/* { dg-do compile } */
> +/* { dg-options "-mindirect-branch=thunk-extern -mfunction-return=thunk-extern -mindirect-branch-table -O2" } */
> +
> +int a;
> +int b (void);
> +void c (int);
> +
> +static void
> +put_page (void)
> +{
> +  if (b ())
> +    c (a);
> +}
> +
> +__attribute__ ((__section__ (".init.text"), __cold__)) void
> +d (void)
> +{
> +  put_page ();
> +  put_page ();
> +}