[gcc r9-8468] cgraphunit: Avoid code generation differences based on -w/TREE_NO_WARNING [PR94277]

[gcc r9-8468] cgraphunit: Avoid code generation differences based on -w/TREE_NO_WARNING [PR94277]

[Jakub Jelinek]

https://gcc.gnu.org/g:4ac9ab60f06020a24e851ebe3eeacc1b3bffa849

commit r9-8468-g4ac9ab60f06020a24e851ebe3eeacc1b3bffa849
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Tue Mar 24 09:33:17 2020 +0100

    cgraphunit: Avoid code generation differences based on -w/TREE_NO_WARNING [PR94277]
    
    The following testcase FAILs with -fcompare-debug, but not because -g vs.
    -g0 would make a difference, but because the second compilation is done with
    -w in order not to emit warnings twice and -w seems to affect the *.gkd dump
    content.
    This is because TREE_NO_WARNING flag, or warn_unused_function does affect
    not just whether a warning/pedwarn is printed, but also whether we set
    TREE_PUBLIC on such decls.
    The following patch makes sure we set it regardless of anything warning
    related (TREE_NO_WARNING or warn_unused_function).
    
    2020-03-24  Jakub Jelinek  <jakub@redhat.com>
    
            PR debug/94277
            * cgraphunit.c (check_global_declaration): For DECL_EXTERNAL and
            non-TREE_PUBLIC non-DECL_ARTIFICIAL FUNCTION_DECLs, set TREE_PUBLIC
            regardless of whether TREE_NO_WARNING is set on it or whether
            warn_unused_function is true or not.
    
            * gcc.dg/pr94277.c: New test.

Diff:
---
 gcc/ChangeLog                  | 10 ++++++++++
 gcc/cgraphunit.c               | 12 ++++++------
 gcc/testsuite/ChangeLog        |  5 +++++
 gcc/testsuite/gcc.dg/pr94277.c | 11 +++++++++++
 4 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2cd4b81ebe9..356e7c14e3b 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,6 +1,16 @@
 2020-04-07  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2020-03-24  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/94277
+	* cgraphunit.c (check_global_declaration): For DECL_EXTERNAL and
+	non-TREE_PUBLIC non-DECL_ARTIFICIAL FUNCTION_DECLs, set TREE_PUBLIC
+	regardless of whether TREE_NO_WARNING is set on it or whether
+	warn_unused_function is true or not.
+
+2020-04-07  Jakub Jelinek  <jakub@redhat.com>
+
 	2020-03-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/94211
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c
index 4a27867b82c..0f933bdc758 100644
--- a/gcc/cgraphunit.c
+++ b/gcc/cgraphunit.c
@@ -967,15 +967,15 @@ check_global_declaration (symtab_node *snode)
       && DECL_INITIAL (decl) == 0
       && DECL_EXTERNAL (decl)
       && ! DECL_ARTIFICIAL (decl)
-      && ! TREE_NO_WARNING (decl)
-      && ! TREE_PUBLIC (decl)
-      && (warn_unused_function
-	  || snode->referred_to_p (/*include_self=*/false)))
+      && ! TREE_PUBLIC (decl))
     {
-      if (snode->referred_to_p (/*include_self=*/false))
+      if (TREE_NO_WARNING (decl))
+	;
+      else if (snode->referred_to_p (/*include_self=*/false))
 	pedwarn (input_location, 0, "%q+F used but never defined", decl);
       else
-	warning (OPT_Wunused_function, "%q+F declared %<static%> but never defined", decl);
+	warning (OPT_Wunused_function, "%q+F declared %<static%> but never "
+				       "defined", decl);
       /* This symbol is effectively an "extern" declaration now.  */
       TREE_PUBLIC (decl) = 1;
     }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 650b8683387..a43da5200a2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,6 +1,11 @@
 2020-04-07  Jakub Jelinek  <jakub@redhat.com>
 
 	Backported from mainline
+	2020-03-24  Jakub Jelinek  <jakub@redhat.com>
+
+	PR debug/94277
+	* gcc.dg/pr94277.c: New test.
+
 	2020-03-19  Jakub Jelinek  <jakub@redhat.com>
 
 	PR gcov-profile/94029
diff --git a/gcc/testsuite/gcc.dg/pr94277.c b/gcc/testsuite/gcc.dg/pr94277.c
new file mode 100644
index 00000000000..dfe38e401a9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr94277.c
@@ -0,0 +1,11 @@
+/* PR debug/94277 */
+/* { dg-do compile } */
+/* { dg-options "-fcompare-debug" } */
+
+static void foo (void);	/* { dg-warning "used but never defined" } */
+
+void
+bar (void)
+{
+  foo ();
+}