[gcc r8-10462] pdp11: Fix handling of common (local and global) vars [PR94134]

[gcc r8-10462] pdp11: Fix handling of common (local and global) vars [PR94134]

[Jakub Jelinek]

https://gcc.gnu.org/g:4910b2e4cfe25c95fef18cf54125b788c190cfb2

commit r8-10462-g4910b2e4cfe25c95fef18cf54125b788c190cfb2
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Mar 11 18:35:13 2020 +0100

    pdp11: Fix handling of common (local and global) vars [PR94134]
    
    As mentioned in the PR, the generic code decides to put the a variable into
    lcomm_section, which is a NOSWITCH section and thus the generic code doesn't
    switch into a particular section before using
    ASM_OUTPUT{_ALIGNED{,_DECL}_}_LOCAL, on many targets that results just in
    .lcomm (or for non-local .comm) directives which don't need a switch to some
    section, other targets put switch_to_section (bss_section) at the start of
    that macro.
    pdp11 doesn't do that (and doesn't have bss_section), and so emits the
    lcomm/comm variables in whatever section is current (it has only .text/.data
    and for DEC assembler rodata).
    
    The following patch fixes that by putting it always into data section, and
    additionally avoids emitting an empty line in the assembly for the lcomm
    vars.
    
    2020-03-11  Jakub Jelinek  <jakub@redhat.com>
    
            PR target/94134
            * config/pdp11/pdp11.c (pdp11_asm_output_var): Call switch_to_section
            at the start to switch to data section.  Don't print extra newline if
            .globl directive has not been emitted.
    
            * gcc.c-torture/execute/pr94134.c: New test.
    
    (cherry picked from commit f1125cf88ac0c97d819e4f81d556fbcd1161270e)

Diff:
---
 gcc/config/pdp11/pdp11.c                      |  3 ++-
 gcc/testsuite/gcc.c-torture/execute/pr94134.c | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/gcc/config/pdp11/pdp11.c b/gcc/config/pdp11/pdp11.c
index 38c55fbb3df..3c4351477e9 100644
--- a/gcc/config/pdp11/pdp11.c
+++ b/gcc/config/pdp11/pdp11.c
@@ -720,14 +720,15 @@ void
 pdp11_asm_output_var (FILE *file, const char *name, int size,
 		      int align, bool global)
 {
+  switch_to_section (data_section);
   if (align > 8)
     fprintf (file, "\n\t.even\n");
   if (global)
     {
       fprintf (file, ".globl ");
       assemble_name (file, name);
+      fprintf (file, "\n");
     }
-  fprintf (file, "\n");
   assemble_name (file, name);
   fprintf (file, ": .=.+ %#ho\n", (unsigned short)size);
 }
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr94134.c b/gcc/testsuite/gcc.c-torture/execute/pr94134.c
new file mode 100644
index 00000000000..b1b44c3b184
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr94134.c
@@ -0,0 +1,14 @@
+/* PR target/94134 */
+
+static volatile int a = 0;
+static volatile int b = 1;
+
+int
+main ()
+{
+  a++;
+  b++;
+  if (a != 1 || b != 2)
+    __builtin_abort ();
+  return 0;
+}