[binutils-gdb] [gdb/testsuite] Fix gdb.threads/schedlock.exp for gcc 4.8.5

[Tom de Vries]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=13d4a4bd5a7a686d8d5473a4c93b7798de97f745

commit 13d4a4bd5a7a686d8d5473a4c93b7798de97f745
Author: Tom de Vries <tdevries@suse.de>
Date:   Mon Feb 20 11:16:02 2023 +0100

    [gdb/testsuite] Fix gdb.threads/schedlock.exp for gcc 4.8.5
    
    Since commit 9af467b8240 ("[gdb/testsuite] Fix gdb.threads/schedlock.exp on
    fast cpu"), the test-case fails for gcc 4.8.5.
    
    The problem is that for gcc 4.8.5, the commit turned a two-line loop:
    ...
    (gdb) next
    78          while (*myp > 0)
    (gdb) next
    81              MAYBE_CALL_SOME_FUNCTION(); (*myp) ++;
    (gdb) next
    78          while (*myp > 0)
    ...
    into a three-line loop:
    ...
    (gdb) next
    83              MAYBE_CALL_SOME_FUNCTION(); (*myp) ++;
    (gdb) next
    84              cnt++;
    (gdb) next
    85            }
    (gdb) next
    83              MAYBE_CALL_SOME_FUNCTION(); (*myp) ++;
    (gdb)
    ...
    and the test-case doesn't expect this.
    
    Fix this by reverting back to the original loop shape as much as possible by:
    - removing the cnt++ line
    - replacing "while (1)" with "while (one)", where one is a volatile variable
      set to 1.
    
    Tested on x86_64-linux, using compilers:
    - gcc 4.8.5, 7.5.0, 12.2.1
    - clang 4.0.1, 13.0.1

Diff:
---
 gdb/testsuite/gdb.threads/schedlock.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gdb/testsuite/gdb.threads/schedlock.c b/gdb/testsuite/gdb.threads/schedlock.c
index c4e77948ad4..fec896883ce 100644
--- a/gdb/testsuite/gdb.threads/schedlock.c
+++ b/gdb/testsuite/gdb.threads/schedlock.c
@@ -75,13 +75,12 @@ volatile int call_function = 0;
 void *thread_function(void *arg) {
     int my_number =  (long) arg;
     unsigned long long int *myp = (unsigned long long int *) &args[my_number];
-    volatile unsigned int cnt = 0;
+    volatile unsigned int one = 1;
 
-    while (1)
+    while (one)
       {
 	/* schedlock.exp: main loop.  */
 	MAYBE_CALL_SOME_FUNCTION(); (*myp) ++;
-	cnt++;
       }
 
     pthread_exit(NULL);