[binutils-gdb] sim/cgen: mask uninitialized variable warning in cgen-run.c

[Andrew Burgess]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=cb9d1609da6e623158ba5a8cb4a2712bcea4f57f

commit cb9d1609da6e623158ba5a8cb4a2712bcea4f57f
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Wed Oct 12 11:07:24 2022 +0100

    sim/cgen: mask uninitialized variable warning in cgen-run.c
    
    I see an uninitialized variable warning (with gcc 9.3.1) from
    cgen-run.c, like this:
    
      /tmp/build/sim/../../src/sim/cris/../common/cgen-run.c: In function ‘sim_resume’:
      /tmp/build/sim/../../src/sim/cris/../common/cgen-run.c:259:5: warning: ‘engine_fns$’ may be used uninitialized in this function [-Wmaybe-uninitialized]
        259 |    (* engine_fns[next_cpu_nr]) (cpu);
            |    ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
      /tmp/build/sim/../../src/sim/cris/../common/cgen-run.c:232:14: note: ‘engine_fns$’ was declared here
        232 |   ENGINE_FN *engine_fns[MAX_NR_PROCESSORS];
            |              ^~~~~~~~~~
    
    This is a false positive - we over allocate engine_fn, and then only
    initialize the nr_cpus entries which we will later go on to use.
    
    However, we can easily silence this warning by initializing the unused
    entries in engine_fns to NULL, this might also help if anyone ever
    looks at engine_fns in a debugger, it should now be obvious which
    entries are in use, and which are not.
    
    With this change the warning is gone.
    
    There should be no change in behaviour with this commit.

Diff:
---
 sim/common/cgen-run.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/sim/common/cgen-run.c b/sim/common/cgen-run.c
index 9a13b0ca416..a9a493c01b9 100644
--- a/sim/common/cgen-run.c
+++ b/sim/common/cgen-run.c
@@ -242,6 +242,11 @@ engine_run_n (SIM_DESC sd, int next_cpu_nr, int nr_cpus, int max_insns, int fast
       prime_cpu (cpu, max_insns);
     }
 
+  /* Ensure the remaining engine_fns slots are initialized, this silences a
+     compiler warning when engine_fns is used below.  */
+  for (i = nr_cpus; i < MAX_NR_PROCESSORS; ++i)
+    engine_fns[i] = NULL;
+
   while (1)
     {
       SIM_ENGINE_PREFIX_HOOK (sd);