[gcc r13-1257] testsuite: Remove reliance on argc in lto/pr101868_0.c

[gcc r13-1257] testsuite: Remove reliance on argc in lto/pr101868_0.c

[Dimitar Dimitrov]

https://gcc.gnu.org/g:b1d0d3520e96802dee37e8fc1c56e19c13d598b1

commit r13-1257-gb1d0d3520e96802dee37e8fc1c56e19c13d598b1
Author: Dimitar Dimitrov <dimitar@dinux.eu>
Date:   Sun May 15 17:30:52 2022 +0300

    testsuite: Remove reliance on argc in lto/pr101868_0.c
    
    Some embedded targets do not pass any argv arguments.  When argc is
    zero, this causes spurious failures for lto/pr101868_0.c.  Fix by
    following the strategy in r0-114701-g2c49569ecea56d.  Use a volatile
    variable instead of argc to inject a runtime value into the test.
    
    I validated the following:
      - No changes in testresults for x86_64-pc-linux-gnu.
      - The spurious failures are fixed for PRU target.
      - lto/pr101868_0.c still fails on x86_64-pc-linux-gnu, if
        the PR/101868 fix (r12-2254-gfedcf3c476aff7) is reverted.
    
            PR tree-optimization/101868
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/lto/pr101868_0.c (zero): New volatile variable.
            (main): Use it instead of argc.
    
    Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>

Diff:
---
 gcc/testsuite/gcc.dg/lto/pr101868_0.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/gcc/testsuite/gcc.dg/lto/pr101868_0.c b/gcc/testsuite/gcc.dg/lto/pr101868_0.c
index c84d19b0267..03124308267 100644
--- a/gcc/testsuite/gcc.dg/lto/pr101868_0.c
+++ b/gcc/testsuite/gcc.dg/lto/pr101868_0.c
@@ -22,12 +22,13 @@ repro(VALUE dummy, VALUE hash)
 
 static VALUE (*that)(VALUE dummy, VALUE hash) = repro;
 
+volatile int zero = 0;
+
 int
 main(int argc, char **argv)
 {
-        argc--;
-        that(0, argc);
+        that(0, zero);
 
-        rb_check_type(argc, argc);
+        rb_check_type(zero, zero);
 
 }