[gcc r12-3726] Evaluate 'random ()' to '0' in 'pass_omp_oacc_neuter_broadcast'

[gcc r12-3726] Evaluate 'random ()' to '0' in 'pass_omp_oacc_neuter_broadcast'

[Thomas Schwinge]

https://gcc.gnu.org/g:e87789f197e47259c94349821d3446f7d959e08f

commit r12-3726-ge87789f197e47259c94349821d3446f7d959e08f
Author: Thomas Schwinge <thomas@codesourcery.com>
Date:   Tue Sep 21 08:54:49 2021 +0200

    Evaluate 'random ()' to '0' in 'pass_omp_oacc_neuter_broadcast'
    
    Julian Brown,
    <http://mid.mail-archive.com/20210920134603.16459021@squid.athome>:
    
    | [...] the randomness shouldn't be necessary for the
    | correctness of the patch (i.e. it could just be "base = bounds_lo", or
    | indeed folded into the line after).
    |
    | The "ar.invalid ()" case happens when we fail to allocate a block of
    | memory in LDS space for broadcasting a particular set of variables,
    | and trigger a fall-back path in the broadcasting code that adds extra
    | barriers around the broadcast in question. I imagine I was thinking
    | that adding randomness could mean we can "get lucky" sometimes and
    | avoid needing those barriers in some cases, but in fact I don't think
    | that was implemented, so the randomness is useless. (Or it could just
    | have been leftover debug code... oops).
    
            gcc/
            PR other/102408
            * omp-oacc-neuter-broadcast.cc (oacc_do_neutering): Evaluate
            'random ()' to '0'.

Diff:
---
 gcc/omp-oacc-neuter-broadcast.cc | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gcc/omp-oacc-neuter-broadcast.cc b/gcc/omp-oacc-neuter-broadcast.cc
index aa5990ed7a1..e43338f3abf 100644
--- a/gcc/omp-oacc-neuter-broadcast.cc
+++ b/gcc/omp-oacc-neuter-broadcast.cc
@@ -1782,9 +1782,8 @@ oacc_do_neutering (unsigned HOST_WIDE_INT bounds_lo,
 
       if (ar.invalid ())
 	{
-	  unsigned HOST_WIDE_INT base;
-	  base = bounds_lo + random () % 512;
-	  base = (base + align - 1) & ~(align - 1);
+	  unsigned HOST_WIDE_INT base
+	    = (bounds_lo + align - 1) & ~(align - 1);
 	  if (base + size > bounds_hi)
 	    error_at (UNKNOWN_LOCATION, "shared-memory region overflow");
 	  std::pair<unsigned HOST_WIDE_INT, bool> base_inrng