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 --git a/gcc/omp-oacc-neuter-broadcast.cc b/gcc/omp-oacc-neuter-broadcast.cc
index aa5990e..e43338f 100644 (file)
--- 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