[Bug testsuite/64930] [5 regression] FAIL: gcc.target/powerpc/atomic-p7.c scan-assembler-times isync 12

[amodra at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64930

--- Comment #9 from Alan Modra <amodra at gmail dot com> ---
My point was that if you write a testcase that specifically tests for consume
and get acquire code then that is a fail.  The code generated is using a bigger
hammer than necessary.  Imagine for a moment if gcc promoted everything to
seq_cst.  That would also be "supporting" the atomics, but for powerpc we'd be
quite unhappy and would want to know about such a change with a testsuite
failure..

I recognize that the testcase doesn't properly test consume semantics, and that
teaching gcc to track dependencies is not simple.

Huh, I just checked and it appears powerpc emits unnecessary isyncs for
atomic_load consumes prior to the pr59448 change, probably in recognition that
dependency tracking isn't done.  So I withdraw my objection to adjusting the
isync counts.