[nvptx, committed] Add missing probabilities in nvptx_lock{less,full}_update

[Tom de Vries]

[ was: Re: [PATCH] update edge profile info in nvptx.c ]
On 07/13/2017 06:53 PM, Cesar Philippidis wrote:
The recent basic block profiling changes broke a couple of libgomp
OpenACC execution tests involving reductions with nvptx offloading. For
gang and worker reductions, the nvptx BE updates the original reduction
variable using a lock-free atomic algorithm. This lock-free algorithm
utilizes a polling loop to check the state of the variable being
updated. This loop introduced a new basic block edge, but it wasn't
assigned a branch probability.

Right, and the same problem occurs in nvptx_lockfull_update.

Because of the highly threaded nature of
CUDA accelerators, I set the branch probability for that edge as even.

I don't have any experimental data to make a good estimation, so 50/50 
sounds fine to me.

As before, the setting of the probability of the non-loop edge was missing.

I've added that, and committed.

Thanks,
- Tom
Add missing probabilities in nvptx_lock{less,full}_update

2017-08-02  Tom de Vries  <t...@codesourcery.com>
	    Cesar Philippidis  <ce...@codesourcery.com>

	* config/nvptx/nvptx.c (nvptx_lockless_update, nvptx_lockfull_update):
	Add missing edge probabilities.

---
 gcc/config/nvptx/nvptx.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/config/nvptx/nvptx.c b/gcc/config/nvptx/nvptx.c
index 208b115..0d21eb1 100644
--- a/gcc/config/nvptx/nvptx.c
+++ b/gcc/config/nvptx/nvptx.c
@@ -5072,7 +5072,9 @@ nvptx_lockless_update (location_t loc, gimple_stmt_iterator *gsi,
   *gsi = gsi_for_stmt (gsi_stmt (*gsi));
 
   post_edge->flags ^= EDGE_TRUE_VALUE | EDGE_FALLTHRU;
+  post_edge->probability = profile_probability::even ();
   edge loop_edge = make_edge (loop_bb, loop_bb, EDGE_FALSE_VALUE);
+  loop_edge->probability = profile_probability::even ();
   set_immediate_dominator (CDI_DOMINATORS, loop_bb, pre_bb);
   set_immediate_dominator (CDI_DOMINATORS, post_bb, loop_bb);
 
@@ -5145,7 +5147,9 @@ nvptx_lockfull_update (location_t loc, gimple_stmt_iterator *gsi,
   
   /* Create the lock loop ... */
   locked_edge->flags ^= EDGE_TRUE_VALUE | EDGE_FALLTHRU;
-  make_edge (lock_bb, lock_bb, EDGE_FALSE_VALUE);
+  locked_edge->probability = profile_probability::even ();
+  edge loop_edge = make_edge (lock_bb, lock_bb, EDGE_FALSE_VALUE);
+  loop_edge->probability = profile_probability::even ();
   set_immediate_dominator (CDI_DOMINATORS, lock_bb, entry_bb);
   set_immediate_dominator (CDI_DOMINATORS, update_bb, lock_bb);