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nir/gcm: Rework the schedule late loop 

This fixes a bug in code motion that occurred when the best block is the
same as the schedule early block.  In this case, because we're checking
(lca != def->parent_instr->block) at the top of the loop, we never get to
the check for loop depth so we wouldn't move it out of the loop.  This
commit reworks the loop to be a simple for loop up the dominator chain and
we place the (lca != def->parent_instr->block) check at the end of the
loop.

Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Jason Ekstrand 2016-12-01 13:51:03 -08:00 committed by Jason Ekstrand
parent e9a4ec4bd8
commit 087e172179
1 changed files with 6 additions and 5 deletions
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11
src/compiler/nir/nir_opt_gcm.c
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@ -326,12 +326,13 @@ gcm_schedule_late_def(nir_ssa_def *def, void *void_state)
* as far outside loops as we can get.
*/
nir_block *best = lca;
while (lca != def->parent_instr->block) {
assert(lca);
if (state->blocks[lca->index].loop_depth <
for (nir_block *block = lca; block != NULL; block = block->imm_dom) {
if (state->blocks[block->index].loop_depth <
state->blocks[best->index].loop_depth)
best = lca;
lca = lca->imm_dom;
best = block;
if (block == def->parent_instr->block)
break;
}
def->parent_instr->block = best;