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nir: fix opt_if_loop_last_continue()

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Rather than skipping code that looked like this:

     loop {
        ...
        if (cond) {
           do_work_1();
           continue;
        } else {
           break;
        }
        do_work_2();
     }

Previously we would turn this into:

     loop {
        ...
        if (cond) {
           do_work_1();
           continue;
        } else {
           do_work_2();
           break;
        }
     }

This was clearly wrong. This change checks for this case and makes
sure we now leave it for nir_opt_dead_cf() to clean up.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
This commit is contained in:
Timothy Arceri 2019-03-20 22:59:40 +11:00
parent 620df57dbb
commit a1bd9dd5bc
1 changed files with 6 additions and 10 deletions
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16
src/compiler/nir/nir_opt_if.c
View file

@ -855,7 +855,8 @@ opt_if_loop_last_continue(nir_loop *loop)
/* If both branches end in a continue do nothing, this should be handled
* by nir_opt_dead_cf().
*/
if (then_ends_in_continue && else_ends_in_continue)
if ((then_ends_in_continue || nir_block_ends_in_break(then_block)) &&
(else_ends_in_continue || nir_block_ends_in_break(else_block)))
return false;
if (!then_ends_in_continue && !else_ends_in_continue)
@ -872,15 +873,10 @@ opt_if_loop_last_continue(nir_loop *loop)
nir_cf_list tmp;
nir_cf_extract(&tmp, nir_after_cf_node(if_node),
nir_after_block(last_block));
if (then_ends_in_continue) {
nir_cursor last_blk_cursor = nir_after_cf_list(&nif->else_list);
nir_cf_reinsert(&tmp,
nir_after_block_before_jump(last_blk_cursor.block));
} else {
nir_cursor last_blk_cursor = nir_after_cf_list(&nif->then_list);
nir_cf_reinsert(&tmp,
nir_after_block_before_jump(last_blk_cursor.block));
}
if (then_ends_in_continue)
nir_cf_reinsert(&tmp, nir_after_cf_list(&nif->else_list));
else
nir_cf_reinsert(&tmp, nir_after_cf_list(&nif->then_list));
/* In order to avoid running nir_lower_regs_to_ssa_impl() every time an if
* opt makes progress we leave nir_opt_trivial_continues() to remove the