Reinserting code directly before a jump means the block gets split
and merged, removing the original block and replacing it in the
process.
Hence keeping a pointer to the continue block over a reinsert
causes issues.
This code changes nir_opt_if to simply look for the new continue
block.
CC: 18.1 <mesa-sta...@lists.freedesktop.org>
---
src/compiler/nir/nir_opt_if.c | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)
diff --git a/src/compiler/nir/nir_opt_if.c b/src/compiler/nir/nir_opt_if.c
index a52de120ad6..658ff654169 100644
--- a/src/compiler/nir/nir_opt_if.c
+++ b/src/compiler/nir/nir_opt_if.c
@@ -26,6 +26,28 @@
#include "nir_control_flow.h"
#include "nir_loop_analyze.h"
+/**
+ * Gets the single block that jumps back to the loop header. Already assumes
+ * there is exactly one such block.
+ */
+static nir_block* find_continue_block(nir_loop *loop)
+{
+ nir_block *header_block = nir_loop_first_block(loop);
+ nir_block *prev_block =
+ nir_cf_node_as_block(nir_cf_node_prev(&loop->cf_node));
+
+ assert(header_block->predecessors->entries == 2);
+
+ nir_block *continue_block = NULL;
+ struct set_entry *pred_entry;
+ set_foreach(header_block->predecessors, pred_entry) {
+ if (pred_entry->key != prev_block)
+ continue_block = (void *)pred_entry->key;
+ }
+
+ return continue_block;
+}
+
/**
* This optimization detects if statements at the tops of loops where the
* condition is a phi node of two constants and moves half of the if to above
@@ -97,12 +119,7 @@ opt_peel_loop_initial_if(nir_loop *loop)
if (header_block->predecessors->entries != 2)
return false;
- nir_block *continue_block = NULL;
- struct set_entry *pred_entry;
- set_foreach(header_block->predecessors, pred_entry) {
- if (pred_entry->key != prev_block)
- continue_block = (void *)pred_entry->key;
- }
+ nir_block *continue_block = find_continue_block(loop);
nir_cf_node *if_node = nir_cf_node_next(&header_block->cf_node);
if (!if_node || if_node->type != nir_cf_node_if)
@@ -193,6 +210,10 @@ opt_peel_loop_initial_if(nir_loop *loop)
nir_cf_reinsert(&tmp, nir_before_cf_node(&loop->cf_node));
nir_cf_reinsert(&header, nir_after_block_before_jump(continue_block));
+
+ /* Get continue block again as the previous reinsert might have removed the
block. */
+ continue_block = find_continue_block(loop);
+
nir_cf_extract(&tmp, nir_before_cf_list(continue_list),
nir_after_cf_list(continue_list));
nir_cf_reinsert(&tmp, nir_after_block_before_jump(continue_block));
--
2.18.0
_______________________________________________
mesa-dev mailing list
mesa-dev@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/mesa-dev
