When stitching two blocks A and B, where A's last instruction is a jump,
it is not required that B is empty; it can be plainly removed.
This can happen in a situation like this:
vec1 1 ssa_1 = load_const (true)
vec1 1 ssa_2 = load_const (false)
block block_1:
[...]
loop {
vec1 ssa_3 = phi block_1: ssa_2, block_4: ssa_1
if ssa_3 {
block block_2:
[...]
break
} else {
block block_3:
}
vec1 ssa_4 = <alu operation>
if ssa_4 {
block block_4:
continue
} else {
block block_5:
}
block block_6:
[...]
}
And opt_peel_loop_initial_if is applied. In this case, we would be
ending up stitching block_2 (which finalizes with a jump) with
block_4, which is not empty.
CC: Jason Ekstrand <ja...@jlekstrand.net>
---
src/compiler/nir/nir_control_flow.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/src/compiler/nir/nir_control_flow.c
b/src/compiler/nir/nir_control_flow.c
index ddba2e55b45..27508f230d6 100644
--- a/src/compiler/nir/nir_control_flow.c
+++ b/src/compiler/nir/nir_control_flow.c
@@ -550,7 +550,6 @@ stitch_blocks(nir_block *before, nir_block *after)
*/
if (nir_block_ends_in_jump(before)) {
- assert(exec_list_is_empty(&after->instr_list));
if (after->successors[0])
remove_phi_src(after->successors[0], after);
if (after->successors[1])
--
2.20.1
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