From 0e945fdf23bac5a62c15edfcbfd9d6ac4eee592f Mon Sep 17 00:00:00 2001 From: Bas Nieuwenhuizen Date: Sun, 22 Apr 2018 19:05:19 +0200 Subject: [PATCH] nir: Do not use progress for unreachable code in return lowering. We seem to use progress for two cases: 1) When we lowered some returns. 2) When we remove unreachable code. If just case 2 happens we assert as state->return_flag has not been allocated yet, but we are still trying to do insert all predicates based on it. This splits the concerns. We only use progress internally for case 1 and then keep track of 2 in a separate variable to indicate progress in the return value of the pass. This is slightly better than transforming the assert into if (!state->return_flag) return, as the solution in this patch avoids inserting predicates even if some other part of the might need them. Fixes: 6e22ad6edc "nir: return early when lowering a return at the end of a function" CC: 18.1 Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=106174 Reviewed-by: Timothy Arceri --- src/compiler/nir/nir_lower_returns.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/src/compiler/nir/nir_lower_returns.c b/src/compiler/nir/nir_lower_returns.c index 3ea69e25204..9c4881112e3 100644 --- a/src/compiler/nir/nir_lower_returns.c +++ b/src/compiler/nir/nir_lower_returns.c @@ -37,6 +37,8 @@ struct lower_returns_state { * needs to be predicated on the return flag variable. */ bool has_predicated_return; + + bool removed_unreachable_code; }; static bool lower_returns_in_cf_list(struct exec_list *cf_list, @@ -162,8 +164,9 @@ lower_returns_in_block(nir_block *block, struct lower_returns_state *state) */ return false; } else { + state->removed_unreachable_code = true; nir_cf_delete(&list); - return true; + return false; } } @@ -262,9 +265,11 @@ nir_lower_returns_impl(nir_function_impl *impl) state.loop = NULL; state.return_flag = NULL; state.has_predicated_return = false; + state.removed_unreachable_code = false; nir_builder_init(&state.builder, impl); bool progress = lower_returns_in_cf_list(&impl->body, &state); + progress = progress || state.removed_unreachable_code; if (progress) { nir_metadata_preserve(impl, nir_metadata_none);