From 20b0daf82de91fd57b7e8d825786789149f6358d Mon Sep 17 00:00:00 2001 From: Bryan Cain Date: Thu, 8 Dec 2011 13:48:27 -0600 Subject: [PATCH] glsl_to_tgsi: fix a bug in eliminate_dead_code_advanced() The bug, reported to me by Vadim Girlin on IRC, was causing overzealous elimination of code in parallel if statements such as the following: if (x) { r = false; } if (y) { r = true; } Before this commit, the assignment inside the first if block would be misdetected as dead code and removed. --- src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp index 59b5ffd4c32..6cc655d70cf 100644 --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp @@ -3514,25 +3514,23 @@ glsl_to_tgsi_visitor::eliminate_dead_code_advanced(void) break; case TGSI_OPCODE_ENDIF: - --level; - break; - case TGSI_OPCODE_ELSE: - /* Clear all channels written inside the preceding if block from the - * write array, but leave those that were not touched. - * - * FIXME: This destroys opportunities to remove dead code inside of - * IF blocks that are followed by an ELSE block. + /* Promote the recorded level all channels written inside the preceding + * if or else block to the level above the if/else block. */ for (int r = 0; r < this->next_temp; r++) { for (int c = 0; c < 4; c++) { if (!writes[4 * r + c]) continue; - if (write_level[4 * r + c] >= level) - writes[4 * r + c] = NULL; + if (write_level[4 * r + c] == level) + write_level[4 * r + c] = level-1; } } + + if(inst->op == TGSI_OPCODE_ENDIF) + --level; + break; case TGSI_OPCODE_IF: -- 2.30.2