The TGSI DCE pass doesn't eliminate dead assignments like MOV TEMP[0], TEMP[1] in presence of loops because it assumes that the visitor doesn't emit dead code. This assumption is actually wrong and this situation happens.
However, it appears that the merge_registers() pass accidentally takes care of this for some weird reasons. But since this pass has been disabled for RadeonSI and Nouveau, the renumber_registers() pass which is called *after*, can't do its job correctly. This is because it assumes that no dead code is present. But if there is still a dead assignment, it might re-use the TEMP register id incorrectly and emits wrong code. This patches eliminates all dead assignments by tracking all temporary register reads like what the renumber_registers() actually does. The best solution would be to rewrite that DCE pass entirely but it's more work. This should fix Unigine Heaven on RadeonSI and Nouveau. shader-db results with RadeonSI: 47109 shaders in 29632 tests Totals: SGPRS: 1919548 -> 1919572 (0.00 %) VGPRS: 1139205 -> 1139209 (0.00 %) Spilled SGPRs: 1865 -> 1867 (0.11 %) Spilled VGPRs: 65 -> 65 (0.00 %) Private memory VGPRs: 1184 -> 1184 (0.00 %) Scratch size: 1308 -> 1308 (0.00 %) dwords per thread Code Size: 60083036 -> 60083244 (0.00 %) bytes LDS: 1077 -> 1077 (0.00 %) blocks Max Waves: 431200 -> 431200 (0.00 %) Wait states: 0 -> 0 (0.00 %) It's still interesting to disable the merge_registers() pass. Signed-off-by: Samuel Pitoiset <samuel.pitoi...@gmail.com> --- src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 36 +++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp index 0f8688a41c..01b5a4dc98 100644 --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp @@ -5085,9 +5085,13 @@ glsl_to_tgsi_visitor::eliminate_dead_code(void) glsl_to_tgsi_instruction *, this->next_temp * 4); int *write_level = rzalloc_array(mem_ctx, int, this->next_temp * 4); + int *first_reads = rzalloc_array(mem_ctx, int, this->next_temp); int level = 0; int removed = 0; + for (int i = 0; i < this->next_temp; i++) + first_reads[i] = -1; + foreach_in_list(glsl_to_tgsi_instruction, inst, &this->instructions) { assert(inst->dst[0].file != PROGRAM_TEMPORARY || inst->dst[0].index < this->next_temp); @@ -5148,8 +5152,12 @@ glsl_to_tgsi_visitor::eliminate_dead_code(void) src_chans |= 1 << GET_SWZ(inst->src[i].swizzle, 3); for (int c = 0; c < 4; c++) { - if (src_chans & (1 << c)) + if (src_chans & (1 << c)) { writes[4 * inst->src[i].index + c] = NULL; + + if (first_reads[inst->src[i].index] == -1) + first_reads[inst->src[i].index] = level; + } } } } @@ -5167,8 +5175,12 @@ glsl_to_tgsi_visitor::eliminate_dead_code(void) src_chans |= 1 << GET_SWZ(inst->tex_offsets[i].swizzle, 3); for (int c = 0; c < 4; c++) { - if (src_chans & (1 << c)) + if (src_chans & (1 << c)) { writes[4 * inst->tex_offsets[i].index + c] = NULL; + + if (first_reads[inst->tex_offsets[i].index] == -1) + first_reads[inst->tex_offsets[i].index] = level; + } } } } @@ -5211,17 +5223,30 @@ glsl_to_tgsi_visitor::eliminate_dead_code(void) * the writemask of other instructions with dead channels. */ foreach_in_list_safe(glsl_to_tgsi_instruction, inst, &this->instructions) { - if (!inst->dead_mask || !inst->dst[0].writemask) + bool dead_inst = false; + + if (!inst->dst[0].writemask) continue; + /* No amount of dead masks should remove memory stores */ if (inst->info->is_store) continue; - if ((inst->dst[0].writemask & ~inst->dead_mask) == 0) { + if (!inst->dead_mask) { + if (inst->dst[0].file == PROGRAM_TEMPORARY && + first_reads[inst->dst[0].index] == -1) { + dead_inst = true; + } + } else { + if ((inst->dst[0].writemask & ~inst->dead_mask) == 0) + dead_inst = true; + } + + if (dead_inst) { inst->remove(); delete inst; removed++; - } else { + } else if (inst->dead_mask) { if (glsl_base_type_is_64bit(inst->dst[0].type)) { if (inst->dead_mask == WRITEMASK_XY || inst->dead_mask == WRITEMASK_ZW) @@ -5232,6 +5257,7 @@ glsl_to_tgsi_visitor::eliminate_dead_code(void) } ralloc_free(write_level); + ralloc_free(first_reads); ralloc_free(writes); return removed; -- 2.12.2 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev