From 4e974a9cf323d774bfcbdd44d5cb1f7bf6391964 Mon Sep 17 00:00:00 2001 From: Bryan Cain Date: Mon, 5 May 2014 22:23:38 -0500 Subject: [PATCH] glsl_to_tgsi: remove unnecessary dead code elimination pass MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit With the more advanced dead code elimination pass already being run, eliminate_dead_code was making no difference in instruction count, and had an undesirable O(n^2) runtime. So remove it and rename eliminate_dead_code_advanced to eliminate_dead_code. Reviewed-by: Marek Olšák --- src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 50 +++------------------- 1 file changed, 5 insertions(+), 45 deletions(-) diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp index bdee1f4ebc4..f5da5ee3092 100644 --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp @@ -459,8 +459,7 @@ public: int get_last_temp_write(int index); void copy_propagate(void); - void eliminate_dead_code(void); - int eliminate_dead_code_advanced(void); + int eliminate_dead_code(void); void merge_registers(void); void renumber_registers(void); @@ -3672,7 +3671,8 @@ glsl_to_tgsi_visitor::copy_propagate(void) } /* - * Tracks available PROGRAM_TEMPORARY registers for dead code elimination. + * On a basic block basis, tracks available PROGRAM_TEMPORARY registers for dead + * code elimination. * * The glsl_to_tgsi_visitor lazily produces code assuming that this pass * will occur. As an example, a TXP production after copy propagation but @@ -3685,48 +3685,9 @@ glsl_to_tgsi_visitor::copy_propagate(void) * and after this pass: * * 0: TXP TEMP[2], INPUT[4].xyyw, texture[0], 2D; - * - * FIXME: assumes that all functions are inlined (no support for BGNSUB/ENDSUB) - * FIXME: doesn't eliminate all dead code inside of loops; it steps around them - */ -void -glsl_to_tgsi_visitor::eliminate_dead_code(void) -{ - int i; - - for (i=0; i < this->next_temp; i++) { - int last_read = get_last_temp_read(i); - int j = 0; - - foreach_list_safe(node, &this->instructions) { - glsl_to_tgsi_instruction *inst = (glsl_to_tgsi_instruction *) node; - - if (inst->dst.file == PROGRAM_TEMPORARY && inst->dst.index == i && - j > last_read) - { - inst->remove(); - delete inst; - } - - j++; - } - } -} - -/* - * On a basic block basis, tracks available PROGRAM_TEMPORARY registers for dead - * code elimination. This is less primitive than eliminate_dead_code(), as it - * is per-channel and can detect consecutive writes without a read between them - * as dead code. However, there is some dead code that can be eliminated by - * eliminate_dead_code() but not this function - for example, this function - * cannot eliminate an instruction writing to a register that is never read and - * is the only instruction writing to that register. - * - * The glsl_to_tgsi_visitor lazily produces code assuming that this pass - * will occur. */ int -glsl_to_tgsi_visitor::eliminate_dead_code_advanced(void) +glsl_to_tgsi_visitor::eliminate_dead_code(void) { glsl_to_tgsi_instruction **writes = rzalloc_array(mem_ctx, glsl_to_tgsi_instruction *, @@ -5270,9 +5231,8 @@ get_mesa_program(struct gl_context *ctx, /* Perform optimizations on the instructions in the glsl_to_tgsi_visitor. */ v->simplify_cmp(); v->copy_propagate(); - while (v->eliminate_dead_code_advanced()); + while (v->eliminate_dead_code()); - v->eliminate_dead_code(); v->merge_registers(); v->renumber_registers(); -- 2.30.2