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authorBryan Cain <[email protected]>2014-05-05 22:23:38 -0500
committerBryan Cain <[email protected]>2014-05-13 14:57:55 -0500
commit4e974a9cf323d774bfcbdd44d5cb1f7bf6391964 (patch)
tree5c0893e14858e1a79aa405e9a3e474a088067db8 /src/mesa
parent1646f4d0fb0efec04dce62b6dd4d974206acc8ac (diff)
glsl_to_tgsi: remove unnecessary dead code elimination pass
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 <marek.olsak at amd.com>
Diffstat (limited to 'src/mesa')
-rw-r--r--src/mesa/state_tracker/st_glsl_to_tgsi.cpp50
1 files 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();