[Mesa-dev] [PATCH v5 6/6] mesa/st: glsl_to_tgsi: tie in new temporary register merge approach

[Gert Wollny]

This patch ties in the new temporary register lifetime estiamtion and
rename mapping evaluation. In order to enable it, the evironment
variable MESA_GLSL_TO_TGSI_NEW_MERGE must be set.

Performance to compare between the current and the new implementation
were measured by running the shader-db in one thread; Numbers are in
% of total run.

-----------------------------------------------------------
                     old     new(qsort)   new(std::sort)

------------------------ valgrind -------------------------
merge                0.21       0.20          0.13
estimate lifetime    0.03       0.05          0.05
evaluate mapping  (incl=0.16)   0.12          0.06
apply mapping        0.02       0.02          0.02

---   perf (approximate because of statistic sampling) -------
merge                0.24       0.20          0.14
estimate lifetime    0.03       0.05          0.05
evaluate mapping  (incl=0.16)   0.10          0.04
apply mapping        0.05       0.05          0.05
---
 src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 528fc4cc64..d4abee9d02 100644
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -55,7 +55,7 @@
 #include "st_glsl_types.h"
 #include "st_nir.h"
 #include "st_shader_cache.h"
-#include "st_glsl_to_tgsi_private.h"
+#include "st_glsl_to_tgsi_temprename.h"
 
 #include "util/hash_table.h"
 #include <algorithm>
@@ -322,6 +322,7 @@ public:
 
    void merge_two_dsts(void);
    void merge_registers(void);
+   void merge_registers_alternative(void);
    void renumber_registers(void);
 
    void emit_block_mov(ir_assignment *ir, const struct glsl_type *type,
@@ -5139,6 +5140,23 @@ glsl_to_tgsi_visitor::merge_two_dsts(void)
    }
 }
 
+void
+glsl_to_tgsi_visitor::merge_registers_alternative(void)
+{
+   struct rename_reg_pair *renames =
+         rzalloc_array(mem_ctx, struct rename_reg_pair, this->next_temp);
+   struct lifetime *lifetimes =
+         rzalloc_array(mem_ctx, struct lifetime, this->next_temp);
+
+   get_temp_registers_required_lifetimes(mem_ctx, &this->instructions,
+                                         this->next_temp, lifetimes);
+   get_temp_registers_remapping(mem_ctx, this->next_temp, lifetimes, renames);
+   rename_temp_registers(renames);
+
+   ralloc_free(lifetimes);
+   ralloc_free(renames);
+}
+
 /* Merges temporary registers together where possible to reduce the number of
  * registers needed to run a program.
  *
@@ -6603,8 +6621,13 @@ get_mesa_program_tgsi(struct gl_context *ctx,
    while (v->eliminate_dead_code());
 
    v->merge_two_dsts();
-   if (!skip_merge_registers)
-      v->merge_registers();
+   if (!skip_merge_registers) {
+      if (getenv("MESA_GLSL_TO_TGSI_NEW_MERGE") != NULL)
+         v->merge_registers_alternative();
+      else
+         v->merge_registers();
+   }
+
    v->renumber_registers();
 
    /* Write the END instruction. */
-- 
2.13.0