[Mesa-dev] [PATCH 2/3] nir/gcm: Add value numbering support

[Jason Ekstrand]

---
 src/compiler/nir/nir.h         |  2 +-
 src/compiler/nir/nir_opt_gcm.c | 29 ++++++++++++++++++++++++-----
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index c1cf940..ff7c422 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2587,7 +2587,7 @@ bool nir_opt_dce(nir_shader *shader);
 
 bool nir_opt_dead_cf(nir_shader *shader);
 
-void nir_opt_gcm(nir_shader *shader);
+bool nir_opt_gcm(nir_shader *shader, bool value_number);
 
 bool nir_opt_peephole_select(nir_shader *shader);
 
diff --git a/src/compiler/nir/nir_opt_gcm.c b/src/compiler/nir/nir_opt_gcm.c
index 02a9348..77eb8e6 100644
--- a/src/compiler/nir/nir_opt_gcm.c
+++ b/src/compiler/nir/nir_opt_gcm.c
@@ -26,6 +26,7 @@
  */
 
 #include "nir.h"
+#include "nir_instr_set.h"
 
 /*
  * Implements Global Code Motion.  A description of GCM can be found in
@@ -451,8 +452,8 @@ gcm_place_instr(nir_instr *instr, struct gcm_state *state)
    block_info->last_instr = instr;
 }
 
-static void
-opt_gcm_impl(nir_function_impl *impl)
+static bool
+opt_gcm_impl(nir_function_impl *impl, bool value_number)
 {
    struct gcm_state state;
 
@@ -470,6 +471,18 @@ opt_gcm_impl(nir_function_impl *impl)
       gcm_pin_instructions_block(block, &state);
    }
 
+   bool progress = false;
+   if (value_number) {
+      struct set *gvn_set = nir_instr_set_create(NULL);
+      foreach_list_typed_safe(nir_instr, instr, node, &state.instrs) {
+         if (nir_instr_set_add_or_rewrite(gvn_set, instr)) {
+            nir_instr_remove(instr);
+            progress = true;
+         }
+      }
+      nir_instr_set_destroy(gvn_set);
+   }
+
    foreach_list_typed(nir_instr, instr, node, &state.instrs)
       gcm_schedule_early_instr(instr, &state);
 
@@ -486,13 +499,19 @@ opt_gcm_impl(nir_function_impl *impl)
 
    nir_metadata_preserve(impl, nir_metadata_block_index |
                                nir_metadata_dominance);
+
+   return progress;
 }
 
-void
-nir_opt_gcm(nir_shader *shader)
+bool
+nir_opt_gcm(nir_shader *shader, bool value_number)
 {
+   bool progress = false;
+
    nir_foreach_function(function, shader) {
       if (function->impl)
-         opt_gcm_impl(function->impl);
+         progress |= opt_gcm_impl(function->impl, value_number);
    }
+
+   return progress;
 }
-- 
2.5.0.400.gff86faf