[Mesa-dev] [PATCH v3 39/42] intel/compiler: remove MAD/LRP algebraic optimizations from the backend

[Iago Toral Quiroga]

NIR already has these so they are redundant. A run of shader-db confirms
that the only cases where these backend optimizations are activated
are some Tomb Raider shaders where the affected variables are qualified
as "precise", which is why NIR won't apply them and why the backend
shouldn't either (so it is actually a bug).

Suggested-by: Jason Ekstrand <jason at jlekstrand.net>
---
 src/intel/compiler/brw_fs.cpp | 37 -----------------------------------
 1 file changed, 37 deletions(-)

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index 77c955ac435..e7f5a8822a3 100644
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -2568,16 +2568,6 @@ fs_visitor::opt_algebraic()
             break;
          }
          break;
-      case BRW_OPCODE_LRP:
-         if (inst->src[1].equals(inst->src[2])) {
-            inst->opcode = BRW_OPCODE_MOV;
-            inst->src[0] = inst->src[1];
-            inst->src[1] = reg_undef;
-            inst->src[2] = reg_undef;
-            progress = true;
-            break;
-         }
-         break;
       case BRW_OPCODE_CMP:
          if ((inst->conditional_mod == BRW_CONDITIONAL_Z ||
               inst->conditional_mod == BRW_CONDITIONAL_NZ) &&
@@ -2654,33 +2644,6 @@ fs_visitor::opt_algebraic()
             }
          }
          break;
-      case BRW_OPCODE_MAD:
-         if (inst->src[1].is_zero() || inst->src[2].is_zero()) {
-            inst->opcode = BRW_OPCODE_MOV;
-            inst->src[1] = reg_undef;
-            inst->src[2] = reg_undef;
-            progress = true;
-         } else if (inst->src[0].is_zero()) {
-            inst->opcode = BRW_OPCODE_MUL;
-            inst->src[0] = inst->src[2];
-            inst->src[2] = reg_undef;
-            progress = true;
-         } else if (inst->src[1].is_one()) {
-            inst->opcode = BRW_OPCODE_ADD;
-            inst->src[1] = inst->src[2];
-            inst->src[2] = reg_undef;
-            progress = true;
-         } else if (inst->src[2].is_one()) {
-            inst->opcode = BRW_OPCODE_ADD;
-            inst->src[2] = reg_undef;
-            progress = true;
-         } else if (inst->src[1].file == IMM && inst->src[2].file == IMM) {
-            inst->opcode = BRW_OPCODE_ADD;
-            inst->src[1].f *= inst->src[2].f;
-            inst->src[2] = reg_undef;
-            progress = true;
-         }
-         break;
       case SHADER_OPCODE_BROADCAST:
          if (is_uniform(inst->src[0])) {
             inst->opcode = BRW_OPCODE_MOV;
-- 
2.17.1