[Mesa-dev] [PATCH] i965: Clean up FBH code.

[Matt Turner]

It did a bunch of unnecessary stuff, emitting an extra MOV included.
---
 src/mesa/drivers/dri/i965/brw_fs_nir.cpp   |  7 +++----
 src/mesa/drivers/dri/i965/brw_vec4_nir.cpp | 18 +++++-------------
 2 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
index 9c1f95c..b596614 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_nir.cpp
@@ -906,12 +906,11 @@ fs_visitor::nir_emit_alu(const fs_builder &bld, nir_alu_instr *instr)
        * from the LSB side. If FBH didn't return an error (0xFFFFFFFF), then
        * subtract the result from 31 to convert the MSB count into an LSB count.
        */
-
       bld.CMP(bld.null_reg_d(), result, fs_reg(-1), BRW_CONDITIONAL_NZ);
-      fs_reg neg_result(result);
-      neg_result.negate = true;
-      inst = bld.ADD(result, neg_result, fs_reg(31));
+
+      inst = bld.ADD(result, result, fs_reg(31));
       inst->predicate = BRW_PREDICATE_NORMAL;
+      inst->src[0].negate = true;
       break;
    }
 
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
index 33cc02e..5463f3e 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_nir.cpp
@@ -1291,26 +1291,18 @@ vec4_visitor::nir_emit_alu(nir_alu_instr *instr)
 
    case nir_op_ufind_msb:
    case nir_op_ifind_msb: {
-      src_reg temp = src_reg(this, glsl_type::uint_type);
-
-      inst = emit(FBH(dst_reg(temp), op[0]));
-      inst->dst.writemask = WRITEMASK_XYZW;
+      emit(FBH(retype(dst, BRW_REGISTER_TYPE_UD), op[0]));
 
       /* FBH counts from the MSB side, while GLSL's findMSB() wants the count
        * from the LSB side. If FBH didn't return an error (0xFFFFFFFF), then
        * subtract the result from 31 to convert the MSB count into an LSB count.
        */
+      src_reg src(dst);
+      emit(CMP(dst_null_d(), src, src_reg(-1), BRW_CONDITIONAL_NZ));
 
-      /* FBH only supports UD type for dst, so use a MOV to convert UD to D. */
-      temp.swizzle = BRW_SWIZZLE_NOOP;
-      emit(MOV(dst, temp));
-
-      src_reg src_tmp = src_reg(dst);
-      emit(CMP(dst_null_d(), src_tmp, src_reg(-1), BRW_CONDITIONAL_NZ));
-
-      src_tmp.negate = true;
-      inst = emit(ADD(dst, src_tmp, src_reg(31)));
+      inst = emit(ADD(dst, src, src_reg(31)));
       inst->predicate = BRW_PREDICATE_NORMAL;
+      inst->src[0].negate = true;
       break;
    }
 
-- 
2.4.9