Mesa (main): aco: Implement uclz.

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Module: Mesa
Branch: main
Commit: 529ec3d7dc1dd74060bda205743e1e3ae4a88349
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=529ec3d7dc1dd74060bda205743e1e3ae4a88349

Author: Georg Lehmann <dadschoorse at gmail.com>
Date:   Fri Nov 19 14:27:06 2021 +0100

aco: Implement uclz.

Signed-off-by: Georg Lehmann <dadschoorse at gmail.com>
Reviewed-by: Timur Kristóf <timur.kristof at gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13895>

---

 src/amd/compiler/aco_instruction_selection.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index 63ac939e20f..e09c2c281c9 100644
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -1768,6 +1768,19 @@ visit_alu_instr(isel_context* ctx, nir_alu_instr* instr)
       }
       break;
    }
+   case nir_op_uclz: {
+      Temp src = get_alu_src(ctx, instr->src[0]);
+      if (src.regClass() == s1) {
+         Temp msb_rev = bld.sop1(aco_opcode::s_flbit_i32_b32, bld.def(s1), src);
+         bld.sop2(aco_opcode::s_min_u32, Definition(dst), Operand::c32(32u), msb_rev);
+      } else if (src.regClass() == v1) {
+         Temp msb_rev = bld.vop1(aco_opcode::v_ffbh_u32, bld.def(v1), src);
+         bld.vop2(aco_opcode::v_min_u32, Definition(dst), Operand::c32(32u), msb_rev);
+      } else {
+         isel_err(&instr->instr, "Unimplemented NIR instr bit size");
+      }
+      break;
+   }
    case nir_op_bitfield_reverse: {
       if (dst.regClass() == s1) {
          bld.sop1(aco_opcode::s_brev_b32, Definition(dst), get_alu_src(ctx, instr->src[0]));