[Mesa-dev] [RFC 01/10] nir/lower_double_ops: lower abs()

[Elie Tournier]

Signed-off-by: Elie Tournier <elie.tournier at collabora.com>
---
 src/compiler/nir/nir.h                  |  3 ++-
 src/compiler/nir/nir_lower_double_ops.c | 20 ++++++++++++++++++++
 src/intel/compiler/brw_nir.c            |  3 ++-
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
index ce5b434d56..0ec09f54e2 100644
--- a/src/compiler/nir/nir.h
+++ b/src/compiler/nir/nir.h
@@ -2568,7 +2568,8 @@ typedef enum {
    nir_lower_dceil = (1 << 5),
    nir_lower_dfract = (1 << 6),
    nir_lower_dround_even = (1 << 7),
-   nir_lower_dmod = (1 << 8)
+   nir_lower_dmod = (1 << 8),
+   nir_lower_dabs = (1 << 9)
 } nir_lower_doubles_options;
 
 bool nir_lower_doubles(nir_shader *shader, nir_lower_doubles_options options);
diff --git a/src/compiler/nir/nir_lower_double_ops.c b/src/compiler/nir/nir_lower_double_ops.c
index b3543bc696..4ea8d339cc 100644
--- a/src/compiler/nir/nir_lower_double_ops.c
+++ b/src/compiler/nir/nir_lower_double_ops.c
@@ -456,6 +456,16 @@ lower_mod(nir_builder *b, nir_ssa_def *src0, nir_ssa_def *src1)
                     nir_imm_double(b, 0.0));
 }
 
+static nir_ssa_def *
+lower_fabs64(nir_builder *b, nir_ssa_def *src)
+{
+   nir_ssa_def *src_lo = nir_unpack_64_2x32_split_x(b, src);
+   nir_ssa_def *src_hi = nir_unpack_64_2x32_split_y(b, src);
+   /* Clear the sign bit */
+   nir_ssa_def *new_src_hi = nir_iand(b, src_hi, nir_imm_int(b, 0x7FFFFFFF));
+   return nir_pack_64_2x32_split(b, src_lo, new_src_hi);
+}
+
 static bool
 lower_doubles_instr(nir_alu_instr *instr, nir_lower_doubles_options options)
 {
@@ -509,6 +519,11 @@ lower_doubles_instr(nir_alu_instr *instr, nir_lower_doubles_options options)
          return false;
       break;
 
+   case nir_op_fabs:
+      if (!(options & nir_lower_dabs))
+         return false;
+      break;
+
    default:
       return false;
    }
@@ -554,6 +569,11 @@ lower_doubles_instr(nir_alu_instr *instr, nir_lower_doubles_options options)
       result = lower_mod(&bld, src, src1);
    }
       break;
+
+   case nir_op_fabs:
+      result = lower_fabs64(&bld, src);
+      break;
+
    default:
       unreachable("unhandled opcode");
    }
diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c
index 36ccdf3cb1..8e41a6eaea 100644
--- a/src/intel/compiler/brw_nir.c
+++ b/src/intel/compiler/brw_nir.c
@@ -509,7 +509,8 @@ nir_optimize(nir_shader *nir, const struct brw_compiler *compiler,
                              nir_lower_dceil |
                              nir_lower_dfract |
                              nir_lower_dround_even |
-                             nir_lower_dmod);
+                             nir_lower_dmod |
+                             nir_lower_dabs);
       OPT(nir_lower_64bit_pack);
    } while (progress);
 
-- 
2.11.0