nir: fix denorms in unpack_half_1x16()

According to VK_KHR_shader_float_controls:

"Denormalized values obtained via unpacking an integer into a vector
 of values with smaller bit width and interpreting those values as
 floating-point numbers must: be flushed to zero, unless the entry
 point is declared with the code:DenormPreserve execution mode."

v2:
- Add nir_op_unpack_half_2x16_flush_to_zero opcode (Connor).

v3:
- Adapt to use the new NIR lowering framework (Andres).

v4:
- Updated to renamed shader info member and enum values (Andres).

v5:
- Simplify flags logic operations (Caio).

Signed-off-by: Samuel Iglesias Gonsálvez <[email protected]>
Signed-off-by: Andres Gomez <[email protected]>
Reviewed-by: Connor Abbott <[email protected]> [v2]

1 files changed, 12 insertions, 4 deletions

diff --git a/src/compiler/spirv/vtn_glsl450.c b/src/compiler/spirv/vtn_glsl450.c
index 753e74cf73c..dd72a86e21c 100644
--- a/src/compiler/spirv/vtn_glsl450.c
+++ b/src/compiler/spirv/vtn_glsl450.c
@@ -387,7 +387,8 @@ build_atan2(nir_builder *b, nir_ssa_def *y, nir_ssa_def *x)
 
 static nir_op
 vtn_nir_alu_op_for_spirv_glsl_opcode(struct vtn_builder *b,
-                                     enum GLSLstd450 opcode)
+                                     enum GLSLstd450 opcode,
+                                     unsigned execution_mode)
 {
    switch (opcode) {
    case GLSLstd450Round:         return nir_op_fround_even;
@@ -433,7 +434,11 @@ vtn_nir_alu_op_for_spirv_glsl_opcode(struct vtn_builder *b,
    case GLSLstd450UnpackUnorm4x8:   return nir_op_unpack_unorm_4x8;
    case GLSLstd450UnpackSnorm2x16:  return nir_op_unpack_snorm_2x16;
    case GLSLstd450UnpackUnorm2x16:  return nir_op_unpack_unorm_2x16;
-   case GLSLstd450UnpackHalf2x16:   return nir_op_unpack_half_2x16;
+   case GLSLstd450UnpackHalf2x16:
+      if (execution_mode & FLOAT_CONTROLS_DENORM_FLUSH_TO_ZERO_FP16)
+         return nir_op_unpack_half_2x16_flush_to_zero;
+      else
+         return nir_op_unpack_half_2x16;
    case GLSLstd450UnpackDouble2x32: return nir_op_unpack_64_2x32;
 
    default:
@@ -678,13 +683,16 @@ handle_glsl450_alu(struct vtn_builder *b, enum GLSLstd450 entrypoint,
       return;
    }
 
-   default:
+   default: {
+      unsigned execution_mode =
+         b->shader->info.float_controls_execution_mode;
       val->ssa->def =
          nir_build_alu(&b->nb,
-                       vtn_nir_alu_op_for_spirv_glsl_opcode(b, entrypoint),
+                       vtn_nir_alu_op_for_spirv_glsl_opcode(b, entrypoint, execution_mode),
                        src[0], src[1], src[2], NULL);
       return;
    }
+   }
 }
 
 static void