spirv: Add support for the CL Round instruction

Add a round() implementation that's conformant with the CL spec.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6256>

diff --git a/src/compiler/spirv/vtn_opencl.c b/src/compiler/spirv/vtn_opencl.c
index 6018184fe216cd1fe0ca96eab3061c4cf5b3b9d9..a4eb41d241bf5e9745cd6843c46618ff54c6b6e0 100644 (file)
--- a/src/compiler/spirv/vtn_opencl.c
+++ b/src/compiler/spirv/vtn_opencl.c
@@ -281,6 +281,21 @@ handle_printf(struct vtn_builder *b, enum OpenCLstd_Entrypoints opcode,
    return nir_imm_int(&b->nb, -1);
 }
 
+static nir_ssa_def *
+handle_round(struct vtn_builder *b, enum OpenCLstd_Entrypoints opcode,
+             unsigned num_srcs, nir_ssa_def **srcs,
+             const struct glsl_type *dest_type)
+{
+   nir_ssa_def *src = srcs[0];
+   nir_builder *nb = &b->nb;
+   nir_ssa_def *half = nir_imm_floatN_t(nb, 0.5, src->bit_size);
+   nir_ssa_def *truncated = nir_ftrunc(nb, src);
+   nir_ssa_def *remainder = nir_fsub(nb, src, truncated);
+
+   return nir_bcsel(nb, nir_fge(nb, nir_fabs(nb, remainder), half),
+                    nir_fadd(nb, truncated, nir_fsign(nb, src)), truncated);
+}
+
 static nir_ssa_def *
 handle_shuffle(struct vtn_builder *b, enum OpenCLstd_Entrypoints opcode, unsigned num_srcs,
                nir_ssa_def **srcs, const struct glsl_type *dest_type)
@@ -435,6 +450,9 @@ vtn_handle_opencl_instruction(struct vtn_builder *b, SpvOp ext_opcode,
    case OpenCLstd_Shuffle2:
       handle_instr(b, cl_opcode, w, count, handle_shuffle2);
       return true;
+   case OpenCLstd_Round:
+      handle_instr(b, cl_opcode, w, count, handle_round);
+      return true;
    case OpenCLstd_Printf:
       handle_instr(b, cl_opcode, w, count, handle_printf);
       return true;