broadcom/compiler: support nir_intrinsic_load_sample_id

This adds support for the intrinsic as well as the vir_SAMPID
instruction that corresponds to it in vir.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6356>

src/broadcom/compiler/nir_to_vir.c

@@ -2392,6 +2392,10 @@ ntq_emit_intrinsic(struct v3d_compile *c, nir_intrinsic_instr *instr)
                                vir_uniform(c, QUNIFORM_FB_LAYERS, 0));
                 break;
 
+        case nir_intrinsic_load_sample_id:
+                ntq_store_dest(c, &instr->dest, 0, vir_SAMPID(c));
+                break;
+
         default:
                 fprintf(stderr, "Unknown intrinsic: ");
                 nir_print_instr(&instr->instr, stderr);

src/broadcom/compiler/v3d_compiler.h

@@ -1084,6 +1084,7 @@ VIR_A_ALU0(YCD)
 VIR_A_ALU0(MSF)
 VIR_A_ALU0(REVF)
 VIR_A_ALU0(BARRIERID)
+VIR_A_ALU0(SAMPID)
 VIR_A_NODST_1(VPMSETUP)
 VIR_A_NODST_0(VPMWT)
 VIR_A_ALU2(FCMP)