jay, nir: Make a dispatch_mask_intel intrinsic

jay is trying to use the fragment shader dispatch mask for helper
invocation lowering, but it was using load_sample_mask_in for that
(now load_coverage_mask_intel).  But this isn't the MSAA coverage
mask, the two are different payload fields.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/41688>

src/compiler/nir/nir_divergence_analysis.c

@@ -1012,6 +1012,7 @@ visit_intrinsic(nir_intrinsic_instr *instr, struct divergence_state *state)
    case nir_intrinsic_dpas_intel:
    case nir_intrinsic_convert_cmat_intel:
    case nir_intrinsic_load_coverage_mask_intel:
+   case nir_intrinsic_load_dispatch_mask_intel:
    case nir_intrinsic_isberd_nv:
    case nir_intrinsic_isbewr_nv:
    case nir_intrinsic_vild_nv:

src/compiler/nir/nir_intrinsics.py

@@ -2646,6 +2646,9 @@ system_value("simd_width_intel", 1)
 # IndirectDataStartAddress
 system_value("indirect_address_intel", 1)
 
+# The dispatch mask as provided in the FS payload.
+system_value("dispatch_mask_intel", 1)
+
 # The raw coverage mask as provided in the FS payload.
 # The semantics of it depend on the HW state.
 system_value("coverage_mask_intel", 1)

src/intel/compiler/jay/jay_from_nir.c

@@ -1327,7 +1327,7 @@ jay_emit_intrinsic(struct nir_to_jay_state *nj, nir_intrinsic_instr *intr)
          JAY_TYPE_U32;
       break;
 
-   case nir_intrinsic_load_coverage_mask_intel: {
+   case nir_intrinsic_load_dispatch_mask_intel: {
       jay_def mask = jay_extract(nj->payload.u0, 15);
 
       if (nj->s->dispatch_width == 32) {

src/intel/compiler/jay/jay_nir.c

@@ -51,7 +51,7 @@ lower_helper_invocation(nir_builder *b, nir_intrinsic_instr *intr, void *_)
    /* TODO: Is this right for multisampling? */
    b->cursor = nir_before_instr(&intr->instr);
    nir_def *active =
-      nir_inot(b, nir_inverse_ballot(b, nir_load_coverage_mask_intel(b)));
+      nir_inot(b, nir_inverse_ballot(b, nir_load_dispatch_mask_intel(b)));
 
    nir_def_replace(&intr->def, active);
    return true;