+ /* Copy Primitive IDs from GS threads to the LDS address corresponding
+ * to the ES thread of the provoking vertex.
+ */
+ if (ctx->stage == MESA_SHADER_VERTEX &&
+ ctx->options->key.vs_common_out.export_prim_id) {
+ /* TODO: streamout */
+
+ ac_build_ifcc(&ctx->ac, is_gs_thread, 5400);
+ /* Extract the PROVOKING_VTX_INDEX field. */
+ LLVMValueRef provoking_vtx_in_prim =
+ LLVMConstInt(ctx->ac.i32, 0, false);
+
+ /* provoking_vtx_index = vtxindex[provoking_vtx_in_prim]; */
+ LLVMValueRef indices = ac_build_gather_values(&ctx->ac, vtxindex, 3);
+ LLVMValueRef provoking_vtx_index =
+ LLVMBuildExtractElement(builder, indices, provoking_vtx_in_prim, "");
+
+ LLVMBuildStore(builder, ctx->abi.gs_prim_id,
+ ac_build_gep0(&ctx->ac, ctx->esgs_ring, provoking_vtx_index));
+ ac_build_endif(&ctx->ac, 5400);
+ }