radeonsi: extract si_prolog_get_internal_binding_slot

To be shared with ps prolog.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24989>

src/gallium/drivers/radeonsi/si_shader_internal.h

@@ -200,6 +200,7 @@ LLVMValueRef si_insert_input_ret_float(struct si_shader_context *ctx, LLVMValueR
 LLVMValueRef si_insert_input_ptr(struct si_shader_context *ctx, LLVMValueRef ret,
                                  struct ac_arg param, unsigned return_index);
 LLVMValueRef si_prolog_get_internal_bindings(struct si_shader_context *ctx);
+LLVMValueRef si_prolog_get_internal_binding_slot(struct si_shader_context *ctx, unsigned slot);
 LLVMValueRef si_unpack_param(struct si_shader_context *ctx, struct ac_arg param, unsigned rshift,
                              unsigned bitwidth);
 bool si_llvm_compile_shader(struct si_screen *sscreen, struct ac_llvm_compiler *compiler,

src/gallium/drivers/radeonsi/si_shader_llvm.c

@@ -301,6 +301,18 @@ LLVMValueRef si_prolog_get_internal_bindings(struct si_shader_context *ctx)
    return list;
 }
 
+LLVMValueRef si_prolog_get_internal_binding_slot(struct si_shader_context *ctx, unsigned slot)
+{
+   LLVMValueRef list = LLVMBuildIntToPtr(
+      ctx->ac.builder, ac_get_arg(&ctx->ac, ctx->args->internal_bindings),
+      ac_array_in_const32_addr_space(ctx->ac.v4i32), "");
+   LLVMValueRef index = LLVMConstInt(ctx->ac.i32, slot, 0);
+
+   return ac_build_load_to_sgpr(&ctx->ac,
+                                (struct ac_llvm_pointer) { .t = ctx->ac.v4i32, .v = list },
+                                index);
+}
+
 /* Ensure that the esgs ring is declared.
  *
  * We declare it with 64KB alignment as a hint that the

src/gallium/drivers/radeonsi/si_shader_llvm_vs.c

@@ -141,17 +141,9 @@ void si_llvm_build_vs_prolog(struct si_shader_context *ctx, union si_shader_part
    }
 
    /* Compute vertex load indices from instance divisors. */
-   LLVMValueRef instance_divisor_constbuf = NULL;
-
-   if (key->vs_prolog.states.instance_divisor_is_fetched) {
-      LLVMValueRef list = ac_get_arg(&ctx->ac, args->internal_bindings);
-      list = LLVMBuildIntToPtr(ctx->ac.builder, list,
-                               ac_array_in_const32_addr_space(ctx->ac.v4i32), "");
-
-      LLVMValueRef buf_index = LLVMConstInt(ctx->ac.i32, SI_VS_CONST_INSTANCE_DIVISORS, 0);
-      instance_divisor_constbuf = ac_build_load_to_sgpr(&ctx->ac,
-         (struct ac_llvm_pointer) { .v = list, .t = ctx->ac.v4i32 }, buf_index);
-   }
+   LLVMValueRef instance_divisor_constbuf =
+      key->vs_prolog.states.instance_divisor_is_fetched ?
+      si_prolog_get_internal_binding_slot(ctx, SI_VS_CONST_INSTANCE_DIVISORS) : NULL;
 
    for (int i = 0; i < key->vs_prolog.num_inputs; i++) {
       LLVMValueRef index = get_vertex_index(ctx, &key->vs_prolog.states, i,