nir/lower_out_to_temp: Add an "entrypoint" parameter

Previously, the pass assumed that the entrypoint would be whatever function
happened to have the name "main".  We really shouldn't trust in the
function names.

Reviewed-by: Rob Clark <robdclark@gmail.com>

src/compiler/nir/glsl_to_nir.cpp

@@ -143,7 +143,7 @@ glsl_to_nir(const struct gl_shader_program *shader_prog,
    v2.run(sh->ir);
    visit_exec_list(sh->ir, &v1);
 
-   nir_lower_outputs_to_temporaries(shader);
+   nir_lower_outputs_to_temporaries(shader, nir_shader_get_entrypoint(shader));
 
    shader->info.name = ralloc_asprintf(shader, "GLSL%d", shader_prog->Name);
    if (shader_prog->Label)

src/compiler/nir/nir.h

@@ -2174,7 +2174,8 @@ bool nir_lower_indirect_derefs(nir_shader *shader, uint32_t mode_mask);
 
 bool nir_lower_locals_to_regs(nir_shader *shader);
 
-void nir_lower_outputs_to_temporaries(nir_shader *shader);
+void nir_lower_outputs_to_temporaries(nir_shader *shader,
+                                      nir_function *entrypoint);
 
 void nir_assign_var_locations(struct exec_list *var_list,
                               unsigned *size,

src/compiler/nir/nir_lower_outputs_to_temporaries.c

@@ -74,7 +74,7 @@ emit_output_copies_block(nir_block *block, void *state)
 }
 
 void
-nir_lower_outputs_to_temporaries(nir_shader *shader)
+nir_lower_outputs_to_temporaries(nir_shader *shader, nir_function *entrypoint)
 {
    struct lower_outputs_state state;
 
@@ -117,7 +117,7 @@ nir_lower_outputs_to_temporaries(nir_shader *shader)
           * before each EmitVertex call.
           */
          nir_foreach_block(function->impl, emit_output_copies_block, &state);
-      } else if (strcmp(function->name, "main") == 0) {
+      } else if (function == entrypoint) {
          /* For all other shader types, we need to do the copies right before
           * the jumps to the end block.
           */