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      1 /*
      2  * Copyright  2015 Red Hat
      3  *
      4  * Permission is hereby granted, free of charge, to any person obtaining a
      5  * copy of this software and associated documentation files (the "Software"),
      6  * to deal in the Software without restriction, including without limitation
      7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
      8  * and/or sell copies of the Software, and to permit persons to whom the
      9  * Software is furnished to do so, subject to the following conditions:
     10  *
     11  * The above copyright notice and this permission notice (including the next
     12  * paragraph) shall be included in all copies or substantial portions of the
     13  * Software.
     14  *
     15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
     21  * DEALINGS IN THE SOFTWARE.
     22  */
     23 
     24 /**
     25  * \file lower_subroutine.cpp
     26  *
     27  * lowers subroutines to an if ladder.
     28  */
     29 
     30 #include "compiler/glsl_types.h"
     31 #include "glsl_parser_extras.h"
     32 #include "ir.h"
     33 #include "ir_builder.h"
     34 
     35 using namespace ir_builder;
     36 namespace {
     37 
     38 class lower_subroutine_visitor : public ir_hierarchical_visitor {
     39 public:
     40    lower_subroutine_visitor(struct _mesa_glsl_parse_state *state)
     41       : state(state)
     42    {
     43       this->progress = false;
     44    }
     45 
     46    ir_visitor_status visit_leave(ir_call *);
     47    ir_call *call_clone(ir_call *call, ir_function_signature *callee);
     48    bool progress;
     49    struct _mesa_glsl_parse_state *state;
     50 };
     51 
     52 }
     53 
     54 bool
     55 lower_subroutine(exec_list *instructions, struct _mesa_glsl_parse_state *state)
     56 {
     57    lower_subroutine_visitor v(state);
     58    visit_list_elements(&v, instructions);
     59    return v.progress;
     60 }
     61 
     62 ir_call *
     63 lower_subroutine_visitor::call_clone(ir_call *call, ir_function_signature *callee)
     64 {
     65    void *mem_ctx = ralloc_parent(call);
     66    ir_dereference_variable *new_return_ref = NULL;
     67    if (call->return_deref != NULL)
     68       new_return_ref = call->return_deref->clone(mem_ctx, NULL);
     69 
     70    exec_list new_parameters;
     71 
     72    foreach_in_list(ir_instruction, ir, &call->actual_parameters) {
     73       new_parameters.push_tail(ir->clone(mem_ctx, NULL));
     74    }
     75 
     76    return new(mem_ctx) ir_call(callee, new_return_ref, &new_parameters);
     77 }
     78 
     79 ir_visitor_status
     80 lower_subroutine_visitor::visit_leave(ir_call *ir)
     81 {
     82    if (!ir->sub_var)
     83       return visit_continue;
     84 
     85    void *mem_ctx = ralloc_parent(ir);
     86    ir_if *last_branch = NULL;
     87 
     88    for (int s = this->state->num_subroutines - 1; s >= 0; s--) {
     89       ir_rvalue *var;
     90       ir_function *fn = this->state->subroutines[s];
     91       ir_constant *lc = new(mem_ctx)ir_constant(fn->subroutine_index);
     92 
     93       bool is_compat = false;
     94 
     95       for (int i = 0; i < fn->num_subroutine_types; i++) {
     96          if (ir->sub_var->type->without_array() == fn->subroutine_types[i]) {
     97             is_compat = true;
     98             break;
     99          }
    100       }
    101       if (is_compat == false)
    102          continue;
    103 
    104       if (ir->array_idx != NULL)
    105          var = ir->array_idx->clone(mem_ctx, NULL);
    106       else
    107          var = new(mem_ctx) ir_dereference_variable(ir->sub_var);
    108 
    109       ir_function_signature *sub_sig =
    110          fn->exact_matching_signature(this->state,
    111                                       &ir->actual_parameters);
    112 
    113       ir_call *new_call = call_clone(ir, sub_sig);
    114       if (!last_branch)
    115          last_branch = if_tree(equal(subr_to_int(var), lc), new_call);
    116       else
    117          last_branch = if_tree(equal(subr_to_int(var), lc), new_call, last_branch);
    118    }
    119    if (last_branch)
    120       ir->insert_before(last_branch);
    121    ir->remove();
    122 
    123    return visit_continue;
    124 }
    125