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/*
* Copyright © 2010 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
/**
* \file ir_basic_block.cpp
*
* Basic block analysis of instruction streams.
*/
#include "ir.h"
#include "ir_visitor.h"
#include "ir_basic_block.h"
#include "glsl_types.h"
class ir_has_call_visitor : public ir_hierarchical_visitor {
public:
ir_has_call_visitor()
{
has_call = false;
}
virtual ir_visitor_status visit_enter(ir_call *ir)
{
(void) ir;
has_call = true;
return visit_stop;
}
bool has_call;
};
/**
* Calls a user function for every basic block in the instruction stream.
*
* Basic block analysis is pretty easy in our IR thanks to the lack of
* unstructured control flow. We've got:
*
* ir_loop (for () {}, while () {}, do {} while ())
* ir_loop_jump (
* ir_if () {}
* ir_return
* ir_call()
*
* Note that the basic blocks returned by this don't encompass all
* operations performed by the program -- for example, if conditions
* don't get returned, nor do the assignments that will be generated
* for ir_call parameters.
*/
void call_for_basic_blocks(exec_list *instructions,
void (*callback)(ir_instruction *first,
ir_instruction *last,
void *data),
void *data)
{
ir_instruction *leader = NULL;
ir_instruction *last = NULL;
foreach_iter(exec_list_iterator, iter, *instructions) {
ir_instruction *ir = (ir_instruction *)iter.get();
ir_if *ir_if;
ir_loop *ir_loop;
ir_function *ir_function;
if (!leader)
leader = ir;
if ((ir_if = ir->as_if())) {
callback(leader, ir, data);
leader = NULL;
call_for_basic_blocks(&ir_if->then_instructions, callback, data);
call_for_basic_blocks(&ir_if->else_instructions, callback, data);
} else if ((ir_loop = ir->as_loop())) {
callback(leader, ir, data);
leader = NULL;
call_for_basic_blocks(&ir_loop->body_instructions, callback, data);
} else if (ir->as_return() || ir->as_call()) {
callback(leader, ir, data);
leader = NULL;
} else if ((ir_function = ir->as_function())) {
/* A function definition doesn't interrupt our basic block
* since execution doesn't go into it. We should process the
* bodies of its signatures for BBs, though.
*
* Note that we miss an opportunity for producing more
* maximal BBs between the instructions that precede main()
* and the body of main(). Perhaps those instructions ought
* to live inside of main().
*/
foreach_iter(exec_list_iterator, fun_iter, *ir_function) {
ir_function_signature *ir_sig;
ir_sig = (ir_function_signature *)fun_iter.get();
call_for_basic_blocks(&ir_sig->body, callback, data);
}
} else if (ir->as_assignment()) {
ir_has_call_visitor v;
/* If there's a call in the expression tree being assigned,
* then that ends the BB too.
*
* The assumption is that any consumer of the basic block
* walker is fine with the fact that the call is somewhere in
* the tree even if portions of the tree may be evaluated
* after the call.
*
* A consumer that has an issue with this could not process
* the last instruction of the basic block. If doing so,
* expression flattener may be useful before using the basic
* block finder to get more maximal basic blocks out.
*/
ir->accept(&v);
if (v.has_call) {
callback(leader, ir, data);
leader = NULL;
}
}
last = ir;
}
if (leader) {
callback(leader, last, data);
}
}
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