SPIRV-Tools/source/val/construct.h
alan-baker 60aaafbc70 Allows breaks selection breaks to switches (#2605)
Fixes #2604

* Allow selection constructs to branch to the nearest selection merge
whose header is terminated by an OpSwitch
  * Cleanup break and continue checks generally
  * add tests
2019-05-21 22:49:37 -07:00

171 lines
6.3 KiB
C++

// Copyright (c) 2015-2016 The Khronos Group Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef SOURCE_VAL_CONSTRUCT_H_
#define SOURCE_VAL_CONSTRUCT_H_
#include <cstdint>
#include <set>
#include <vector>
#include "source/val/basic_block.h"
namespace spvtools {
namespace val {
class ValidationState_t;
/// Functor for ordering BasicBlocks. BasicBlock pointers must not be null.
struct less_than_id {
bool operator()(const BasicBlock* lhs, const BasicBlock* rhs) const {
return lhs->id() < rhs->id();
}
};
enum class ConstructType : int {
kNone = 0,
/// The set of blocks dominated by a selection header, minus the set of blocks
/// dominated by the header's merge block
kSelection,
/// The set of blocks dominated by an OpLoopMerge's Continue Target and post
/// dominated by the corresponding back
kContinue,
/// The set of blocks dominated by a loop header, minus the set of blocks
/// dominated by the loop's merge block, minus the loop's corresponding
/// continue construct
kLoop,
/// The set of blocks dominated by an OpSwitch's Target or Default, minus the
/// set of blocks dominated by the OpSwitch's merge block (this construct is
/// only defined for those OpSwitch Target or Default that are not equal to
/// the OpSwitch's corresponding merge block)
kCase
};
class Function;
/// @brief This class tracks the CFG constructs as defined in the SPIR-V spec
class Construct {
public:
Construct(ConstructType type, BasicBlock* dominator,
BasicBlock* exit = nullptr,
std::vector<Construct*> constructs = std::vector<Construct*>());
/// Returns the type of the construct
ConstructType type() const;
const std::vector<Construct*>& corresponding_constructs() const;
std::vector<Construct*>& corresponding_constructs();
void set_corresponding_constructs(std::vector<Construct*> constructs);
/// Returns the dominator block of the construct.
///
/// This is usually the header block or the first block of the construct.
const BasicBlock* entry_block() const;
/// Returns the dominator block of the construct.
///
/// This is usually the header block or the first block of the construct.
BasicBlock* entry_block();
/// Returns the exit block of the construct.
///
/// For a continue construct it is the backedge block of the corresponding
/// loop construct. For the case construct it is the block that branches to
/// the OpSwitch merge block or other case blocks. Otherwise it is the merge
/// block of the corresponding header block
const BasicBlock* exit_block() const;
/// Returns the exit block of the construct.
///
/// For a continue construct it is the backedge block of the corresponding
/// loop construct. For the case construct it is the block that branches to
/// the OpSwitch merge block or other case blocks. Otherwise it is the merge
/// block of the corresponding header block
BasicBlock* exit_block();
/// Sets the exit block for this construct. This is useful for continue
/// constructs which do not know the back-edge block during construction
void set_exit(BasicBlock* exit_block);
// Returns whether the exit block of this construct is the merge block
// for an OpLoopMerge or OpSelectionMerge
bool ExitBlockIsMergeBlock() const {
return type_ == ConstructType::kLoop || type_ == ConstructType::kSelection;
}
using ConstructBlockSet = std::set<BasicBlock*, less_than_id>;
// Returns the basic blocks in this construct. This function should not
// be called before the exit block is set and dominators have been
// calculated.
ConstructBlockSet blocks(Function* function) const;
// Returns true if |dest| is structured exit from the construct. Structured
// exits depend on the construct type.
// Selection:
// * branch to the associated merge
// * branch to the merge or continue of the innermost loop containing the
// selection
// * branch to the merge block of the innermost switch containing the
// selection
// Loop:
// * branch to the associated merge or continue
// Continue:
// * back-edge to the associated loop header
// * branch to the associated loop merge
//
// Note: the validator does not generate case constructs. Switches are
// checked separately from other constructs.
bool IsStructuredExit(ValidationState_t& _, BasicBlock* dest) const;
private:
/// The type of the construct
ConstructType type_;
/// These are the constructs that are related to this construct. These
/// constructs can be the continue construct, for the corresponding loop
/// construct, the case construct that are part of the same OpSwitch
/// instruction
///
/// Here is a table that describes what constructs are included in
/// @p corresponding_constructs_
/// | this construct | corresponding construct |
/// |----------------|----------------------------------|
/// | loop | continue |
/// | continue | loop |
/// | case | other cases in the same OpSwitch |
///
/// kContinue and kLoop constructs will always have corresponding
/// constructs even if they are represented by the same block
std::vector<Construct*> corresponding_constructs_;
/// @brief Dominator block for the construct
///
/// The dominator block for the construct. Depending on the construct this may
/// be a selection header, a continue target of a loop, a loop header or a
/// Target or Default block of a switch
BasicBlock* entry_block_;
/// @brief Exiting block for the construct
///
/// The exit block for the construct. This can be a merge block for the loop
/// and selection constructs, a back-edge block for a continue construct, or
/// the branching block for the case construct
BasicBlock* exit_block_;
};
} // namespace val
} // namespace spvtools
#endif // SOURCE_VAL_CONSTRUCT_H_