SPIRV-Tools/source/val/construct.cpp
alan-baker fae1e61ab8
Fix bug in construct block calculation (#1964)
Fixes #1960

* Only allows blocks that are dominated by the header
* Fixed a bad loop fusion test
* Added a test derived from the reported bug
2018-10-10 11:14:01 -04:00

132 lines
4.0 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.
#include "source/val/construct.h"
#include <cassert>
#include <cstddef>
#include <unordered_set>
#include "source/val/function.h"
namespace spvtools {
namespace val {
Construct::Construct(ConstructType construct_type, BasicBlock* entry,
BasicBlock* exit, std::vector<Construct*> constructs)
: type_(construct_type),
corresponding_constructs_(constructs),
entry_block_(entry),
exit_block_(exit) {}
ConstructType Construct::type() const { return type_; }
const std::vector<Construct*>& Construct::corresponding_constructs() const {
return corresponding_constructs_;
}
std::vector<Construct*>& Construct::corresponding_constructs() {
return corresponding_constructs_;
}
bool ValidateConstructSize(ConstructType type, size_t size) {
switch (type) {
case ConstructType::kSelection:
return size == 0;
case ConstructType::kContinue:
return size == 1;
case ConstructType::kLoop:
return size == 1;
case ConstructType::kCase:
return size >= 1;
default:
assert(1 == 0 && "Type not defined");
}
return false;
}
void Construct::set_corresponding_constructs(
std::vector<Construct*> constructs) {
assert(ValidateConstructSize(type_, constructs.size()));
corresponding_constructs_ = constructs;
}
const BasicBlock* Construct::entry_block() const { return entry_block_; }
BasicBlock* Construct::entry_block() { return entry_block_; }
const BasicBlock* Construct::exit_block() const { return exit_block_; }
BasicBlock* Construct::exit_block() { return exit_block_; }
void Construct::set_exit(BasicBlock* block) { exit_block_ = block; }
Construct::ConstructBlockSet Construct::blocks(Function* function) const {
auto header = entry_block();
auto merge = exit_block();
assert(header);
assert(merge);
int header_depth = function->GetBlockDepth(const_cast<BasicBlock*>(header));
ConstructBlockSet construct_blocks;
std::unordered_set<BasicBlock*> corresponding_headers;
for (auto& other : corresponding_constructs()) {
corresponding_headers.insert(other->entry_block());
}
std::vector<BasicBlock*> stack;
stack.push_back(const_cast<BasicBlock*>(header));
while (!stack.empty()) {
BasicBlock* block = stack.back();
stack.pop_back();
if (merge == block && ExitBlockIsMergeBlock()) {
// Merge block is not part of the construct.
continue;
}
if (corresponding_headers.count(block)) {
// Entered a corresponding construct.
continue;
}
int block_depth = function->GetBlockDepth(block);
if (block_depth < header_depth) {
// Broke to outer construct.
continue;
}
// In a loop, the continue target is at a depth of the loop construct + 1.
// A selection construct nested directly within the loop construct is also
// at the same depth. It is valid, however, to branch directly to the
// continue target from within the selection construct.
if (block_depth == header_depth && type() == ConstructType::kSelection &&
block->is_type(kBlockTypeContinue)) {
// Continued to outer construct.
continue;
}
if (!construct_blocks.insert(block).second) continue;
if (merge != block) {
for (auto succ : *block->successors()) {
// All blocks in the construct must be dominated by the header.
if (header->dominates(*succ)) {
stack.push_back(succ);
}
}
}
}
return construct_blocks;
}
} // namespace val
} // namespace spvtools