SPIRV-Tools/source/opt/licm_pass.cpp
dan sinclair c7da51a085
Cleanup extraneous namespace qualifies in source/opt. (#1716)
This CL follows up on the opt namespacing CLs by removing the
unnecessary opt:: and opt::analysis:: namespace prefixes.
2018-07-12 15:14:43 -04:00

117 lines
3.4 KiB
C++

// Copyright (c) 2018 Google LLC.
//
// 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 "opt/licm_pass.h"
#include "opt/module.h"
#include "opt/pass.h"
#include <queue>
#include <utility>
namespace spvtools {
namespace opt {
Pass::Status LICMPass::Process() {
return ProcessIRContext() ? Status::SuccessWithChange
: Status::SuccessWithoutChange;
}
bool LICMPass::ProcessIRContext() {
bool modified = false;
Module* module = get_module();
// Process each function in the module
for (Function& f : *module) {
modified |= ProcessFunction(&f);
}
return modified;
}
bool LICMPass::ProcessFunction(Function* f) {
bool modified = false;
LoopDescriptor* loop_descriptor = context()->GetLoopDescriptor(f);
// Process each loop in the function
for (Loop& loop : *loop_descriptor) {
// Ignore nested loops, as we will process them in order in ProcessLoop
if (loop.IsNested()) {
continue;
}
modified |= ProcessLoop(&loop, f);
}
return modified;
}
bool LICMPass::ProcessLoop(Loop* loop, Function* f) {
bool modified = false;
// Process all nested loops first
for (Loop* nested_loop : *loop) {
modified |= ProcessLoop(nested_loop, f);
}
std::vector<BasicBlock*> loop_bbs{};
modified |= AnalyseAndHoistFromBB(loop, f, loop->GetHeaderBlock(), &loop_bbs);
for (size_t i = 0; i < loop_bbs.size(); ++i) {
BasicBlock* bb = loop_bbs[i];
// do not delete the element
modified |= AnalyseAndHoistFromBB(loop, f, bb, &loop_bbs);
}
return modified;
}
bool LICMPass::AnalyseAndHoistFromBB(Loop* loop, Function* f, BasicBlock* bb,
std::vector<BasicBlock*>* loop_bbs) {
bool modified = false;
std::function<void(Instruction*)> hoist_inst =
[this, &loop, &modified](Instruction* inst) {
if (loop->ShouldHoistInstruction(this->context(), inst)) {
HoistInstruction(loop, inst);
modified = true;
}
};
if (IsImmediatelyContainedInLoop(loop, f, bb)) {
bb->ForEachInst(hoist_inst, false);
}
DominatorAnalysis* dom_analysis = context()->GetDominatorAnalysis(f);
DominatorTree& dom_tree = dom_analysis->GetDomTree();
for (DominatorTreeNode* child_dom_tree_node : *dom_tree.GetTreeNode(bb)) {
if (loop->IsInsideLoop(child_dom_tree_node->bb_)) {
loop_bbs->push_back(child_dom_tree_node->bb_);
}
}
return modified;
}
bool LICMPass::IsImmediatelyContainedInLoop(Loop* loop, Function* f,
BasicBlock* bb) {
LoopDescriptor* loop_descriptor = context()->GetLoopDescriptor(f);
return loop == (*loop_descriptor)[bb->id()];
}
void LICMPass::HoistInstruction(Loop* loop, Instruction* inst) {
BasicBlock* pre_header_bb = loop->GetOrCreatePreHeaderBlock();
inst->InsertBefore(std::move(&(*pre_header_bb->tail())));
context()->set_instr_block(inst, pre_header_bb);
}
} // namespace opt
} // namespace spvtools