SPIRV-Tools/source/opt/eliminate_dead_functions_pass.cpp
Steven Perron 476cae6f7d Add the IRContext (part 1)
This is the first part of adding the IRContext.  This class is meant to
hold the extra data that is build on top of the module that it
owns.

The first part will simply create the IRContext class and get it passed
to the passes in place of the module.  For now it does not have any
functionality of its own, but it acts more as a wrapper for the module.

The functions that I added to the IRContext are those that either
traverse the headers or add to them.  I did this because we may decide
to have other ways of dealing with these sections (for example adding a
type pool, or use the decoration manager).

I also added the function that add to the header because the IRContext
needs to know when an instruction is added to update other data
structures appropriately.

Note that there is still lots of work that needs to be done.  There are
still many places that change the module, and do not inform the context.
That will be the next step.
2017-10-31 13:46:05 -04:00

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// Copyright (c) 2017 Google 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 "eliminate_dead_functions_pass.h"
#include <unordered_set>
namespace spvtools {
namespace opt {
Pass::Status EliminateDeadFunctionsPass::Process(ir::IRContext* c) {
InitializeProcessing(c);
// Identify live functions first. Those that are not live
// are dead.
std::unordered_set<const ir::Function*> live_function_set;
ProcessFunction mark_live = [&live_function_set](ir::Function* fp) {
live_function_set.insert(fp);
return false;
};
ProcessReachableCallTree(mark_live, context());
bool modified = false;
for (auto funcIter = get_module()->begin();
funcIter != get_module()->end();) {
if (live_function_set.count(&*funcIter) == 0) {
modified = true;
EliminateFunction(&*funcIter);
funcIter = funcIter.Erase();
} else {
++funcIter;
}
}
return modified ? Pass::Status::SuccessWithChange
: Pass::Status::SuccessWithoutChange;
}
void EliminateDeadFunctionsPass::EliminateFunction(ir::Function* func) {
// Remove all of the instruction in the function body
func->ForEachInst(
[this](ir::Instruction* inst) {
KillNamesAndDecorates(inst);
get_def_use_mgr()->KillInst(inst);
},
true);
}
} // namespace opt
} // namespace spvtools