SPIRV-Tools/source/opt/cfg_cleanup_pass.cpp
Diego Novillo 98281ed411 Add analysis to compute mappings between instructions and basic blocks.
This analysis builds a map from instructions to the basic block that
contains them.  It is accessed via get_instr_block().  Once built, it is kept
up-to-date by the IRContext, as long as instructions are removed via
KillInst.

I have not yet marked passes that preserve this analysis. I will do it
in a separate change.

Other changes:

- Add documentation about analysis values requirement to be powers of 2.
- Force a re-build of the def-use manager in tests.
- Fix AllPreserveFirstOnlyAfterPassWithChange to use the
  DummyPassPreservesFirst pass.
- Fix sentinel value for IRContext::Analysis enum.

- Fix logic for checking if the instr<->block mapping is valid in KillInst.
2017-11-13 13:21:48 -05:00

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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.
// This file implements a pass to cleanup the CFG to remove superfluous
// constructs (e.g., unreachable basic blocks, empty control flow structures,
// etc)
#include <queue>
#include <unordered_set>
#include "cfg_cleanup_pass.h"
#include "function.h"
#include "module.h"
namespace spvtools {
namespace opt {
void CFGCleanupPass::Initialize(ir::IRContext* c) {
InitializeProcessing(c);
}
Pass::Status CFGCleanupPass::Process(ir::IRContext* c) {
Initialize(c);
// Process all entry point functions.
ProcessFunction pfn = [this](ir::Function* fp) { return CFGCleanup(fp); };
bool modified = ProcessReachableCallTree(pfn, context());
return modified ? Pass::Status::SuccessWithChange
: Pass::Status::SuccessWithoutChange;
}
} // namespace opt
} // namespace spvtools