third_party_spirv-tools/source/opt/cfg_cleanup_pass.cpp
Steven Perron 2d2a512691
Don't inline recursive functions. (#2130)
* Move ProcessFunction* function from pass to the context.

There are a few functions that are used to traverse the call tree.
They currently live in the Pass class, but they have nothing to do with
a pass, and may be needed outside of a pass.  They would be better in
the ir context, or in a specific call tree class if we ever have a need
for it.

* Don't inline recursive functions.

Inlining does not check if a function is recursive or not.  This has
been fine as long as the shader was a Vulkan shader, which forbid
recursive functions.  However, not all shaders are vulkan, so either
we limit inlining to Vulkan shaders or we teach it to look for recursive
functions.

I prefer to keep the passes as general as is reasonable.  The change
does not require much new code in inlining and gives a reason to refactor
some other code.

The changes are to add a member function to the Function class that
checks if that function is recursive or not.

Then this is used in inlining to not inlining a function call if it calls
a recursive function.

* Add id to function analysis

There are a few places that build a map from ids to Function whose
result is that id.  I decided to add an analysis to the context for this
to reduce that code, and simplify some of the functions.

* Add missing file.
2018-11-29 14:24:58 -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 "source/opt/cfg_cleanup_pass.h"
#include "source/opt/function.h"
#include "source/opt/module.h"
namespace spvtools {
namespace opt {
Pass::Status CFGCleanupPass::Process() {
// Process all entry point functions.
ProcessFunction pfn = [this](Function* fp) { return CFGCleanup(fp); };
bool modified = context()->ProcessReachableCallTree(pfn);
return modified ? Pass::Status::SuccessWithChange
: Pass::Status::SuccessWithoutChange;
}
} // namespace opt
} // namespace spvtools