1 //===- SimplifyCFG.h - Simplify and canonicalize the CFG --------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 /// \file
9 /// This file provides the interface for the pass responsible for both
10 /// simplifying and canonicalizing the CFG.
11 ///
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_TRANSFORMS_SCALAR_SIMPLIFYCFG_H
15 #define LLVM_TRANSFORMS_SCALAR_SIMPLIFYCFG_H
16 
17 #include "llvm/Transforms/Utils/Local.h"
18 #include "llvm/IR/Function.h"
19 #include "llvm/IR/PassManager.h"
20 
21 namespace llvm {
22 
23 /// A pass to simplify and canonicalize the CFG of a function.
24 ///
25 /// This pass iteratively simplifies the entire CFG of a function. It may change
26 /// or remove control flow to put the CFG into a canonical form expected by
27 /// other passes of the mid-level optimizer. Depending on the specified options,
28 /// it may further optimize control-flow to create non-canonical forms.
29 class SimplifyCFGPass : public PassInfoMixin<SimplifyCFGPass> {
30   SimplifyCFGOptions Options;
31 
32 public:
33   /// The default constructor sets the pass options to create canonical IR,
34   /// rather than optimal IR. That is, by default we bypass transformations that
35   /// are likely to improve performance but make analysis for other passes more
36   /// difficult.
37   SimplifyCFGPass()
38       : SimplifyCFGPass(SimplifyCFGOptions()
39                             .forwardSwitchCondToPhi(false)
40                             .convertSwitchToLookupTable(false)
41                             .needCanonicalLoops(true)
42                             .sinkCommonInsts(false)) {}
43 
44 
45   /// Construct a pass with optional optimizations.
46   SimplifyCFGPass(const SimplifyCFGOptions &PassOptions);
47 
48   /// Run the pass over the function.
49   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
50 };
51 
52 }
53 
54 #endif
55