|
121
|
1 //===- SimpleLoopUnswitch.h - Hoist loop-invariant control flow -*- C++ -*-===//
|
|
|
2 //
|
|
|
3 // The LLVM Compiler Infrastructure
|
|
|
4 //
|
|
|
5 // This file is distributed under the University of Illinois Open Source
|
|
|
6 // License. See LICENSE.TXT for details.
|
|
|
7 //
|
|
|
8 //===----------------------------------------------------------------------===//
|
|
|
9
|
|
|
10 #ifndef LLVM_TRANSFORMS_SCALAR_SIMPLELOOPUNSWITCH_H
|
|
|
11 #define LLVM_TRANSFORMS_SCALAR_SIMPLELOOPUNSWITCH_H
|
|
|
12
|
|
|
13 #include "llvm/Analysis/LoopAnalysisManager.h"
|
|
|
14 #include "llvm/Analysis/LoopInfo.h"
|
|
|
15 #include "llvm/IR/PassManager.h"
|
|
|
16 #include "llvm/Transforms/Scalar/LoopPassManager.h"
|
|
|
17
|
|
|
18 namespace llvm {
|
|
|
19
|
|
|
20 /// This pass transforms loops that contain branches on loop-invariant
|
|
|
21 /// conditions to have multiple loops. For example, it turns the left into the
|
|
|
22 /// right code:
|
|
|
23 ///
|
|
|
24 /// for (...) if (lic)
|
|
|
25 /// A for (...)
|
|
|
26 /// if (lic) A; B; C
|
|
|
27 /// B else
|
|
|
28 /// C for (...)
|
|
|
29 /// A; C
|
|
|
30 ///
|
|
|
31 /// This can increase the size of the code exponentially (doubling it every time
|
|
|
32 /// a loop is unswitched) so we only unswitch if the resultant code will be
|
|
|
33 /// smaller than a threshold.
|
|
|
34 ///
|
|
|
35 /// This pass expects LICM to be run before it to hoist invariant conditions out
|
|
|
36 /// of the loop, to make the unswitching opportunity obvious.
|
|
|
37 ///
|
|
|
38 class SimpleLoopUnswitchPass : public PassInfoMixin<SimpleLoopUnswitchPass> {
|
|
134
|
39 bool NonTrivial;
|
|
|
40
|
|
121
|
41 public:
|
|
134
|
42 SimpleLoopUnswitchPass(bool NonTrivial = false) : NonTrivial(NonTrivial) {}
|
|
121
|
43
|
|
|
44 PreservedAnalyses run(Loop &L, LoopAnalysisManager &AM,
|
|
|
45 LoopStandardAnalysisResults &AR, LPMUpdater &U);
|
|
|
46 };
|
|
|
47
|
|
|
48 /// Create the legacy pass object for the simple loop unswitcher.
|
|
|
49 ///
|
|
|
50 /// See the documentaion for `SimpleLoopUnswitchPass` for details.
|
|
134
|
51 Pass *createSimpleLoopUnswitchLegacyPass(bool NonTrivial = false);
|
|
121
|
52
|
|
|
53 } // end namespace llvm
|
|
|
54
|
|
|
55 #endif // LLVM_TRANSFORMS_SCALAR_SIMPLELOOPUNSWITCH_H
|
