LLVM  10.0.0svn
MakeGuardsExplicit.h
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1 //===-- MakeGuardsExplicit.h - Turn guard intrinsics into guard branches --===//
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 //
9 // This pass lowers the @llvm.experimental.guard intrinsic to the new form of
10 // guard represented as widenable explicit branch to the deopt block. The
11 // difference between this pass and LowerGuardIntrinsic is that after this pass
12 // the guard represented as intrinsic:
13 //
14 // call void(i1, ...) @llvm.experimental.guard(i1 %old_cond) [ "deopt"() ]
15 //
16 // transforms to a guard represented as widenable explicit branch:
17 //
18 // %widenable_cond = call i1 @llvm.experimental.widenable.condition()
19 // br i1 (%old_cond & %widenable_cond), label %guarded, label %deopt
20 //
21 // Here:
22 // - The semantics of @llvm.experimental.widenable.condition allows to replace
23 // %widenable_cond with the construction (%widenable_cond & %any_other_cond)
24 // without loss of correctness;
25 // - %guarded is the lower part of old guard intrinsic's parent block split by
26 // the intrinsic call;
27 // - %deopt is a block containing a sole call to @llvm.experimental.deoptimize
28 // intrinsic.
29 //
30 // Therefore, this branch preserves the property of widenability.
31 //
32 //===----------------------------------------------------------------------===//
33 #ifndef LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H
34 #define LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H
35 
36 #include "llvm/IR/PassManager.h"
37 
38 namespace llvm {
39 
40 struct MakeGuardsExplicitPass : public PassInfoMixin<MakeGuardsExplicitPass> {
42 };
43 
44 } // namespace llvm
45 
46 #endif //LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H
This class represents lattice values for constants.
Definition: AllocatorList.h:23
F(f)
A CRTP mix-in to automatically provide informational APIs needed for passes.
Definition: PassManager.h:372
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM)
A container for analyses that lazily runs them and caches their results.
This header defines various interfaces for pass management in LLVM.