include/llvm/Transforms/Scalar/MakeGuardsExplicit.h

   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> {
  41   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  42 };
  43
  44 } // namespace llvm
  45
  46 #endif //LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H