include/llvm/CodeGen/UnreachableBlockElim.h

   1 //===-- UnreachableBlockElim.h - Remove unreachable blocks for codegen --===//
   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 is an extremely simple version of the SimplifyCFG pass.  Its sole
  10 // job is to delete LLVM basic blocks that are not reachable from the entry
  11 // node.  To do this, it performs a simple depth first traversal of the CFG,
  12 // then deletes any unvisited nodes.
  13 //
  14 // Note that this pass is really a hack.  In particular, the instruction
  15 // selectors for various targets should just not generate code for unreachable
  16 // blocks.  Until LLVM has a more systematic way of defining instruction
  17 // selectors, however, we cannot really expect them to handle additional
  18 // complexity.
  19 //
  20 //===----------------------------------------------------------------------===//
  21
  22 #ifndef LLVM_LIB_CODEGEN_UNREACHABLEBLOCKELIM_H
  23 #define LLVM_LIB_CODEGEN_UNREACHABLEBLOCKELIM_H
  24
  25 #include "llvm/IR/PassManager.h"
  26
  27 namespace llvm {
  28
  29 class UnreachableBlockElimPass
  30     : public PassInfoMixin<UnreachableBlockElimPass> {
  31 public:
  32   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  33 };
  34 } // end namespace llvm
  35
  36 #endif // LLVM_LIB_CODEGEN_UNREACHABLEBLOCKELIM_H