llvm/lib/Target/AMDGPU/AMDGPUUnifyDivergentExitNodes.h

   1 //===- AMDGPUUnifyDivergentExitNodes.h ------------------------------------===//
   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 is a variant of the UnifyFunctionExitNodes pass. Rather than ensuring
  10 // there is at most one ret and one unreachable instruction, it ensures there is
  11 // at most one divergent exiting block.
  12 //
  13 // StructurizeCFG can't deal with multi-exit regions formed by branches to
  14 // multiple return nodes. It is not desirable to structurize regions with
  15 // uniform branches, so unifying those to the same return block as divergent
  16 // branches inhibits use of scalar branching. It still can't deal with the case
  17 // where one branch goes to return, and one unreachable. Replace unreachable in
  18 // this case with a return.
  19 //
  20 //===----------------------------------------------------------------------===//
  21
  22 #ifndef LLVM_LIB_TARGET_AMDGPU_AMDGPUUNIFYDIVERGENTEXITNODES_H
  23 #define LLVM_LIB_TARGET_AMDGPU_AMDGPUUNIFYDIVERGENTEXITNODES_H
  24
  25 #include "AMDGPU.h"
  26
  27 namespace llvm {
  28 class AMDGPUUnifyDivergentExitNodesPass
  29     : public PassInfoMixin<AMDGPUUnifyDivergentExitNodesPass> {
  30 public:
  31   PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
  32 };
  33
  34 } // end namespace llvm
  35
  36 #endif // LLVM_LIB_TARGET_AMDGPU_AMDGPUUNIFYDIVERGENTEXITNODES_H