xref: /freebsd/contrib/llvm-project/llvm/lib/Target/AMDGPU/AMDGPUUnifyDivergentExitNodes.h (revision a03411e84728e9b267056fd31c7d1d9d1dc1b01e)
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
37