tree d6166728b7ccea5c5ea4fdb59896edb30f3982a6
parent 6209d969a239ac03f0493e51f6c6c51d1d4679fd
author Changpeng Fang <changpeng.fang@gmail.com> 1526575501 +0000
committer Changpeng Fang <changpeng.fang@gmail.com> 1526575501 +0000

AMDGPU/SI: Handle infinite loop for the structurizer to work with CFG with infinite loops.

Summary:
  The current StructurizeCFG pass only works for CFG with one exit. AMDGPUUnifyDivergentExitNodes combines multiple "return" blocks and/or "unreachable" blocks
to one exit block for the Structurizer to work. However, infinite loop is another kind of special "exit", and if we don't handle it, the case of multiple exits will prevent the structurizer from working.

In this work, for each infinite loop, we add a dummy edge to the "return" block, and thus the AMDGPUUnifyDivergentExitNodes pass will work with infinite loops.
This will make CFG with infinite loops be structurized.

Reviewer:
  nhaehnle

Differential Revision:
  https://reviews.llvm.org/D46340

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332625 91177308-0d34-0410-b5e6-96231b3b80d8