[PATCH] D146191: [MachineOutliner][MCP][RISCV] Don't run MCP on outlined functions

[Wang Pengcheng via Phabricator via llvm-commits]

pcwang-thead added a comment.

In D146191#4201151 <https://reviews.llvm.org/D146191#4201151>, @jrtc27 wrote:

> Is there a reason we can't instead add the right live-outs?

I tried, but it seems to be hard.
We call these outlined functions as `function`, but they are just shared code fragments with only one basic block. There are some differences between normal functions and outlined functions:

1. For outlined functions, they end with a JALR instruction (in which `isReturn` is false); while for normal functions, they end with a `PseudoRET` (in which `isReturn` is true). So the only basic block in outlined function is not `ReturnBlock`(See MachineBasicBlock::isReturnBlock()).
2. For normal functions, the live-outs of `ReturnBlock` are callee-saved registers and return value(s)? (IIUC, correct me if I am wrong). But all defs in outlined functions should be live.

I digged into `LivePhysRegs.cpp` and I could't find a way to add live-outs manually.


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