[all-commits] [llvm/llvm-project] 8cb842: [M68k] Fix ODR violation in GISel code (#72797)

[Vadim Petrochenkov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 8cb842879d44ba7b5c1d3e158b8824cae1db6092
      https://github.com/llvm/llvm-project/commit/8cb842879d44ba7b5c1d3e158b8824cae1db6092
  Author: Vadim Petrochenkov <vadim.petrochenkov at gmail.com>
  Date:   2023-12-14 (Thu, 14 Dec 2023)

  Changed paths:
    M llvm/lib/Target/M68k/GISel/M68kCallLowering.cpp
    M llvm/lib/Target/M68k/GISel/M68kCallLowering.h

  Log Message:
  -----------
  [M68k] Fix ODR violation in GISel code (#72797)

It prevents LLVM from being linked with LLD at least on Windows, with
errors like this:

```
  = note: ld.lld: error: duplicate symbol: vtable for llvm::FormalArgHandler
          >>> defined at librustc_llvm-a81737dd65a7c126.rlib(M68kCallLowering.cpp.obj)
          >>> defined at librustc_llvm-a81737dd65a7c126.rlib(PPCCallLowering.cpp.obj)
```

Binutils linker also complains about this, but only with warnings.

`FormalArgHandler` has a base class `M68kIncomingValueHandler` which
doesn't have a virtual method `markPhysRegUsed` like
`IncomingValueHandler`s for all other targets including PPC, so it
results in a conflict.
The simplest fix is to rename the `FormalArgHandler` structure (rather
than to add virtual methods for compatibility).

cc https://github.com/rust-lang/rust/issues/107668