[PATCH] D41728: [TableGen][AsmMatcherEmitter] Remove boolean 'Hack' parameter

[Florian Hahn via Phabricator via llvm-commits]

fhahn requested changes to this revision.
fhahn added a comment.
This revision now requires changes to proceed.

I do not think just removing the error message for the hack is the right thing to do.

With this patch, it is possible to define instruction aliases like (AArch64 example)

`def : InstAlias<"mov $dst, $src, $src, $src", (ORRWrs GPR32:$dst, WZR, GPR32:$src, 0), 2>;`

And now

  bar:
          mov w1, w0, w2, w3
          mov w1, w0, w0, w0

gets encoded to the following by llvm-mc:

  bar:
  	orr	w1, wzr, w0             // encoding: [0xe1,0x03,0x00,0x2a]
  	orr	w1, wzr, w0             // encoding: [0xe1,0x03,0x00,0x2a]

If we want to support instruction aliases with tied operands, it seems like we have to add tied constraints for strings with repeated operands automatically or provide a way to specify the alias as "mov $dst, $src1, $src2, $src3" with "$src1 = $src2 = $src3"


https://reviews.llvm.org/D41728