[PATCH] D130932: [MIPS] Expose the ZERO register as a constant physical register

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

It seems not so easy to construct a test. I've tried

  declare i64 @llvm.read_register.i64(metadata)
   
  define i64 @get_gp() {
    %1 = call i64 @llvm.read_register.i64(metadata !0)
    %2 = call i64 @llvm.read_register.i64(metadata !0)
    %sub = sub i64 %1, %2
    ret i64 %sub
  }
   
  !0 = !{!"$28"}

which doesn't have benefit in another target which has implemented isConstantPhysReg.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D130932/new/

https://reviews.llvm.org/D130932