[PATCH] D151848: [X86, Peephole] Enable FoldImmediate for X86

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/CodeGen/PeepholeOptimizer.cpp:1391
+      // FoldImmediate can delete ImmDefMI if MI was its only user. If ImmDefMI
+      // is not deleted, and we happenly get a same MI, we can delete MI and
+      // replace its users.
----------------
Carrot wrote:
> craig.topper wrote:
> > happenly?
> The case I encountered is
> ```
>      %1 = MOV32ri   4
>      %2 = COPY %1
>       // other uses of %1
>      ...
> ```
> After FoldImmediate it becomes
> ```
>     %1 = MOV32ri 4
>     %2 = MOV32ri 4
> ```
> Becuase %1 has multiple uses, so it can't be deleted by FoldImmediate. These two instructions are identical now, so we can replace the uses of %2 by %1, and delete the definition of %2.
I was questioning whether "happenly" is a real word.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D151848/new/

https://reviews.llvm.org/D151848