[all-commits] [llvm/llvm-project] 73863a: [InstCombine] Add tests for folding `(add/sub/disj...

[goldsteinn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 73863a48352c48b0c37a49c5dcfa521eb0cfcb5b
      https://github.com/llvm/llvm-project/commit/73863a48352c48b0c37a49c5dcfa521eb0cfcb5b
  Author: Noah Goldstein <goldstein.w.n at gmail.com>
  Date:   2024-01-15 (Mon, 15 Jan 2024)

  Changed paths:
    A llvm/test/Transforms/InstCombine/fold-ctpop-of-not.ll

  Log Message:
  -----------
  [InstCombine] Add tests for folding `(add/sub/disjoint_or/icmp C, (ctpop (not x)))`; NFC


  Commit: 60e8915d2277ab784f4d27139c479868255b22bf
      https://github.com/llvm/llvm-project/commit/60e8915d2277ab784f4d27139c479868255b22bf
  Author: Noah Goldstein <goldstein.w.n at gmail.com>
  Date:   2024-01-15 (Mon, 15 Jan 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    M llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    M llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
    M llvm/lib/Transforms/InstCombine/InstCombineInternal.h
    M llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
    M llvm/test/Transforms/InstCombine/fold-ctpop-of-not.ll

  Log Message:
  -----------
  [InstCombine] Add folds for `(add/sub/disjoint_or/icmp C, (ctpop (not x)))`

`(ctpop (not x))` <-> `(sub nuw nsw BitWidth(x), (ctpop x))`. The
`sub` expression can sometimes be constant folded depending on the use
case of `(ctpop (not x))`.

This patch adds fold for the following cases:

`(add/sub/disjoint_or C, (ctpop (not x))`
    -> `(add/sub/disjoint_or C', (ctpop x))`
`(cmp pred C, (ctpop (not x))`
    -> `(cmp swapped_pred C', (ctpop x))`

Where `C'` depends on how we constant fold `C` with `BitWidth(x)` for
the given opcode.

Proofs: https://alive2.llvm.org/ce/z/qUgfF3

Closes #77859


Compare: https://github.com/llvm/llvm-project/compare/f9b089a7c01d...60e8915d2277