[all-commits] [llvm/llvm-project] c877eb: [InstCombine] Add tests for folding `(add X, (sext...

[goldsteinn via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: c877eb3754ad1a61db2717530141eded580c3533
      https://github.com/llvm/llvm-project/commit/c877eb3754ad1a61db2717530141eded580c3533
  Author: Noah Goldstein <goldstein.w.n at gmail.com>
  Date:   2024-06-01 (Sat, 01 Jun 2024)

  Changed paths:
    A llvm/test/Transforms/InstCombine/fold-ext-eq-c-with-op.ll

  Log Message:
  -----------
  [InstCombine] Add tests for folding `(add X, (sext/zext (icmp eq X, C)))`; NFC


  Commit: 0310f7f2d0c56a5697710251cec9803cbf7b4d56
      https://github.com/llvm/llvm-project/commit/0310f7f2d0c56a5697710251cec9803cbf7b4d56
  Author: Noah Goldstein <goldstein.w.n at gmail.com>
  Date:   2024-06-01 (Sat, 01 Jun 2024)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
    M llvm/test/Transforms/InstCombine/apint-shift.ll
    M llvm/test/Transforms/InstCombine/fold-ext-eq-c-with-op.ll

  Log Message:
  -----------
  [InstCombine] Fold `(add X, (sext/zext (icmp eq X, C)))`

We can convert this to a select based on the `(icmp eq X, C)`, then
constant fold the addition the true arm begin `(add C, (sext/zext 1))`
and the false arm being `(add X, 0)` e.g

    - `(select (icmp eq X, C), (add C, (sext/zext 1)), (add X, 0))`.

This is essentially a specialization of the only case that sees to
actually show up from #89020

Closes #93840


Compare: https://github.com/llvm/llvm-project/compare/e7e6e1ecadc5...0310f7f2d0c5

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