[all-commits] [llvm/llvm-project] 877552: [flang][Transforms] Add SelectOpsConversion pass

[Kareem Ergawy via All-commits]

  Branch: refs/heads/users/ergawy/lower-fir-switch-to-cf
  Home:   https://github.com/llvm/llvm-project
  Commit: 877552125de71adb20acf492c35ddf94830e26e5
      https://github.com/llvm/llvm-project/commit/877552125de71adb20acf492c35ddf94830e26e5
  Author: ergawy <kareem.ergawy at gmail.com>
  Date:   2026-07-30 (Thu, 30 Jul 2026)

  Changed paths:
    M flang/include/flang/Optimizer/Transforms/Passes.td
    M flang/lib/Optimizer/Passes/Pipelines.cpp
    M flang/lib/Optimizer/Transforms/CMakeLists.txt
    A flang/lib/Optimizer/Transforms/SelectOpsConversion.cpp
    M flang/test/Driver/bbc-mlir-pass-pipeline.f90
    M flang/test/Driver/mlir-debug-pass-pipeline.f90
    M flang/test/Driver/mlir-pass-pipeline.f90
    A flang/test/Fir/SelectOpsConversion/select.fir
    A flang/test/Fir/SelectOpsConversion/select_case.fir
    A flang/test/Fir/SelectOpsConversion/select_rank.fir
    M flang/test/Fir/basic-program.fir
    M flang/test/Fir/select.fir
    M flang/test/Lower/volatile3.f90

  Log Message:
  -----------
  [flang][Transforms] Add SelectOpsConversion pass

Introduces `--fir-select-ops-conversion`, which lowers `fir.select`,
`fir.select_case`, and `fir.select_rank` to the control-flow dialect
(`cf.switch` / `cf.cond_br` / `cf.br`) while preserving the CFG shape.
`fir.select_case` becomes an if-then-else ladder of `arith.cmpi` +
`cf.cond_br`; Fortran `UNSIGNED` selectors use `ule`. Signed / unsigned
FIR integer values are normalized to signless via `fir.convert` first.

`fir.select_type` is not handled here — it is already lowered by
`--fir-polymorphic-op` (`PolymorphicOpConversion`).

The pass runs in the default FIR optimizer pipeline right after
`PolymorphicOpConversion`. Pipeline-check tests are updated to expect
`SelectOpsConversion` in the sequence; `Fir/select.fir` and
`Lower/volatile3.f90` are relaxed to accept the newly-canonicalized form
of the lowered output.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply at anthropic.com>



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