[all-commits] [llvm/llvm-project] e10d4e: AArch64/GlobalISel: Add IR test for scalar multiplies

[Matt Arsenault via All-commits]

  Branch: refs/heads/users/arsenm/global-isel-use-uadde-narrow-umulh
  Home:   https://github.com/llvm/llvm-project
  Commit: e10d4e81ac6a2136f203252f765a1421a8ddb798
      https://github.com/llvm/llvm-project/commit/e10d4e81ac6a2136f203252f765a1421a8ddb798
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2024-07-02 (Tue, 02 Jul 2024)

  Changed paths:
    A llvm/test/CodeGen/AArch64/GlobalISel/mul.ll

  Log Message:
  -----------
  AArch64/GlobalISel: Add IR test for scalar multiplies

I didn't see an existing, simple test covering mul. There
appeared to be no wide multiply tests.


  Commit: 26052805305f1f9dcbf3ab4102eb6b2372eb8dce
      https://github.com/llvm/llvm-project/commit/26052805305f1f9dcbf3ab4102eb6b2372eb8dce
  Author: Matt Arsenault <Matthew.Arsenault at amd.com>
  Date:   2024-07-02 (Tue, 02 Jul 2024)

  Changed paths:
    M llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
    M llvm/test/CodeGen/AArch64/GlobalISel/mul.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-mul.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-sdiv.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-srem.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-udiv.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-umulh.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-umulo.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/legalize-urem.mir
    M llvm/test/CodeGen/AMDGPU/GlobalISel/sdiv.i64.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/sdivrem.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/srem.i64.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/udiv.i64.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/udivrem.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/urem.i64.ll
    M llvm/test/CodeGen/Mips/GlobalISel/legalizer/mul.mir
    M llvm/test/CodeGen/Mips/GlobalISel/llvm-ir/mul.ll
    M llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-mul-ext-rv32.mir
    M llvm/test/CodeGen/RISCV/GlobalISel/legalizer/legalize-mul-ext-rv64.mir

  Log Message:
  -----------
  GlobalISel: Use G_UADDE when narrowing G_UMULH

This greatly shrinks the AMDGPU div64 expansion.

Instead of adding a zext of the condition output, add a zero and use
the carry in to G_UADDE. This is closer to how the DAG expansion using
umulh does it, and it seems more natural to leave the boolean output
as a boolean input. We should have a combine to form G_UADDE from this
pattern, but the legalizer shouldn't create extra work for the
combiner if it can help it.

The Mips cases are regressions, but the DAG lowering for muli128 seems
to not use the expansion involving MULHU/MULHS at all. The DAG output
is radically different than GlobalISel as-is, so it seems like Mips
should be using a different legalization strategy here to begin with.

The RISCV legalizer tests look worse for the mul i96 case, but those
didn't exist when I wrote this patch and forgot about it 4 years ago,
so I haven't really looked into why. We've entered the age where most tests
should just be using IR, so I don't  know if this matters or not (the IR mul
test doesn't seem to cover i96)


Compare: https://github.com/llvm/llvm-project/compare/bcae30eeab62...26052805305f

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