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[Downstream Change] sincos() vectorization #87

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MacDue opened this issue Feb 11, 2025 · 2 comments
Open
3 tasks

[Downstream Change] sincos() vectorization #87

MacDue opened this issue Feb 11, 2025 · 2 comments

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@MacDue
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MacDue commented Feb 11, 2025

This issue tracks the downstream changes needed to enable sincos() vectorization in the Arm toolchain. These changes are only for the release 20.x branch (https://github.com/arm/arm-toolchain/tree/release/arm-software/20.x) as we intend to complete up-streaming the changes for LLVM 21.

The patches were not possible to upstream for LLVM 20 due to long review times.

@kiranchandramohan
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Can you also provide links to the llvm-project main branch patches? Have these landed or are they in review?

@MacDue
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MacDue commented Feb 12, 2025

Can you also provide links to the llvm-project main branch patches? Have these landed or are they in review?

Added the upstream PR links (above). The upstream patches have not landed.

dcandler pushed a commit that referenced this issue Feb 24, 2025
…izing literal struct return values (#82)

This patch adds initial support for vectorizing literal struct return
values. Currently, this is limited to the case where the struct is
homogeneous (all elements have the same type) and not packed. The users
of the call also must all be `extractvalue` instructions.

The intended use case for this is vectorizing intrinsics such as:

```
declare { float, float } @llvm.sincos.f32(float %x)
```

Mapping them to structure-returning library calls such as:

```
declare { <4 x float>, <4 x i32> } @Sleef_sincosf4_u10advsimd(<4 x float>)
```

Or their widened form (such as `@llvm.sincos.v4f32` in this case).

Implementing this required two main changes:

1. Supporting widening `extractvalue`
2. Adding support for vectorized struct types in LV
  * This is mostly limited to parts of the cost model and scalarization

Since the supported use case is narrow, the required changes are
relatively small.

---

Downstream issue: #87
dcandler pushed a commit that referenced this issue Feb 24, 2025
…l] calls to llvm.sincos.* when -fno-math-errno is set (#83)

This will allow vectorizing these calls (after a few more patches). This
should not change the codegen for targets that enable the use of AA
during the codegen (in `TargetSubtargetInfo::useAA()`). This includes
targets such as AArch64. This notably does not include x86 but can be
worked around by passing `-mllvm -combiner-global-alias-analysis=true`
to clang.

---

Downstream issue: #87
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