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[0027] Avoid using undef for dx.op.MaybeReorderThread #487

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[0027] Avoid using undef for dx.op.MaybeReorderThread #487

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60658d9
Avoid using undef for dx.op.MaybeReorderThread
rasmusnv Apr 12, 2025
5a2127c
Merge branch 'main' into ser_reorder_params
rasmusnv Apr 12, 2025
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11 changes: 6 additions & 5 deletions proposals/0027-shader-execution-reordering.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1393,9 +1393,9 @@ Validation errors:
#### MaybeReorderThread

Operation that reorders the current thread based on the supplied hints and
`HitObject`. The canonical lowering of the
HLSL intrinsic `MaybeReorderThread( uint CoherenceHint, uint NumCoherenceHintBitsFromLSB )`
uses `undef` for the `HitObject` parameter.
`HitObject`. The HLSL overload without `HitObject` is lowered to the same intrinsic
with a NOP-HitObject (`HitObject_MakeNop`). The HLSL overload without coherence
hints is lowered by specifying `0` for `number of coherence hint bits from LSB`.

```DXIL
declare void @dx.op.MaybeReorderThread(
Expand All @@ -1407,8 +1407,9 @@ declare void @dx.op.MaybeReorderThread(
```

Validation errors:
- Validate that `coherence hint` is not undef.
- Validate that `num coherence hint bits from LSB` is not undef.
- Validate that `coherence hint` is not `undef` if `num coherence hint bits from LSB` is nonzero.
- Validate that `hit object` is not `undef`.
- Validate that `num coherence hint bits from LSB` is not `undef`.

#### HitObject_SetShaderTableIndex

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