Four small tests stacked on top of llvm#1275, each isolating one
shader-observable PSO raytracing surface. They follow the same shape as
the inline-RT batch already in llvm#1271 / llvm#1272 / llvm#1274 / llvm#1276 — one .test
file per behavior, single-purpose shader, exact buffer comparison.

  - `dispatch-rays-index.test` — 4x1x1 dispatch, raygen writes
    `DispatchRaysIndex().x` into `Output[index]`. Confirms the
    dispatch grid plumbs through to the per-lane system value with no
    BLAS / TLAS / hit groups in play (RT-pipeline-only, no AS binding).
  - `dispatch-rays-dimensions.test` — 2x3x1 dispatch, raygen packs the
    constant `DispatchRaysDimensions()` into one uint per lane.
    Confirms every lane sees the host-side `{W, H, D}` even when only
    one dimension > 1.
  - `miss-shader-index.test` — two miss shaders writing distinct
    sentinels (0xAA / 0xBB). 2-lane dispatch picks `MissShaderIndex` 0
    and 1 respectively; rays start far enough from the geometry that
    every ray misses. Verifies the SBT miss region's per-record
    routing.
  - `ray-contribution-to-hit-group-index.test` — two hit groups with
    distinct closest-hit shaders (0xA1 / 0xB2). 2-lane dispatch picks
    `RayContributionToHitGroupIndex` 0 and 1, every ray hits the same
    triangle. Verifies the SBT hit-group region's per-record routing.

The first two have no AS / Miss / HitGroup in their pipeline at all —
just a raygen + a UAV — which exercises the minimum viable RT pipeline
shape (one raygen group, zero-sized miss / hit / callable SBT regions).
The latter two reuse the single-triangle BLAS/TLAS from
`raygen-roundtrip.test`.

All four tests are `# REQUIRES: raytracing-pipeline` with `# XFAIL: Clang`
— Clang (`clang-dxc`) doesn't yet lower `[shader("…")]` entry points to
either DXIL libraries or SPIR-V. With the Metal RT bring-up rebased on
top, all four pass natively on Apple Silicon and Metal is dropped from
the XFAIL list.

Locally verified end-to-end on the user's Linux box:
  - Vulkan via the native offloader against an NVIDIA RTX 3060:
    all four tests PASS.
  - D3D12 via Wine + vkd3d-proton + the cross-compiled offloader.exe
    on the same GPU: all four tests PASS.
And on macOS 15 / metal-irconverter 3.1.1:
  - Metal via the native offloader: all four tests PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Four small tests stacked on top of llvm#1275, each isolating one
shader-observable PSO raytracing surface. They follow the same shape as
the inline-RT batch already in llvm#1271 / llvm#1272 / llvm#1274 / llvm#1276 — one .test
file per behavior, single-purpose shader, exact buffer comparison.

  - `dispatch-rays-index.test` — 4x1x1 dispatch, raygen writes
    `DispatchRaysIndex().x` into `Output[index]`. Confirms the
    dispatch grid plumbs through to the per-lane system value with no
    BLAS / TLAS / hit groups in play (RT-pipeline-only, no AS binding).
  - `dispatch-rays-dimensions.test` — 2x3x1 dispatch, raygen packs the
    constant `DispatchRaysDimensions()` into one uint per lane.
    Confirms every lane sees the host-side `{W, H, D}` even when only
    one dimension > 1.
  - `miss-shader-index.test` — two miss shaders writing distinct
    sentinels (0xAA / 0xBB). 2-lane dispatch picks `MissShaderIndex` 0
    and 1 respectively; rays start far enough from the geometry that
    every ray misses. Verifies the SBT miss region's per-record
    routing.
  - `ray-contribution-to-hit-group-index.test` — two hit groups with
    distinct closest-hit shaders (0xA1 / 0xB2). 2-lane dispatch picks
    `RayContributionToHitGroupIndex` 0 and 1, every ray hits the same
    triangle. Verifies the SBT hit-group region's per-record routing.

The first two have no AS / Miss / HitGroup in their pipeline at all —
just a raygen + a UAV — which exercises the minimum viable RT pipeline
shape (one raygen group, zero-sized miss / hit / callable SBT regions).
The latter two reuse the single-triangle BLAS/TLAS from
`raygen-roundtrip.test`.

All four tests are `# REQUIRES: raytracing-pipeline` with `# XFAIL: Clang`
— Clang (`clang-dxc`) doesn't yet lower `[shader("…")]` entry points to
either DXIL libraries or SPIR-V. With the Metal RT bring-up rebased on
top, all four pass natively on Apple Silicon and Metal is dropped from
the XFAIL list.

Locally verified end-to-end on the user's Linux box:
  - Vulkan via the native offloader against an NVIDIA RTX 3060:
    all four tests PASS.
  - D3D12 via Wine + vkd3d-proton + the cross-compiled offloader.exe
    on the same GPU: all four tests PASS.
And on macOS 15 / metal-irconverter 3.1.1:
  - Metal via the native offloader: all four tests PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

## Summary

Stacks on top of #1232 / #1245. Three TLAS instances at `x = -5, 0, +5`
with `InstanceMask` values `0x01` / `0x02` / `0x04` and `InstanceID`s
`0` / `1` / `2`. A 3-lane dispatch fires one ray per lane straight down
at its own instance column, but every ray uses `InstanceInclusionMask =
0x02` — so only the middle instance survives the mask test. Lane 1
reports `InstanceID = 1`; lanes 0 and 2 miss.

Covers the `InstanceInclusionMask` filtering bullet in the inline-RT
coverage epic (#1258).

Independent of the other InlineRT test PRs (#1271, #1272) — only adds a
new test file.

## Test plan

Local on an NVIDIA RTX 3060:
- [x] Linux Vulkan (native `offloader`)
- [x] Linux D3D12 (Wine + vkd3d-proton + cross-compiled `offloader.exe`)
- [ ] Windows Vulkan (native `offloader.exe`)
- [ ] Windows D3D12 (native `offloader.exe`)

CI (RT-capable runners):
- [ ] windows-nvidia D3D12 (`RaytracingTier 1.2`)
- [ ] windows-intel VK (`VK_KHR_ray_tracing_pipeline`)
- [x] macOS Metal (`supportsRaytracing`)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

## Summary

Stacks on top of #1232 / #1245. Two rays at the existing single-triangle
BLAS — one from +z (sees the front face per the default winding
convention all three backends share) and one from -z (sees the back
face) — with the `RAY_FLAG_CULL_BACK_FACING_TRIANGLES` template flag
set. Lane 0 must hit and lane 1 must miss.

Independent of the other InlineRT test PRs (#1271, #1272, #1274) — only
adds a new test file.

## Test plan

Local on an NVIDIA RTX 3060:
- [x] Linux Vulkan (native `offloader`)
- [x] Linux D3D12 (Wine + vkd3d-proton + cross-compiled `offloader.exe`)
- [ ] Windows Vulkan (native `offloader.exe`)
- [ ] Windows D3D12 (native `offloader.exe`)

CI (RT-capable runners):
- [x] windows-nvidia D3D12 (`RaytracingTier 1.2`)
- [ ] windows-intel VK (`VK_KHR_ray_tracing_pipeline`)
- [x] macOS Metal (`supportsRaytracing`)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Four small tests stacked on top of llvm#1275, each isolating one
shader-observable PSO raytracing surface. They follow the same shape as
the inline-RT batch already in llvm#1271 / llvm#1272 / llvm#1274 / llvm#1276 — one .test
file per behavior, single-purpose shader, exact buffer comparison.

  - `dispatch-rays-index.test` — 4x1x1 dispatch, raygen writes
    `DispatchRaysIndex().x` into `Output[index]`. Confirms the
    dispatch grid plumbs through to the per-lane system value with no
    BLAS / TLAS / hit groups in play (RT-pipeline-only, no AS binding).
  - `dispatch-rays-dimensions.test` — 2x3x1 dispatch, raygen packs the
    constant `DispatchRaysDimensions()` into one uint per lane.
    Confirms every lane sees the host-side `{W, H, D}` even when only
    one dimension > 1.
  - `miss-shader-index.test` — two miss shaders writing distinct
    sentinels (0xAA / 0xBB). 2-lane dispatch picks `MissShaderIndex` 0
    and 1 respectively; rays start far enough from the geometry that
    every ray misses. Verifies the SBT miss region's per-record
    routing.
  - `ray-contribution-to-hit-group-index.test` — two hit groups with
    distinct closest-hit shaders (0xA1 / 0xB2). 2-lane dispatch picks
    `RayContributionToHitGroupIndex` 0 and 1, every ray hits the same
    triangle. Verifies the SBT hit-group region's per-record routing.

The first two have no AS / Miss / HitGroup in their pipeline at all —
just a raygen + a UAV — which exercises the minimum viable RT pipeline
shape (one raygen group, zero-sized miss / hit / callable SBT regions).
The latter two reuse the single-triangle BLAS/TLAS from
`raygen-roundtrip.test`.

All four tests are `# REQUIRES: raytracing-pipeline` with `# XFAIL: Clang`
— Clang (`clang-dxc`) doesn't yet lower `[shader("…")]` entry points to
either DXIL libraries or SPIR-V. With the Metal RT bring-up rebased on
top, all four pass natively on Apple Silicon and Metal is dropped from
the XFAIL list.

Locally verified end-to-end on the user's Linux box:
  - Vulkan via the native offloader against an NVIDIA RTX 3060:
    all four tests PASS.
  - D3D12 via Wine + vkd3d-proton + the cross-compiled offloader.exe
    on the same GPU: all four tests PASS.
And on macOS 15 / metal-irconverter 3.1.1:
  - Metal via the native offloader: all four tests PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Four small tests stacked on top of llvm#1275, each isolating one
shader-observable PSO raytracing surface. They follow the same shape as
the inline-RT batch already in llvm#1271 / llvm#1272 / llvm#1274 / llvm#1276 — one .test
file per behavior, single-purpose shader, exact buffer comparison.

  - `dispatch-rays-index.test` — 4x1x1 dispatch, raygen writes
    `DispatchRaysIndex().x` into `Output[index]`. Confirms the
    dispatch grid plumbs through to the per-lane system value with no
    BLAS / TLAS / hit groups in play (RT-pipeline-only, no AS binding).
  - `dispatch-rays-dimensions.test` — 2x3x1 dispatch, raygen packs the
    constant `DispatchRaysDimensions()` into one uint per lane.
    Confirms every lane sees the host-side `{W, H, D}` even when only
    one dimension > 1.
  - `miss-shader-index.test` — two miss shaders writing distinct
    sentinels (0xAA / 0xBB). 2-lane dispatch picks `MissShaderIndex` 0
    and 1 respectively; rays start far enough from the geometry that
    every ray misses. Verifies the SBT miss region's per-record
    routing.
  - `ray-contribution-to-hit-group-index.test` — two hit groups with
    distinct closest-hit shaders (0xA1 / 0xB2). 2-lane dispatch picks
    `RayContributionToHitGroupIndex` 0 and 1, every ray hits the same
    triangle. Verifies the SBT hit-group region's per-record routing.

The first two have no AS / Miss / HitGroup in their pipeline at all —
just a raygen + a UAV — which exercises the minimum viable RT pipeline
shape (one raygen group, zero-sized miss / hit / callable SBT regions).
The latter two reuse the single-triangle BLAS/TLAS from
`raygen-roundtrip.test`.

All four tests are `# REQUIRES: raytracing-pipeline` with `# XFAIL: Clang`
— Clang (`clang-dxc`) doesn't yet lower `[shader("…")]` entry points to
either DXIL libraries or SPIR-V. With the Metal RT bring-up rebased on
top, all four pass natively on Apple Silicon and Metal is dropped from
the XFAIL list.

Locally verified end-to-end on the user's Linux box:
  - Vulkan via the native offloader against an NVIDIA RTX 3060:
    all four tests PASS.
  - D3D12 via Wine + vkd3d-proton + the cross-compiled offloader.exe
    on the same GPU: all four tests PASS.
And on macOS 15 / metal-irconverter 3.1.1:
  - Metal via the native offloader: all four tests PASS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Depends on #1281

## Summary

Four small PSO raytracing tests stacked on top of #1275, each isolating
one shader-observable surface from the 👍 list in #1268. Same shape as
the inline-RT batch already in flight in #1271 / #1272 / #1274 / #1276 —
one `.test` file per behavior, single-purpose shader, exact buffer
comparison.

- `dispatch-rays-index.test` — 4x1x1 dispatch, raygen writes
`DispatchRaysIndex().x` into `Output[index]`. Confirms the dispatch grid
plumbs through to the per-lane system value with no BLAS / TLAS / hit
groups in play (RT-pipeline-only, no AS binding).
- `dispatch-rays-dimensions.test` — 2x3x1 dispatch, raygen packs the
constant `DispatchRaysDimensions()` into one uint per lane. Confirms
every lane sees the host-side `{W, H, D}` even when only one dimension >
1.
- `miss-shader-index.test` — two miss shaders writing distinct sentinels
(0xAA / 0xBB). 2-lane dispatch picks `MissShaderIndex` 0 and 1
respectively; rays start far enough from the geometry that every ray
misses. Verifies the SBT miss region's per-record routing.
- `ray-contribution-to-hit-group-index.test` — two hit groups with
distinct closest-hit shaders (0xA1 / 0xB2). 2-lane dispatch picks
`RayContributionToHitGroupIndex` 0 and 1, every ray hits the same
triangle. Verifies the SBT hit-group region's per-record routing.

The first two have no AS / Miss / HitGroup in their pipeline at all —
just a raygen + a UAV — which doubles as a regression check for the
minimum viable RT pipeline shape (one raygen group, zero-sized miss /
hit / callable SBT regions). The latter two reuse the single-triangle
BLAS / TLAS from `raygen-roundtrip.test`.

All four tests are `# REQUIRES: raytracing-pipeline` with `# XFAIL:
Clang` — `clang-dxc` doesn't yet lower `[shader("…")]` entry points to
either DXIL libraries or SPIR-V. With the Metal RT bring-up in #1281
rebased underneath this branch, all four pass natively on Apple Silicon
and `Metal` is dropped from the XFAIL list.

## Test plan

Local on an NVIDIA RTX 3060:
- [x] Linux Vulkan (native `offloader`)
- [x] Linux D3D12 (Wine + vkd3d-proton + cross-compiled `offloader.exe`)
- [ ] Windows Vulkan (native `offloader.exe`)
- [ ] Windows D3D12 (native `offloader.exe`)

CI (RT-capable runners):
- [ ] windows-nvidia D3D12 (`RaytracingTier 1.2`)
- [ ] windows-intel VK (`VK_KHR_ray_tracing_pipeline`)
- [x] macOS Metal (`supportsRaytracing`)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>