[WARP][Clang] WaveActiveBallot tests fail due to integer truncation to bool

Nobody has claimed this yet.

The tests `WaveActiveBallot.Wave32`, `WaveActiveBallot.Wave64`, and `WaveActiveBallot.Wave128` started failing on WARP with Clang after https://github.com/llvm/llvm-project/commit/faa4b97b10c6facb362c5a8d2f0f5c442389a103 was merged into LLVM.

The change in the IR before and after the commit comes from InstCombine being applied to
```hlsl
Out[3] = WaveActiveBallot(threadID.x % 2 == 1);
```

InstCombine transforms instances of `icmp` instructions into `trunc` to `i1`, such as
```llvm
%rem.i = and i32 %1, 1
%cmp8.i = icmp ne i32 %rem.i, 0
```
into the following equivalent truncation:
```llvm
%cmp8.i = trunc i32 %1 to i1
```

This issue also only appears to affect WARP, as can be observed from the following Clang test results on all the machines:

Wave32
```
╭────┬──────────────────────┬─────────────┬────────────────────────────────┬─────────────┬──────────────────────────────────────╮
│ # │ timestamp │ run-id │ workflow │ status │ test │
├────┼──────────────────────┼─────────────┼────────────────────────────────┼─────────────┼──────────────────────────────────────┤
│ 0 │ 2026-02-03T18:15:57Z │ 21642188487 │ Windows D3D12 Warp Clang │ FAIL │ WaveOps/WaveActiveBallot.Wave32.test │
│ 1 │ 2026-02-03T18:21:13Z │ 21642357057 │ Windows ARM64 D3D12 Warp Clang │ FAIL │ WaveOps/WaveActiveBallot.Wave32.test │
│ 2 │ 2026-02-03T20:11:21Z │ 21646031461 │ Windows D3D12 NVIDIA Clang │ PASS │ WaveOps/WaveActiveBallot.Wave32.test │
│ 3 │ 2026-02-03T20:10:06Z │ 21645986872 │ Windows D3D12 Intel Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 4 │ 2026-02-03T18:19:27Z │ 21642301201 │ Windows D3D12 QC Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 5 │ 2026-02-03T20:46:23Z │ 21647192379 │ macOS Metal Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 6 │ 2026-02-03T18:20:50Z │ 21642345045 │ Windows Vulkan AMD Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 7 │ 2026-02-03T20:10:20Z │ 21645995911 │ Windows Vulkan Intel Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 8 │ 2026-02-03T20:07:07Z │ 21645882341 │ Windows Vulkan NVIDIA Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 9 │ 2026-02-03T18:19:19Z │ 21642296487 │ Windows Vulkan QC Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave32.test │
│ 10 │ 2026-02-03T18:19:36Z │ 21642305507 │ Windows D3D12 AMD Clang │ XFAIL │ WaveOps/WaveActiveBallot.Wave32.test │
╰────┴──────────────────────┴─────────────┴────────────────────────────────┴─────────────┴──────────────────────────────────────╯
```

Wave64
```
╭────┬──────────────────────┬─────────────┬────────────────────────────────┬─────────────┬──────────────────────────────────────╮
│ # │ timestamp │ run-id │ workflow │ status │ test │
├────┼──────────────────────┼─────────────┼────────────────────────────────┼─────────────┼──────────────────────────────────────┤
│ 0 │ 2026-02-03T18:15:57Z │ 21642188487 │ Windows D3D12 Warp Clang │ FAIL │ WaveOps/WaveActiveBallot.Wave64.test │
│ 1 │ 2026-02-03T18:21:13Z │ 21642357057 │ Windows ARM64 D3D12 Warp Clang │ FAIL │ WaveOps/WaveActiveBallot.Wave64.test │
│ 2 │ 2026-02-03T18:19:27Z │ 21642301201 │ Windows D3D12 QC Clang │ PASS │ WaveOps/WaveActiveBallot.Wave64.test │
│ 3 │ 2026-02-03T20:10:06Z │ 21645986872 │ Windows D3D12 Intel Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 4 │ 2026-02-03T20:11:21Z │ 21646031461 │ Windows D3D12 NVIDIA Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 5 │ 2026-02-03T20:46:23Z │ 21647192379 │ macOS Metal Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 6 │ 2026-02-03T18:20:50Z │ 21642345045 │ Windows Vulkan AMD Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 7 │ 2026-02-03T20:10:20Z │ 21645995911 │ Windows Vulkan Intel Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 8 │ 2026-02-03T20:07:07Z │ 21645882341 │ Windows Vulkan NVIDIA Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 9 │ 2026-02-03T18:19:19Z │ 21642296487 │ Windows Vulkan QC Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave64.test │
│ 10 │ 2026-02-03T18:19:36Z │ 21642305507 │ Windows D3D12 AMD Clang │ XFAIL │ WaveOps/WaveActiveBallot.Wave64.test │
╰────┴──────────────────────┴─────────────┴────────────────────────────────┴─────────────┴──────────────────────────────────────╯
```

Wave128
```
╭────┬──────────────────────┬─────────────┬────────────────────────────────┬─────────────┬───────────────────────────────────────╮
│ # │ timestamp │ run-id │ workflow │ status │ test │
├────┼──────────────────────┼─────────────┼────────────────────────────────┼─────────────┼───────────────────────────────────────┤
│ 0 │ 2026-02-03T18:15:57Z │ 21642188487 │ Windows D3D12 Warp Clang │ FAIL │ WaveOps/WaveActiveBallot.Wave128.test │
│ 1 │ 2026-02-03T18:21:13Z │ 21642357057 │ Windows ARM64 D3D12 Warp Clang │ FAIL │ WaveOps/WaveActiveBallot.Wave128.test │
│ 2 │ 2026-02-03T18:19:27Z │ 21642301201 │ Windows D3D12 QC Clang │ PASS │ WaveOps/WaveActiveBallot.Wave128.test │
│ 3 │ 2026-02-03T18:19:36Z │ 21642305507 │ Windows D3D12 AMD Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 4 │ 2026-02-03T20:10:06Z │ 21645986872 │ Windows D3D12 Intel Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 5 │ 2026-02-03T20:11:21Z │ 21646031461 │ Windows D3D12 NVIDIA Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 6 │ 2026-02-03T20:46:23Z │ 21647192379 │ macOS Metal Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 7 │ 2026-02-03T18:20:50Z │ 21642345045 │ Windows Vulkan AMD Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 8 │ 2026-02-03T20:10:20Z │ 21645995911 │ Windows Vulkan Intel Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 9 │ 2026-02-03T20:07:07Z │ 21645882341 │ Windows Vulkan NVIDIA Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
│ 10 │ 2026-02-03T18:19:19Z │ 21642296487 │ Windows Vulkan QC Clang │ UNSUPPORTED │ WaveOps/WaveActiveBallot.Wave128.test │
╰────┴──────────────────────┴─────────────┴────────────────────────────────┴─────────────┴───────────────────────────────────────╯
```

Example logs (Windows D3D12 Warp Clang): https://github.com/llvm/offload-test-suite/actions/runs/21642188487/job/62384638556#step:12:770
```
********************
FAIL: OffloadTest-clang-warp-d3d12 :: WaveOps/WaveActiveBallot.Wave32.test (301 of 335)
******************** TEST 'OffloadTest-clang-warp-d3d12 :: WaveOps/WaveActiveBallot.Wave32.test' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 61
c:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\bin\split-file.exe C:\actions-runner\_work\offload-test-suite\offload-test-suite\OffloadTest\test\WaveOps\WaveActiveBallot.Wave32.test C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp
# executed command: 'c:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\bin\split-file.exe' 'C:\actions-runner\_work\offload-test-suite\offload-test-suite\OffloadTest\test\WaveOps\WaveActiveBallot.Wave32.test' 'C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp'
# RUN: at line 62
c:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\bin\clang-dxc.exe --dxv-path=C:/actions-runner/_work/offload-test-suite/offload-test-suite/DXC/build/bin -T cs_6_6 -Fo C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp.o C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp/source.hlsl
# executed command: 'c:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\bin\clang-dxc.exe' --dxv-path=C:/actions-runner/_work/offload-test-suite/offload-test-suite/DXC/build/bin -T cs_6_6 -Fo 'C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp.o' 'C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp/source.hlsl'
# .---command stdout------------
# | Signed DxilContainer written to "C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp.o"
# | Validation succeeded.
# `-----------------------------
# RUN: at line 63
c:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\bin\offloader.exe -warp -debug-layer C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp/pipeline.yaml C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp.o
# executed command: 'c:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\bin\offloader.exe' -warp -debug-layer 'C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp/pipeline.yaml' 'C:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-warp-d3d12\WaveOps\Output\WaveActiveBallot.Wave32.test.tmp.o'
# .---command stdout------------
# | Using DirectX API
# | Configuring execution on device: Microsoft Basic Render Driver
# | RootSignature created.
# | Descriptor heap created.
# | Command structures created.
# | Event prepared.
# | Creating UAV: { Size = 64, Register = u1, Space = 0, HasCounter = 0 }
# | EltSize = 4 NumElts = 16
# | UAV: HeapIdx = 0 EltSize = 4 NumElts = 16 HasCounter = 0
# | Buffers created.
# | PSO created.
# | Compute command list created.
# | Compute commands executed.
# | Read data back.
# `-----------------------------
# .---command stderr------------
# | Test failed: Test
# | Comparison Rule: BufferExact
# | Expected:
# | ---
# | Name: ExpectedOut
# | Format: UInt32
# | Stride: 4
# | Data: [ 3221225471, 0, 0, 0, 65535, 0, 0, 0, 0, 0, 0, 0, 2863311530,
# | 0, 0, 0 ]
# | OutputProps:
# | Height: 0
# | Width: 0
# | Depth: 0
# | ...
# | Got:
# | ---
# | Name: Out
# | Format: UInt32
# | Stride: 4
# | Data: [ 3221225471, 0, 0, 0, 65535, 0, 0, 0, 0, 0, 0, 0, 4294967294,
# | 0, 0, 0 ]
# | OutputProps:
# | Height: 0
# | Width: 0
# | Depth: 0
# | ...
# | Full Hex 64bit representation of Expected Buffer Values:
# | [ 0xbfffffff, 0x0, 0x0, 0x0, 0xffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xaaaaaaaa, 0x0, 0x0, 0x0 ]
# | Full Hex 64bit representation of Actual Buffer Values:
# | [ 0xbfffffff, 0x0, 0x0, 0x0, 0xffff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0xfffffffe, 0x0, 0x0, 0x0 ]
# |
# `-----------------------------
# error: command failed with exit status: 1

--
```

Start with the WaveOps/WaveActiveBallot.Wave32.test, Wave64.test, and Wave128.test cases and compare the HLSL ballot expression with the Clang IR before and after InstCombine. Run the Clang WARP D3D12 tests shown in the issue; done means these tests produce the expected ballot masks instead of the reported truncated values.

Written by the indexing model from the issue text.