[HLSL] Add MatVec interpretation and bias coverage for LinAlg

[Jack Elliott (JoeCitizen)]

Proposal 0035 permits a thread-scope Multiply vector to be native or an InterpretedVector, pairing a packed vector with an interpretation type. The interpreted forms had no coverage.

These six tests cover non-uniform F16 in row-major and column-major layouts, packed SInt8 and UInt8 inputs, unsigned UInt32 output, and MultiplyAdd with the bias in a separate resource. The UInt8 case reuses the SInt8 bytes so high-bit lanes decode differently under the two interpretations. Expected values come from overflow-checked host dot products, and the full output allocation including padding and guard bytes is compared against a poison fill.

Column-major is required rather than gated: a thread-scope load permits row-major, column-major and optimal layouts, and only transposed loads need a driver query. MatVecMulAdd_Thread_4x8_F16_IndependentBias fails on WARP, which advertises the F16 tuple then rejects dx.op.linAlgMatVecMulAdd as an invalid overload, matching two existing failures on the merge base.

[Copilot]

Pull request overview

Adds thread-scope LinAlg matrix-vector tests for layouts, interpreted inputs, unsigned output, and independent bias.

Changes:

• Adds six Multiply/MultiplyAdd execution tests.
• Adds host-side encoding, overflow-checked oracles, capability checks, and guard-byte validation.

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[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[Damyan Pepper (damyanp)]

Some observations, none of these should block the PR after it has been reviewed by someone with more domain knowledge than me.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (2)

tools/clang/unittests/HLSLExec/LinAlgTests.cpp:2287

• Please use the explicit result type under the repository's almost-never-auto convention. runShaderOp declares this as std::shared_ptr<st::ShaderOpTestResult> in HlslExecTestUtils.h:601.

  auto Result =

tools/clang/unittests/HLSLExec/LinAlgTests.cpp:2272

• Per the repository's almost-never-auto convention, this straightforward return type should be explicit. createComputeOp is declared as returning std::unique_ptr<st::ShaderOp> in HlslExecTestUtils.h:571.

This issue also appears on line 2287 of the same file.

  auto Op = createComputeOp(Shader, "cs_6_10", RootSignature, Args->c_str());

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.

Suppressed comments (2)

tools/clang/unittests/HLSLExec/LinAlgTests.cpp:1924

• The host oracle performs the dot product with unchecked signed int64_t multiplication and addition. A valid supported case using large U32 operands can therefore trigger signed-overflow undefined behavior and produce unreliable expected bytes, contrary to the PR description's overflow-checked oracle claim. Please use checked or wider arithmetic and reject results that cannot be represented before encoding them.

      Expected[Row] +=
          Case.MatrixValues[static_cast<size_t>(Row) * Case.N + Column] *
          Case.InterpretedVectorValues[Column];

tools/clang/unittests/HLSLExec/LinAlgTests.cpp:1811

• This round-trip check can itself invoke undefined behavior: INT64_MAX rounds to 2^63 when converted to float, and converting that out-of-range float back to int64_t is undefined. Check that FloatValue is within the half-open int64_t range before performing the cast, then do the exactness comparison.

This issue also appears on line 1922 of the same file.

      if (static_cast<int64_t>(FloatValue) != Value)
        return reportUnrepresentable(Type, Value);

[Damyan Pepper (damyanp)]

LGTM - my previous comments are all addressed.