[DevMSAN] Unpoison sret argument for builtin function to get spec constant

[zhaomaosu]

• For builtin func like "__sycl_getComposite2020SpecConstantValue", if structs which are larger than 64b will be returned via sret arguments and will be initialized inside the function. So we need to unpoison the sret arguments.
• Always set ZE_AFFINITY_MAST to 0 when running device sanitizer tests since device sanitizer only support one GPU card now.

[Copilot]

Pull Request Overview

This pull request implements support for unpoisoning sret (struct return) arguments for SYCL builtin functions that return large structs (>64 bits) in MemorySanitizer. The main change addresses the fact that these builtin functions initialize struct return values internally, requiring the memory sanitizer to mark these return values as clean.

• Adds special handling for __sycl_getComposite2020SpecConstantValue builtin function in MemorySanitizer
• Implements a new runtime function __msan_unpoison_shadow for unpoisoning arbitrary memory regions
• Updates test configurations to set ZE_AFFINITY_MASK=0 for sanitizer tests

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp	Adds detection and handling of SYCL builtin functions with sret parameters, unpoisoning their return values
libdevice/sanitizer/msan_rtl.cpp	Implements new __msan_unpoison_shadow runtime function and refactors debug message constants
llvm/test/Instrumentation/MemorySanitizer/SPIRV/spec_constants.ll	Adds test case verifying correct unpoisoning of sret arguments for spec constant builtin functions
sycl/test-e2e/ThreadSanitizer/lit.local.cfg	Sets ZE_AFFINITY_MASK environment variable for test isolation
sycl/test-e2e/MemorySanitizer/lit.local.cfg	Sets ZE_AFFINITY_MASK environment variable for test isolation
sycl/test-e2e/AddressSanitizer/lit.local.cfg	Sets ZE_AFFINITY_MASK environment variable for test isolation

[zhaomaosu]

Hi @intel/llvm-gatekeepers, this PR is ready to be merged. Thanks.