[clang] [Driver][SYCL] Add tests for -Xarch_<arch> option forwarding to SYCL JIT compilation. (PR #178025)

[Alexey Bader via cfe-commits]

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+// Test passing of -Xarch_<arch> <option> to SYCL offload compilations.
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+// Verify that -Xarch_spirv64 forwards options to the SYCL device compilation
+// and clang-linker-wrapper call.
+// RUN: %clang -fsycl -Xarch_spirv64 -O3 -### %s 2>&1 \
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bader wrote:

> `-fsycl` implicitly implies `spirv64` target.

If this changes, the test for `-Xarch` will fail. Can we explicitly set the target with `--offload-targets` to make it independent from the default (implied) SYCL target?

https://github.com/llvm/llvm-project/pull/178025