[clang] [Clang][SYCL] Introduce clang-sycl-linker to link SYCL offloading device code (Part 1 of many) (PR #112245)

[Alexey Bader via cfe-commits]

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+// Tests the clang-sycl-linker tool.
+//
+// Test a simple case without arguments.
+// RUN: %clangxx -fsycl -emit-llvm -c %s -o %t.bc
+// RUN: clang-sycl-linker --dry-run -triple spirv64 %t.bc -o a.spv 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=SIMPLE
+// SIMPLE: "{{.*}}llvm-link{{.*}}" {{.*}}.bc -o [[FIRSTLLVMLINKOUT:.*]].bc --suppress-warnings
+// SIMPLE-NEXT: "{{.*}}llvm-spirv{{.*}}" {{.*}}-o a.spv [[FIRSTLLVMLINKOUT]].bc
+//
+// Test a simple case with device library files specified.
+// RUN: echo ' ' > %T/lib1.bc
+// RUN: echo ' ' > %T/lib2.bc
+// RUN: clang-sycl-linker --dry-run -triple spirv64 %t.bc --library-path=%T --device-libs=lib1.bc,lib2.bc -o a.spv 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=DEVLIBS
+// DEVLIBS: "{{.*}}llvm-link{{.*}}" {{.*}}.bc -o [[FIRSTLLVMLINKOUT:.*]].bc --suppress-warnings
+// DEVLIBS-NEXT: "{{.*}}llvm-link{{.*}}" -only-needed [[FIRSTLLVMLINKOUT]].bc {{.*}}lib1.bc {{.*}}lib2.bc -o [[SECONDLLVMLINKOUT:.*]].bc --suppress-warnings
+// DEVLIBS-NEXT: "{{.*}}llvm-spirv{{.*}}" {{.*}}-o a.spv [[SECONDLLVMLINKOUT]].bc
+//
+// Test a simple case with .o (fat object) as input.
+// TODO: Remove this test once fat object support is added.
+// RUN: %clangxx -fsycl -c %s -o %t.o
+// RUN: not clang-sycl-linker --dry-run -triple spirv64 %t.o -o a.spv 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=FILETYPEERROR
+// FILETYPEERROR: Unsupported file type
+//
+// Test to see if device library related errors are emitted.
+// RUN: not clang-sycl-linker --dry-run -triple spirv64 %t.bc --library-path=%T --device-libs= -o a.spv 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=DEVLIBSERR1
+// DEVLIBSERR1: Number of device library files cannot be zero
+// RUN: not clang-sycl-linker --dry-run -triple spirv64 %t.bc --library-path=%T --device-libs=lib3.bc -o a.spv 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=DEVLIBSERR2
+// DEVLIBSERR2: SYCL device library file is not found
----------------
bader wrote:

```suggestion
// DEVLIBSERR2: lib3.bc SYCL device library file is not found
```
Please, check that error message contains the name of the library file, we can't find.

https://github.com/llvm/llvm-project/pull/112245