[Driver][SYCL] Add support for exporting symbols for AOT (#9991)

Add support for -ftarget-export-symbols. This option when used with
-fsycl -fsycl-targets=spir64_gen when creating shared libraries. This
exposes the exported symbols in the library so they can be available for
other modules.

Author: mdtoguchi

clang/include/clang/Driver/Options.td

@@ -3137,6 +3137,11 @@ def fsycl_max_parallel_jobs_EQ : Joined<["-"], "fsycl-max-parallel-link-jobs=">,
 def ftarget_compile_fast : Flag<["-"], "ftarget-compile-fast">,
   Flags<[CoreOption]>, HelpText<"Experimental feature: Reduce target "
   "compilation time, with potential runtime performance trade-off.">;
+def ftarget_export_symbols : Flag<["-"], "ftarget-export-symbols">,
+  Flags<[CoreOption]>, HelpText<"Expose exported symbols in a generated "
+  "target library to allow for visibilty to other modules.">;
+def fno_target_export_symbols : Flag<["-"], "fno-target-export-symbols">,
+  Flags<[CoreOption]>;
 def : Flag<["-"], "fsycl-rdc">, Flags<[CoreOption]>, Alias<fgpu_rdc>;
 def : Flag<["-"], "fno-sycl-rdc">, Flags<[CoreOption]>, Alias<fno_gpu_rdc>;
 def fsycl_optimize_non_user_code : Flag<["-"], "fsycl-optimize-non-user-code">,

clang/lib/Driver/ToolChains/SYCL.cpp

@@ -991,9 +991,12 @@ void SYCLToolChain::AddImpliedTargetArgs(const llvm::Triple &Triple,
       CmdArgs.push_back(Args.MakeArgString(DepInfo));
     }
     // -ftarget-compile-fast AOT
-    if (Args.hasArg(options::OPT_ftarget_compile_fast)) {
+    if (Args.hasArg(options::OPT_ftarget_compile_fast))
       BeArgs.push_back("-igc_opts 'PartitionUnit=1,SubroutineThreshold=50000'");
-    }
+    // -ftarget-export-symbols
+    if (Args.hasFlag(options::OPT_ftarget_export_symbols,
+                     options::OPT_fno_target_export_symbols, false))
+      BeArgs.push_back("-library-compilation");
   } else if (Triple.getSubArch() == llvm::Triple::NoSubArch &&
              Triple.isSPIR()) {
     // -ftarget-compile-fast JIT

clang/test/Driver/ftarget-export-symbols.cpp

@@ -0,0 +1,29 @@
+// Test -ftarget-export-symbols behavior
+
+// RUN: %clang -### -target x86_64-unknown-linux-gnu -fsycl \
+// RUN:    -fsycl-targets=spir64_gen -ftarget-export-symbols %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=TARGET_EXPORT %s
+// RUN: %clang_cl -### --target=x86_64-pc-windows-msvc -fsycl \
+// RUN:     -fsycl-targets=spir64_gen -ftarget-export-symbols %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=TARGET_EXPORT %s
+// RUN: %clang -### -target x86_64-unknown-linux-gnu -fsycl \
+// RUN:    -fsycl-targets=spir64_gen -ftarget-export-symbols \
+// RUN:    -fno-target-export-symbols %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=NO_TARGET_EXPORT %s
+
+// TARGET_EXPORT: ocloc{{.*}} "-output"
+// TARGET_EXPORT: "-options" "-library-compilation"
+// NO_TARGET_EXPORT-NOT: "-library-compilation"
+
+// 'unused' for non-spir64_gen targets
+// RUN: %clang -### -target x86_64-unknown-linux-gnu -fsycl \
+// RUN:    -fsycl-targets=spir64 -ftarget-export-symbols %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=UNUSED %s
+// RUN: %clang -### -target x86_64-unknown-linux-gnu -fsycl \
+// RUN:    -fsycl-targets=spir64_x86_64 -ftarget-export-symbols %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=UNUSED %s
+// RUN: %clang -### -target x86_64-unknown-linux-gnu -fsycl \
+// RUN:    -fsycl-targets=spir64_fpga -ftarget-export-symbols %s 2>&1 \
+// RUN:   | FileCheck -check-prefix=UNUSED %s
+
+// UNUSED: argument unused during compilation: '-ftarget-export-symbols'

sycl/doc/UsersManual.md

@@ -416,6 +416,13 @@ and not recommended to use in production environment.
     Instructs the target backend to reduce compilation time, potentially
     at the cost of runtime performance. Currently only supported on Intel GPUs.
 
+**`-f[no-]target-export-symbols`**
+
+    Exposes exported symbols in a generated target library to allow for
+    visibility to other modules.
+
+    NOTE: This flag is only supported for spir64_gen AOT targets.
+
 # Example: SYCL device code compilation
 
 To invoke SYCL device compiler set `-fsycl-device-only` flag.