[SYCL] Add support for auxiliary triple specification to Frontend

[bader]

Summary

Add host predefined macros to compilation for SYCL device, which is
required for pre-processing host specific includes (e.g. system
headers).

[bader]

I'm looking for test suggestions as I was not able to find tests covering similar changes for OpenMP compiler.

https://github.com/llvm/llvm-project/commit/59d7b77b16bf11810091fe75a4348198783d3fbc modifies driver and front-end, but adds only driver tests.

[ABataev]

Most probably, just missed the testing of the frontend part here

[merge_guards_bot]

Build result: pass - 60674 tests passed, 0 failed and 726 were skipped.

Log files: console-log.txt, CMakeCache.txt

[bader]

In D71286#1777894, @ABataev wrote:

Most probably, just missed the testing of the frontend part here

Should I add test for both: SYCL and OpenMP?
What is the right place for this kind of tests: clang/test/Preprocessor/ or clang/test/Frontend/?

[ABataev]

In D71286#1777917, @bader wrote:

In D71286#1777894, @ABataev wrote:

Most probably, just missed the testing of the frontend part here

Should I add test for both: SYCL and OpenMP?
What is the right place for this kind of tests: clang/test/Preprocessor/ or clang/test/Frontend/?

It would good but make in different patches. For OpenMP tests there is a directory clang/test/OpenMP. For SYCL, probably, clang/test/Frontend, since it is going to be a test for the frontend.

[bader]

Added LIT test.

If it's okay, I'll add similar test for OpenMP device compiler to clang/test/OpenMP directory.

[ABataev]

LG

[merge_guards_bot]

Build result: pass - 60675 tests passed, 0 failed and 726 were skipped.

Log files: console-log.txt, CMakeCache.txt

clang/lib/Frontend/CompilerInstance.cpp

if (!Act.PrepareToExecute(*this))
     return false;
 
   // Create the target instance.
   setTarget(TargetInfo::CreateTargetInfo(getDiagnostics(),
                                          getInvocation().TargetOpts));
   if (!hasTarget())
     return false;
 
-  // Create TargetInfo for the other side of CUDA and OpenMP compilation.
-  if ((getLangOpts().CUDA || getLangOpts().OpenMPIsDevice) &&
+  // Create TargetInfo for the other side of CUDA/OpenMP/SYCL compilation.
+  if ((getLangOpts().CUDA || getLangOpts().OpenMPIsDevice ||
+       getLangOpts().SYCLIsDevice) &&
       !getFrontendOpts().AuxTriple.empty()) {
     auto TO = std::make_shared<TargetOptions>();
     TO->Triple = llvm::Triple::normalize(getFrontendOpts().AuxTriple);
     TO->HostTriple = getTarget().getTriple().str();
     setAuxTarget(TargetInfo::CreateTargetInfo(getDiagnostics(), TO));
   }
 
   // Inform the target of the language options.

clang/lib/Frontend/InitPreprocessor.cpp

void clang::InitializePreprocessor(
   // in this mode.
   if (!PP.getLangOpts().AsmPreprocessor)
     Builder.append("# 1 \"<built-in>\" 3");
 
   // Install things like __POWERPC__, __GNUC__, etc into the macro table.
   if (InitOpts.UsePredefines) {
     // FIXME: This will create multiple definitions for most of the predefined
     // macros. This is not the right way to handle this.
-    if ((LangOpts.CUDA || LangOpts.OpenMPIsDevice) && PP.getAuxTargetInfo())
+    if ((LangOpts.CUDA || LangOpts.OpenMPIsDevice || LangOpts.SYCLIsDevice) &&
+        PP.getAuxTargetInfo())
       InitializePredefinedMacros(*PP.getAuxTargetInfo(), LangOpts, FEOpts,
                                  PP.getPreprocessorOpts(), Builder);
 
     InitializePredefinedMacros(PP.getTargetInfo(), LangOpts, FEOpts,
                                PP.getPreprocessorOpts(), Builder);
 
     // Install definitions to make Objective-C++ ARC work well with various
     // C++ Standard Library implementations.

clang/test/Frontend/sycl-aux-triple.cpp

+// RUN: %clang_cc1 %s -triple spir -aux-triple x86_64-unknown-linux-gnu -E -dM | FileCheck %s
+// RUN: %clang_cc1 %s -fsycl-is-device -triple spir -aux-triple x86_64-unknown-linux-gnu -E -dM | FileCheck --check-prefix=CHECK-SYCL %s
+
+// CHECK-NOT:#define __x86_64__ 1
+// CHECK-SYCL:#define __x86_64__ 1