[cfe-dev] aarch64 openmp offloading support

[Jeffrey Sandoval via cfe-dev]

Hello all,

Are there any known issues with OpenMP offloading to aarch64?  The latest "OpenMP Support" documentation indicates that it should work: "Clang supports offloading to X86_64, AArch64, PPC64[LE] ..." (https://clang.llvm.org/docs/OpenMPSupport.html).

But when I try it (using an 8.0.0 development build), the "-fopenmp-targets" option accepts x86_64 and ppc64, but not aarch64:

$ clang -fopenmp -fopenmp-targets=x86_64 -c hello.c
$ clang -fopenmp -fopenmp-targets=ppc64 -c hello.c
$ clang -fopenmp -fopenmp-targets=aarch64 -c hello.c
error: OpenMP target is invalid: 'aarch64'

I can get it to work with a very simple change:

--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -2679,7 +2679,8 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args, InputKind IK,
             TT.getArch() == llvm::Triple::nvptx ||
             TT.getArch() == llvm::Triple::nvptx64 ||
             TT.getArch() == llvm::Triple::x86 ||
-            TT.getArch() == llvm::Triple::x86_64))
+            TT.getArch() == llvm::Triple::x86_64 ||
+            TT.getArch() == llvm::Triple::aarch64))
         Diags.Report(diag::err_drv_invalid_omp_target) << A->getValue(i);
       else
         Opts.OMPTargetTriples.push_back(TT);

I haven't done extensive testing, but my simple "hello world" test case now works.  Before pursuing this further, does anyone foresee any issues with this change?

Thanks,
Jeff