[HIP] Let assembler output bitcode for amdgcn

[yaxunl]

Summary

amdgcn does not support linking of object files, therefore let
assembler output bitcode for HIP for amdgcn.

[rjmccall]

I think the right solution here is to make a CompileJobAction with type TY_LLVM_BC in the first place. You should get the advice of a driver expert, though.

[yaxunl]

In D46489#1088940, @rjmccall wrote:

I think the right solution here is to make a CompileJobAction with type TY_LLVM_BC in the first place. You should get the advice of a driver expert, though.

There is already JobAction for TY_LLVM_BC. I just want to skip the backend and assemble phase when offloading HIP. I will try achieving that through HIP action builder.

[rjmccall]

In D46489#1099979, @yaxunl wrote:

In D46489#1088940, @rjmccall wrote:

I think the right solution here is to make a CompileJobAction with type TY_LLVM_BC in the first place. You should get the advice of a driver expert, though.

There is already JobAction for TY_LLVM_BC. I just want to skip the backend and assemble phase when offloading HIP. I will try achieving that through HIP action builder.

Right, that's what I mean. This is something we already support for LTO and other purposes. You can just check what happens in the driver if you pass -c -emit-llvm.

[yaxunl]

I have updated D46476 to skip backend and assembler phases for amdgcn, therefore this patch is no longer needed.

lib/Driver/ToolChains/Clang.cpp

       CmdArgs.push_back("-Eonly");
     else {
       CmdArgs.push_back("-E");
       if (Args.hasArg(options::OPT_rewrite_objc) &&
           !Args.hasArg(options::OPT_g_Group))
         CmdArgs.push_back("-P");
     }
   } else if (isa<AssembleJobAction>(JA)) {
-    CmdArgs.push_back("-emit-obj");
+    // AMDGCN does not support linking obj files.
+    if (IsHIP && Triple.getArch() == llvm::Triple::amdgcn)
+      CmdArgs.push_back("-emit-llvm-bc");
+    else
+      CmdArgs.push_back("-emit-obj");
 
     CollectArgsForIntegratedAssembler(C, Args, CmdArgs, D);
 
     // Also ignore explicit -force_cpusubtype_ALL option.
     (void)Args.hasArg(options::OPT_force__cpusubtype__ALL);
   } else if (isa<PrecompileJobAction>(JA)) {
     // Use PCH if the user requested it.
     bool UsePCH = D.CCCUsePCH;