Pass MCSubtargetInfo instead of CPU and Triple to createMCAsmBackend

[aturetsk]

Summary

Pass MCSubtargetInfo instead of CPU and Triple to AsmBackend in order to be able to reach feature bits there (e.g. for ckecking of long nop support).
CPU and Triple are taken from MCSubtargetInfo.

[echristo]

I followed up in the original thread, I don't think this is going to be the right direction.

Thanks.

-eric

[aturetsk]

New version in https://reviews.llvm.org/D21374

tools/driver/cc1as_main.cpp

static bool ExecuteAssembler(AssemblerInvocation &Opts,
   // FIXME: There is a bit of code duplication with addPassesToEmitFile.
   if (Opts.OutputType == AssemblerInvocation::FT_Asm) {
     MCInstPrinter *IP = TheTarget->createMCInstPrinter(
         llvm::Triple(Opts.Triple), Opts.OutputAsmVariant, *MAI, *MCII, *MRI);
     MCCodeEmitter *CE = nullptr;
     MCAsmBackend *MAB = nullptr;
     if (Opts.ShowEncoding) {
       CE = TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx);
-      MAB = TheTarget->createMCAsmBackend(*MRI, Opts.Triple, Opts.CPU);
+      MAB = TheTarget->createMCAsmBackend(*STI, *MRI);
     }
     auto FOut = llvm::make_unique<formatted_raw_ostream>(*Out);
     Str.reset(TheTarget->createAsmStreamer(
         Ctx, std::move(FOut), /*asmverbose*/ true,
         /*useDwarfDirectory*/ true, IP, CE, MAB, Opts.ShowInst));
   } else if (Opts.OutputType == AssemblerInvocation::FT_Null) {
     Str.reset(createNullStreamer(Ctx));
   } else {
     assert(Opts.OutputType == AssemblerInvocation::FT_Obj &&
            "Invalid file type!");
     if (!FDOS->supportsSeeking()) {
       BOS = make_unique<buffer_ostream>(*FDOS);
       Out = BOS.get();
     }
 
     MCCodeEmitter *CE = TheTarget->createMCCodeEmitter(*MCII, *MRI, Ctx);
-    MCAsmBackend *MAB = TheTarget->createMCAsmBackend(*MRI, Opts.Triple,
-                                                      Opts.CPU);
+    MCAsmBackend *MAB =
+        TheTarget->createMCAsmBackend(*STI, *MRI);
     Triple T(Opts.Triple);
     Str.reset(TheTarget->createMCObjectStreamer(
         T, Ctx, *MAB, *Out, CE, *STI, Opts.RelaxAll,
         Opts.IncrementalLinkerCompatible,
         /*DWARFMustBeAtTheEnd*/ true));
     Str.get()->InitSections(Opts.NoExecStack);
   }