[PATCH] Use ".arch_extension" ARM directive to specify the additional CPU features

[Sumanth Gundapaneni]

================
Comment at: include/llvm/MC/MCStreamer.h:142
@@ -141,2 +141,3 @@
   virtual void emitArch(unsigned Arch);
+  virtual void emitArchExtension(StringRef StringValue);
   virtual void emitObjectArch(unsigned Arch);
----------------
sgundapa wrote:
> t.p.northover wrote:
> > rengolin wrote:
> > > sgundapa wrote:
> > > > t.p.northover wrote:
> > > > > I think this either needs a generic implementation, or (probably better for now) moving to ARMELFStreamer.cpp entirely. OK, so it's not called, but 
> > > > p
> > > ARMELFStreamer? But this is assembly only...
> > Yep, but it's essentially en ELF-dialect assembly feature so the AsmStreamer seems to live in the same file.
> A quick google on ".arch_extension" suggests that this directive is specific to ARM as.
> It is fair to move it to the ARMELFStreamer.cpp file at this moment
> 
Ignore my previous comment as I thought I added the member to MCTargetStreamer.
emitArchExtension is part of ARMTargetStreamer. My code is based on below comments in MCStreamer.h
Any thing wrong here ?

/// If target foo wants to use this, it should implement 3 classes:
/// * FooTargetStreamer : public MCTargetStreamer
/// * FooTargetAsmStreamer : public FooTargetStreamer
/// * FooTargetELFStreamer : public FooTargetStreamer
///
/// FooTargetStreamer should have a pure virtual method for each directive. For
/// example, for a ".bar symbol_name" directive, it should have
/// virtual emitBar(const MCSymbol &Symbol) = 0;
///
/// The FooTargetAsmStreamer and FooTargetELFStreamer classes implement the
/// method. The assembly streamer just prints ".bar symbol_name". The object
/// streamer does whatever is needed to implement .bar in the object file.

http://reviews.llvm.org/D7316

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/