[PATCH] [AArch64] Add -mgeneral_regs_only option

[Bernie Ogden]

Copying in cfe-commits.

> -----Original Message-----
> From: Bernard Ogden
> Sent: 23 January 2014 15:08
> To: reviews+D2586+public+4d171e861f82b113 at llvm-reviews.chandlerc.com;
> Amara Emerson; t.p.northover at gmail.com
> Cc: cfe-commits at cs.uiuc.edu
> Subject: RE: [PATCH] [AArch64] Add -mgeneral_regs_only option
> 
> Hi Amara,
> 
> LGTM.
> 
> We might want to get AArch32 side to accept this option too, but that's
> a separate patch/discussion.
> 
> Regards,
> 
> BErnie
> 
> > -----Original Message-----
> > From: cfe-commits-bounces at cs.uiuc.edu [mailto:cfe-commits-
> > bounces at cs.uiuc.edu] On Behalf Of Amara Emerson
> > Sent: 21 January 2014 08:25
> > To: Amara Emerson; t.p.northover at gmail.com
> > Cc: cfe-commits at cs.uiuc.edu
> > Subject: [PATCH] [AArch64] Add -mgeneral_regs_only option
> >
> > Add support for the -mgeneral_regs_only option (in AArch64 only),
> which
> > restricts LLVM to generate code using only the general purpose
> > registers. The command line argument is already supported by AArch64
> > GCC.
> >
> > This patch essentially replaces the existing -mfpu=none option, as -
> > mfpu will soon be dropped entirely.
> >
> > http://llvm-reviews.chandlerc.com/D2586
> >
> > Files:
> >   docs/UsersManual.rst
> >   include/clang/Driver/Options.td
> >   lib/Driver/Tools.cpp
> >   test/Driver/aarch64-mfpu.c
> >   test/Driver/aarch64-mgeneral_regs_only.c
> >
> > Index: docs/UsersManual.rst
> > ===================================================================
> > --- docs/UsersManual.rst
> > +++ docs/UsersManual.rst
> > @@ -1061,6 +1061,13 @@
> >
> >     CRC instructions are enabled by default on ARMv8.
> >
> > +.. option:: -mgeneral_regs_only
> > +
> > +   Generate code which only uses the general purpose registers.
> > +
> > +   This option restricts the generated code to use general registers
> > +   only. This only applies to the AArch64 architecture.
> > +
> >
> >  Controlling Size of Debug Information
> >  -------------------------------------
> > Index: include/clang/Driver/Options.td
> > ===================================================================
> > --- include/clang/Driver/Options.td
> > +++ include/clang/Driver/Options.td
> > @@ -72,6 +72,7 @@
> >  def m_x86_Features_Group  : OptionGroup<"<m x86 features group>">,
> > Group<m_Group>;
> >  def m_hexagon_Features_Group  : OptionGroup<"<m hexagon features
> > group>">, Group<m_Group>;
> >  def m_arm_Features_Group  : OptionGroup<"<m arm features group>">,
> > Group<m_Group>;
> > +def m_aarch64_Features_Group  : OptionGroup<"<m aarch64 features
> > group>">, Group<m_Group>;
> >  def m_ppc_Features_Group  : OptionGroup<"<m ppc features group>">,
> > Group<m_Group>;
> >  def u_Group               : OptionGroup<"<u group>">;
> >
> > @@ -1052,6 +1053,9 @@
> >  def mnocrc : Flag<["-"], "mnocrc">, Group<m_arm_Features_Group>,
> >    HelpText<"Disallow use of CRC instructions (ARM only)">;
> >
> > +def mgeneral_regs_only : Flag<["-"], "mgeneral_regs_only">,
> > Group<m_aarch64_Features_Group>,
> > +  HelpText<"Generate code which only uses the general purpose
> > registers (AArch64 only)">;
> > +
> >  def mvsx : Flag<["-"], "mvsx">, Group<m_ppc_Features_Group>;
> >  def mno_vsx : Flag<["-"], "mno-vsx">, Group<m_ppc_Features_Group>;
> >  def mfprnd : Flag<["-"], "mfprnd">, Group<m_ppc_Features_Group>;
> > Index: lib/Driver/Tools.cpp
> > ===================================================================
> > --- lib/Driver/Tools.cpp
> > +++ lib/Driver/Tools.cpp
> > @@ -515,10 +515,6 @@
> >      Features.push_back("+crypto");
> >    } else if (FPU == "neon") {
> >      Features.push_back("+neon");
> > -  } else if (FPU == "none") {
> > -    Features.push_back("-fp-armv8");
> > -    Features.push_back("-crypto");
> > -    Features.push_back("-neon");
> >    } else
> >      D.Diag(diag::err_drv_clang_unsupported) << A->getAsString(Args);
> >  }
> > @@ -1434,6 +1430,12 @@
> >    // Honor -mfpu=.
> >    if (const Arg *A = Args.getLastArg(options::OPT_mfpu_EQ))
> >      getAArch64FPUFeatures(D, A, Args, Features);
> > +
> > +  if (Args.getLastArg(options::OPT_mgeneral_regs_only)) {
> > +    Features.push_back("-fp-armv8");
> > +    Features.push_back("-crypto");
> > +    Features.push_back("-neon");
> > +  }
> >  }
> >
> >  static void getTargetFeatures(const Driver &D, const llvm::Triple
> > &Triple,
> > Index: test/Driver/aarch64-mfpu.c
> > ===================================================================
> > --- test/Driver/aarch64-mfpu.c
> > +++ test/Driver/aarch64-mfpu.c
> > @@ -19,8 +19,3 @@
> >  // CHECK-CRYPTO-NEON-FP-ARMV8: "-target-feature" "+neon"
> >  // CHECK-CRYPTO-NEON-FP-ARMV8: "-target-feature" "+crypto"
> >
> > -// RUN: %clang -target aarch64-linux-eabi -mfpu=none %s -### 2>&1 \
> > -// RUN:   | FileCheck --check-prefix=CHECK-NO-FP %s
> > -// CHECK-NO-FP: "-target-feature" "-fp-armv8"
> > -// CHECK-NO-FP: "-target-feature" "-crypto"
> > -// CHECK-NO-FP: "-target-feature" "-neon"
> > Index: test/Driver/aarch64-mgeneral_regs_only.c
> > ===================================================================
> > --- /dev/null
> > +++ test/Driver/aarch64-mgeneral_regs_only.c
> > @@ -0,0 +1,7 @@
> > +// Test the -mgeneral_regs_only option
> > +
> > +// RUN: %clang -target aarch64-linux-eabi -mgeneral_regs_only %s -
> ###
> > 2>&1 \
> > +// RUN:   | FileCheck --check-prefix=CHECK-NO-FP %s
> > +// CHECK-NO-FP: "-target-feature" "-fp-armv8"
> > +// CHECK-NO-FP: "-target-feature" "-crypto"
> > +// CHECK-NO-FP: "-target-feature" "-neon"