[PATCHv2] PowerPC: Add msingle-pic-base option.

Do not generate fPIC/fpic prologue nor save
and restore PIC register.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>

---

 - Use Var instead of Mask and add some docs per
   Michael Meissner <meissner@linux.vnet.ibm.com>

 gcc/config/rs6000/rs6000.c   |    7 ++++++-
 gcc/config/rs6000/rs6000.opt |    4 ++++
 gcc/doc/invoke.texi          |    9 ++++++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

This patch is okay, but would you please make the order consistent in
the first hunk so both are

(reg == RS6000_PIC_OFFSET_TABLE_REGNUM
             && !TARGET_SINGLE_PIC_BASE

Thanks, David

On Tue, Nov 23, 2010 at 10:36 AM, Joakim Tjernlund
<Joakim.Tjernlund@transmode.se> wrote:
> Do not generate fPIC/fpic prologue nor save
> and restore PIC register.
>
> Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
>
> ---
>
>  - Use Var instead of Mask and add some docs per
>   Michael Meissner <meissner@linux.vnet.ibm.com>
>
>  gcc/config/rs6000/rs6000.c   |    7 ++++++-
>  gcc/config/rs6000/rs6000.opt |    4 ++++
>  gcc/doc/invoke.texi          |    9 ++++++++-
>  3 files changed, 18 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 63f8ef9..bf5b5d3 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -16036,8 +16036,10 @@ rs6000_reg_live_or_pic_offset_p (int reg)
>   return ((df_regs_ever_live_p (reg)
>            && (!call_used_regs[reg]
>                || (reg == RS6000_PIC_OFFSET_TABLE_REGNUM
> -                   && TARGET_TOC && TARGET_MINIMAL_TOC)))
> +                   && TARGET_TOC && TARGET_MINIMAL_TOC
> +                  && !TARGET_SINGLE_PIC_BASE)))
>           || (reg == RS6000_PIC_OFFSET_TABLE_REGNUM
> +             && !TARGET_SINGLE_PIC_BASE
>               && ((DEFAULT_ABI == ABI_V4 && flag_pic != 0)
>                   || (DEFAULT_ABI == ABI_DARWIN && flag_pic))));
>  }
> @@ -16737,6 +16739,9 @@ rs6000_emit_prologue (void)
>       insn = emit_insn (generate_set_vrsave (reg, info, 0));
>     }
>
> +  if (TARGET_SINGLE_PIC_BASE)
> +    return; /* Do not set PIC register */
> +
>   /* If we are using RS6000_PIC_OFFSET_TABLE_REGNUM, we need to set it up.  */
>   if ((TARGET_TOC && TARGET_MINIMAL_TOC && get_pool_size () != 0)
>       || (DEFAULT_ABI == ABI_V4
> diff --git a/gcc/config/rs6000/rs6000.opt b/gcc/config/rs6000/rs6000.opt
> index 8a62352..2adb6dd 100644
> --- a/gcc/config/rs6000/rs6000.opt
> +++ b/gcc/config/rs6000/rs6000.opt
> @@ -119,6 +119,10 @@ mupdate
>  Target Report RejectNegative InverseMask(NO_UPDATE, UPDATE)
>  Generate load/store with update instructions
>
> +msingle-pic-base
> +Target Report Var(TARGET_SINGLE_PIC_BASE) Init(0)
> +Do not load the PIC register in function prologues
> +
>  mavoid-indexed-addresses
>  Target Report Var(TARGET_AVOID_XFORM) Init(-1)
>  Avoid generation of indexed load/store instructions when possible
> diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
> index 393e418..fc30537 100644
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -728,7 +728,7 @@ See RS/6000 and PowerPC Options.
>  -mstrict-align  -mno-strict-align  -mrelocatable @gol
>  -mno-relocatable  -mrelocatable-lib  -mno-relocatable-lib @gol
>  -mtoc  -mno-toc  -mlittle  -mlittle-endian  -mbig  -mbig-endian @gol
> --mdynamic-no-pic  -maltivec  -mswdiv @gol
> +-mdynamic-no-pic  -maltivec  -mswdiv  -msingle-pic-base @gol
>  -mprioritize-restricted-insns=@var{priority} @gol
>  -msched-costly-dep=@var{dependence_type} @gol
>  -minsert-sched-nops=@var{scheme} @gol
> @@ -14129,6 +14129,13 @@ relocatable, but that its external references are relocatable.  The
>  resulting code is suitable for applications, but not shared
>  libraries.
>
> +@item -msingle-pic-base
> +@opindex msingle-pic-base
> +Treat the register used for PIC addressing as read-only, rather than
> +loading it in the prologue for each function.  The run-time system is
> +responsible for initializing this register with an appropriate value
> +before execution begins.
> +
>  @item -mprioritize-restricted-insns=@var{priority}
>  @opindex mprioritize-restricted-insns
>  This option controls the priority that is assigned to
> --
> 1.7.2.2
>
>