On Fri, Nov 14, 2014 at 3:16 PM, Michael Meissner
<meiss...@linux.vnet.ibm.com> wrote:
> I tracked down the regression in the spec benchmarks, and it was due to
> turning
> off pre-increment/pre-decrement for floating point values, and these two
> benchmarks use pre-increment/pre-decrement quite a bit. My secondary reload
> handlers are capable of adding in the pre-increment/pre-decrement if such an
> operation is attempted on an Altivec register.
>
> I am also including a patch to make the compiler work with -ffast-math. If
> you
> use -ffast-math, the easy_fp_constant predicate says that all constants are
> easy in order to enable using the reciprocal approximation instructions for
> division. I put in a define_split to move the constants to the constant pool
> after the reciprocal approximation work has been done but before reload
> starts. I had had this patch in when I was doing the development, but I
> thought I did not need it when making up the patches, but perhaps recent
> changes to the register allocator need it again.
>
> I added an option (-mupper-regs) to simplify setting both -mupper-regs-sf and
> -mupper-regs-df. It will only set the options that the particular machine
> supports.
>
> Finally, I made the default to turn on -mupper-regs-df on power7/power8
> systems, and -mupper-regs-sf on power8 systems. I have run the regression
> test
> suite with these options on, and there were no regressions. Once all of the
> other patches go in, can I check in these patches?
>
> If you would prefer the default for GCC 5.0 not to enable the upper register
> support, let me know, and I can remove the lines in rs6000-cpu.def that sets
> the default.
>
> 2014-11-14 Michael Meissner <meiss...@linux.vnet.ibm.com>
>
> * config/rs6000/predicates.md (memory_fp_constant): New predicate
> to return true if the operand is a floating point constant that
> must be put into the constant pool, before register allocation
> occurs.
>
> * config/rs6000/rs6000-cpus.def (ISA_2_6_MASKS_SERVER): Enable
> -mupper-regs-df by default.
> (ISA_2_7_MASKS_SERVER): Enable -mupper-regs-sf by default.
> (POWERPC_MASKS): Add -mupper-regs-{sf,df} as options set by the
> various -mcpu=... options.
> (power7 cpu): Enable -mupper-regs-df by default.
>
> * config/rs6000/rs6000.opt (-mupper-regs): New combination option
> that sets -mupper-regs-sf and -mupper-regs-df by default if the
> cpu supports the instructions.
>
> * config/rs6000/rs6000.c (rs6000_setup_reg_addr_masks): Allow
> pre-increment and pre-decrement on floating point, even if the
> -mupper-regs-{sf,df} options were used.
> (rs6000_option_override_internal): If -mupper-regs, set both
> -mupper-regs-sf and -mupper-regs-df, depending on the underlying
> cpu.
>
> * config/rs6000/rs6000.md (DFmode splitter): Add a define_split to
> move floating point constants to the constant pool before register
> allocation. Normally constants are put into the pool immediately,
> but -ffast-math delays putting them into the constant pool for the
> reciprocal approximation support.
> (SFmode splitter): Likewise.
>
> * doc/invoke.texi (RS/6000 and PowerPC Options): Document
> -mupper-regs.
Okay.
Thanks, David
