[PATCH], rs6000 cleanup, make constraints tighter

[Michael Meissner <meissner at linux dot vnet dot ibm dot com>]

I'm starting to look at updating my old address branch with an eye towards
getting the changes committed in GCC 4.10.  The address branch is meant to
rewrite handling of addresses in the rs6000 backend, to generalize the
addresses before register allocation to allow more general forms, and then
within register allocation, be more specific, depending on the register classes
involved.

The goals of the address work are:

   1)	On power7, enable using the traditional Altivec registers to hold
	double precision floating point;

   2)	On power8, enable using the traditional Altivec registers to hold
	single precision floating point;

   3)	On power8, enable better fusion support for loads, by keeping the
	extended addressing forms together, so more fused instructions can be
	emitted.

I believe that for the first two features, we will also need to flip the switch
on LRA, to make it default, in order to better deal with having reg+offset
addressing in the traditional floating point registers, but only reg+reg
addressing in the traditional Altivec registers.

These patches primarily tighten the constraints, so that the "wa" constraing
(all VSX registers) is not used on types that are not allowed in the
traditional Altivec registers.  This can throw off the pressure sensitive
optimizations like -fsched-pressure because the pass thinks there are more
registers available than could be allocated.

I also have a simplification in rs6000.c that makes it easier to decide if
scalar values can go in traditional Altivec registers in the patch.

I have done bootstrap and C/C++ regression testing on power7, power8 big
endian, and power8 little endian systems with no regressions.  At this time, I
have not run the fortran regression tests, since there are various failures due
to memory allocation in the trunk when I tested it (bugzilla 61950).  Are these
patches ok to be installed in the trunk?  I would like to install them in 4.9
and 4.8 trees as well.

2014-08-07  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/constraints.md (wh constraint): New constraint,
	for FP registers if direct move is available.
	(wi constraint): New constraint, for VSX/FP registers that can
	handle 64-bit integers.
	(wj constraint): New constraint for VSX/FP registers that can
	handle 64-bit integers for direct moves.
	(wk constraint): New constraint for VSX/FP registers that can
	handle 64-bit doubles for direct moves.
	(wy constraint): Make documentation match implementation.

	* config/rs6000/rs6000.c (struct rs6000_reg_addr): Add
	scalar_in_vmx_p field to simplify tests of whether SFmode or
	DFmode can go in the Altivec registers.
	(rs6000_hard_regno_mode_ok): Use scalar_in_vmx_p field.
	(rs6000_setup_reg_addr_masks): Likewise.
	(rs6000_debug_print_mode): Add debug support for scalar_in_vmx_p
	field, and wh/wi/wj/wk constraints.
	(rs6000_init_hard_regno_mode_ok): Setup scalar_in_vmx_p field, and
	the wh/wi/wj/wk constraints.
	(rs6000_preferred_reload_class): If SFmode/DFmode can go in the
	upper registers, prefer VSX registers unless the operation is a
	memory operation with REG+OFFSET addressing.

	* config/rs6000/vsx.md (VSr mode attribute): Add support for
	DImode.  Change SFmode to use ww constraint instead of d to allow
	SF registers in the upper registers.
	(VSr2): Likewise.
	(VSr3): Likewise.
	(VSr5): Fix thinko in comment.
	(VSa): New mode attribute that is an alternative to wa, that
	returns the VSX register class that a mode can go in, but may not
	be the preferred register class.
	(VS_64dm): New mode attribute for appropriate register classes for
	referencing 64-bit elements of vectors for direct moves and normal
	moves.
	(VS_64reg): Likewise.
	(vsx_mov<mode>): Change wa constraint to <VSa> to limit the
	register allocator to only registers the data type can handle.
	(vsx_le_perm_load_<mode>): Likewise.
	(vsx_le_perm_store_<mode>): Likewise.
	(vsx_xxpermdi2_le_<mode>): Likewise.
	(vsx_xxpermdi4_le_<mode>): Likewise.
	(vsx_lxvd2x2_le_<mode>): Likewise.
	(vsx_lxvd2x4_le_<mode>): Likewise.
	(vsx_stxvd2x2_le_<mode>): Likewise.
	(vsx_add<mode>3): Likewise.
	(vsx_sub<mode>3): Likewise.
	(vsx_mul<mode>3): Likewise.
	(vsx_div<mode>3): Likewise.
	(vsx_tdiv<mode>3_internal): Likewise.
	(vsx_fre<mode>2): Likewise.
	(vsx_neg<mode>2): Likewise.
	(vsx_abs<mode>2): Likewise.
	(vsx_nabs<mode>2): Likewise.
	(vsx_smax<mode>3): Likewise.
	(vsx_smin<mode>3): Likewise.
	(vsx_sqrt<mode>2): Likewise.
	(vsx_rsqrte<mode>2): Likewise.
	(vsx_tsqrt<mode>2_internal): Likewise.
	(vsx_fms<mode>4): Likewise.
	(vsx_nfma<mode>4): Likewise.
	(vsx_eq<mode>): Likewise.
	(vsx_gt<mode>): Likewise.
	(vsx_ge<mode>): Likewise.
	(vsx_eq<mode>_p): Likewise.
	(vsx_gt<mode>_p): Likewise.
	(vsx_ge<mode>_p): Likewise.
	(vsx_xxsel<mode>): Likewise.
	(vsx_xxsel<mode>_uns): Likewise.
	(vsx_copysign<mode>3): Likewise.
	(vsx_float<VSi><mode>2): Likewise.
	(vsx_floatuns<VSi><mode>2): Likewise.
	(vsx_fix_trunc<mode><VSi>2): Likewise.
	(vsx_fixuns_trunc<mode><VSi>2): Likewise.
	(vsx_x<VSv>r<VSs>i): Likewise.
	(vsx_x<VSv>r<VSs>ic): Likewise.
	(vsx_btrunc<mode>2): Likewise.
	(vsx_b2trunc<mode>2): Likewise.
	(vsx_floor<mode>2): Likewise.
	(vsx_ceil<mode>2): Likewise.
	(vsx_<VS_spdp_insn>): Likewise.
	(vsx_xscvspdp): Likewise.
	(vsx_xvcvspuxds): Likewise.
	(vsx_float_fix_<mode>2): Likewise.
	(vsx_set_<mode>): Likewise.
	(vsx_extract_<mode>_internal1): Likewise.
	(vsx_extract_<mode>_internal2): Likewise.
	(vsx_extract_<mode>_load): Likewise.
	(vsx_extract_<mode>_store): Likewise.
	(vsx_splat_<mode>): Likewise.
	(vsx_xxspltw_<mode>): Likewise.
	(vsx_xxspltw_<mode>_direct): Likewise.
	(vsx_xxmrghw_<mode>): Likewise.
	(vsx_xxmrglw_<mode>): Likewise.
	(vsx_xxsldwi_<mode>): Likewise.
	(vsx_xscvdpspn): Tighten constraints to only use register classes
	the types use.
	(vsx_xscvspdpn): Likewise.
	(vsx_xscvdpspn_scalar): Likewise.

	* config/rs6000/rs6000.h (enum rs6000_reg_class_enum): Add wh, wi,
	wj, and wk constraints.
	(GPR_REG_CLASS_P): New helper macro for register classes targeting
	general purpose registers.

	* config/rs6000/rs6000.md (f32_dm): Use wh constraint for SDmode
	direct moves.
	(zero_extendsidi2_lfiwz): Use wj constraint for direct move of
	DImode instead of wm.  Use wk constraint for direct move of DFmode
	instead of wm.
	(extendsidi2_lfiwax): Likewise.
	(lfiwax): Likewise.
	(lfiwzx): Likewise.
	(movdi_internal64): Likewise.

	* doc/md.texi (PowerPC and IBM RS6000): Document wh, wi, wj, and
	wk constraints. Make the wy constraint documentation match them
	implementation.


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.vnet.ibm.com, phone: +1 (978) 899-4797

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