PowerPC: Add support for 1,024 bit DMR registers.

PowerPC: Add support for 1,024 bit DMR registers.

This patch is a prelimianry patch to add the full 1,024 bit dense math register
(DMRs) for -mcpu=future.  The MMA 512-bit accumulators map onto the top of the
DMR register.

This patch only adds the new 1,024 bit register support.  It does not add
support for any instructions that need 1,024 bit registers instead of 512 bit
registers.

I used the new mode 'TDOmode' to be the opaque mode used for 1,024 bit
registers.  The 'wD' constraint added in previous patches is used for these
registers.  I added support to do load and store of DMRs via the VSX registers,
since there are no load/store dense math instructions.  I added the new keyword
'__dmr' to create 1,024 bit types that can be loaded into DMRs.  At present, I
don't have aliases for __dmr512 and __dmr1024 that we've discussed internally.

The patches have been tested on both little and big endian systems.  Can I check
it into the master branch?

2024-03-19   Michael Meissner  <meissner@linux.ibm.com>

gcc/

	* config/rs6000/mma.md (UNSPEC_DM_INSERT512_UPPER): New unspec.
	(UNSPEC_DM_INSERT512_LOWER): Likewise.
	(UNSPEC_DM_EXTRACT512): Likewise.
	(UNSPEC_DMR_RELOAD_FROM_MEMORY): Likewise.
	(UNSPEC_DMR_RELOAD_TO_MEMORY): Likewise.
	(movtdo): New define_expand and define_insn_and_split to implement 1,024
	bit DMR registers.
	(movtdo_insert512_upper): New insn.
	(movtdo_insert512_lower): Likewise.
	(movtdo_extract512): Likewise.
	(reload_dmr_from_memory): Likewise.
	(reload_dmr_to_memory): Likewise.
	* config/rs6000/rs6000-builtin.cc (rs6000_type_string): Add DMR
	support.
	(rs6000_init_builtins): Add support for __dmr keyword.
	* config/rs6000/rs6000-call.cc (rs6000_return_in_memory): Add support
	for TDOmode.
	(rs6000_function_arg): Likewise.
	* config/rs6000/rs6000-modes.def (TDOmode): New mode.
	* config/rs6000/rs6000.cc (rs6000_hard_regno_nregs_internal): Add
	support for TDOmode.
	(rs6000_hard_regno_mode_ok_uncached): Likewise.
	(rs6000_hard_regno_mode_ok): Likewise.
	(rs6000_modes_tieable_p): Likewise.
	(rs6000_debug_reg_global): Likewise.
	(rs6000_setup_reg_addr_masks): Likewise.
	(rs6000_init_hard_regno_mode_ok): Add support for TDOmode.  Setup reload
	hooks for DMR mode.
	(reg_offset_addressing_ok_p): Add support for TDOmode.
	(rs6000_emit_move): Likewise.
	(rs6000_secondary_reload_simple_move): Likewise.
	(rs6000_preferred_reload_class): Likewise.
	(rs6000_secondary_reload_class): Likewise.
	(rs6000_mangle_type): Add mangling for __dmr type.
	(rs6000_dmr_register_move_cost): Add support for TDOmode.
	(rs6000_split_multireg_move): Likewise.
	(rs6000_invalid_conversion): Likewise.
	* config/rs6000/rs6000.h (VECTOR_ALIGNMENT_P): Add TDOmode.
	(enum rs6000_builtin_type_index): Add DMR type nodes.
	(dmr_type_node): Likewise.
	(ptr_dmr_type_node): Likewise.

gcc/testsuite/

	* gcc.target/powerpc/dm-1024bit.c: New test.