[Patch]: PR49868: Named address space support for AVR, #5

[Georg-Johann Lay]

Denis Chertykov wrote:

> Let's wait for
> http://gcc.gnu.org/ml/gcc-patches/2011-10/msg01874.html
> Denis.

This are yet more intrinsic named address spaces:

* __pgm1, ... __pgm5 are 16-bit address spaces that refer to
  the n-th 64k chunk of flash. Counting starts at 0.
  The 0-th address space __pgm is already upstream.

* __pgmx is a 24-bit address space located in flash.


The annoyance in this patch is the movmemhi insn:

* Register allocator does a bad job and might lead to spills
  inside the copy loop so that it is no more guaranteed that
  tmp_reg contains the value to be copied because move insns
  use that register implicitly.  Besides that, spilling in
  the copy loop leads to unfortunate code. See respective
  FIXMEs in avr.c:avr_emit_movmemhi()

* Using match_dup in respective patterns shreds web.c to that
  the insns need up to with 11 operands.

Besides that there are caveats and binutils is missing some support:

* To place variables in __pgm1 ... __pgm5 in appropriate sections
  a custom linker script is needed.  Data is put in sections
  progmem1.data ... __progmem5.data, respectively, and these
  sections must be treated in the linker script.

* Address computation for the 24-bit address space is performed
  as signed 16-bit.  Thus, accessing an array var[i] for example
  it is not possible to reach locations that are farther away
  than +/- 32768 bytes from var[0].

* It is not possible to assemble a 24-bit address, see the
  assembler warning generated in avr.c:avr_assemble_integer().

  This warning is triggered for code like

	extern const __pgmx int ivar;
	const __pgmx void * var = &ivar;

	.global	var
		.data
		.type	var, @object
		.size	var, 3
	var:
		.word	ivar
		.warning	"24-bit address needs binutils extension for hh8(ivar)"
		.byte	0	 ;  hh8(ivar)



The patch passes C tests with one FAIL less (SVN 181349):

gcc.dg/pr43300.c (internal compiler error)

./gcc.dg/pr43300.c: In function 'foo':
./gcc.dg/pr43300.c:19:1: internal compiler error: in commit_one_edge_insertion,
at cfgrtl.c:1582

This tests passes now; seems that the changes to movmemhi allow that test to
PASS now (for whatever reason).

Ok for trunk?

Johann

gcc/
	PR target/49868
	* config/avr/avr.h (base_arch_s): Add field n_segments.
	(ADDR_SPACE_PGM1, ADDR_SPACE_PGM2, ADDR_SPACE_PGM3,
	ADDR_SPACE_PGM4, ADDR_SPACE_PGM5, ADDR_SPACE_PGMX): New address spaces.
	(AVR_HAVE_ELPM, AVR_HAVE_ELPMX): New defines.
	(INIT_EXPANDERS): New define.
	* config/avr/avr-protos.h (avr_mem_pgmx_p): New.
	(avr_init_expanders): New.
	(avr_emit_movmemhi, avr_out_movmem): New.
	(avr_xload_libgcc_p): New.
	* config/avr/avr-c.c (avr_register_target_pragmas): Register
	address spaces __pgm1, __pgm2,  __pgm3,  __pgm4  __pgm5,  __pgmx.
	(avr_cpu_cpp_builtins): Add built-in defines __PGM1,
	__PGM2, __PGM3, __PGM4, __PGM5, __PGMX.
	* config/avr/avr-devices.c (avr_arch_types): Set field n_segments.

	* config/avr/avr.c (AVR_SECTION_PROGMEM): Change define to cover
	3 bits instead of just 1.
	(xstring_empty, xstring_e, rampz_rtx): New static GTYed variables.
	(progmem_section): Change from section to array of sections.
	(progmem_section_prefix): New static variable.
	(avr_file_start): Print set for __RAMPZ__
	(avr_option_override): Move initialization of RTXes from here...
	(avr_init_expanders): ...to this new function.
	(avr_pgm_segment): New static function.
	(avr_decl_pgm_p): Handle error_mark_node.
	(avr_mem_pgmx_p, avr_decl_pgmx_p): New static functions.
	(avr_out_xload,	avr_find_unused_d_reg): New static functions.
	(expand_prologue, expand_epilogue): Use rampz_rtx.
	(print_operand): Hande CONST_STRING.
	(avr_xload_libgcc_p): New static function.
	(avr_out_lpm_no_lpmx, avr_out_lpm): Handle ELPM.
	(avr_progmem_p): Return 2 for 24-bit flash address space.
	(avr_out_sbxx_branch): Clean-up code from ASn macros.
	(out_movqi_r_mr, out_movqi_mr_r): Ditto. And recognize RAMPZ's
	address and print symbolically.
	(avr_asm_named_section, avr_section_type_flags,
	avr_encode_section_info, avr_asm_select_section,
	avr_addr_space_address_mode, avr_addr_space_pointer_mode,
	avr_addr_space_legitimate_address_p, avr_addr_space_convert,
	avr_addr_space_legitimize_address): Handle new address spaces.
	(avr_output_progmem_section_asm_op): New static function.
	(avr_asm_init_sections): Initialize progmem_section[].
	(adjust_insn_length): Handle ADJUST_LEN_XLOAD, ADJUST_LEN_MOVMEM.
	(avr_const_address_lo16): New static function.
	(avr_assemble_integer): Use it to handle 3-byte integers.
	(avr_emit_movmemhi, avr_out_movmem): New functions.
	
	* config/avr/constraints.md (Cpp): New constraint.
	* config/avr/predicates.md (nox_general_operand): Handle new
	address spaces.
	* config/avr/avr.md (unspec): Add UNSPEC_MOVMEM.
	(adjust_len): Add xload, movmem.
	(SP_ADDR): New define_constants.
	(isa): Add "lpm", "lpmx", "elpm", "elpmx".
	(enabled): Handle them.
	(load<mode>_libgcc): New expander.
	(*load.<mode>.libgcc): Rename to load_<mode>_libgcc.
	(xload8_A, xload<mode>_A, n_extendhipsi2): New insn-and-splits.
	(xload_8, xload_<mode>_libgcc, xload_<mode>, loadmem_elpm): New insns.
	(mov<mode>): Handle new address spaces.
	(movmemhi): Rewrite using avr_emit_movmemhi.
	(MOVMEM_r_d): New mode attribute.
	(movmem_<mode>, movmem_qi_elpm): New insns.
	(setmemhi, *clrmemqi, *clrmemhi, strlenhi, *strlenhi): Unquote
	C-code.  Use label instead of hard-coded instrunction lengths.
	
libgcc/
	PR target/49868
	* config/avr/t-avr (LIB1ASMFUNCS): Add _xload_2 _xload_3 _xload_4.
	* config/avr/lib1funcs.S (__xload_2, __xload_3, __xload_4):
	New functions.

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