2012/1/10 Georg-Johann Lay <a...@gjlay.de>: > This patch extends the semantics of 24-bit __pgmx address space qualifier to > cover RAM and Flash. > > RAM is represented by setting the high byte of 24-bit address to 0x80. The > code > to read from 24-bit address space decides at runtime what instruction to use > to > read by if-else decision depending on bit 23 of the address, i.e. the code > looks like. > > if address.23 > return LD reg, Z // read from RAM > else > if have RAMPZ > RAMPZ = address.msb > return LPM reg, Z // read from Flash > > The code in avr.c actually gets simpler because more work is shifted to libgcc > as the code to emit gets more complex. > > Moreover, there is better separation of 16-bit address spaces and 24-bit > address spaces because even on small devices with just 1 flash segment 24-bit > pointers make sense now. > > Ok for trunk? > > This should be the last patch for 4.7 from my side that adds new > functionality, > so that all what remains is documentation and release note updates, test cases > and bug fixes. > > Unfortunately, the address space implementation in GCC is odd from the user > perspective, in particular when dealing with literals. > > Johann > > libgcc/ > PR target/49868 > Extend __pgmx semantics to linearize memory. > * config/avr/t-avr (LIB1ASMFUNCS): Add _xload_1, _movmemx. > * config/avr/lib1funcs.S (__xload_1): New function. > (__movmemx_qi, __movmemx_hi): New functions. > (__xload_2, __xload_3, __xload_4): Rewrite to fit new __pgmx > semantics. > > gcc/ > PR target/49868 > Extend __pgmx semantics to linearize memory. > * config/avr/avr.md (mov<mode>): Use avr_xload_libgcc_p to > determine if code comes inline or from libgcc. > (MOVMEM_r_d:HI): Add "w" to constraint for better preference. > (movmem_qi, movmem_qi): Set constraint #2 to "n". > (movmem_qi_elpm, movmem_hi_elpm): Remove insns. > (movmemx_qi, movmemx_hi): New insns. > (xload_<mode>_libgcc): Rewrite to new insn condition. > (xload_<mode>): Remove insns. > * config/avr/avr.c (avr_out_xload): Rewrite: Only need to handle > cases that don't satisfy avr_xload_libgcc_p(). > (avr_addr_space_convert): Allow converting in any direction. > (avr_addr_space_subset_p): Return always true. > (avr_xload_libgcc_p): Rewrite to fit new __pgmx semantics. > (avr_emit_movmemhi): Ditto. > (avr_out_lpm): No need to handle ADDR_SPACE_PGMX any more. > (avr_out_movmem): Ditto. > (AVR_SYMBOL_FLAG_PROGMEM): New macro. > (AVR_SYMBOL_SET_ADDR_SPACE): New macro. > (AVR_SYMBOL_GET_ADDR_SPACE): New macro. > (avr_encode_section_info): Encode 'progmem' in symbol flags. > (output_reload_in_const): Don't zero-extend any 24-bit symbols.
Approved. Denis.
