On Friday 09 June 2017 03:59 PM, Georg-Johann Lay wrote:
Hi,
This patch adds support for devices that can access flash memory
by LD* instructions, hence there is no need to put .rodata in RAM.
The default linker script for the new multilib versions already
supports this feature, it's similar to avrtiny, cf.
https://sourceware.org/PR21472
This patch does the following:
* Add multilib variants avrxmega3 and avrxmega3/short-calls.
* Add new option -mshort-calls for multilib selection between
devices with <= 8KiB flash and > 8KiB flash.
* Add specs handling for -mshort-calls: The compiler knows
if this option is needed or not appropriate (similar to -msp8).
* Add new ISA feature AVR_ISA_RCALL for multilib selection
via -mshort-calls.
* Add a new row to architecture description that contains the
start address of flash memory in the RAM address range.
(The actual value is not needed).
* For devices with flash in RAM space, don't let .rodata
objects trigger need for __do_copy_data.
* Add some devices.
* Add configure test for Binutils PR21472.
* Adjust documentation etc.
Even the smaller devices with flash <= 8KiB support JMP+CALL,
but we get better code by assuming RJMP+RCALL: Jump tables
are more efficient and insn length computation is more exact
(CALL -> RCALL relaxation would need -mrelax and insn size
would still be 4 bytes).
Moreover, avr-libc uses __AVR_HAVE_JMP_CALL__ to determine
vector entry size, and libgcc uses that macro for flash size
estimation.
Hi Johann,
+ AVR_ISA_RCALL = 0x10 /* Use RJMP / RCALL even though RJMP / RCALL
+ are available (-mshort-calls). */
I think you meant "even though JMP/ CALL are avariable".
+AVR_MCU ("attiny817", ARCH_AVRXMEGA3, AVR_ISA_RCALL,
"__AVR_ATtiny817__", 0x3e00, 0x0, 0x2000)
+AVR_MCU ("attiny1616", ARCH_AVRXMEGA3, AVR_ISA_NONE,
"__AVR_ATtiny1616__", 0x3800, 0x0, 0x4000)
Add attiny1614 device.
AVR_MCU ("attiny1614", ARCH_AVRXMEGA3, AVR_ISA_NONE,
"__AVR_ATtiny1614__", 0x3800, 0x0, 0x4000)
Regards,
Pitchumani
