Georg-Johann Lay wrote:
> This patch fixes several issues with RAMP registers:
> * On Devices with more than 64 KiB RAM, RAMPZ is used as high-byte of
> RAM address. If RAMPZ is used to read flash, it must be reset to 0
> after the read so that RAM-read will operate correctly in the remainder.
> There is no support for RAM > 64 Ki so RAMPZ = 0 is in order.
> * The ISR epilogue restored RAMP* registers in the wrong order.
> * As RAMPZ is used both in ELPM and LD/LDD on some xmega core, the right
> condition to set RAMPZ prior to ELPM is "have ELPM", not "have RAMPZ".
> * Never read unintentionally from RAM because a flash address interpreted
> as a RAM address might point to the I/O area.
> Ok for trunk and 4.7?
The following change in expand_prologue is wrong:
- if (AVR_HAVE_RAMPZ
+ if (AVR_HAVE_RAMPD /* sic! */
similar in expand_epilogue.
Ok without that change?
> PR target/52461
> * config/avr/lib1funcs.S (__do_copy_data): Clear RAMPZ after usage
> if RAMPZ affects reading from RAM.
> (__tablejump_elpm__): Ditto.
> (.xload): Ditto.
> (__movmemx_hi): Ditto.
> (__do_global_ctors): Right condition for RAMPZ usage is "have ELPM".
> (__do_global_dtors): Ditto.
> (__xload_1, __xload_2, __xload_3, __xload_4): Ditto. And make weak.
> (__movmemx_hi): Ditto. And fix RAM-loop label.
> (__xload_1): Never read unintentionally from RAM.
> PR target/52461
> * gcc/config/avr/avr.c (expand_prologue): Depend save/restore of
> RAMPZ on HAVE_RAMPD, not HAVE_RAMPZ.
> (expand_epilogue): Ditto. And fix order of restoration to:
> RAMPZ, RAMPY, RAMPX, RAMPD.
> (avr_xload_libgcc_p): Always load __memx by lilbgcc call on
> big-RAM devices.
> (avr_out_lpm): Clear RAMPZ after usage if RAMPZ affects reading
> from RAM.
> (avr_out_xload): Never read unintentionally from RAM.
> * config/avr/avr.md (xload_8): Adjust insn length.