2009/3/13 Paolo Bonzini <bonz...@gnu.org>: > These are all the !SHIFT_COUNT_TRUNCATED targets. > > For 4.5 I would like to improve our RTL canonicalization so that no > out-of-range shifts are ever in the RTL representation. > > This in turn means that the description given by SHIFT_COUNT_TRUNCATED > must be exact. Right now !SHIFT_COUNT_TRUNCATED means "I don't know", > I want it to mean "it is never truncated". > > I would like to know whether for avr,bfin,cris,frv,h8300,pdp11,rs6000 > (which define SHIFT_COUNT_TRUNCATED as 0) and for mcore,sh,vax (which > do not define it at all) it is right that shift counts are never > truncated.
AVR target do not define SHIFT_COUNT_TRUNCATED at all. > In addition, for arm and m68k I'd like to know whether bitfield > instructions truncate the bit position the same as shifts (8 bits for > arm, 6 bits for m68k). > > This information is particularly important for targets that do not > have a simulator in src. AVR don't have a hardware instructions for variable shifts. While AVR port emulate such shifts the 8bits register used for shift count. AVR port truncate shift counter to 8 bits. Denis.
