Denis Chertykov schrieb: > 2011/6/9 Georg-Johann Lay : >> This is a tentative patch to fix PR46779 and hopefully also related >> issues like PR45291. >> > - /* Disallow QImode in stack pointer regs. */ > - if ((regno == REG_SP || regno == (REG_SP + 1)) && mode == QImode) > + /* Don't allocate data to non-GENERAL_REGS registers. */ > + > + if (regno >= 32) > return 0; > > I think that we not need in this code. > GCC core must bother about this. > > + > + if (GET_MODE_SIZE (mode) == 1) > return 1; > > I'm agree with this. > > + > + /* Disallow big registers that overlap the frame pointer. > + This will hopefully reduce the number of spill failures. */ > + > + if (GET_MODE_SIZE (mode) > 2 > + && regno <= REG_Y > + && regno + GET_MODE_SIZE (mode) >= REG_Y + 1) > + { > + return 0; > + } > > Fragment from GCC info: > -------------------------------------- > HARD_REGNO_MODE_OK (regno, mode)A C expression that is nonzero if it > is permissible to store a value of mode mode in hard register number > regno (or in several registers starting with that one). For a machine > where all registers are equivalent, a suitable definition is > > #define HARD_REGNO_MODE_OK(REGNO, MODE) 1 > > You need not include code to check for the numbers of fixed registers, > because the allocation mechanism considers them to be always occupied. > ----------------------------------------- > Again, GCC core must bother about this. > > - /* Otherwise disallow all regno/mode combinations that span r28:r29. */ > - if (regno <= (REG_Y + 1) && (regno + GET_MODE_SIZE (mode)) >= (REG_Y + 1)) > - return 0; > - > - if (mode == QImode) > - return 1; > - > - /* Modes larger than QImode occupy consecutive registers. */ > - if (regno + GET_MODE_SIZE (mode) > FIRST_PSEUDO_REGISTER) > - return 0; > - > > This is a right change. > > Denis. So the patch turns avr_hard_regno_mode_ok into plain vanilla... Johann -- PR target/46779 * config/avr/avr.c (avr_hard_regno_mode_ok): Rewrite. In particular, allow 8-bit values in r28 and r29. (avr_hard_regno_scratch_ok): Disallow any register that might be part of the frame pointer. (avr_hard_regno_rename_ok): Same.