On Sun, Sep 20, 2009 at 6:10 PM, Andreas Schwab <sch...@linux-m68k.org> wrote: > Why is postreload converting (set (REGX) (CONST_INT A)) ... (set (REGX) > (CONST_INT B)) into (set (STRICT_LOW_PART (REGX)) (CONST_INT B))? That > looks like a pessimisation especially if the constants are small, since > STRICT_LOW_PART must not touch the high part. Is there a way for the > backend to stop postreload from doing this if the constants are in some > range? On the m68k, loading a constant in the range -128..127 in SI > mode is better than loading it in strict QI mode.
It's probably an omission of a check if A & ~GET_MODE_MASK (narrow_mode) is equal to zero. And of course a cost check is completely missing. Richard. > Andreas. > > -- > Andreas Schwab, sch...@linux-m68k.org > GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5 > "And now for something completely different." >