On Sun, Mar 20, 2005 at 01:59:44PM +0300, Denis Chertykov wrote: > The reload will generate addhi3 and reload will have a problem with > two modified regs (ZCMP_FLAGS, CARRY_FLAGS) which will be a bad > surprise for reload. :( As I remember.
In order to expose the flags register before reload, you *must* have load, store, reg-reg move, and add operations that do not modify the flags. Note, for instance, that i386 "add" instruction always modifies the flags, but the "lea" instruction does not. So we emit the later when reload emits an add. If you cannot meet these requirements, then you must represent "setcc" and "compare-and-branch" patterns as a single insn until after reload. You can then split them apart, followed by peep2 patterns to remove compare patterns that are redundant with immediately preceeding arithmetic. r~
