diff options
Diffstat (limited to 'gcc/rtlanal.c')
| -rw-r--r-- | gcc/rtlanal.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c index 2f9696cc1fc..c9152ab0f8e 100644 --- a/gcc/rtlanal.c +++ b/gcc/rtlanal.c @@ -1020,6 +1020,45 @@ set_noop_p (set) return (GET_CODE (src) == REG && GET_CODE (dst) == REG && REGNO (src) == REGNO (dst)); } + +/* Return nonzero if an insn consists only of SETs, each of which only sets a + value to itself. */ + +int +noop_move_p (insn) + rtx insn; +{ + rtx pat = PATTERN (insn); + + /* Insns carrying these notes are useful later on. */ + if (find_reg_note (insn, REG_EQUAL, NULL_RTX)) + return 0; + + if (GET_CODE (pat) == SET && set_noop_p (pat)) + return 1; + + if (GET_CODE (pat) == PARALLEL) + { + int i; + /* If nothing but SETs of registers to themselves, + this insn can also be deleted. */ + for (i = 0; i < XVECLEN (pat, 0); i++) + { + rtx tem = XVECEXP (pat, 0, i); + + if (GET_CODE (tem) == USE + || GET_CODE (tem) == CLOBBER) + continue; + + if (GET_CODE (tem) != SET || ! set_noop_p (tem)) + return 0; + } + + return 1; + } + return 0; +} + /* Return the last thing that X was assigned from before *PINSN. If VALID_TO is not NULL_RTX then verify that the object is not modified up to VALID_TO. |