rtx inc_src;
rtx condition;
rtx pattern;
+ rtx cc_reg = NULL_RTX;
+ rtx reg_orig = NULL_RTX;
/* The canonical doloop pattern we expect has one of the following
forms:
2) (set (reg) (plus (reg) (const_int -1))
(set (pc) (if_then_else (reg != 0)
(label_ref (label))
- (pc))). */
+ (pc))).
+
+ Some targets (ARM) do the comparison before the branch, as in the
+ following form:
+
+ 3) (parallel [(set (cc) (compare ((plus (reg) (const_int -1), 0)))
+ (set (reg) (plus (reg) (const_int -1)))])
+ (set (pc) (if_then_else (cc == NE)
+ (label_ref (label))
+ (pc))) */
pattern = PATTERN (doloop_pat);
{
rtx cond;
rtx prev_insn = prev_nondebug_insn (doloop_pat);
+ rtx cmp_arg1, cmp_arg2;
+ rtx cmp_orig;
- /* We expect the decrement to immediately precede the branch. */
+ /* In case the pattern is not PARALLEL we expect two forms
+ of doloop which are cases 2) and 3) above: in case 2) the
+ decrement immediately precedes the branch, while in case 3)
+ the compare and decrement instructions immediately precede
+ the branch. */
if (prev_insn == NULL_RTX || !INSN_P (prev_insn))
return 0;
cmp = pattern;
- inc = PATTERN (PREV_INSN (doloop_pat));
+ if (GET_CODE (PATTERN (prev_insn)) == PARALLEL)
+ {
+ /* The third case: the compare and decrement instructions
+ immediately precede the branch. */
+ cmp_orig = XVECEXP (PATTERN (prev_insn), 0, 0);
+ if (GET_CODE (cmp_orig) != SET)
+ return 0;
+ if (GET_CODE (SET_SRC (cmp_orig)) != COMPARE)
+ return 0;
+ cmp_arg1 = XEXP (SET_SRC (cmp_orig), 0);
+ cmp_arg2 = XEXP (SET_SRC (cmp_orig), 1);
+ if (cmp_arg2 != const0_rtx
+ || GET_CODE (cmp_arg1) != PLUS)
+ return 0;
+ reg_orig = XEXP (cmp_arg1, 0);
+ if (XEXP (cmp_arg1, 1) != GEN_INT (-1)
+ || !REG_P (reg_orig))
+ return 0;
+ cc_reg = SET_DEST (cmp_orig);
+
+ inc = XVECEXP (PATTERN (prev_insn), 0, 1);
+ }
+ else
+ inc = PATTERN (prev_insn);
/* We expect the condition to be of the form (reg != 0) */
cond = XEXP (SET_SRC (cmp), 0);
if (GET_CODE (cond) != NE || XEXP (cond, 1) != const0_rtx)
return 0;
-
}
else
{
return 0;
if ((XEXP (condition, 0) == reg)
+ /* For the third case: */
+ || ((cc_reg != NULL_RTX)
+ && (XEXP (condition, 0) == cc_reg)
+ && (reg_orig == reg))
|| (GET_CODE (XEXP (condition, 0)) == PLUS
- && XEXP (XEXP (condition, 0), 0) == reg))
+ && XEXP (XEXP (condition, 0), 0) == reg))
{
if (GET_CODE (pattern) != PARALLEL)
- /* The second form we expect:
+ /* For the second form we expect:
(set (reg) (plus (reg) (const_int -1))
(set (pc) (if_then_else (reg != 0)
(set (reg) (plus (reg) (const_int -1)))
(additional clobbers and uses)])
- So we return that form instead.
+ For the third form we expect:
+
+ (parallel [(set (cc) (compare ((plus (reg) (const_int -1)), 0))
+ (set (reg) (plus (reg) (const_int -1)))])
+ (set (pc) (if_then_else (cc == NE)
+ (label_ref (label))
+ (pc)))
+
+ which is equivalent to the following:
+
+ (parallel [(set (cc) (compare (reg, 1))
+ (set (reg) (plus (reg) (const_int -1)))
+ (set (pc) (if_then_else (NE == cc)
+ (label_ref (label))
+ (pc))))])
+
+ So we return the second form instead for the two cases.
+
*/
condition = gen_rtx_fmt_ee (NE, VOIDmode, inc_src, const1_rtx);