On 11/19/13 10:17, Steven Bosscher wrote:
On Tue, Nov 19, 2013 at 5:43 PM, Richard Earnshaw wrote:
PR 54300 is a problem in regcprop where the compiler sees
(parallel [(set (x) (y)
(set (y) (x)]) (REG_UNUSED (y))
as a single-set insn (since the other operand, y, is not used) and
replaces a use of x with a use of y. However, it fails to take into
account that y has been clobbered in the insn itself.
Ah, wait. Incorrect use of single_set().
Try
------
}
- set = single_set (insn);
+ set = multiple_sets (insn) ? NULL_RTX : single_set (insn);
extract_insn (insn);
if (! constrain_operands (1))
fatal_insn_not_found (insn);
preprocess_constraints ();
single_set is defined to be true if we have a parallel with multiple
sets where all but one of those multiple sets are marked with REG_UNUSED.
I don't remember the history here, but that may have been to better
support divmod and similar insns.
jeff
