On Fri, Jan 10, 2014 at 7:14 AM, Richard Earnshaw <rearn...@arm.com> wrote: > It's incorrect to use CMN to compare with a negated operand if the > following condition is an inequality. This is because of boundary > conditions when the negated operations overflow (or when zero), since > the flags are then not the swapped version of the comparison.
I think the functions in the testcase need noclone attribute also. Thanks, Andrew > > This patch restricts the pattern to CC_Zmode (a new mode for the > comparison flags). > > gcc: > PR target/59744 > * aarch64-modes.def (CC_Zmode): New flags mode. > * aarch64.c (aarch64_select_cc_mode): Only allow NEG when the > condition represents an equality. > (aarch64_get_condition_code0): Handle CC_Zmode. > * aarch64.md (compare_neg<mode>): Restrict to equality > operations. > > testsuite: > PR target/59744 > * gcc.target/aarch64/cmn-neg.c: Use equality comparisons. > * gcc.target/aarch64/cmn-neg2.c: New test. > > Committed to trunk. > > R.
