On 10/01/14 17:37, Andrew Pinski wrote: > 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. >
Why? R. > 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. >
