http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60431
--- Comment #3 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- The semantics of the abssi2 insn pattern on the most negative integer are that it returns the argument unchanged (RTL operations are generally modulo; the semantics don't depend on whether -fwrapv is used). Thus, a saturating abs instruction is unsuitable for implementing that pattern; you need to make the machine-independent compiler able to use ssabssi2 to expand ABS_EXPR-with-undefined-overflow (i.e. ABS_EXPR without flag_wrapv or flag_trapv), when the saturating pattern is present but not the non-saturating pattern.
