[Bug target/60431] [PATCH] [TIC6X] target description missing abssi2 insn
joseph at codesourcery dot com
gcc-bugzilla@gcc.gnu.org
Wed Mar 5 18:26:00 GMT 2014
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.
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