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[Bug target/46091] missed optimization: x86 bt/btc/bts instructions
- From: "avi at cloudius-systems dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 11 Aug 2017 22:23:38 +0000
- Subject: [Bug target/46091] missed optimization: x86 bt/btc/bts instructions
- Auto-submitted: auto-generated
- References: <bug-46091-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46091
--- Comment #2 from Avi Kivity <avi@cloudius-systems.com> ---
Another instance:
unsigned long clear(unsigned long x) {
return x & ~ ((unsigned long)1 << 63);
}
This compiles to movabs+andq, while it could compile to a single btr
instruction.