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From: "nizze86 at hotmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/42516] New: [m68k] Suboptimal halfword swap on coldfire Date: Sun, 27 Dec 2009 16:53:00 -0000 [thread overview] Message-ID: <bug-42516-15704@http.gcc.gnu.org/bugzilla/> (raw) When compiling the following function for a coldfire target, such as mcf5249: (using the following command line m68k-elf-gcc hswap.c -mcpu=5249 -S -O2) unsigned hswap(unsigned x) { return (x << 16) | (x >> 16); } gcc produces: hswap: link.w %fp,#0 move.l 8(%fp),%d1 move.l %d1,%d0 clr.w %d0 swap %d0 swap %d1 clr.w %d1 or.l %d1,%d0 unlk %fp rts Optimization level affects only instr ordering. the same function compiled for 68020 (using the following command line m68k-elf-gcc hswap.c -mcpu=68020 -S -O2) hswap: link.w %fp,#0 move.l 8(%fp),%d0 swap %d0 unlk %fp rts which is valid code for the coldfire target too and much smaller and faster this is using gcc 4.4.2 configured with --enable-languages=c --disable-libssp --with-arch=cf --with-cpu=5249 the same behaviour is present in gcc 3.4.6 too. -- Summary: [m68k] Suboptimal halfword swap on coldfire Product: gcc Version: 4.4.2 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: nizze86 at hotmail dot com GCC host triplet: amd64-unknown-linux GCC target triplet: m68k-elf http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42516
next reply other threads:[~2009-12-27 16:53 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2009-12-27 16:53 nizze86 at hotmail dot com [this message] 2009-12-27 17:19 ` [Bug target/42516] " schwab at linux-m68k dot org 2009-12-27 20:05 ` mkuvyrkov at gcc dot gnu dot org 2009-12-30 23:04 ` schwab at gcc dot gnu dot org 2009-12-30 23:05 ` schwab at linux-m68k dot org
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