OK, I filed a bug to trace it. http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42671
thanks Guozhi On Thu, Jan 7, 2010 at 6:23 PM, Richard Earnshaw <rearn...@arm.com> wrote: > > On Wed, 2010-01-06 at 18:26 +0000, Paul Brook wrote: >> On Wednesday 06 January 2010, Carrot Wei wrote: >> > So thumb2 can also use the instructions similar to thumb1, right? It >> > potentially has better performance and smaller code size. >> >> Technically yes, however in ARMv7 the relevant instruction (add.n <reg>, pc) >> is deprecated. > > Where'd you get that idea? > > Annex D of the ARM ARM says that the 16-bit instructions that add SP and > PC together (writing either SP or PC) are deprecated, but there's > nothing else using PC that's mentioned there other than trying to move > PC into SP or vice-versa. All the deprecated instructions in this area > are pretty meaningless in real life anyway. > > R. > >
