On Wed, Aug 26, 2009 at 06:30:44AM -0700, Ian Lance Taylor wrote: > Bradley Lucier <luc...@math.purdue.edu> writes: > > > I've never seen the answer to the following question: Why do some > > versions of gcc that I build not have string substitutions in error > > messages? > > Perhaps you configured with --disable-intl? > > > > So, is -fschedule-insns an option to be avoided? > > -fschedule-insns should be avoided on Intel architectures. In general > -fschedule-insns tends to increase register lifespan, and because of the > small number of available registers this can sometimes befuddle the > register allocator, especially when asm instructions as used.
When I worked at AMD, I was starting to suspect that it may be more beneficial to re-enable the first schedule insns pass if you were compiling in 64-bit mode, since you have more registers available, and the new registers do not have hard wired uses, which in the past always meant a lot of spills (also, the default floating point unit is SSE instead of the x87 stack). I never got around to testing this before AMD and I parted company. > On PPC -fschedule-insns is normally beneficial, and it is turned on by > -O2. > > Ian -- Michael Meissner, IBM 4 Technology Place Drive, MS 2203A, Westford, MA, 01886, USA meiss...@linux.vnet.ibm.com
