Hi Allen On Tue, Jul 10, 2012 at 10:45 AM, Allen Martin <amar...@nvidia.com> wrote: > On Sat, Jul 07, 2012 at 03:15:36AM -0700, Albert ARIBAUD wrote: >> Hi Allen, >> >> On Fri, 6 Jul 2012 16:17:19 -0700, Allen Martin <amar...@nvidia.com> wrote:
[snip] >> > And I forgot to mention, the code bloat from disabling the >> > optimization is about 400 bytes (185136 -> 185540), so it's not bad, >> > but it still seems a shame to disable all short branches because of >> > one misoptimized one. 0.2% be my calcs >> >> Can this not be limited to compiling the object files which are known to be >> sensitive to the problem? >> > > I understand this issue fairly well now. It's a known bug in the > assembler that has already been fixed: > > http://sourceware.org/bugzilla/show_bug.cgi?id=12532 > > It only impacts preembtable symbols, and since u-boot doesn't have any > dynamic loadable objects it's only explictly defined weak symbols that > should trigger the bug. > > I built a new toolchain with binutils 2.22 and verified the bug is no > longer present there, and -fno-optimize-sibling-calls is the correct > workaround for toolchains that do have the bug, so conditionally > disabling the optimization for binutils < 2.22 seems like the right > fix. > > I ran a quick scrub of the u-boot tree and there's 195 instances of > __attribute__((weak)) spread across 123 source files, so I think just > disabling optimization on the failing object files may be too fragile, > as code movement could cause others to crop up. Adding -fno-optimize-sibling-calls for binutils < 2.22 - 0.2% code size increase for people using slightly older tools Maintain the tweaking of a set of files - someone using binutils >= 2.22 adds __attribute__((weak)) to a single function and *BAM* three months later someone complains that something broke I vote option 1 I do wonder, though, if we should spit out warnings when applying workaraounds for older tool-chains? Regards, Graeme _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
