Joseph S. Myers wrote:
I tried building GCC with Graphite enabled and all the libraries it requires in a Canadian cross configuration (build = i686-pc-linux-gnu, host = i686-mingw32, target = arm-none-eabi). This failed with:
configure:11279: checking for the possibility to control the FPU configure:11282: error: in `/scratch/gcc/nightly-2009-03-19-mainline/arm-none-eabi/obj/ppl-mainline-0-arm-none-eabi-i686-mingw32': configure:11285: error: cannot run test program while cross compiling See `config.log' for more details.
If you use AC_RUN_IFELSE you need to have a (safe) default (fourth argument) for cross compiling. An individual case is of course straightforward to fix, but it appears there are other such problems in PPL. For example, the GMP checks appear to treat GMP as not available in the cross compiling case; they should fall back to a compile/link test if they can't do an execution test; having found that I didn't go on to try to work out whether other defaults are safe or not. While the cross case may result in slightly less efficient code (if workarounds have to be enabled for bugs that may in fact not be present), it needs to allow the library to be built and to have all its features (or at least all the features used by GCC: the behavior of GCC on a host must not depend on whether PPL was cross compiled).
Hi Joseph,
thanks for the detailed explanation. I admit we always have postoponed the issue of cross-compilation... to the point we almost forgot it. We will fix the PPL asap. Can we come back to you in case we are unsure about which defaults can be considered safe?
Would it be possible to have an official 0.10.1 bug-fix release with this fixed (and preferably without changes that would affect the code generated by GCC) for use with GCC 4.4 so that it is possible to enable Graphite in such configurations?
Work has already started for producing an official PPL 0.11 release. This will contain fixes for all the problems we discovered since the release of PPL 0.10 (mainly portability ones), a new "formatted output" feature that is needed in the MELT branch, plus other improvements, none of which affecting the code generated by GCC. I will write again when we can be more precise about the release schedule. All the best,
Roberto