On 19/02/16 17:52, Jakub Jelinek wrote:
On Fri, Feb 19, 2016 at 05:42:34PM +0000, Alan Lawrence wrote:
This relates to FORTRAN code where different modules give different sizes to the
same array in a COMMON block (contrary to the fortran language specification).
SPEC have refused to patch the source code
(https://www.spec.org/cpu2006/Docs/faq.html#Run.05).
Hence, this patch provides a Fortran-specific option -funknown-commons that
marks such arrays as having unknown size - that is, NULL_TREE for both
TYPE_SIZE and max value of TYPE_DOMAIN. DECL_SIZE is preserved for e.g. output
in varasm.c.
On AArch64, it fixes the 416.gamess issue, and allows compiling 416.gamess
without the -fno-aggressive-loop-optimizations previously required (numerous
other PRs relating to 416.gamess).
I had to fix up a couple of places to deal with null TYPE_SIZE but in most cases
I think it is wrong to touch TYPE_SIZE/TYPE_SIZE_UNIT, IMHO it is much better
just
to ignore DECL_SIZE/DECL_SIZE_UNIT in the selected few places
(get_ref_base_and_extent, the tree-ssa-loop-niters.c analysis) if the switch
is on, for selected decls (aggregates with flexible array members and other
similar trailing arrays, arrays themselves; all only if DECL_COMMON).
So do you see...
(a) A global command-line option, which we check alongside DECL_COMMON, in (all
or some of the) places which currently deal with flexible array members? (I
guess the flag would have no effect for compiling C code...or
(b) do we require it to 'enable' the existing flexible array member support?)
(c) A new flag on each DECL, which we check in the places dealing with flexible
array members, which we set on those decls in the fortran frontend if a
fortran-frontend-only command-line option is passed?
(d) A new flag on each DECL, which replaces the check for flexible array
members, plus a global command-line option, which controls both setting the flag
(on DECL_COMMONs) in the fortran frontend, and also setting it on flexible array
members in the C frontend? This might be 'cleanest' but is also probably the
most change and I doubt I'm going to have time to do this for GCC 6...
(e) Some other scheme that I've not understood yet?
Thanks,
Alan
