On Wed, Mar 30, 2011 at 11:13 AM, Ira Rosen <ira.ro...@linaro.org> wrote: > Hi, > > With this patch a data-ref is marked as unconditionally read or > written also if its adjacent field is read or written unconditionally > in the loop. > My concern is that this is not safe enough, even though the fields > have to be non-pointers and non-aggregates, and this optimization is > applied only with -ftree-loop-if-convert-stores flag. > > Bootstrapped on powerpc64-suse-linux and tested on x86_64-suse-linux. > > OK for trunk?
The restrictions do not make too much sense to me. For the C++ memory model we can't do speculative stores at all, but for the rest I'd say just checking if the data-refs access the same object is enough, thus, instead of same_data_refs (a, b) simply check operand_equal_p (DR_BASE_ADDRESS (a), DR_BASE_ADDRESS (b), 0) or operand_equal_p (get_base_address (DR_REF (a)), get_base_address (DR_REF (b)), 0), whatever makes more sense (I always confuse what the contents of the various DR fields are). Thanks, Richard. > Thanks, > Ira > > > ChangeLog: > > * tree-if-conv.c (memrefs_read_or_written_unconditionally): Return > true > if an adjacent field of the data-ref is accessed unconditionally. > > testsuite/ChangeLog: > > * gcc.dg/vect/if-cvt-stores-vect-ifcvt-18.c: New test. > * gcc.dg/vect/vect.exp: Run if-cvt-stores-vect* tests with > -ftree-loop-if-convert-stores. >
