On Thu, Jul 14, 2011 at 11:44 PM, Eric Botcazou <ebotca...@adacore.com> wrote: > Hi, > > this is a regression present on mainline and 4.6 branch. The compiler crashes > during gimplification because there is a COMPOUND_EXPR shared between the > TYPE_SIZE and TYPE_SIZE_UNIT expressions of an array type. Now this isn't > supposed to happen because we run an unsharing pass before gimplification. > > The problem here is that we have a forward declaration (DECL_EXPR) of a > pointer > type to the array type. So, during the marking phase of the unsharing pass, > the array type gets marked as visited through the pointer, which prevents it > from being walked during the same phase when its own DECL_EXPR is processed. > > This pointer/pointed-to type business is an old pattern. Five years ago, > Olivier changed gimplify_type_sizes like so: > > 2006-10-06 Olivier Hainque <hain...@adacore.com> > > * gimplify.c (gimplify_type_sizes) [POINTER_TYPE, REFERENCE_TYPE]: > Don't recurse on the pointed-to type. > > because of a related problem. It turns out that we need the same change in > the > DECL_EXPR case of walk_tree_1 to fix the bug at hand, which is sort of logical > as there is a strong relationship between them: > > case DECL_EXPR: > /* If this is a TYPE_DECL, walk into the fields of the type that it's > defining. We only want to walk into these fields of a type in this > case and not in the general case of a mere reference to the type. > > The criterion is as follows: if the field can be an expression, it > must be walked only here. This should be in keeping with the fields > that are directly gimplified in gimplify_type_sizes in order for the > mark/copy-if-shared/unmark machinery of the gimplifier to work with > variable-sized types. > > Note that DECLs get walked as part of processing the BIND_EXPR. */ > > > Tested on x86_64-suse-linux, OK for mainline and 4.6 branch?
Ok. Thanks, Richard. > > 2011-07-14 Eric Botcazou <ebotca...@adacore.com> > > PR middle-end/49732 > * tree.c (walk_tree_1) <DECL_EXPR>: Do not walk a pointed-to type. > > > 2011-07-14 Eric Botcazou <ebotca...@adacore.com> > > * gnat.dg/pointer_controlled.adb: New test. > > > -- > Eric Botcazou >
