On 9/16/18 1:58 PM, Bernd Edlinger wrote: > Hi, > > this is a cleanup of the recently added strlen/strcpy/stpcpy > no nul warning code. > > Most importantly it moves the SSA_NAME handling from > unterminated_array to string_constant, thereby fixing > another round of xfails in the strlen and stpcpy test cases. > > I need to say that the fix for bug 86622 is relying in > type info on the pointer which is probably not safe in > GIMPLE in the light of the recent discussion. > > I had to add two further exceptions, which should > be safe in general: that is a pointer arithmentic on a string > literal is okay, and arithmetic on a string constant > that is exactly the size of the whole DECL, cannot > access an adjacent member. > > > Bootstrapped and reg-tested on x86_64-pc-linux-gnu. > Is it OK for trunk? > > > Thanks > Bernd. > > > patch-cleanup-no-nul.diff > > gcc: > 2018-09-16 Bernd Edlinger <bernd.edlin...@hotmail.de> > > * builtins.h (unterminated_array): Remove prototype. > * builtins.c (unterminated_array): Simplify. Make static. > (expand_builtin_strcpy_args): Don't use TREE_NO_WARNING here. > (expand_builtin_stpcpy_1): Remove warn_string_no_nul without effect. > * expr.c (string_constant): Handle SSA_NAME. Add more exceptions > where pointer arithmetic is safe. > * gimple-fold.c (get_range_strlen): Handle nonstr like in c_strlen. > (get_max_strlen): Remove the unnecessary mynonstr handling. > (gimple_fold_builtin_strcpy): Simplify. > (gimple_fold_builtin_stpcpy): Simplify. > (gimple_fold_builtin_sprintf): Remove NO_WARNING propagation > without effect. > (gimple_fold_builtin_strlen): Simplify. So my thinking right now is to go forward with the API change to allow c_strlen to fill in a structure with relevant tidbits about the string.
That in turn allows us to use simplify unterminated_array in a manner similar to what you've done in your patch -- while carrying forward the capabilities we need for Martin's nul terminator warnings. This would be combined with the expr.c chunks from your patch. However, most of the changes to drop NO_WARNING stuff should be handled separately. I don't think they're safe as-is. I'm also pretty sure the stpcpy changes in builtins.c aren't correct as-is. Jeff
