On 02/02/2017 10:10 PM, Martin Sebor wrote:
Bug 79352 points out that the gimple-ssa-printf pass doesn't allow for an array at the end of a struct to be treated as a poor man's flexible array member and hold a string that's longer than the upper bound of the array. Rather, the pass assumes that the string's length must at most as long as the upper bound of the array - 1.To allow for this the attached patch adjusts the get_range_strlen function the pass uses to obtain the range of string lengths to expose that bit of information. The patch introduces a call to array_at_struct_end_p to determine this but since the array is in a COMPONENT_REF that array_at_struct_end_p doesn't consider the patch extends the function to allow it to handle that case. When the string can reference such an array the pass considers it to be potentially unbounded in the worst (unlikely) case. Martin gcc-79352.diff PR tree-optimization/79352 - -fprintf-return-value doesn't handle flexible-like array members properly gcc/ChangeLog: PR tree-optimization/79352 * gimple-fold.c (get_range_strlen): Add argument. (get_range_strlen): Change return type to bool. (get_maxval_strlen): Pass in a dummy argument. * gimple-fold.h (get_range_strlen): Change return type to bool. * gimple-ssa-sprintf.c (get_string_length): Set unlikely counter. * tree.h (array_at_struct_end_p): Add argument. * tree.c (array_at_struct_end_p): Handle it.
OK. Jeff
