https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99824
--- Comment #16 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-10 branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:ee15832c53d52656e562c29110f2be1cfb66c450 commit r10-9618-gee15832c53d52656e562c29110f2be1cfb66c450 Author: Richard Biener <rguent...@suse.de> Date: Tue Mar 30 11:22:52 2021 +0200 tree-optimization/99824 - avoid excessive integer type precision in VN VN sometimes builds new integer types to handle accesss where precision of the access type does not match the access size. The way ao_ref_init_from_vn_reference is computing the access size ignores the access type in case the ref operands have an outermost COMPONENT_REF which, in case it is an array for example, can be way larger than the access size. This can cause us to try building an integer type with precision larger than WIDE_INT_MAX_PRECISION eventually leading to memory corruption. The following adjusts ao_ref_init_from_vn_reference to only lower access sizes via the outermost COMPONENT_REF but otherwise honor the access size as specified by the access type. It also places an assert in integer type building that we remain in the limits of WIDE_INT_MAX_PRECISION. I chose the shared code where we set TYPE_MIN/MAX_VALUE because that will immediately cross the wide_ints capacity otherwise. 2021-03-30 Richard Biener <rguent...@suse.de> PR tree-optimization/99824 * stor-layout.c (set_min_and_max_values_for_integral_type): Assert the precision is within the bounds of WIDE_INT_MAX_PRECISION. * tree-ssa-sccvn.c (ao_ref_init_from_vn_reference): Use the outermost component ref only to lower the access size and initialize that from the access type. * gcc.dg/torture/pr99824.c: New testcase.
