ada: Refine upper array bound for bit packed array
8 September 2023 at 15:15
ada: Refine upper array bound for bit packed array When using bit-packed arrays, the compiler creates new array subtypes of 1-bit component indexed by integers. The existing routine checks the index subtype to find the min/max values. Bit-packed arrays being indexed by integers, the routines gives up as returning the maximum possible integer carries no useful information. This change adds a simple max_value routine that can evaluate very simple expressions by substituting variables by their min/max value. Bit-packed array subtypes are currently declared as: subtype bp_array is packed_bytes1 (0 .. integer((1 * Var + 7) / 8 - 1)); The simple max_value evaluator handles the bare minimum for this expression pattern. gcc/ada/ChangeLog: * gcc-interface/utils.cc (max_value): New. * gcc-interface/gigi.h (max_value): New. * gcc-interface/decl.cc (gnat_to_gnu_entity) <E_Array_Subtype>: When computing gnu_min/gnu_max, try to use max_value if there is an initial expression.