------- Additional Comments From rguenth at gcc dot gnu dot org 2005-08-25 15:13 ------- Ok, here are some numbers. Unpatched vs. patched with the default of 4 results in about 1% compile time increase for tramp3d-v4 while decreasing runtime by about 15%. Raising it to higher levels does not improve runtime, but, f.i. with 16 it takes a 2% compile-time hit.
Times for building stage2 with 4/16 are not different, as are building stage3 with the built compiler. A good default number for Fortran would be so that it would be able to tell all members of array descriptors apart, for C/C++ 4 should be generally ok, though raising it to the Fortran default is an option. Specifically for GCC one could search for the largest in-struct array -- maybe the operands array in the tree structure. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22548
