------- Additional Comments From nathan at gcc dot gnu dot org 2004-11-03 11:29 ------- I believe this is a problem with the tree optimizers being ABI blind. on 64bit ppc integral parameters and return values are correctly extended to 64 bits. This sign extension is inserted during the tree->rtl translation, and therefore cannot leverage any ssa-vrp information. Unfortunately RTL does not have VRP itself, but only condition-code propagation. Combine does not track values across basic blocks, so it too is blind in this case, as the register is written in two blocks.
-- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16802
