------- Comment #3 from hjl dot tools at gmail dot com 2010-06-15 00:57 ------- We should consider:
1. The x86-64 psABI doesn't say how char/short should be extended as function parameters. 2. Gcc may not touch upper bits, PR 42324. 3. Gcc never depends on the upper bits which are properly extended in function parameters. 4. Icc may not touch the upper bits in function parameters on stack. 5. For a function without proper prototype, caller may not properly extend function parameters. I think the current way is safer. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44532