strange warnings

[Roberto Ierusalimschy <roberto@...>]

When compiling Lua 5.1.4 with gcc (version 4.4.3) with option
-Wstrict-overflow=2, I get two warnings that I cannot understand:

lvm.c: In function ‘luaV_concat’:
lvm.c:300: warning: assuming signed overflow does not occur when simplifying conditional to constant

lua.c: In function ‘pmain’:
lua.c:353: warning: assuming signed overflow does not occur when simplifying conditional to constant

Does anyone have a clue about the cause of these warnings and/or how
to remove them? (The question is not about that kind of warning in
general, but why gcc signals it in these two specific cases.)

-- Roberto