>>583
gccのinfoより引用。
---
`-Wstrict-aliasing'
This option is only active when `-fstrict-aliasing' is active. It
warns about code which might break the strict aliasing rules that
the compiler is using for optimization. The warning does not catch
all cases, but does attempt to catch the more common pitfalls. It
is included in `-Wall'.
---

ポインタの aliasing ってのは、結構最適化に影響を与えるものだ。
C99で登場した restrict ポインタなんてのは、そのためにできたものだし。
http://seclan.dll.jp/c99d/c99d07.htm#dt19991018