[Bug rtl-optimization/57425] [4.8 Regression] RTL alias analysis unprepared to handle stack slot sharing

[mikpelinux at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57425

--- Comment #13 from Mikael Pettersson <mikpelinux at gmail dot com> ---
Created attachment 32343
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32343&action=edit
4.8 backport of Joern's fixes

This is the backport of Joern's fixes to 4.8 I did last summer.  Tested w/o
regressions on x86_64, sparc64, powerpc64, armv5tel, and m68k.