tree ced61048fff2011df88a073d54aec11a2f109780
parent a11f22f60673c6c9556976b49e64bf7fa751f4eb
author Jordan Rose <jordan_rose@apple.com> 1361990997 +0000
committer Jordan Rose <jordan_rose@apple.com> 1361990997 +0000

[analyzer] Teach FindLastStoreBRVisitor to understand stores of the same value.

Consider this case:

  int *p = 0;
  p = getPointerThatMayBeNull();
  *p = 1;

If we inline 'getPointerThatMayBeNull', we might know that the value of 'p'
is NULL, and thus emit a null pointer dereference report. However, we
usually want to suppress such warnings as error paths, and we do so by using
FindLastStoreBRVisitor to see where the NULL came from. In this case, though,
because 'p' was NULL both before and after the assignment, the visitor
would decide that the "last store" was the initialization, not the
re-assignment.

This commit changes FindLastStoreBRVisitor to consider all PostStore nodes
that assign to this region. This still won't catches changes made directly
by checkers if they re-assign the same value, but it does handle the common
case in user-written code and will trigger ReturnVisitor's suppression
machinery as expected.

<rdar://problem/13299738>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176201 91177308-0d34-0410-b5e6-96231b3b80d8