[PATCH] [analyzer] Do not reinitialize static globals when the function is called more than once along a path

Ted Kremenek kremenek at apple.com
Wed Feb 6 15:24:48 PST 2013

On Feb 6, 2013, at 3:21 PM, Ted Kremenek <kremenek at apple.com> wrote:

> On Feb 6, 2013, at 3:15 PM, Anna Zaks <ganna at apple.com> wrote:
>> Currently, we reset the static variables with initializers on every visit to the function along a path. The solution might be a bit hacky as we check if the region has been stored something other than a LazyCompoundVal to find out if the static variable has been assigned to previously.
> Hi Anna,
> Why not just record the initialization in a side-table in the GDM?  That seems a lot cleaner.  This patch seems to rely on all the other pieces working correctly.  It also doesn't seem correct.  A static variable for an Objective-C pointer is guaranteed to be a valid value (it is zero-initialized), even if we haven't visited the initializer yet.  For example:
>   static id x;  // this is always zero-initialized
> Ted

Put another way, this patch seems to rely on the value of a variable being "uninitialized" to indicate whether or not the initializer has been executed.  That's not a valid assumption.  For example:

  static id x = foo(x);

is "okay" in Objective-C.
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