ASDenysPetrov added a comment.
@steakhal
> If index1 and index2 has the same value, we should not be confident that the
> x == y holds.
Thanks! Now I see. Shame on me =)
> We know where it points to (aka. the pointer's value is conjured), but we
> don't know what the value if there.
Absolutely right. I looked at this patch after a while and don't currently see
a proper solution.
> I feel like this problem should be handled by some sort of invalidation
> mechanism.
Definitely it should be some criteria/mark/flag about the region invalidation.
Maybe someone more confident could prompt us how to.
================
Comment at: clang/test/Analysis/PR9289.cpp:13-21
+int index_int(const int *a, int index) {
+ int var;
+ int ret = 0;
+ if (a[42] < 2)
+ var = 1;
+ if (a[42] < 2)
+ ret = var; // no warning about garbage value
----------------
steakhal wrote:
> Why do we test this?
> Here we can //reason// about the index.
> This patch preserves the current behavior relating to this.
This is a root case of the bug which this patch came from. I decided to vary it
by using an explicit index.
================
Comment at: clang/test/Analysis/PR9289.cpp:36-40
+ if (a[index] < 2)
+ var = 1;
+ index = index2;
+ if (a[index] < 2)
+ ret = var; // expected-warning{{Assigned value is garbage or undefined
[core.uninitialized.Assign]}}
----------------
steakhal wrote:
> I'm not sure why do you overwrite the `index` if you could simply index with
> `index2` instead in the following expression. That would make no difference,
> only make the test more readable IMO.
> Same comment for all the`*_change` test cases.
My intention is to retain `index` inside brackets. Just to check that `index`
changed indeed.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D81254/new/
https://reviews.llvm.org/D81254
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