Summary:
## Problem
In method specialization, we don't translate the loads of specialized blocks (e.g. `n$0 = block:_fn_`) and only add them to the id map. Later on, when the block is called with arguments (`n$0(arg1,..argn))` we lookup the id and use the substitution for the block. However, this means, if the program uses the id loading the block (n$0) anywhere else in the program, we have no declaration for it.
## When does this happen?
For blocks that return a nullable result, objC programs usually do a null check as in the following example:
```
typedef id _Nullable (^BlockType)(id object);
+ (void)useBlock:(int) x
myBlock:(BlockType)myBlock{
if (myBlock){
myBlock(x);
}
}
+ (void)callUseBlock{
[X useBlock 1 myBlock:^id(id object) {
return nil;
}];
}
```
Here, method specialization currently ignores the loads of this block (`n$0=*&myBlock:_fn_(*)`) which results in having variables in prune nodes that are not defined anywhere in the CFG (like `n$0`).
This confuses control variable analysis when the conditional is wrapped in a loop because it cannot lookup where `n$0` is coming from.
## Fix
This diff fixes the issue by translating the loading of the blocks.
Reviewed By: dulmarod
Differential Revision: D21642924
fbshipit-source-id: 2bc0442ff
Ezgi Çiçek
7b75ee7f5a
