[PATCH] D120000: [1/2] TLS loads opimization (hoist)

[Xiang Zhang via Phabricator via llvm-commits]

xiangzhangllvm added inline comments.


================
Comment at: llvm/lib/Transforms/Scalar/TLSVariableHoist.cpp:198
+
+  BasicBlock *PreHeader = L->getLoopPredecessor();
+
----------------
craig.topper wrote:
> Predecessor and PreHeader aren't quite the same thing. A PreHeader also has the loop as it's only successor.
Sorry, not much clear about it.
My understand is the PreHeader here not in loop (currently it is the outermost loop), so if here has  PreHeader for the loop, we can directly insert the bitcast instruction in  PreHeader. 
Because the PreHeader must dominate the Loop (It is the only way to go to Loop).


```
PreHeader
    |
    V
   Loop
```


Repository:
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  https://reviews.llvm.org/D120000/new/

https://reviews.llvm.org/D120000