[PATCH] D13595: [SCEV][LV] Add SCEV Predicates and use them to re-implement stride versioning

[Sanjoy Das via llvm-commits]

sanjoy added inline comments.

================
Comment at: lib/Analysis/ScalarEvolution.cpp:9396
@@ +9395,3 @@
+  if (auto *I = dyn_cast<Instruction>(V))
+    return I->getParent() == Loc->getParent() ? I : nullptr;
+  return nullptr;
----------------
I know I'm bikeshedding a lot on this, but I think a better utility would be 

```
BasicBlock *getValueParent(Value *V) {
  if (I = dyn_cast<Instruction>(V))
    return I->getParent();
  return nullptr;
}
```

then where you call `getFirstInst` you could instead do

```
if (!FirstInst && getValueParent(C) == Loc)
  FirstInst = cast<Instruction>(C);
```

I think that will be clearer and almost as concise -- reading `getFirstInst(A,B,C)` does not really tell me anything about what it is supposed to do, especially since one of the parameters is named `FirstInst`.


http://reviews.llvm.org/D13595