[PATCH] D16197: [LV] Vectorize first-order recurrences

[Matthew Simpson via llvm-commits]

mssimpso marked 4 inline comments as done.

================
Comment at: lib/Transforms/Vectorize/LoopVectorize.cpp:3564-3567
@@ +3563,6 @@
+  // recurrences are of the form "current = phi(initial, previous)".
+  auto *Initial = Phi->getIncomingValue(0);
+  auto *Previous = Phi->getIncomingValue(1);
+  if (!OrigLoop->isLoopInvariant(Initial))
+    std::swap(Initial, Previous);
+
----------------
mssimpso wrote:
> anemet wrote:
> > assert that Previous is loop-invariant at this point?
> Good idea.
We actually want the previous value to be loop-varying here. The initial value should be loop-invariant. I've added this assertion as well as a few others. 


http://reviews.llvm.org/D16197