[PATCH] D23032: Rewrite the use optimizer to be less memory intensive and 50% faster.Fixes PR28670

[Daniel Berlin via llvm-commits]

dberlin marked 10 inline comments as done.

================
Comment at: lib/Transforms/Utils/MemorySSA.cpp:1226
@@ +1225,3 @@
+  // increment the PopEpoch to account for this.
+  while (!DT->dominates(VersionStack.back()->getBlock(), BB)) {
+    VersionStack.pop_back();
----------------
george.burgess.iv wrote:
> Looks like we can query the DT a lot less if we delete all `VersionStack` elements with the same BB as `VersionStack.back()`. Unsure how expensive those queries are, though, so it may or may not matter.
FWIW: It doesn't matter.
But i changed it.



https://reviews.llvm.org/D23032