[PATCH] D44564: [BasicAA] Relax restriction on PHI node handling.

[Max Kazantsev via Phabricator via llvm-commits]

mkazantsev added inline comments.


================
Comment at: lib/Analysis/BasicAliasAnalysis.cpp:1517
   bool isRecursive = false;
-  for (Value *PV1 : PN->incoming_values()) {
-    if (isa<PHINode>(PV1))
-      // If any of the source itself is a PHI, return MayAlias conservatively
-      // to avoid compile time explosion. The worst possible case is if both
-      // sides are PHI nodes. In which case, this is O(m x n) time where 'm'
-      // and 'n' are the number of PHI sources.
-      return MayAlias;
+  unsigned phiCount = 0;
+  do {
----------------
Please follow LLVM naming convention.


================
Comment at: lib/Analysis/BasicAliasAnalysis.cpp:1553
+    // is O(m x n) time where 'm' and 'n' are the number of PHI sources.
+    if (phiCount > 0 && V1Srcs.size() > 0)
+      return MayAlias;
----------------
`V1Srcs.empty()`?


================
Comment at: lib/Analysis/BasicAliasAnalysis.cpp:1566
   AliasResult Alias =
       aliasCheck(V2, V2Size, V2AAInfo, V1Srcs[0],
                  PNSize, PNAAInfo, UnderV2);
----------------
How do we know that V1Srcs is not empty at this point?


Repository:
  rL LLVM

https://reviews.llvm.org/D44564