[PATCH] D28181: [MemDep] NFC walk invariant.group graph only down

[Piotr Padlewski via Phabricator via llvm-commits]

Prazek created this revision.
Prazek added a reviewer: reames.
Prazek added a subscriber: llvm-commits.

By using stripPointerCasts we can get to the root
value and then walk down the bitcast graph


https://reviews.llvm.org/D28181

Files:
  lib/Analysis/MemoryDependenceAnalysis.cpp


Index: lib/Analysis/MemoryDependenceAnalysis.cpp
===================================================================
--- lib/Analysis/MemoryDependenceAnalysis.cpp
+++ lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -358,24 +358,13 @@
       LoadOperandsQueue.push_back(V);
   };
 
-  TryInsertToQueue(LoadOperand);
+  // Insert the ptr after all casts and geps 0. This way we can search
+  // cast graph down only
+  TryInsertToQueue(LoadOperand->stripPointerCasts());
   while (!LoadOperandsQueue.empty()) {
     const Value *Ptr = LoadOperandsQueue.pop_back_val();
     assert(Ptr);
-    if (isa<GlobalValue>(Ptr))
-      continue;
-
-    // Value comes from bitcast: Ptr = bitcast x. Insert x.
-    if (auto *BCI = dyn_cast<BitCastInst>(Ptr))
-      TryInsertToQueue(BCI->getOperand(0));
-    // Gep with zeros is equivalent to bitcast.
-    // FIXME: we are not sure if some bitcast should be canonicalized to gep 0
-    // or gep 0 to bitcast because of SROA, so there are 2 forms. When typeless
-    // pointers will be upstream then both cases will be gone (and this BFS
-    // also won't be needed).
-    if (auto *GEP = dyn_cast<GetElementPtrInst>(Ptr))
-      if (GEP->hasAllZeroIndices())
-        TryInsertToQueue(GEP->getOperand(0));
+    assert(!isa<GlobalValue>(Ptr));
 
     for (const Use &Us : Ptr->uses()) {
       auto *U = dyn_cast<Instruction>(Us.getUser());
@@ -388,7 +377,11 @@
         TryInsertToQueue(U);
         continue;
       }
-      // U = getelementptr Ptr, 0, 0...
+      // Gep with zeros is equivalent to bitcast.
+      // FIXME: we are not sure if some bitcast should be canonicalized to gep 0
+      // or gep 0 to bitcast because of SROA, so there are 2 forms. When typeless
+      // pointers will be ready then both cases will be gone (and this BFS
+      // also won't be needed).
       if (auto *GEP = dyn_cast<GetElementPtrInst>(U))
         if (GEP->hasAllZeroIndices()) {
           TryInsertToQueue(U);


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