From 2dbbd64cb7b3340ca692eb75e789048196b9d33b Mon Sep 17 00:00:00 2001
From: Max Kazantsev <max.kazantsev@azul.com>
Date: Mon, 6 Aug 2018 11:14:18 +0000
Subject: Re-enable "[ValueTracking] Teach
 isKnownNonNullFromDominatingCondition about AND"

The patch was reverted because of bug detected by sanitizer. The bug is fixed,
respective tests added.

Differential Revision: https://reviews.llvm.org/D50172

llvm-svn: 339005
---
 llvm/lib/Analysis/ValueTracking.cpp | 43 ++++++++++++++++++++++++++++---------
 1 file changed, 33 insertions(+), 10 deletions(-)

(limited to 'llvm/lib/Analysis/ValueTracking.cpp')

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index edd46c5..afaa800 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1860,19 +1860,42 @@ static bool isKnownNonNullFromDominatingCondition(const Value *V,
         (Pred != ICmpInst::ICMP_EQ && Pred != ICmpInst::ICMP_NE))
       continue;
 
+    SmallVector<const User *, 4> WorkList;
+    SmallPtrSet<const User *, 4> Visited;
     for (auto *CmpU : U->users()) {
-      if (const BranchInst *BI = dyn_cast<BranchInst>(CmpU)) {
-        assert(BI->isConditional() && "uses a comparison!");
+      assert(WorkList.empty() && "Should be!");
+      if (Visited.insert(CmpU).second)
+        WorkList.push_back(CmpU);
+
+      while (!WorkList.empty()) {
+        auto *Curr = WorkList.pop_back_val();
+
+        // If a user is an AND, add all its users to the work list. We only
+        // propagate "pred != null" condition through AND because it is only
+        // correct to assume that all conditions of AND are met in true branch.
+        // TODO: Support similar logic of OR and EQ predicate?
+        if (Pred == ICmpInst::ICMP_NE)
+          if (auto *BO = dyn_cast<BinaryOperator>(Curr))
+            if (BO->getOpcode() == Instruction::And) {
+              for (auto *BOU : BO->users())
+                if (Visited.insert(BOU).second)
+                  WorkList.push_back(BOU);
+              continue;
+            }
+
+        if (const BranchInst *BI = dyn_cast<BranchInst>(Curr)) {
+          assert(BI->isConditional() && "uses a comparison!");
 
-        BasicBlock *NonNullSuccessor =
-            BI->getSuccessor(Pred == ICmpInst::ICMP_EQ ? 1 : 0);
-        BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor);
-        if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent()))
+          BasicBlock *NonNullSuccessor =
+              BI->getSuccessor(Pred == ICmpInst::ICMP_EQ ? 1 : 0);
+          BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor);
+          if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent()))
+            return true;
+        } else if (Pred == ICmpInst::ICMP_NE &&
+                   match(Curr, m_Intrinsic<Intrinsic::experimental_guard>()) &&
+                   DT->dominates(cast<Instruction>(Curr), CtxI)) {
           return true;
-      } else if (Pred == ICmpInst::ICMP_NE &&
-                 match(CmpU, m_Intrinsic<Intrinsic::experimental_guard>()) &&
-                 DT->dominates(cast<Instruction>(CmpU), CtxI)) {
-        return true;
+        }
       }
     }
   }
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