[ValueTracking] Teach isKnownNonNullFromDominatingCondition about AND

`isKnownNonNullFromDominatingCondition` is able to prove non-null basing on `br` or `guard`
by `%p != null` condition, but is unable to do so basing on `(%p != null) && %other_cond`.
This patch allows it to do so.

Differential Revision: https://reviews.llvm.org/D50172
Reviewed By: reames

llvm-svn: 338990

1 files changed, 28 insertions, 10 deletions

diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index edd46c5..65c5d0e 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1861,18 +1861,36 @@ static bool isKnownNonNullFromDominatingCondition(const Value *V,
       continue;
 
     for (auto *CmpU : U->users()) {
-      if (const BranchInst *BI = dyn_cast<BranchInst>(CmpU)) {
-        assert(BI->isConditional() && "uses a comparison!");
+      SmallVector<const User *, 4> WorkList;
+      SmallPtrSet<const User *, 4> Visited;
+      Visited.insert(CmpU);
+      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.
+        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;
+        }
       }
     }
   }