[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

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;
+        }
       }
     }
   }

llvm/test/Transforms/LICM/hoist-deref-load.ll

@@ -556,5 +556,87 @@ for.end:                                          ; preds = %for.inc, %entry, %e
   ret void
 }
 
+; Check that branch by condition "null check AND something" allows to hoist the
+; load.
+define void @test14(i32* noalias %a, i32* %b, i32* dereferenceable_or_null(4) %c, i32 %n, i1 %dummy_cond) #0 {
+
+; CHECK-LABEL: @test14
+; CHECK: load i32, i32* %c, align 4
+; CHECK: for.body:
+
+entry:
+  %not_null = icmp ne i32* %c, null
+  %dummy_and = and i1 %not_null, %dummy_cond
+  br i1 %dummy_and, label %not.null, label %for.end
+
+not.null:
+  %cmp11 = icmp sgt i32 %n, 0
+  br i1 %cmp11, label %for.body, label %for.end
+
+for.body:                                         ; preds = %not.null, %for.inc
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %not.null ]
+  %arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
+  %0 = load i32, i32* %arrayidx, align 4
+  %cmp1 = icmp sgt i32 %0, 0
+  br i1 %cmp1, label %if.then, label %for.inc
+
+if.then:                                          ; preds = %for.body
+  %1 = load i32, i32* %c, align 4
+  %arrayidx3 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
+  %2 = load i32, i32* %arrayidx3, align 4
+  %mul = mul nsw i32 %2, %1
+  store i32 %mul, i32* %arrayidx, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body, %if.then
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.inc, %entry, %not.null
+  ret void
+}
+
+; Check that guard by condition "null check AND something" allows to hoist the
+; load.
+define void @test15(i32* noalias %a, i32* %b, i32* dereferenceable_or_null(4) %c, i32 %n, i1 %dummy_cond) #0 {
+
+; CHECK-LABEL: @test15
+; CHECK: load i32, i32* %c, align 4
+; CHECK: for.body:
+
+entry:
+  %not_null = icmp ne i32* %c, null
+  %dummy_and = and i1 %not_null, %dummy_cond
+  call void(i1, ...) @llvm.experimental.guard(i1 %dummy_and) [ "deopt"() ]
+  %cmp11 = icmp sgt i32 %n, 0
+  br i1 %cmp11, label %for.body, label %for.end
+
+for.body:                                         ; preds = %entry, %for.inc
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
+  %arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
+  %0 = load i32, i32* %arrayidx, align 4
+  %cmp1 = icmp sgt i32 %0, 0
+  br i1 %cmp1, label %if.then, label %for.inc
+
+if.then:                                          ; preds = %for.body
+  %1 = load i32, i32* %c, align 4
+  %arrayidx3 = getelementptr inbounds i32, i32* %b, i64 %indvars.iv
+  %2 = load i32, i32* %arrayidx3, align 4
+  %mul = mul nsw i32 %2, %1
+  store i32 %mul, i32* %arrayidx, align 4
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body, %if.then
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %n
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.inc, %entry
+  ret void
+}
+
 attributes #0 = { nounwind uwtable }
 !0 = !{i64 4}