[ConstraintElim] Extend checkOrAndOpImpliedByOther to handle and/or expr trees.

llvm/lib/Transforms/Scalar/ConstraintElimination.cpp

@@ -1498,9 +1498,6 @@ static bool checkOrAndOpImpliedByOther(
     FactOrCheck &CB, ConstraintInfo &Info, Module *ReproducerModule,
     SmallVectorImpl<ReproducerEntry> &ReproducerCondStack,
     SmallVectorImpl<StackEntry> &DFSInStack) {
-
-  CmpInst::Predicate Pred;
-  Value *A, *B;
   Instruction *JoinOp = CB.getContextInst();
   CmpInst *CmpToCheck = cast<CmpInst>(CB.getInstructionToSimplify());
   unsigned OtherOpIdx = JoinOp->getOperand(0) == CmpToCheck ? 1 : 0;
@@ -1511,22 +1508,40 @@ static bool checkOrAndOpImpliedByOther(
   if (OtherOpIdx != 0 && isa<SelectInst>(JoinOp))
     return false;
 
-  if (!match(JoinOp->getOperand(OtherOpIdx),
-             m_ICmp(Pred, m_Value(A), m_Value(B))))
-    return false;
-
-  // For OR, check if the negated condition implies CmpToCheck.
-  bool IsOr = match(JoinOp, m_LogicalOr());
-  if (IsOr)
-    Pred = CmpInst::getInversePredicate(Pred);
-
   // Optimistically add fact from first condition.
   unsigned OldSize = DFSInStack.size();
-  Info.addFact(Pred, A, B, CB.NumIn, CB.NumOut, DFSInStack);
+  auto InfoRestorer = make_scope_exit([&]() {
+    // Remove entries again.
+    while (OldSize < DFSInStack.size()) {
+      StackEntry E = DFSInStack.back();
+      removeEntryFromStack(E, Info, ReproducerModule, ReproducerCondStack,
+                           DFSInStack);
+    }
+  });
+  // For OR, check if the negated condition implies CmpToCheck.
+  bool IsOr = match(JoinOp, m_LogicalOr());
+  SmallVector<Value *, 4> Worklist({JoinOp->getOperand(OtherOpIdx)});
+  while (!Worklist.empty()) {
+    Value *Val = Worklist.pop_back_val();
+    Value *LHS, *RHS;
+    ICmpInst::Predicate Pred;
+    if (match(Val, m_ICmp(Pred, m_Value(LHS), m_Value(RHS)))) {
+      if (IsOr)
+        Pred = CmpInst::getInversePredicate(Pred);
+      Info.addFact(Pred, LHS, RHS, CB.NumIn, CB.NumOut, DFSInStack);
+      continue;
+    }
+    if (IsOr ? match(Val, m_LogicalOr(m_Value(LHS), m_Value(RHS)))
+             : match(Val, m_LogicalAnd(m_Value(LHS), m_Value(RHS)))) {
+      Worklist.push_back(LHS);
+      Worklist.push_back(RHS);
+      continue;
+    }
+    return false;
+  }
   if (OldSize == DFSInStack.size())
     return false;
 
-  bool Changed = false;
   // Check if the second condition can be simplified now.
   if (auto ImpliedCondition =
           checkCondition(CmpToCheck->getPredicate(), CmpToCheck->getOperand(0),
@@ -1540,16 +1555,10 @@ static bool checkOrAndOpImpliedByOther(
           1 - OtherOpIdx,
           ConstantInt::getBool(JoinOp->getType(), *ImpliedCondition));
 
-    Changed = true;
+    return true;
   }
 
-  // Remove entries again.
-  while (OldSize < DFSInStack.size()) {
-    StackEntry E = DFSInStack.back();
-    removeEntryFromStack(E, Info, ReproducerModule, ReproducerCondStack,
-                         DFSInStack);
-  }
-  return Changed;
+  return false;
 }
 
 void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,

llvm/test/Transforms/ConstraintElimination/or.ll

@@ -124,7 +124,7 @@ define i1 @test_or_chain_ule_1(i4 %x, i4 %y, i4 %z, i4 %a, i4 %b) {
 ; CHECK-NEXT:    [[C_3:%.*]] = icmp ule i4 2, [[X]]
 ; CHECK-NEXT:    [[C_4:%.*]] = icmp ule i4 2, [[A:%.*]]
 ; CHECK-NEXT:    [[OR_1:%.*]] = or i1 [[C_1]], [[C_2]]
-; CHECK-NEXT:    [[OR_2:%.*]] = or i1 [[OR_1]], [[C_3]]
+; CHECK-NEXT:    [[OR_2:%.*]] = or i1 [[OR_1]], true
 ; CHECK-NEXT:    [[OR_3:%.*]] = or i1 [[C_4]], [[OR_2]]
 ; CHECK-NEXT:    br i1 [[OR_3]], label [[BB1:%.*]], label [[EXIT:%.*]]
 ; CHECK:       bb1:

llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll

@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -p constraint-elimination -S %s | FileCheck %s
+
+define void @f(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: define void @f(
+; CHECK-SAME: i32 noundef [[V0:%.*]], i32 noundef [[V1:%.*]], i32 noundef [[V2:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*:]]
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0]], [[V1]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2]]
+; CHECK-NEXT:    [[AND1:%.*]] = and i1 [[CMP0]], [[CMP1]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND2:%.*]] = and i1 false, [[AND1]]
+; CHECK-NEXT:    br i1 [[AND2]], label %[[IF_THEN:.*]], label %[[RETURN:.*]]
+; CHECK:       [[IF_THEN]]:
+; CHECK-NEXT:    call void @side_effect()
+; CHECK-NEXT:    br label %[[RETURN]]
+; CHECK:       [[RETURN]]:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cmp0 = icmp sge i32 %v0, %v1
+  %cmp1 = icmp sge i32 %v1, %v2
+  %and1 = and i1 %cmp0, %cmp1
+  %cmp2 = icmp slt i32 %v0, %v2
+  %and2 = and i1 %cmp2, %and1
+  br i1 %and2, label %if.then, label %return
+
+if.then:
+  call void @side_effect()
+  br label %return
+
+return:
+  ret void
+}
+
+declare void @side_effect()