[ConstraintElim] Extend checkOrAndOpImpliedByOther to handle and/or expr trees. (#117123)

dtcxzyw · web-flow · commit 0f0c0c36e3e9 · 2024-11-27T09:04:52.000+08:00
This patch extends `checkOrAndOpImpliedByOther` to handle and/or trees. Limitation: At least one of the operands of root and/or instruction should be an icmp. That is, this patch doesn't support expressions like `(cmp1 & cmp2) & (cmp3 & cmp4)`. Closes #117107. Compile-time impact: http://llvm-compile-time-tracker.com/compare.php?from=69cc3f096ccbdef526bbd5a065a25c95122e87ee&to=919416d2c4c71e3b9fe533af2c168a36c7893be5&stat=instructions%3Au
diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/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 +1508,39 @@ 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);
+    }
+  });
+  bool IsOr = match(JoinOp, m_LogicalOr());
+  SmallVector<Value *, 4> Worklist({JoinOp->getOperand(OtherOpIdx)});
+  // Do a traversal of the AND/OR tree to add facts from leaf compares.
+  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)))) {
+      // For OR, check if the negated condition implies CmpToCheck.
+      if (IsOr)
+        Pred = CmpInst::getInversePredicate(Pred);
+      // Optimistically add fact from the other compares in the AND/OR.
+      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);
+    }
+  }
   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 +1554,10 @@ 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,
diff --git a/llvm/test/Transforms/ConstraintElimination/and-implied-by-operands.ll b/llvm/test/Transforms/ConstraintElimination/and-implied-by-operands.ll
@@ -497,4 +497,221 @@ entry:
   ret i1 %and
 }
 
+define void @and_tree_second_implies_first(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: @and_tree_second_implies_first(
+; 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
+}
+
+define void @and_tree_second_implies_first_perm1(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: @and_tree_second_implies_first_perm1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0:%.*]], [[V1:%.*]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2:%.*]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND1:%.*]] = and i1 [[CMP2]], [[CMP1]]
+; 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
+  %cmp2 = icmp slt i32 %v0, %v2
+  %and1 = and i1 %cmp2, %cmp1
+  %and2 = and i1 %cmp0, %and1
+  br i1 %and2, label %if.then, label %return
+
+if.then:
+  call void @side_effect()
+  br label %return
+
+return:
+  ret void
+}
+
+
+define void @and_tree_second_implies_first_perm2(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: @and_tree_second_implies_first_perm2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0:%.*]], [[V1:%.*]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2:%.*]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND1:%.*]] = and i1 [[CMP0]], [[CMP2]]
+; 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
+  %cmp2 = icmp slt i32 %v0, %v2
+  %and1 = and i1 %cmp0, %cmp2
+  %and2 = and i1 %cmp1, %and1
+  br i1 %and2, label %if.then, label %return
+
+if.then:
+  call void @side_effect()
+  br label %return
+
+return:
+  ret void
+}
+
+define void @logical_and_tree_second_implies_first(i32 %v0, i32 %v1, i32 %v2) {
+; CHECK-LABEL: @logical_and_tree_second_implies_first(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0:%.*]], [[V1:%.*]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2:%.*]]
+; CHECK-NEXT:    [[AND1:%.*]] = select i1 [[CMP0]], i1 [[CMP1]], i1 false
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND2:%.*]] = select i1 [[CMP2]], i1 [[AND1]], i1 false
+; 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 = select i1 %cmp0, i1 %cmp1, i1 false
+  %cmp2 = icmp slt i32 %v0, %v2
+  %and2 = select i1 %cmp2, i1 %and1, i1 false
+  br i1 %and2, label %if.then, label %return
+
+if.then:
+  call void @side_effect()
+  br label %return
+
+return:
+  ret void
+}
+
+define void @or_tree_second_implies_first(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: @or_tree_second_implies_first(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0:%.*]], [[V1:%.*]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2:%.*]]
+; CHECK-NEXT:    [[AND1:%.*]] = or i1 [[CMP0]], [[CMP1]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND2:%.*]] = or i1 true, [[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 = or i1 %cmp0, %cmp1
+  %cmp2 = icmp slt i32 %v0, %v2
+  %and2 = or i1 %cmp2, %and1
+  br i1 %and2, label %if.then, label %return
+
+if.then:
+  call void @side_effect()
+  br label %return
+
+return:
+  ret void
+}
+
+define void @or_tree_second_implies_first_with_unknown_cond(i64 %x, i1 %cond) {
+; CHECK-LABEL: @or_tree_second_implies_first_with_unknown_cond(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ugt i64 [[X:%.*]], 1
+; CHECK-NEXT:    [[OR1:%.*]] = select i1 [[CMP1]], i1 [[COND:%.*]], i1 false
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp ult i64 [[X]], 2
+; CHECK-NEXT:    [[OR2:%.*]] = select i1 [[OR1]], i1 false, i1 false
+; CHECK-NEXT:    br i1 [[OR2]], label [[IF_THEN:%.*]], label [[IF_END:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    call void @side_effect()
+; CHECK-NEXT:    br label [[IF_END]]
+; CHECK:       if.end:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cmp1 = icmp ugt i64 %x, 1
+  %or1 = select i1 %cmp1, i1 %cond, i1 false
+  %cmp2 = icmp ult i64 %x, 2
+  %or2 = select i1 %or1, i1 %cmp2, i1 false
+  br i1 %or2, label %if.then, label %if.end
+
+if.then:
+  call void @side_effect()
+  br label %if.end
+
+if.end:
+  ret void
+}
+
+define void @negative_and_or_tree_second_implies_first(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: @negative_and_or_tree_second_implies_first(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[CMP0:%.*]] = icmp sge i32 [[V0:%.*]], [[V1:%.*]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2:%.*]]
+; CHECK-NEXT:    [[AND1:%.*]] = or i1 [[CMP0]], [[CMP1]]
+; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT:    [[AND2:%.*]] = and i1 [[CMP2]], [[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 = or 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()
 declare void @no_noundef(i1 noundef)
diff --git a/llvm/test/Transforms/ConstraintElimination/or.ll 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:
