[InstCombine] Extend foldICmpBinOp to add-like or.

InstCombine canonicalizes `add` to `or` when possible, but this makes
some optimizations applicable to `add` to be missed because they don't
realize that the `or` is equivalent to `add`.

In this patch we generalize `foldICmpBinOp` to handle such cases.

Author: mgudim

llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp

@@ -4629,31 +4629,38 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
   }
 
   bool NoOp0WrapProblem = false, NoOp1WrapProblem = false;
-  if (BO0 && isa<OverflowingBinaryOperator>(BO0))
-    NoOp0WrapProblem =
-        ICmpInst::isEquality(Pred) ||
-        (CmpInst::isUnsigned(Pred) && BO0->hasNoUnsignedWrap()) ||
-        (CmpInst::isSigned(Pred) && BO0->hasNoSignedWrap());
-  if (BO1 && isa<OverflowingBinaryOperator>(BO1))
-    NoOp1WrapProblem =
-        ICmpInst::isEquality(Pred) ||
-        (CmpInst::isUnsigned(Pred) && BO1->hasNoUnsignedWrap()) ||
-        (CmpInst::isSigned(Pred) && BO1->hasNoSignedWrap());
-
+  bool Op0HasNUW = false, Op1HasNUW = false;
+  bool Op0HasNSW = false, Op1HasNSW = false;
   // Analyze the case when either Op0 or Op1 is an add instruction.
   // Op0 = A + B (or A and B are null); Op1 = C + D (or C and D are null).
   Value *A = nullptr, *B = nullptr, *C = nullptr, *D = nullptr;
-  if (BO0 && BO0->getOpcode() == Instruction::Add) {
-    A = BO0->getOperand(0);
-    B = BO0->getOperand(1);
+  auto hasNoWrapProblem = [&](const BinaryOperator &BO, const Value *X,
+                              const Value *Y, bool &HasNSW,
+                              bool &HasNUW) -> bool {
+    if (isa<OverflowingBinaryOperator>(BO)) {
+      HasNUW = BO.hasNoUnsignedWrap();
+      HasNSW = BO.hasNoSignedWrap();
+      return ICmpInst::isEquality(Pred) ||
+             (CmpInst::isUnsigned(Pred) && HasNUW) ||
+             (CmpInst::isSigned(Pred) && HasNSW);
+    } else if (BO0->getOpcode() == Instruction::Or) {
+      HasNUW = true;
+      HasNSW = true;
+      return true;
+    } else {
+      return false;
+    }
+  };
+
+  if (BO0) {
+    match(BO0, m_AddLike(m_Value(A), m_Value(B)));
+    NoOp0WrapProblem = hasNoWrapProblem(*BO0, A, B, Op0HasNSW, Op0HasNUW);
   }
-  if (BO1 && BO1->getOpcode() == Instruction::Add) {
-    C = BO1->getOperand(0);
-    D = BO1->getOperand(1);
+  if (BO1) {
+    match(BO1, m_AddLike(m_Value(C), m_Value(D)));
+    NoOp1WrapProblem = hasNoWrapProblem(*BO1, C, D, Op1HasNSW, Op1HasNUW);
   }
 
-  // icmp (A+B), A -> icmp B, 0 for equalities or if there is no overflow.
-  // icmp (A+B), B -> icmp A, 0 for equalities or if there is no overflow.
   if ((A == Op1 || B == Op1) && NoOp0WrapProblem)
     return new ICmpInst(Pred, A == Op1 ? B : A,
                         Constant::getNullValue(Op1->getType()));
@@ -4769,17 +4776,15 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
       APInt AP2Abs = AP2->abs();
       if (AP1Abs.uge(AP2Abs)) {
         APInt Diff = *AP1 - *AP2;
-        bool HasNUW = BO0->hasNoUnsignedWrap() && Diff.ule(*AP1);
-        bool HasNSW = BO0->hasNoSignedWrap();
         Constant *C3 = Constant::getIntegerValue(BO0->getType(), Diff);
-        Value *NewAdd = Builder.CreateAdd(A, C3, "", HasNUW, HasNSW);
+        Value *NewAdd = Builder.CreateAdd(
+            A, C3, "", Op0HasNUW && Diff.ule(*AP1), Op0HasNSW);
         return new ICmpInst(Pred, NewAdd, C);
       } else {
         APInt Diff = *AP2 - *AP1;
-        bool HasNUW = BO1->hasNoUnsignedWrap() && Diff.ule(*AP2);
-        bool HasNSW = BO1->hasNoSignedWrap();
         Constant *C3 = Constant::getIntegerValue(BO0->getType(), Diff);
-        Value *NewAdd = Builder.CreateAdd(C, C3, "", HasNUW, HasNSW);
+        Value *NewAdd = Builder.CreateAdd(
+            C, C3, "", Op1HasNUW && Diff.ule(*AP1), Op1HasNSW);
         return new ICmpInst(Pred, A, NewAdd);
       }
     }
@@ -4873,16 +4878,14 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
                   isKnownNonZero(Z, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
         // if Z != 0 and nsw(X * Z) and nsw(Y * Z)
         //    X * Z eq/ne Y * Z -> X eq/ne Y
-        if (NonZero && BO0 && BO1 && BO0->hasNoSignedWrap() &&
-            BO1->hasNoSignedWrap())
+        if (NonZero && BO0 && BO1 && Op0HasNUW && Op1HasNSW)
           return new ICmpInst(Pred, X, Y);
       } else
         NonZero = isKnownNonZero(Z, Q.DL, /*Depth=*/0, Q.AC, Q.CxtI, Q.DT);
 
       // If Z != 0 and nuw(X * Z) and nuw(Y * Z)
       //    X * Z u{lt/le/gt/ge}/eq/ne Y * Z -> X u{lt/le/gt/ge}/eq/ne Y
-      if (NonZero && BO0 && BO1 && BO0->hasNoUnsignedWrap() &&
-          BO1->hasNoUnsignedWrap())
+      if (NonZero && BO0 && BO1 && Op0HasNUW && Op1HasNUW)
         return new ICmpInst(Pred, X, Y);
     }
   }
@@ -4982,8 +4985,8 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
       return new ICmpInst(Pred, BO0->getOperand(0), BO1->getOperand(0));
 
     case Instruction::Shl: {
-      bool NUW = BO0->hasNoUnsignedWrap() && BO1->hasNoUnsignedWrap();
-      bool NSW = BO0->hasNoSignedWrap() && BO1->hasNoSignedWrap();
+      bool NUW = Op0HasNUW && Op1HasNUW;
+      bool NSW = Op0HasNSW && Op1HasNSW;
       if (!NUW && !NSW)
         break;
       if (!NSW && I.isSigned())

llvm/test/Transforms/InstCombine/disjoint-or-icmp.ll

@@ -0,0 +1,14 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+define i1 @simplify_icmp(i32 %x, i32 %y) {
+; CHECK-LABEL: define i1 @simplify_icmp(
+; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
+; CHECK-NEXT:    [[ICMP_:%.*]] = icmp sle i32 [[X]], [[Y]]
+; CHECK-NEXT:    ret i1 [[ICMP_]]
+;
+  %add0_ = or disjoint i32 %x, 1
+  %add1_ = add nsw i32 %y, 1
+  %icmp_ = icmp sle i32 %add0_, %add1_
+  ret i1 %icmp_
+}