[llvm] [InstCombine] Extend `foldICmpBinOp` to `add`-like `or`. (PR #71396)

[Nikita Popov via llvm-commits]

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@@ -4624,31 +4624,37 @@ 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, CmpInst::Predicate Pred,
+                             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 (BO.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, Pred, 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, Pred, 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.
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nikic wrote:

Why was this comment removed?

https://github.com/llvm/llvm-project/pull/71396