[llvm] [InstCombine] simplify `(X * C0) / (X * C1)` into `C0 / C1`. (PR #73204)

[Yingwei Zheng via llvm-commits]

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@@ -1207,6 +1207,18 @@ Instruction *InstCombinerImpl::commonIDivTransforms(BinaryOperator &I) {
     }
   }
 
+  // (X * C0) / (X * C1) --> C0 / C1
+  Constant *C0, *C1;
+  if (match(Op0, m_c_Mul(m_Value(X), m_Constant(C0))) &&
+      match(Op1, m_c_Mul(m_Specific(X), m_Constant(C1)))) {
+    auto OB0HasNSW = cast<OverflowingBinaryOperator>(Op0)->hasNoSignedWrap();
+    auto OB0HasNUW = cast<OverflowingBinaryOperator>(Op0)->hasNoUnsignedWrap();
+    if ((IsSigned && OB0HasNSW) || (!IsSigned && OB0HasNUW)) {
+      replaceOperand(I, 0, C0);
+      replaceOperand(I, 1, C1);
+      return &I;
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dtcxzyw wrote:

Please use `BinaryOperator::CreateUDiv` and `BinaryOperator::CreateSDiv`.


https://github.com/llvm/llvm-project/pull/73204