[llvm] [InstCombine] Fold xored one-complemented operand comparisons (PR #69882)

[via llvm-commits]

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@@ -7127,6 +7127,20 @@ Instruction *InstCombinerImpl::visitICmpInst(ICmpInst &I) {
       return new ICmpInst(I.getInversePredicate(), Builder.CreateAnd(A, B),
                           Op1);
 
+    // Transform (~A ^ B) s< ~A --> (A ^ B) s> A,
+    //           (~A ^ B) s> ~A --> (A ^ B) s< A,
+    //           (~A ^ B) s<= ~A --> (A ^ B) s>= A,
+    //           (~A ^ B) s>= ~A --> (A ^ B) s<= A,
+    //           (~A ^ B) u< ~A --> (A ^ B) u< A,
+    //           (~A ^ B) u> ~A --> (A ^ B) u< A,
+    //           (~A ^ B) u<= ~A --> (A ^ B) u>= A,
+    // and       (~A ^ B) u>= ~A --> (A ^ B) <= A
+    if (match(&I, m_c_ICmp(Pred, m_c_Xor(m_Not(m_Value(A)), m_Value(B)),
+                           m_Not(m_Value(C)))) &&
+        !I.isEquality())
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elhewaty wrote:

@I didn't write them because they are handled.
Aliv2: https://godbolt.org/z/qaTh55fsa

https://github.com/llvm/llvm-project/pull/69882