Implement PR2298. This transforms:
~x < ~y --> y < x
-x == -y --> x == y
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50882 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 772ef63..e8b60f8 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -5658,8 +5658,21 @@
return R;
}
+ // ~x < ~y --> y < x
+ { Value *A, *B;
+ if (match(Op0, m_Not(m_Value(A))) &&
+ match(Op1, m_Not(m_Value(B))))
+ return new ICmpInst(I.getPredicate(), B, A);
+ }
+
if (I.isEquality()) {
Value *A, *B, *C, *D;
+
+ // -x == -y --> x == y
+ if (match(Op0, m_Neg(m_Value(A))) &&
+ match(Op1, m_Neg(m_Value(B))))
+ return new ICmpInst(I.getPredicate(), A, B);
+
if (match(Op0, m_Xor(m_Value(A), m_Value(B)))) {
if (A == Op1 || B == Op1) { // (A^B) == A -> B == 0
Value *OtherVal = A == Op1 ? B : A;