From d334f0c3f1adfa130efc94aa76e4dded7673e5c2 Mon Sep 17 00:00:00 2001
From: SwapnilGaikwad <swapnil.gaikwad@arm.com>
Date: Fri, 16 Jun 2023 20:18:30 +0100
Subject: [PATCH] Fix invalid lowering for SELECT over mixed neg/not operands
 (#87674)

---
 src/coreclr/jit/lowerarmarch.cpp              |  2 +-
 .../JIT/opt/Compares/conditionalNegates.cs    | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/coreclr/jit/lowerarmarch.cpp b/src/coreclr/jit/lowerarmarch.cpp
index 64826c428b77f..25d07c53e0929 100644
--- a/src/coreclr/jit/lowerarmarch.cpp
+++ b/src/coreclr/jit/lowerarmarch.cpp
@@ -2579,7 +2579,7 @@ void Lowering::TryLowerCselToCinvOrCneg(GenTreeOp* select, GenTree* cond)
 
     assert(trueVal->OperIs(GT_NOT, GT_NEG) || falseVal->OperIs(GT_NOT, GT_NEG));
 
-    if (trueVal->OperIs(GT_NOT) || trueVal->OperIs(GT_NEG))
+    if ((isCneg && trueVal->OperIs(GT_NEG)) || (!isCneg && trueVal->OperIs(GT_NOT)))
     {
         shouldReverseCondition  = true;
         invertedOrNegatedVal    = trueVal->gtGetOp1();
diff --git a/src/tests/JIT/opt/Compares/conditionalNegates.cs b/src/tests/JIT/opt/Compares/conditionalNegates.cs
index 8366f1b9b9db6..b612756576010 100644
--- a/src/tests/JIT/opt/Compares/conditionalNegates.cs
+++ b/src/tests/JIT/opt/Compares/conditionalNegates.cs
@@ -129,4 +129,23 @@ public static void cneg_shifted_true_oper(int op1, int op2, int expected)
         int result = op1 < 51 ? -(op1 >> 3) : op2;
         Assert.Equal(expected, result);
     }
+
+    [Theory]
+    [InlineData(1, -1)]
+    [InlineData(55, ~55)]
+    [MethodImpl(MethodImplOptions.NoInlining)]
+    public static void cneg_mixed_not_and_neg_oper(int op1, int expected)
+    {
+        //ARM64-FULL-LINE: cmp {{w[0-9]+}}, #52
+        //ARM64-FULL-LINE-NEXT: csneg {{w[0-9]+}}, {{w[0-9]+}}, {{w[0-9]+}}, {{gt|le}}
+        if (op1 <= 52)
+        {
+            op1 = -op1;
+        }
+        else
+        {
+            op1 = ~op1;
+        }
+        Assert.Equal(expected, op1);
+    }
 }