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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
// Regression test for insufficient guard on inference of initial values
// of induction variables.
using System.Numerics;
namespace N
{
public static class C
{
public static int Main(string[] args)
{
int x = 0;
// When bottom-testing sees this loop, it (questionably for performance,
// but correctly) copies only the first part of the disjunctive loop condition
// so we get
//
// B1: i = Count // initialization
// B2: if (i < Count) goto B6 // duplicated loop condition (note the "zero trip" case goes to the 2nd loop condition disjunct)
// B3: x += i // loop body
// B4: ++i // increment
// B5: if (i < Count) goto B3 // first disjunct of loop condition
// B6: if (i < 20) goto B3 // second disjunct of loop condition
// B7: return x - 84 // post-loop
//
// At which point B3..B6 is an irreducible loop, but B3..B5 is a natural loop.
// This is a regression test for a bug where optRecordLoop would incorrectly
// identify B1 as the initial value of loop B3..B5 -- this is incorrect because
// the edge from B6 to B3 enters the loop with different values of i.
//
// The testcase is intentionally structured so that loop unrolling will try
// to unroll loop B3..B5 and generate incorrect code due to the incorrect
// initial value.
for (int i = Vector<int>.Count; i < Vector<int>.Count || i < 20; ++i)
{
x += i;
}
// After running the loop above, the value of x should be (Count + 19) * (20 - Count) / 2.
// Return 100 + x - (expected x) so the test will return 100 on success.
return 100 + x - ((Vector<int>.Count + 19) * (20 - Vector<int>.Count) / 2);
}
}
}
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