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[JIT] ARM64 - Fix 'x < 0' for unsigned #83656

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Merged
merged 1 commit into from
Mar 20, 2023
Merged

[JIT] ARM64 - Fix 'x < 0' for unsigned #83656

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3 changes: 2 additions & 1 deletion src/coreclr/jit/codegenarm64.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -4536,7 +4536,8 @@ void CodeGen::genCodeForCompare(GenTreeOp* tree)
regNumber op1Reg = op1->GetRegNum();

if (compiler->opts.OptimizationEnabled() && (ins == INS_cmp) && (targetReg != REG_NA) &&
tree->OperIs(GT_LT) && intConst->IsIntegralConst(0) && ((cmpSize == EA_4BYTE) || (cmpSize == EA_8BYTE)))
tree->OperIs(GT_LT) && !tree->IsUnsigned() && intConst->IsIntegralConst(0) &&
((cmpSize == EA_4BYTE) || (cmpSize == EA_8BYTE)))
{
emit->emitIns_R_R_I(INS_lsr, cmpSize, targetReg, op1Reg, (int)cmpSize * 8 - 1);
genProduceReg(tree);
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28 changes: 28 additions & 0 deletions src/tests/JIT/opt/Regressions/Regression7.cs
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@@ -0,0 +1,28 @@
// Licensed to the .NET Foundation under one or more agreements.
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I think we usually put such regressions to JitBlue folder (historical reasons) and name them like Github_XXX

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That's fair. Next time, I'll put them there. Just got so used to putting them in here.

// The .NET Foundation licenses this file to you under the MIT license.

// Generated by Fuzzlyn v1.5 on 2023-03-19 17:44:38
// Run on Arm64 Linux
// Seed: 516098027771570682
public class C0
{
public uint F1;
public C0(uint f1)
{
F1 = f1;
}
}

public class Program
{
// This test was testing an ARM64 regression when optimizing 'x < 0' when it didn't take into account an unsigned operation.
public static int Main()
{
var vr1 = new C0(4294967295U);
bool vr3 = !(vr1.F1 > -1);
if (!vr3)
return 100;
else
return 0;
}
}
12 changes: 12 additions & 0 deletions src/tests/JIT/opt/Regressions/Regression7.csproj
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@@ -0,0 +1,12 @@
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<OutputType>Exe</OutputType>
</PropertyGroup>
<PropertyGroup>
<DebugType>None</DebugType>
<Optimize>True</Optimize>
</PropertyGroup>
<ItemGroup>
<Compile Include="$(MSBuildProjectName).cs" />
</ItemGroup>
</Project>