Skip to content

⚡ Bolt: Optimize TryValidateRange bounds checks in VirtualMemory #85

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
manupawickramasinghe wants to merge 1 commit into
base: main
Choose a base branch
from
Open

⚡ Bolt: Optimize TryValidateRange bounds checks in VirtualMemory #85

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 10 additions & 19 deletions src/SharpEmu.Core/Memory/VirtualMemory.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,7 @@ public bool TryWrite(ulong virtualAddress, ReadOnlySpan<byte> source)
return true;
}

/// <remarks>Performance optimization: Elides Math.Min calls, redundant branch checks, and casting inside the hot path validation loop for optimal MSIL generation.</remarks>
private bool TryValidateRange(
ulong virtualAddress,
int length,
Expand All @@ -141,39 +142,29 @@ private bool TryValidateRange(

var span = System.Runtime.InteropServices.CollectionsMarshal.AsSpan(_regions);
var currentAddress = virtualAddress;
var remaining = length;
var currentIndex = regionIndex;
while (true)
{
if (currentIndex >= span.Length)
{
return false;
}
var remaining = (ulong)length;

ref var region = ref span[currentIndex];
for (var i = regionIndex; i < span.Length; i++)
{
ref var region = ref span[i];
if (currentAddress < region.Region.VirtualAddress ||
currentAddress >= region.EndAddress ||
(region.Region.Protection & requiredProtection) == 0)
{
return false;
}

if (remaining == 0)
{
return true;
}

var available = region.EndAddress - currentAddress;
var chunkLength = (int)Math.Min((ulong)remaining, available);
remaining -= chunkLength;
if (remaining == 0)
if (remaining <= available)
{
return true;
}

currentAddress += (ulong)chunkLength;
currentIndex++;
remaining -= available;
currentAddress += available;
}

return false;
}

private int FindContainingRegionIndex(ulong virtualAddress)
Expand Down
Loading