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[Cpu] Read import stack arguments from the thread's own stack without a region query 

Every import copies six stack argument slots (twice, with the per-thread
diagnostics). The per-thread readable-range cache is keyed by the host mapping
generation, which every tracker protection change bumps, so on macOS nearly
each slot fell through to a locked host region query: about half of the busy
managed samples at Octopath Traveler II's title were in that query or waiting
for its lock. Addresses inside the calling guest thread's stack, which the
backend maps read-write for the thread's lifetime, are now read directly.
This commit is contained in:
kuba 2026-09-30 00:11:15 +02:00
parent e99fcb9651
commit fd8a78ad73
1 changed files with 11 additions and 0 deletions
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11
src/SharpEmu.Core/Cpu/Native/DirectExecutionBackend.Imports.cs
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@ -1231,6 +1231,17 @@ public sealed partial class DirectExecutionBackend
return TryReadHostQword(address, out value);
}
// Stack arguments sit on the calling guest thread's own stack, which the backend mapped read-write
// for the thread's lifetime and no tracker ever protects. Reading inside it needs no query: the
// cached range below is keyed by a mapping generation that every tracker protection change bumps,
// so falling through here cost a locked host region query per argument on nearly every import.
if (_activeGuestThreadState is { StackSize: > 0 } thread &&
address >= thread.StackBase && address <= thread.StackBase + thread.StackSize - sizeof(ulong))
{
value = *(ulong*)address;
return true;
}
var generation = HostMemory.MappingGeneration;
if (generation == _importReadableGeneration &&
address >= _importReadableStart && address <= _importReadableEnd - 8)