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ARM64EC: Only clear the trap flag when handling an exception

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Better matches Windows emulator behaviour.
This commit is contained in:
Billy Laws committed 2024-08-05 17:38:45 +00:00
1 parent 7ffd3e55d5
commit 7f3582bb23
1 file changed
+4 -5
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Source/Windows/ARM64EC/Module.cpp
+4 -5
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@@ -162,12 +162,11 @@ static EXCEPTION_RECORD HandleGuestException(const EXCEPTION_RECORD& Src, ARM64_
EXCEPTION_RECORD Dst = Src;
Dst.ExceptionAddress = reinterpret_cast<void*>(Context.Pc);
// Windows always clears TF, DF and AF when handling an exception, restoring after.
// TODO: Check windows behaviour for the restoring after, quite awkward to achieve with the BT API. Would need to fixup flags after a
// rethrow and keep track of context pointers on the stack so if a SEH handler changes flags they can be restored in BeginContext after
// the NtContinue syscall (which will convert to an ARM64 context and back, losing these flags).
// X64 Windows always clears TF, DF and AF when handling an exception, restoring after.
// Current ARM64EC windows can only restore NZCV+SS when returning from an exception and other flags are left untouched from the handler context.
// TODO: Can extend wine to support this by mapping the remaining EFlags into reserved cpsr members.
uint32_t EFlags = CTX->ReconstructCompactedEFLAGS(Thread, true, Context.X, Context.Cpsr);
EFlags &= ~((1 << FEXCore::X86State::RFLAG_DF_RAW_LOC) | (1 << FEXCore::X86State::RFLAG_TF_LOC) | (1 << FEXCore::X86State::RFLAG_AF_RAW_LOC));
EFlags &= (1 << FEXCore::X86State::RFLAG_TF_LOC);
CTX->SetFlagsFromCompactedEFLAGS(Thread, EFlags);
if (!Fault.FaultToTopAndGeneratedException) {