Invalidate code that HLE and the debugger write over

Helper thread stubs, fake syscall stubs and the module start trampoline go into memory that may
have held code (freed kernel memory, a reused thread stack), and the debugger memory views can
edit code. Invalidate what they write, which so far only happened by accident when the write hit
the first instruction of a JIT block.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Core/HLE/HLEHelperThread.cpp

@@ -24,6 +24,7 @@
 #include "Core/HLE/KernelWaitHelpers.h"
 #include "Core/HLE/sceKernelThread.h"
 #include "Core/HLE/sceKernelMemory.h"
+#include "Core/MIPS/MIPS.h"
 #include "Core/MIPS/MIPSCodeUtils.h"
 
 HLEHelperThread::HLEHelperThread(const char *threadName, const u32 instructions[], u32 instrCount, u32 prio, int stacksize) {
@@ -36,6 +37,8 @@ HLEHelperThread::HLEHelperThread(const char *threadName, const u32 instructions[
 	// Just to simplify things, we add the return here.
 	Memory::WriteUnchecked_U32(MIPS_MAKE_JR_RA(), entry_ + instrBytes + 0);
 	Memory::WriteUnchecked_U32(MIPS_MAKE_NOP(), entry_ + instrBytes + 4);
+	// The memory may have held another helper's code, already compiled.
+	currentMIPS->InvalidateICacheRangeDeferred(entry_, totalBytes);
 
 	Create(threadName, prio, stacksize);
 }
@@ -46,6 +49,7 @@ HLEHelperThread::HLEHelperThread(const char *threadName, const char *module, con
 	_dbg_assert_(Memory::IsValid4AlignedAddress(entry_));  // after AllocEntry.
 	Memory::WriteUnchecked_U32(MIPS_MAKE_JR_RA(), entry_ + 0);
 	Memory::WriteUnchecked_U32(MIPS_MAKE_SYSCALL(module, func), entry_ + 4);
+	currentMIPS->InvalidateICacheRangeDeferred(entry_, bytes);
 
 	Create(threadName, prio, stacksize);
 }