Make threading lock-free

The core and the headless tools no longer use mutexes, condition variables,
spinlocks, std::atomic, std::thread or volatile flags. Threads hand off through
libretro-common's retro_atomic and rthreads plus a few small pieces on top of
them in Common/Thread: Thread, MpscQueue, EventCounter, ParkingLot waits and
ReaderGate. Every wait blocks until it's woken; nothing polls on a timer.

State that only one thread touches just loses its lock. The PSP filesystem,
sceIo and the savedata dialog now belong to the emulation thread: async reads
and writes run when they're queued and complete later in emulated time, and
the IO and savedata threads are gone. The friend finder only talks to the
adhoc server and hands what it gets to the emulation thread. GPU init always
runs on the thread that starts the game.

The Vulkan render and compile queues, pipeline and render pass caches, delete
list and SPIR-V cache, the GL render queue, the software renderer's jit caches,
the file loader caches, the web debugger, UPnP, input, savestates, logging and
the GE debugger all hand off through queues and atomics. The IR jit's spinning
profiler thread goes.

A CPU thread with nothing to run now sleeps until work is queued instead of
spinning. Headless with --debugger waits for a client while stopped, and ends
the run once every client that connected has left. Web server shutdown keeps
servicing the CPU queue until the server has finished.

Core/Debugger/Breakpoints.cpp

@@ -15,8 +15,6 @@
 // Official git repository and contact information can be found at
 // https://github.com/hrydgard/ppsspp and http://www.ppsspp.org/.
 
-#include <atomic>
-
 #include "Common/System/System.h"
 #include "Common/Log.h"
 #include "Core/Core.h"
@@ -104,7 +102,7 @@ size_t BreakpointManager::FindBreakpoint(u32 addr) {
 }
 
 void BreakpointManager::UpdateAnyBreakPoints() {
-	anyBreakPoints_ = !breakPoints_.empty() || tempBreakPoint_.valid;
+	retro_atomic_store_relaxed_int(&anyBreakPoints_, (!breakPoints_.empty() || tempBreakPoint_.valid) ? 1 : 0);
 }
 
 size_t BreakpointManager::FindMemCheck(u32 start, u32 end) {
@@ -126,7 +124,7 @@ size_t BreakpointManager::FindRegBreakpoint(int reg) {
 }
 
 bool BreakpointManager::IsAddressBreakPoint(u32 addr) {
-	if (!anyBreakPoints_)
+	if (!HasBreakPoints())
 		return false;
 	size_t bp = FindBreakpoint(addr);
 	if (bp == INVALID_BREAKPOINT) {
@@ -136,7 +134,7 @@ bool BreakpointManager::IsAddressBreakPoint(u32 addr) {
 }
 
 bool BreakpointManager::IsAddressBreakPoint(u32 addr, bool* enabled) {
-	if (!anyBreakPoints_)
+	if (!HasBreakPoints())
 		return false;
 	size_t bp = FindBreakpoint(addr);
 	if (bp == INVALID_BREAKPOINT) {
@@ -149,7 +147,7 @@ bool BreakpointManager::IsAddressBreakPoint(u32 addr, bool* enabled) {
 }
 
 bool BreakpointManager::NeedsBreakCheckAt(u32 addr) {
-	if (!anyBreakPoints_)
+	if (!HasBreakPoints())
 		return false;
 	if (tempBreakPoint_.valid && tempBreakPoint_.addr == addr)
 		return true;
@@ -159,7 +157,7 @@ bool BreakpointManager::NeedsBreakCheckAt(u32 addr) {
 
 bool BreakpointManager::RangeContainsBreakPoint(u32 addr, u32 size)
 {
-	if (!anyBreakPoints_)
+	if (!HasBreakPoints())
 		return false;
 	const u32 end = addr + size;
 	if (tempBreakPoint_.valid && tempBreakPoint_.addr >= addr && tempBreakPoint_.addr < end)
@@ -300,7 +298,7 @@ bool BreakpointManager::ChangeBreakPointAddress(u32 oldAddr, u32 newAddr) {
 
 // This is not actually called, currently.
 void BreakpointManager::ClearAllBreakPoints() {
-	if (!anyBreakPoints_)
+	if (!HasBreakPoints())
 		return;
 	if (!breakPoints_.empty()) {
 		for (const auto &bp : breakPoints_) {
@@ -353,7 +351,7 @@ void BreakpointManager::ChangeBreakPointLogFormat(u32 addr, const std::string &f
 // and must still let the step complete. Whichever of them pauses, Core_Break() drops the temporary
 // breakpoint, so a step that gets interrupted by something else doesn't leave one armed behind it.
 BreakAction BreakpointManager::ExecBreakPoint(u32 addr) {
-	if (!anyBreakPoints_)
+	if (!HasBreakPoints())
 		return BREAK_ACTION_NONE;
 
 	BreakAction result = BREAK_ACTION_NONE;
@@ -434,7 +432,7 @@ int BreakpointManager::AddMemCheck(u32 start, u32 end, MemCheckCondition cond, B
 		check.action = action;
 
 		memChecks_.push_back(check);
-		bool hadAny = anyMemChecks_.exchange(true);
+		bool hadAny = retro_atomic_exchange_int(&anyMemChecks_, 1) != 0;
 		if (!hadAny) {
 			MemBlockOverrideDetailed();
 		}
@@ -446,7 +444,7 @@ int BreakpointManager::AddMemCheck(u32 start, u32 end, MemCheckCondition cond, B
 		// Update with additional cond and action bits. Not sure if we should OR or override?
 		memChecks_[mc].cond = (MemCheckCondition)(memChecks_[mc].cond | cond);
 		memChecks_[mc].action = memChecks_[mc].action | action;
-		bool hadAny = anyMemChecks_.exchange(true);
+		bool hadAny = retro_atomic_exchange_int(&anyMemChecks_, 1) != 0;
 		if (!hadAny) {
 			MemBlockOverrideDetailed();
 		}
@@ -463,7 +461,7 @@ void BreakpointManager::RemoveMemCheck(u32 start, u32 end)
 	if (mc != INVALID_MEMCHECK)
 	{
 		memChecks_.erase(memChecks_.begin() + mc);
-		bool hadAny = anyMemChecks_.exchange(!memChecks_.empty());
+		bool hadAny = retro_atomic_exchange_int(&anyMemChecks_, memChecks_.empty() ? 0 : 1) != 0;
 		if (hadAny)
 			MemBlockReleaseDetailed();
 		updateMemChecks_ = true;
@@ -490,7 +488,7 @@ void BreakpointManager::ClearAllMemChecks()
 	if (!memChecks_.empty())
 	{
 		memChecks_.clear();
-		bool hadAny = anyMemChecks_.exchange(false);
+		bool hadAny = retro_atomic_exchange_int(&anyMemChecks_, 0) != 0;
 		if (hadAny)
 			MemBlockReleaseDetailed();
 		updateMemChecks_ = true;
@@ -577,7 +575,7 @@ MemCheck *BreakpointManager::FindMemCheckInRange(u32 address, int size) {
 
 BreakAction BreakpointManager::ExecMemCheck(u32 address, bool write, int size, u32 pc, const char *reason)
 {
-	if (!anyMemChecks_)
+	if (!HasMemChecks())
 		return BREAK_ACTION_NONE;
 	MemCheck *check = FindMemCheckInRange(address, size);
 	if (check) {
@@ -631,7 +629,7 @@ void BreakpointManager::RecomputeRegBreakpointMask() {
 		if (bp.result != BREAK_ACTION_NONE)
 			mask |= 1u << bp.reg;
 	}
-	regBreakpointMask_ = mask;
+	retro_atomic_store_relaxed_int(&regBreakpointMask_, (int)mask);
 }
 
 int BreakpointManager::AddRegBreakpoint(int reg) {
@@ -684,7 +682,7 @@ void BreakpointManager::ChangeRegBreakpoint(int reg, BreakAction result) {
 void BreakpointManager::ClearAllRegBreakpoints() {
 	if (!regBreakpoints_.empty()) {
 		regBreakpoints_.clear();
-		regBreakpointMask_ = 0;
+		retro_atomic_store_relaxed_int(&regBreakpointMask_, 0);
 	}
 }
 
@@ -718,7 +716,7 @@ void BreakpointManager::ChangeRegBreakpointLogFormat(int reg, const std::string
 }
 
 bool BreakpointManager::IsRegBreakpoint(int reg) {
-	return (regBreakpointMask_ & (1u << reg)) != 0;
+	return (GetRegBreakpointMask() & (1u << reg)) != 0;
 }
 
 bool BreakpointManager::GetRegBreakpoint(int reg, RegBreakpoint *check) {
@@ -739,7 +737,7 @@ BreakAction BreakpointManager::ExecRegBreakpoint(int reg, u32 pc) {
 	// the whole point of exposing it - a single shift+and in the hot interpreter loop, skipping
 	// a function call entirely in the overwhelmingly common no-breakpoint case), but check again
 	// here too since this is also reachable directly.
-	if ((regBreakpointMask_ & (1u << reg)) == 0)
+	if ((GetRegBreakpointMask() & (1u << reg)) == 0)
 		return BREAK_ACTION_NONE;
 	size_t bp = FindRegBreakpoint(reg);
 	if (bp == INVALID_REG_BREAKPOINT)
@@ -878,7 +876,7 @@ std::vector<BreakPoint> BreakpointManager::GetBreakpoints() {
 }
 
 void BreakpointManager::Frame() {
-	if (anyMemChecks_ && updateMemChecks_) {
+	if (HasMemChecks() && updateMemChecks_) {
 		UpdateCachedMemCheckRanges();
 		updateMemChecks_ = false;
 	}