From 522295472367fa5f05906ad21006f07aac830448 Mon Sep 17 00:00:00 2001
From: Jake Turner <jake@evansturner.co.uk>
Date: Tue, 16 Sep 2025 16:51:02 +0100
Subject: [PATCH] Add a lock when simulating Atomic Memory instructions

---
 renderdoc/driver/shaders/spirv/spirv_debug.cpp | 13 +++++++++++++
 renderdoc/driver/shaders/spirv/spirv_debug.h   |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/renderdoc/driver/shaders/spirv/spirv_debug.cpp b/renderdoc/driver/shaders/spirv/spirv_debug.cpp
index 097e0169f..f0550de20 100644
--- a/renderdoc/driver/shaders/spirv/spirv_debug.cpp
+++ b/renderdoc/driver/shaders/spirv/spirv_debug.cpp
@@ -27,6 +27,7 @@
 #include <time.h>
 #include <limits>
 #include "common/formatting.h"
+#include "common/threading.h"
 #include "core/settings.h"
 #include "maths/half_convert.h"
 #include "os/os_specific.h"
@@ -4259,6 +4260,8 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
     }
     case Op::AtomicLoad:
     {
+      SCOPED_LOCK(debugger.GetAtomicMemoryLock());
+
       OpAtomicLoad load(it);
 
       // ignore for now
@@ -4302,6 +4305,8 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
     }
     case Op::AtomicStore:
     {
+      SCOPED_LOCK(debugger.GetAtomicMemoryLock());
+
       OpAtomicStore store(it);
 
       // ignore for now
@@ -4333,6 +4338,8 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
     }
     case Op::AtomicExchange:
     {
+      SCOPED_LOCK(debugger.GetAtomicMemoryLock());
+
       OpAtomicExchange excg(it);
 
       // ignore for now
@@ -4392,6 +4399,8 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
     }
     case Op::AtomicCompareExchange:
     {
+      SCOPED_LOCK(debugger.GetAtomicMemoryLock());
+
       OpAtomicCompareExchange cmpexcg(it);
 
       // ignore for now
@@ -4475,6 +4484,8 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
     case Op::AtomicIIncrement:
     case Op::AtomicIDecrement:
     {
+      SCOPED_LOCK(debugger.GetAtomicMemoryLock());
+
       OpAtomicIIncrement atomic(it);
 
       // ignore for now
@@ -4560,6 +4571,8 @@ void ThreadState::StepNext(ShaderDebugState *state, const rdcarray<ThreadState>
     case Op::AtomicOr:
     case Op::AtomicXor:
     {
+      SCOPED_LOCK(debugger.GetAtomicMemoryLock());
+
       OpAtomicIAdd atomic(it);
 
       // ignore for now
diff --git a/renderdoc/driver/shaders/spirv/spirv_debug.h b/renderdoc/driver/shaders/spirv/spirv_debug.h
index bb92da7f6..2de5430fd 100644
--- a/renderdoc/driver/shaders/spirv/spirv_debug.h
+++ b/renderdoc/driver/shaders/spirv/spirv_debug.h
@@ -665,6 +665,8 @@ public:
   DeviceOpResult WriteTexel(const ShaderBindIndex &imageBind, const ShaderVariable &coord,
                             uint32_t sample, const ShaderVariable &input) const;
   DeviceOpResult GetBufferLength(const ShaderBindIndex &bind, uint64_t &bufferLen) const;
+
+  Threading::CriticalSection &GetAtomicMemoryLock() const { return atomicMemoryLock; }
 private:
   virtual void PreParse(uint32_t maxId);
   virtual void PostParse();
@@ -799,6 +801,7 @@ private:
   void SyncPendingGpuOps();
   void SyncPendingLanes();
 
+  mutable Threading::CriticalSection atomicMemoryLock;
   mutable Threading::CriticalSection queuedDebugMessagesLock;
   mutable rdcarray<DebugMessage> queuedDebugMessages;
   rdcarray<bool> queuedGpuMathOps;