Fix intermittent debug failures with Debug build (#7369)

This PR replaces enable/disable style C function calls with C++ RAII style code.

In debug build, when an assertion failed in between enable and disable functions, an exception is thrown and the disable function is not called. RAII style code is safer for an exception

6 files changed, 51 insertions, 16 deletions

diff --git a/source/slang/slang-emit.cpp b/source/slang/slang-emit.cpp
index c0c1ba75a..f4d535466 100644
--- a/source/slang/slang-emit.cpp
+++ b/source/slang/slang-emit.cpp
@@ -950,9 +950,10 @@ Result linkAndOptimizeIR(
         if (requiredLoweringPassSet.autodiff)
         {
             dumpIRIfEnabled(codeGenContext, irModule, "BEFORE-AUTODIFF");
-            enableIRValidationAtInsert();
-            changed |= processAutodiffCalls(targetProgram, irModule, sink);
-            disableIRValidationAtInsert();
+            {
+                auto validationScope = enableIRValidationScope();
+                changed |= processAutodiffCalls(targetProgram, irModule, sink);
+            }
             dumpIRIfEnabled(codeGenContext, irModule, "AFTER-AUTODIFF");
         }
 
diff --git a/source/slang/slang-ir-autodiff-cfg-norm.cpp b/source/slang/slang-ir-autodiff-cfg-norm.cpp
index 30e832719..720fdece2 100644
--- a/source/slang/slang-ir-autodiff-cfg-norm.cpp
+++ b/source/slang/slang-ir-autodiff-cfg-norm.cpp
@@ -755,9 +755,10 @@ void normalizeCFG(
     sortBlocksInFunc(func);
     legalizeDefUse(func);
 
-    disableIRValidationAtInsert();
-    constructSSA(module, func);
-    enableIRValidationAtInsert();
+    {
+        auto validationScope = disableIRValidationScope();
+        constructSSA(module, func);
+    }
 
     module->invalidateAnalysisForInst(func);
 #if _DEBUG
diff --git a/source/slang/slang-ir-autodiff-fwd.cpp b/source/slang/slang-ir-autodiff-fwd.cpp
index 003790793..a2ee2bdf9 100644
--- a/source/slang/slang-ir-autodiff-fwd.cpp
+++ b/source/slang/slang-ir-autodiff-fwd.cpp
@@ -1900,12 +1900,11 @@ SlangResult ForwardDiffTranscriber::prepareFuncForForwardDiff(IRFunc* func)
 
     if (SLANG_SUCCEEDED(result))
     {
-        disableIRValidationAtInsert();
+        auto validationScope = disableIRValidationScope();
         auto simplifyOptions = IRSimplificationOptions::getDefault(nullptr);
         simplifyOptions.removeRedundancy = true;
         simplifyOptions.hoistLoopInvariantInsts = true;
         simplifyFunc(autoDiffSharedContext->targetProgram, func, simplifyOptions);
-        enableIRValidationAtInsert();
     }
     return result;
 }
diff --git a/source/slang/slang-ir-autodiff-unzip.h b/source/slang/slang-ir-autodiff-unzip.h
index ec435ee87..80b2038aa 100644
--- a/source/slang/slang-ir-autodiff-unzip.h
+++ b/source/slang/slang-ir-autodiff-unzip.h
@@ -436,9 +436,8 @@ struct DiffUnzipPass
 
         if (intermediateVar)
         {
-            disableIRValidationAtInsert();
+            auto validationScope = disableIRValidationScope();
             diffBuilder->addBackwardDerivativePrimalContextDecoration(callInst, intermediateVar);
-            enableIRValidationAtInsert();
         }
 
         IRInst* diffVal = nullptr;
diff --git a/source/slang/slang-ir-validate.cpp b/source/slang/slang-ir-validate.cpp
index 565ae97d8..b3d6504ab 100644
--- a/source/slang/slang-ir-validate.cpp
+++ b/source/slang/slang-ir-validate.cpp
@@ -273,14 +273,19 @@ void validateIRInstOperands(IRValidateContext* context, IRInst* inst)
 }
 
 static thread_local bool _enableIRValidationAtInsert = false;
-void disableIRValidationAtInsert()
+
+// RAII class implementation for exception-safe IR validation state management
+IRValidationScope::IRValidationScope(bool enableValidation)
+    : m_previousState(_enableIRValidationAtInsert)
 {
-    _enableIRValidationAtInsert = false;
+    _enableIRValidationAtInsert = enableValidation;
 }
-void enableIRValidationAtInsert()
+
+IRValidationScope::~IRValidationScope()
 {
-    _enableIRValidationAtInsert = true;
+    _enableIRValidationAtInsert = m_previousState;
 }
+
 void validateIRInstOperands(IRInst* inst)
 {
     if (!_enableIRValidationAtInsert)
diff --git a/source/slang/slang-ir-validate.h b/source/slang/slang-ir-validate.h
index 722359452..7fc882f37 100644
--- a/source/slang/slang-ir-validate.h
+++ b/source/slang/slang-ir-validate.h
@@ -36,8 +36,38 @@ void validateIRModuleIfEnabled(CompileRequestBase* compileRequest, IRModule* mod
 
 void validateIRModuleIfEnabled(CodeGenContext* codeGenContext, IRModule* module);
 
-void disableIRValidationAtInsert();
-void enableIRValidationAtInsert();
+// RAII class to manage IR validation state in an exception-safe manner
+class [[nodiscard]] IRValidationScope
+{
+public:
+    // Constructor saves current state and sets new state
+    explicit IRValidationScope(bool enableValidation);
+
+    // Destructor automatically restores previous state
+    ~IRValidationScope();
+
+    // Non-copyable to prevent accidental copies
+    IRValidationScope(const IRValidationScope&) = delete;
+    IRValidationScope& operator=(const IRValidationScope&) = delete;
+
+    // Non-movable to keep it simple
+    IRValidationScope(IRValidationScope&&) = delete;
+    IRValidationScope& operator=(IRValidationScope&&) = delete;
+
+private:
+    bool m_previousState;
+};
+
+// Convenience functions to create scoped guards
+[[nodiscard]] inline IRValidationScope enableIRValidationScope()
+{
+    return IRValidationScope(true);
+}
+
+[[nodiscard]] inline IRValidationScope disableIRValidationScope()
+{
+    return IRValidationScope(false);
+}
 
 // Validate that the destination of an atomic operation is appropriate, meaning it's
 // either 'groupshared' or in a device buffer.