Add DebugGlobalVariable instructions to SPIR-V output (#7686)

* Add DebugGlobalVariable instructions to SPIR-V output

Implements generation of DebugGlobalVariable instructions for global variables
like Texture2D and SamplerState in SPIR-V debug information output. Adds debug
type support for texture and sampler types using DebugTypeComposite.

* Handle two more types for DebugGlobalVariable

kIROp_RaytracingAccelerationStructureType and
kIROp_SamplerComparisonStateType had to be handled in
`emitDebugTypeImpl()`

* Fix format

* Refactor debug type emission to reduce duplication

Use IRSamplerStateTypeBase type check and fallback pattern instead of
separate cases for each opcode type.

* Fix compiler warning

* Simplify `emitDebugTypeImpl()` more

2 files changed, 94 insertions, 1 deletions

diff --git a/source/slang/slang-emit-spirv-ops-debug-info-ext.h b/source/slang/slang-emit-spirv-ops-debug-info-ext.h
index 138204af7..ab2d7b730 100644
--- a/source/slang/slang-emit-spirv-ops-debug-info-ext.h
+++ b/source/slang/slang-emit-spirv-ops-debug-info-ext.h
@@ -555,6 +555,42 @@ SpvInst* emitOpDebugLocalVariable(
 }
 
 template<typename T>
+SpvInst* emitOpDebugGlobalVariable(
+    SpvInstParent* parent,
+    IRInst* inst,
+    const T& idResultType,
+    SpvInst* set,
+    IRInst* name,
+    SpvInst* type,
+    IRInst* source,
+    IRInst* line,
+    IRInst* col,
+    SpvInst* scope,
+    IRInst* linkageName,
+    SpvInst* variable,
+    IRInst* flags)
+{
+    static_assert(isSingular<T>);
+    return emitInst(
+        parent,
+        inst,
+        SpvOpExtInst,
+        idResultType,
+        kResultID,
+        set,
+        SpvWord(18), // DebugGlobalVariable opcode in NonSemantic.Shader.DebugInfo.100
+        name,
+        type,
+        source,
+        line,
+        col,
+        scope,
+        linkageName,
+        variable,
+        flags);
+}
+
+template<typename T>
 SpvInst* emitOpDebugInlinedVariable(
     SpvInstParent* parent,
     IRInst* inst,
diff --git a/source/slang/slang-emit-spirv.cpp b/source/slang/slang-emit-spirv.cpp
index 28862f5b8..376a828cd 100644
--- a/source/slang/slang-emit-spirv.cpp
+++ b/source/slang/slang-emit-spirv.cpp
@@ -3215,6 +3215,7 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         if (layout)
             emitVarLayout(param, varInst, layout);
         emitDecorations(param, getID(varInst));
+        maybeEmitDebugGlobalVariable(param, varInst);
         return varInst;
     }
 
@@ -3237,6 +3238,7 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         if (layout)
             emitVarLayout(globalVar, varInst, layout);
         emitDecorations(globalVar, getID(varInst));
+        maybeEmitDebugGlobalVariable(globalVar, varInst);
         return varInst;
     }
 
@@ -3893,6 +3895,39 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
         return nullptr;
     }
 
+    void maybeEmitDebugGlobalVariable(IRInst* globalInst, SpvInst* spvVar)
+    {
+        auto scope = findDebugScope(globalInst->getModule()->getModuleInst());
+        if (!scope)
+            return;
+
+        auto name = getName(globalInst);
+        IRBuilder builder(globalInst);
+        auto varType = tryGetPointedToType(&builder, globalInst->getDataType());
+        auto debugType = emitDebugType(varType);
+
+        // Use default debug source and line info similar to struct debug type emission
+        auto loc = globalInst->findDecoration<IRDebugLocationDecoration>();
+        IRInst* source = loc ? loc->getSource() : m_defaultDebugSource;
+        IRInst* line = loc ? loc->getLine() : builder.getIntValue(builder.getUIntType(), 0);
+        IRInst* col = loc ? loc->getCol() : line;
+
+        emitOpDebugGlobalVariable(
+            getSection(SpvLogicalSectionID::GlobalVariables),
+            nullptr, // Don't associate with IR inst to avoid duplicate registration
+            m_voidType,
+            getNonSemanticDebugInfoExtInst(),
+            name,
+            debugType,
+            source,
+            line,
+            col,
+            scope,
+            name, // linkageName same as name
+            spvVar,
+            builder.getIntValue(builder.getUIntType(), 0)); // flags
+    }
+
     SpvInst* emitMakeUInt64(SpvInstParent* parent, IRInst* inst)
     {
         IRBuilder builder(inst);
@@ -8524,7 +8559,29 @@ struct SPIRVEmitContext : public SourceEmitterBase, public SPIRVEmitSharedContex
                 debugBaseType,
                 builder.getIntValue(builder.getUIntType(), kDebugTypeAtomicQualifier));
         }
-        return ensureInst(m_voidType);
+
+        // Fallback for texture types, raytracing types, and other composite types
+        // Declare variables for debug location like struct handling does
+        IRInst* source = m_defaultDebugSource;
+        IRInst* line = builder.getIntValue(builder.getUIntType(), 0);
+        IRInst* col = line;
+
+        // Emit a composite debug type (struct-like for most types)
+        return emitOpDebugTypeComposite(
+            getSection(SpvLogicalSectionID::ConstantsAndTypes),
+            nullptr,
+            m_voidType,
+            getNonSemanticDebugInfoExtInst(),
+            name,
+            builder.getIntValue(builder.getUIntType(), 0),
+            source,
+            line,
+            col,
+            scope,
+            name,
+            builder.getIntValue(builder.getUIntType(), 0), // Size (unknown)
+            builder.getIntValue(builder.getUIntType(), kUnknownPhysicalLayout),
+            List<SpvInst*>()); // No members
     }
 
     SpvInst* emitDebugType(IRType* type)