microsoft · JoeCitizen · Feb 13, 2026 · Feb 4, 2026 · Feb 4, 2026 · Feb 9, 2026
diff --git a/docs/DXIL.rst b/docs/DXIL.rst
@@ -3329,6 +3329,7 @@ SM.CSNOSIGNATURES                                             Compute shaders mu
 SM.DOMAINLOCATIONIDXOOB                                       DomainLocation component index out of bounds for the domain.
 SM.DSINPUTCONTROLPOINTCOUNTRANGE                              DS input control point count must be [0..%0].  %1 specified.
 SM.DXILVERSION                                                Target shader model requires specific Dxil Version
+SM.EXPLICITTGSMSIZEONENTRY                                    Total Thread Group Shared Memory used by entry must not exceed limit specified by entry attribute.
 SM.GSINSTANCECOUNTRANGE                                       GS instance count must be [1..%0].  %1 specified.
 SM.GSOUTPUTVERTEXCOUNTRANGE                                   GS output vertex count must be [0..%0].  %1 specified.
 SM.GSTOTALOUTPUTVERTEXDATARANGE                               Declared output vertex count (%0) multiplied by the total number of declared scalar components of output data (%1) equals %2.  This value cannot be greater than %3.
@@ -3351,8 +3352,7 @@ SM.INVALIDSAMPLERFEEDBACKTYPE                                 Invalid sampler fe
 SM.INVALIDTEXTUREKINDONUAV                                    TextureCube[Array] resources are not supported with UAVs.
 SM.ISOLINEOUTPUTPRIMITIVEMISMATCH                             Hull Shader declared with IsoLine Domain must specify output primitive point or line. Triangle_cw or triangle_ccw output are not compatible with the IsoLine Domain.
 SM.ISSPECIALFLOAT                                             16 bit IsSpecialFloat overloads require Shader Model 6.9 or higher.
-SM.MAXMSSMSIZE                                                Total Thread Group Shared Memory storage is %0, exceeded %1.
-SM.MAXTGSMSIZE                                                Total Thread Group Shared Memory storage is %0, exceeded %1.
+SM.MAXTGSMSIZEONENTRY                                         Total Thread Group Shared Memory used by entry must not exceed maximum for shader model.
 SM.MAXTHEADGROUP                                              Declared Thread Group Count %0 (X*Y*Z) is beyond the valid maximum of %1.
 SM.MESHPSIGROWCOUNT                                           For shader '%0', primitive output signatures are taking up more than %1 rows.
 SM.MESHSHADERINOUTSIZE                                        For shader '%0', payload plus output size is greater than %1.

diff --git a/include/dxc/DXIL/DxilFunctionProps.h b/include/dxc/DXIL/DxilFunctionProps.h
@@ -109,6 +109,8 @@ struct DxilWaveSize {
 };
 
 struct DxilFunctionProps {
+  static constexpr int kGroupSharedLimitUnset = -1;
+
   DxilFunctionProps() {
     memset(&ShaderProps, 0, sizeof(ShaderProps));
     shaderKind = DXIL::ShaderKind::Invalid;
@@ -117,7 +119,7 @@ struct DxilFunctionProps {
     memset(&Node, 0, sizeof(Node));
     Node.LaunchType = DXIL::NodeLaunchType::Invalid;
     Node.LocalRootArgumentsTableIndex = -1;
-    groupSharedLimitBytes = 0;
+    groupSharedLimitBytes = kGroupSharedLimitUnset;
   }
   union {
     // Geometry shader.
@@ -175,7 +177,7 @@ struct DxilFunctionProps {
   // numThreads shared between multiple shader types and node shaders.
   unsigned numThreads[3];
 
-  unsigned groupSharedLimitBytes;
+  int groupSharedLimitBytes;
 
   struct NodeProps {
     DXIL::NodeLaunchType LaunchType = DXIL::NodeLaunchType::Invalid;

diff --git a/include/dxc/DXIL/DxilModule.h b/include/dxc/DXIL/DxilModule.h
@@ -254,7 +254,6 @@ class DxilModule {
   void SetNumThreads(unsigned x, unsigned y, unsigned z);
   unsigned GetNumThreads(unsigned idx) const;
 
-  unsigned GetGroupSharedLimit() const;
   // The total amount of group shared memory (in bytes) used by the shader.
   unsigned GetTGSMSizeInBytes() const;
 

diff --git a/lib/DXIL/DxilMetadataHelper.cpp b/lib/DXIL/DxilMetadataHelper.cpp
@@ -1626,7 +1626,9 @@ MDTuple *DxilMDHelper::EmitDxilEntryProperties(uint64_t rawShaderFlag,
     }
 
     const hlsl::ShaderModel *SM = GetShaderModel();
-    if (SM->IsSMAtLeast(6, 10)) {
+    if (SM->IsSMAtLeast(6, 10) &&
+        props.groupSharedLimitBytes !=
+            DxilFunctionProps::kGroupSharedLimitUnset) {
       MDVals.emplace_back(
           Uint32ToConstMD(DxilMDHelper::kDxilGroupSharedLimitTag));
       MDVals.emplace_back(Uint32ToConstMD(props.groupSharedLimitBytes));
@@ -1695,13 +1697,31 @@ MDTuple *DxilMDHelper::EmitDxilEntryProperties(uint64_t rawShaderFlag,
                                         MS.maxPrimitiveCount, MS.outputTopology,
                                         MS.payloadSizeInBytes);
     MDVals.emplace_back(pMDTuple);
+
+    const hlsl::ShaderModel *SM = GetShaderModel();
+    if (SM->IsSMAtLeast(6, 10) &&
+        props.groupSharedLimitBytes !=
+            DxilFunctionProps::kGroupSharedLimitUnset) {
+      MDVals.emplace_back(
+          Uint32ToConstMD(DxilMDHelper::kDxilGroupSharedLimitTag));
+      MDVals.emplace_back(Uint32ToConstMD(props.groupSharedLimitBytes));
+    }
   } break;
   case DXIL::ShaderKind::Amplification: {
     auto &AS = props.ShaderProps.AS;
     MDVals.emplace_back(Uint32ToConstMD(DxilMDHelper::kDxilASStateTag));
     MDTuple *pMDTuple =
         EmitDxilASState(props.numThreads, AS.payloadSizeInBytes);
     MDVals.emplace_back(pMDTuple);
+
+    const hlsl::ShaderModel *SM = GetShaderModel();
+    if (SM->IsSMAtLeast(6, 10) &&
+        props.groupSharedLimitBytes !=
+            DxilFunctionProps::kGroupSharedLimitUnset) {
+      MDVals.emplace_back(
+          Uint32ToConstMD(DxilMDHelper::kDxilGroupSharedLimitTag));
+      MDVals.emplace_back(Uint32ToConstMD(props.groupSharedLimitBytes));
+    }
   } break;
   case DXIL::ShaderKind::Node: {
     // The Node specific properties have already been handled by
@@ -1714,6 +1734,15 @@ MDTuple *DxilMDHelper::EmitDxilEntryProperties(uint64_t rawShaderFlag,
     NumThreadVals.emplace_back(Uint32ToConstMD(props.numThreads[1]));
     NumThreadVals.emplace_back(Uint32ToConstMD(props.numThreads[2]));
     MDVals.emplace_back(MDNode::get(m_Ctx, NumThreadVals));
+
+    const hlsl::ShaderModel *SM = GetShaderModel();
+    if (SM->IsSMAtLeast(6, 10) &&
+        props.groupSharedLimitBytes !=
+            DxilFunctionProps::kGroupSharedLimitUnset) {
+      MDVals.emplace_back(
+          Uint32ToConstMD(DxilMDHelper::kDxilGroupSharedLimitTag));
+      MDVals.emplace_back(Uint32ToConstMD(props.groupSharedLimitBytes));
+    }
   } break;
   default:
     break;
@@ -1781,7 +1810,8 @@ void DxilMDHelper::LoadDxilEntryProperties(const MDOperand &MDO,
     } break;
 
     case DxilMDHelper::kDxilGroupSharedLimitTag: {
-      DXASSERT(props.IsCS(), "else invalid shader kind");
+      DXASSERT(props.IsCS() || props.IsMS() || props.IsAS() || props.IsNode(),
+               "else invalid shader kind");
       props.groupSharedLimitBytes = ConstMDToUint32(MDO);
       if (!m_pSM->IsSMAtLeast(6, 10))
         m_bExtraMetadata = true;

diff --git a/lib/DXIL/DxilModule.cpp b/lib/DXIL/DxilModule.cpp
@@ -234,6 +234,12 @@ void DxilModule::SetEntryFunction(Function *pEntryFunc) {
   // Move entry props to new function in order to preserve them.
   std::unique_ptr<DxilEntryProps> Props =
       std::move(m_DxilEntryPropsMap.begin()->second);
+  // For HS, make sure we add the patch constant function to the set of patch
+  // constant functions.
+  m_PatchConstantFunctions.clear();
+  if (Props->props.IsHS() && Props->props.ShaderProps.HS.patchConstantFunc)
+    m_PatchConstantFunctions.insert(
+        Props->props.ShaderProps.HS.patchConstantFunc);
   m_DxilEntryPropsMap.clear();
   m_DxilEntryPropsMap[m_pEntryFunc] = std::move(Props);
 }
@@ -412,15 +418,6 @@ unsigned DxilModule::GetNumThreads(unsigned idx) const {
   return props.numThreads[idx];
 }
 
-unsigned DxilModule::GetGroupSharedLimit() const {
-  DXASSERT(m_DxilEntryPropsMap.size() == 1 &&
-               (m_pSM->IsCS() || m_pSM->IsMS() || m_pSM->IsAS()),
-           "only works for CS/MS/AS profiles");
-  const DxilFunctionProps &props = m_DxilEntryPropsMap.begin()->second->props;
-  DXASSERT_NOMSG(m_pSM->GetKind() == props.shaderKind);
-  return props.groupSharedLimitBytes;
-}
-
 unsigned DxilModule::GetTGSMSizeInBytes() const {
   const DataLayout &DL = m_pModule->getDataLayout();
   unsigned TGSMSize = 0;

diff --git a/lib/DxilValidation/DxilValidation.cpp b/lib/DxilValidation/DxilValidation.cpp
@@ -3916,70 +3916,156 @@ static void ValidateGlobalVariables(ValidationContext &ValCtx) {
   DxilModule &M = ValCtx.DxilMod;
 
   const ShaderModel *pSM = ValCtx.DxilMod.GetShaderModel();
-  bool TGSMAllowed = pSM->IsCS() || pSM->IsAS() || pSM->IsMS() || pSM->IsLib();
-
-  unsigned TGSMSize = 0;
-  std::vector<StoreInst *> FixAddrTGSMList;
   const DataLayout &DL = M.GetModule()->getDataLayout();
+  std::vector<StoreInst *> FixAddrTGSMList;
+
+  auto isTGSMEntry = [](DXIL::ShaderKind Kind) -> bool {
+    return Kind == DXIL::ShaderKind::Compute ||
+           Kind == DXIL::ShaderKind::Amplification ||
+           Kind == DXIL::ShaderKind::Mesh || Kind == DXIL::ShaderKind::Node;
+  };
+
+  auto getMaxTGSM = [](const DxilFunctionProps &Props) -> unsigned {
+    if (Props.groupSharedLimitBytes >= 0)
+      return static_cast<unsigned>(Props.groupSharedLimitBytes);
+    if (Props.IsCS() || Props.IsAS() || Props.IsNode())
+      return DXIL::kMaxTGSMSize;
+    else if (Props.IsMS())
+      return DXIL::kMaxMSSMSize;
+    return 0;
+  };
+
+  DenseMap<const Function *, uint32_t> TGSMInFunc;
+  // Initialize all function TGSM usage to zero
+  for (auto &function : M.GetModule()->getFunctionList())
+    TGSMInFunc[&function] = 0;
+
+  // Map TGSM overages per function, used for error reporting
+  // Tracks first user per GV that caused overage.
+  typedef MapVector<GlobalVariable *, Instruction *> FirstUserMap;
+  typedef DenseMap<const Function *, FirstUserMap> TGSMOverageMap;
+  TGSMOverageMap TGSMOverages;
+
+  auto ReportTGSMOverages = [&](Function *EntryFunc) {
+    unsigned Size = TGSMInFunc[EntryFunc];
+    if (!Size)
+      return; // No TGSM used.
+
+    // Several possibilities:
+    // - Entry point or library function with function properties
+    // - Patch constant function without function properties, TGSM not allowed
+    // - No-inline function without function properties, TGSM counted in entry
+    DXIL::ShaderKind Kind = DXIL::ShaderKind::Invalid;
+    bool IsPatchConstant = M.IsPatchConstantShader(EntryFunc);
+    if (M.HasDxilFunctionProps(EntryFunc))
+      Kind = M.GetDxilEntryProps(EntryFunc).props.shaderKind;
+    else if (!IsPatchConstant)
+      return; // no-inline function, accounted for in entry
+
+    auto Overages = TGSMOverages.find(EntryFunc);
+    if (Overages == TGSMOverages.end())
+      return;
+
+    unsigned MaxSize = 0;
+    ValidationRule Rule = ValidationRule::SmMaxTGSMSizeOnEntry;
+
+    // Props only exist if not a patch constant function.
+    if (!IsPatchConstant) {
+      DxilFunctionProps &Props = M.GetDxilFunctionProps(EntryFunc);
+      MaxSize = getMaxTGSM(Props);
+      Rule = Props.groupSharedLimitBytes !=
+                     DxilFunctionProps::kGroupSharedLimitUnset
+                 ? ValidationRule::SmExplicitTGSMSizeOnEntry
+                 : ValidationRule::SmMaxTGSMSizeOnEntry;
+    }
+
+    for (auto &GVAndUser : Overages->second) {
+      Instruction *UseInst = GVAndUser.second;
+      if (!isTGSMEntry(Kind))
+        ValCtx.EmitInstrFormatError(UseInst, ValidationRule::SmTGSMUnsupported,
+                                    {"from non-compute entry points"});
+      else
+        ValCtx.EmitInstrFormatError(UseInst, Rule,
+                                    {EntryFunc->getName(), std::to_string(Size),
+                                     std::to_string(MaxSize)});
+    }
+  };
+
+  struct WorkListEntry {
+    User *U;
+    // FirstUser tracks the first (inner-most) instruction user of the TGSM
+    // variable for this worklist entry.
+    Instruction *FirstUser;
+  };
+
+  // Collect total groupshared memory potentially used by every function
   for (GlobalVariable &GV : M.GetModule()->globals()) {
     ValidateGlobalVariable(GV, ValCtx);
     if (GV.getType()->getAddressSpace() == DXIL::kTGSMAddrSpace) {
-      if (!TGSMAllowed)
-        ValCtx.EmitGlobalVariableFormatError(
-            &GV, ValidationRule::SmTGSMUnsupported,
-            {std::string("in Shader Model ") + M.GetShaderModel()->GetName()});
-      // Lib targets need to check the usage to know if it's allowed
-      if (pSM->IsLib()) {
-        for (User *U : GV.users()) {
-          if (Instruction *I = dyn_cast<Instruction>(U)) {
-            llvm::Function *F = I->getParent()->getParent();
+      SmallPtrSet<llvm::Function *, 8> completeFuncs;
+      SmallVector<WorkListEntry, 16> WorkList;
+      auto AddUsers = [&WorkList](User *U, Instruction *FirstUser) {
+        for (User *U : U->users()) {
+          if (!FirstUser && isa<Instruction>(U))
+            WorkList.push_back({U, cast<Instruction>(U)});
+          else
+            WorkList.push_back({U, FirstUser});
+        }
+      };
+      uint32_t GVSize = DL.getTypeAllocSize(GV.getType()->getElementType());
+
+      AddUsers(&GV, nullptr);
+
+      while (!WorkList.empty()) {
+        WorkListEntry Info = WorkList.pop_back_val();
+        // If const, keep going until we find something we can use
+        if (isa<Constant>(Info.U)) {
+          AddUsers(Info.U, Info.FirstUser);
+          continue;
+        }
+
+        if (Instruction *I = dyn_cast<Instruction>(Info.U)) {
+          llvm::Function *F = I->getParent()->getParent();
+          if (completeFuncs.insert(F).second) {
+            // If function is new, process it and its users
+            // Add users to the worklist
+            Instruction *FirstUser = Info.FirstUser ? Info.FirstUser : I;
+            AddUsers(F, FirstUser);
+            // Add groupshared size to function's total
+            unsigned &TotalSize = TGSMInFunc[F];
+            TotalSize += GVSize;
+            // If this is an entry function, check the TotalSize against the
+            // limits.
             if (M.HasDxilEntryProps(F)) {
-              DxilFunctionProps &Props = M.GetDxilEntryProps(F).props;
-              if (!Props.IsCS() && !Props.IsAS() && !Props.IsMS() &&
-                  !Props.IsNode()) {
-                ValCtx.EmitInstrFormatError(I,
-                                            ValidationRule::SmTGSMUnsupported,
-                                            {"from non-compute entry points"});
-              }
+              const DxilFunctionProps &Props = M.GetDxilEntryProps(F).props;
+              unsigned MaxSize = getMaxTGSM(Props);
+              if (TotalSize > MaxSize && TGSMOverages[F].count(&GV) == 0)
+                TGSMOverages[F][&GV] = FirstUser;
+            } else if (M.IsPatchConstantShader(F)) {
+              // Collect illegal usage for error reporting
+              if (TGSMOverages[F].count(&GV) == 0)
+                TGSMOverages[F][&GV] = FirstUser;
             }
           }
         }
       }
-      TGSMSize += DL.getTypeAllocSize(GV.getType()->getElementType());
       CollectFixAddressAccess(&GV, FixAddrTGSMList);
     }
   }
 
-  ValidationRule Rule = ValidationRule::SmMaxTGSMSize;
-  unsigned MaxSize = DXIL::kMaxTGSMSize;
-
-  if (M.GetShaderModel()->IsMS()) {
-    Rule = ValidationRule::SmMaxMSSMSize;
-    MaxSize = DXIL::kMaxMSSMSize;
-  }
-
-  // Check if the entry function has attribute to override TGSM size.
-  if (M.HasDxilEntryProps(M.GetEntryFunction())) {
-    DxilEntryProps &EntryProps = M.GetDxilEntryProps(M.GetEntryFunction());
-    if (EntryProps.props.IsCS()) {
-      unsigned SpecifiedTGSMSize = EntryProps.props.groupSharedLimitBytes;
-      if (SpecifiedTGSMSize > 0) {
-        MaxSize = SpecifiedTGSMSize;
-      }
+  if (pSM->IsLib()) {
+    for (auto &F : M.GetModule()->functions()) {
+      if (F.isDeclaration() ||
+          !(M.HasDxilEntryProps(&F) || M.IsPatchConstantShader(&F)))
+        continue;
+      ReportTGSMOverages(&F);
     }
-  }
-
-  if (TGSMSize > MaxSize) {
-    Module::global_iterator GI = M.GetModule()->global_end();
-    GlobalVariable *GV = &*GI;
-    do {
-      GI--;
-      GV = &*GI;
-      if (GV->getType()->getAddressSpace() == hlsl::DXIL::kTGSMAddrSpace)
-        break;
-    } while (GI != M.GetModule()->global_begin());
-    ValCtx.EmitGlobalVariableFormatError(
-        GV, Rule, {std::to_string(TGSMSize), std::to_string(MaxSize)});
+  } else {
+    Function *EntryFunc = M.GetEntryFunction();
+    if (EntryFunc)
+      ReportTGSMOverages(EntryFunc);
+    if (pSM->IsHS())
+      ReportTGSMOverages(M.GetPatchConstantFunction());
   }
 
   if (!FixAddrTGSMList.empty()) {

diff --git a/tools/clang/lib/CodeGen/CGHLSLMS.cpp b/tools/clang/lib/CodeGen/CGHLSLMS.cpp
@@ -1653,13 +1653,8 @@ void CGMSHLSLRuntime::AddHLSLFunctionInfo(Function *F, const FunctionDecl *FD) {
           FD->getAttr<HLSLGroupSharedLimitAttr>()) {
     funcProps->groupSharedLimitBytes = Attr->getLimit();
   } else {
-    if (SM->IsMS()) { // Fallback to default limits
-      funcProps->groupSharedLimitBytes = DXIL::kMaxMSSMSize; // 28k For MS
-    } else if (SM->IsAS() || SM->IsCS()) {
-      funcProps->groupSharedLimitBytes = DXIL::kMaxTGSMSize; // 32k For AS/CS
-    } else {
-      funcProps->groupSharedLimitBytes = 0;
-    }
+    funcProps->groupSharedLimitBytes =
+        DxilFunctionProps::kGroupSharedLimitUnset; // not specified
   }
 
   // Hull shader.

diff --git a/tools/clang/test/CodeGenHLSL/mesh-val/oversizeSM.hlsl b/tools/clang/test/CodeGenHLSL/mesh-val/oversizeSM.hlsl
@@ -1,6 +1,6 @@
 // RUN: %dxc -E main -T ms_6_5 %s | FileCheck %s
 
-// CHECK: Total Thread Group Shared Memory storage is 28676, exceeded 28672
+// CHECK: Total Thread Group Shared Memory used by 'main' is 28676, exceeding maximum: 28672.
 
 #define MAX_VERT 32
 #define MAX_PRIM 16