llvm · efriedma-quic · Jul 3, 2025 · Jun 17, 2025 · Jun 19, 2025 · Jun 23, 2025
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -942,6 +942,8 @@ Arm and AArch64 Support
 
 - For AArch64, added support for generating executable-only code sections by using the
   ``-mexecute-only`` or ``-mpure-code`` compiler flags. (#GH125688)
+- Added ``-msve-streaming-vector-bits=`` flag, which allows specifying the
+  SVE vector width in streaming mode.
 
 Android Support
 ^^^^^^^^^^^^^^^

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3317,6 +3317,9 @@ def err_sve_vector_in_non_sve_target : Error<
   "SVE vector type %0 cannot be used in a target without sve">;
 def err_sve_vector_in_non_streaming_function : Error<
   "SVE vector type %0 cannot be used in a non-streaming function">;
+def err_sve_fixed_vector_in_streaming_function
+    : Error<"fixed width SVE vector type %0 cannot be used in a "
+            "%select{streaming|streaming-compatible}1 function">;
 def err_attribute_riscv_rvv_bits_unsupported : Error<
   "%0 is only supported when '-mrvv-vector-bits=<bits>' is specified with a "
   "value of \"zvl\" or a power 2 in the range [64,65536]">;

diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
@@ -503,6 +503,9 @@ LANGOPT(OmitVTableRTTI, 1, 0,
 LANGOPT(VScaleMin, 32, 0, "Minimum vscale value")
 LANGOPT(VScaleMax, 32, 0, "Maximum vscale value")
 
+LANGOPT(VScaleStreamingMin, 32, 0, "Minimum streaming vscale value")
+LANGOPT(VScaleStreamingMax, 32, 0, "Maximum streaming vscale value")
+
 ENUM_LANGOPT(ExtendIntArgs, ExtendArgsKind, 1, ExtendArgsKind::ExtendTo32,
              "Controls how scalar integer arguments are extended in calls "
              "to unprototyped and varargs functions")

diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
@@ -1034,9 +1034,15 @@ class TargetInfo : public TransferrableTargetInfo,
   /// set of primary and secondary targets.
   virtual llvm::SmallVector<Builtin::InfosShard> getTargetBuiltins() const = 0;
 
+  enum class ArmStreamingKind {
+    NotStreaming,
+    StreamingCompatible,
+    Streaming,
+  };
+
   /// Returns target-specific min and max values VScale_Range.
   virtual std::optional<std::pair<unsigned, unsigned>>
-  getVScaleRange(const LangOptions &LangOpts, bool IsArmStreamingFunction,
+  getVScaleRange(const LangOptions &LangOpts, ArmStreamingKind Mode,
                  llvm::StringMap<bool> *FeatureMap = nullptr) const {
     return std::nullopt;
   }

diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
@@ -5188,6 +5188,14 @@ def msve_vector_bits_EQ : Joined<["-"], "msve-vector-bits=">, Group<m_aarch64_Fe
   Visibility<[ClangOption, FlangOption]>,
   HelpText<"Specify the size in bits of an SVE vector register. Defaults to the"
            " vector length agnostic value of \"scalable\". (AArch64 only)">;
+def msve_streaming_vector_bits_EQ
+    : Joined<["-"], "msve-streaming-vector-bits=">,
+      Group<m_aarch64_Features_Group>,
+      Visibility<[ClangOption, FlangOption]>,
+      HelpText<
+          "Specify the size in bits of an SVE vector register in streaming "
+          "mode. Defaults to the vector length agnostic value of "
+          "\"scalable\". (AArch64 only)">;
 } // let Flags = [TargetSpecific]
 
 def mvscale_min_EQ : Joined<["-"], "mvscale-min=">,
@@ -5199,6 +5207,17 @@ def mvscale_max_EQ : Joined<["-"], "mvscale-max=">,
   HelpText<"Specify the vscale maximum. Defaults to the"
            " vector length agnostic value of \"0\". (AArch64/RISC-V only)">,
   MarshallingInfoInt<LangOpts<"VScaleMax">>;
+def mvscale_streaming_min_EQ
+    : Joined<["-"], "mvscale-streaming-min=">,
+      Visibility<[CC1Option, FC1Option]>,
+      HelpText<"Specify the vscale minimum. Defaults to \"1\". (AArch64 only)">,
+      MarshallingInfoInt<LangOpts<"VScaleStreamingMin">>;
+def mvscale_streaming_max_EQ
+    : Joined<["-"], "mvscale-streaming-max=">,
+      Visibility<[CC1Option, FC1Option]>,
+      HelpText<"Specify the vscale maximum. Defaults to the"
+               " vector length agnostic value of \"0\". (AArch64 only)">,
+      MarshallingInfoInt<LangOpts<"VScaleStreamingMax">>;
 
 def msign_return_address_EQ : Joined<["-"], "msign-return-address=">,
   Visibility<[ClangOption, CC1Option]>,

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
@@ -10513,8 +10513,8 @@ bool ASTContext::areCompatibleVectorTypes(QualType FirstVec,
 /// getRVVTypeSize - Return RVV vector register size.
 static uint64_t getRVVTypeSize(ASTContext &Context, const BuiltinType *Ty) {
   assert(Ty->isRVVVLSBuiltinType() && "Invalid RVV Type");
-  auto VScale =
-      Context.getTargetInfo().getVScaleRange(Context.getLangOpts(), false);
+  auto VScale = Context.getTargetInfo().getVScaleRange(
+      Context.getLangOpts(), TargetInfo::ArmStreamingKind::NotStreaming);
   if (!VScale)
     return 0;
 

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
@@ -4273,7 +4273,8 @@ void CXXNameMangler::mangleRISCVFixedRVVVectorType(const VectorType *T) {
 
   // Apend the LMUL suffix.
   auto VScale = getASTContext().getTargetInfo().getVScaleRange(
-      getASTContext().getLangOpts(), false);
+      getASTContext().getLangOpts(),
+      TargetInfo::ArmStreamingKind::NotStreaming);
   unsigned VLen = VScale->first * llvm::RISCV::RVVBitsPerBlock;
 
   if (T->getVectorKind() == VectorKind::RVVFixedLengthData) {

diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
@@ -823,16 +823,36 @@ AArch64TargetInfo::getTargetBuiltins() const {
 
 std::optional<std::pair<unsigned, unsigned>>
 AArch64TargetInfo::getVScaleRange(const LangOptions &LangOpts,
-                                  bool IsArmStreamingFunction,
+                                  ArmStreamingKind Mode,
                                   llvm::StringMap<bool> *FeatureMap) const {
-  if (LangOpts.VScaleMin || LangOpts.VScaleMax)
+  if (Mode == ArmStreamingKind::NotStreaming &&
+      (LangOpts.VScaleMin || LangOpts.VScaleMax))
     return std::pair<unsigned, unsigned>(
-        LangOpts.VScaleMin ? LangOpts.VScaleMin : 1, LangOpts.VScaleMax);
+        LangOpts.VScaleMin ? LangOpts.VScaleMin : 1,
+        LangOpts.VScaleMax ? LangOpts.VScaleMax : 16);
+
+  if (Mode == ArmStreamingKind::Streaming &&
+      (LangOpts.VScaleStreamingMin || LangOpts.VScaleStreamingMax))
+    return std::pair<unsigned, unsigned>(
+        LangOpts.VScaleStreamingMin ? LangOpts.VScaleStreamingMin : 1,
+        LangOpts.VScaleStreamingMax ? LangOpts.VScaleStreamingMax : 16);
+
+  if (Mode == ArmStreamingKind::StreamingCompatible &&
+      ((LangOpts.VScaleMin && LangOpts.VScaleStreamingMin) ||
+       (LangOpts.VScaleMax && LangOpts.VScaleStreamingMax))) {
+    unsigned Min =
+        std::min(LangOpts.VScaleMin ? LangOpts.VScaleMin : 1,
+                 LangOpts.VScaleStreamingMin ? LangOpts.VScaleStreamingMin : 1);
+    unsigned Max = std::max(
+        LangOpts.VScaleMax ? LangOpts.VScaleMax : 16,
+        LangOpts.VScaleStreamingMax ? LangOpts.VScaleStreamingMax : 16);
+    return std::pair(Min, Max);
+  }
 
   if (hasFeature("sve") || (FeatureMap && (FeatureMap->lookup("sve"))))
     return std::pair<unsigned, unsigned>(1, 16);
 
-  if (IsArmStreamingFunction &&
+  if (Mode == ArmStreamingKind::Streaming &&
       (hasFeature("sme") || (FeatureMap && (FeatureMap->lookup("sme")))))
     return std::pair<unsigned, unsigned>(1, 16);
 

diff --git a/clang/lib/Basic/Targets/AArch64.h b/clang/lib/Basic/Targets/AArch64.h
@@ -198,7 +198,7 @@ class LLVM_LIBRARY_VISIBILITY AArch64TargetInfo : public TargetInfo {
   llvm::SmallVector<Builtin::InfosShard> getTargetBuiltins() const override;
 
   std::optional<std::pair<unsigned, unsigned>>
-  getVScaleRange(const LangOptions &LangOpts, bool IsArmStreamingFunction,
+  getVScaleRange(const LangOptions &LangOpts, ArmStreamingKind Mode,
                  llvm::StringMap<bool> *FeatureMap = nullptr) const override;
   bool doesFeatureAffectCodeGen(StringRef Name) const override;
   bool validateCpuSupports(StringRef FeatureStr) const override;

diff --git a/clang/lib/Basic/Targets/RISCV.cpp b/clang/lib/Basic/Targets/RISCV.cpp
@@ -222,7 +222,7 @@ void RISCVTargetInfo::getTargetDefines(const LangOptions &Opts,
   // Currently we support the v1.0 RISC-V V intrinsics.
   Builder.defineMacro("__riscv_v_intrinsic", Twine(getVersionValue(1, 0)));
 
-  auto VScale = getVScaleRange(Opts, false);
+  auto VScale = getVScaleRange(Opts, ArmStreamingKind::NotStreaming);
   if (VScale && VScale->first && VScale->first == VScale->second)
     Builder.defineMacro("__riscv_v_fixed_vlen",
                         Twine(VScale->first * llvm::RISCV::RVVBitsPerBlock));
@@ -367,7 +367,7 @@ bool RISCVTargetInfo::initFeatureMap(
 
 std::optional<std::pair<unsigned, unsigned>>
 RISCVTargetInfo::getVScaleRange(const LangOptions &LangOpts,
-                                bool IsArmStreamingFunction,
+                                ArmStreamingKind IsArmStreamingFunction,
                                 llvm::StringMap<bool> *FeatureMap) const {
   // RISCV::RVVBitsPerBlock is 64.
   unsigned VScaleMin = ISAInfo->getMinVLen() / llvm::RISCV::RVVBitsPerBlock;

diff --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
@@ -99,7 +99,7 @@ class RISCVTargetInfo : public TargetInfo {
                  const std::vector<std::string> &FeaturesVec) const override;
 
   std::optional<std::pair<unsigned, unsigned>>
-  getVScaleRange(const LangOptions &LangOpts, bool IsArmStreamingFunction,
+  getVScaleRange(const LangOptions &LangOpts, ArmStreamingKind Mode,
                  llvm::StringMap<bool> *FeatureMap = nullptr) const override;
 
   bool hasFeature(StringRef Feature) const override;

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -1109,10 +1109,16 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
 
   // Add vscale_range attribute if appropriate.
   llvm::StringMap<bool> FeatureMap;
-  bool IsArmStreaming = false;
+  auto IsArmStreaming = TargetInfo::ArmStreamingKind::NotStreaming;
   if (FD) {
     getContext().getFunctionFeatureMap(FeatureMap, FD);
-    IsArmStreaming = IsArmStreamingFunction(FD, true);
+    if (const auto *T = FD->getType()->getAs<FunctionProtoType>())
+      if (T->getAArch64SMEAttributes() &
+          FunctionType::SME_PStateSMCompatibleMask)
+        IsArmStreaming = TargetInfo::ArmStreamingKind::StreamingCompatible;
+
+    if (IsArmStreamingFunction(FD, true))
+      IsArmStreaming = TargetInfo::ArmStreamingKind::Streaming;
   }
   std::optional<std::pair<unsigned, unsigned>> VScaleRange =
       getContext().getTargetInfo().getVScaleRange(getLangOpts(), IsArmStreaming,

diff --git a/clang/lib/CodeGen/Targets/RISCV.cpp b/clang/lib/CodeGen/Targets/RISCV.cpp
@@ -544,7 +544,7 @@ ABIArgInfo RISCVABIInfo::coerceVLSVector(QualType Ty, unsigned ABIVLen) const {
   assert(VT->getElementType()->isBuiltinType() && "expected builtin type!");
 
   auto VScale = getContext().getTargetInfo().getVScaleRange(
-      getContext().getLangOpts(), false);
+      getContext().getLangOpts(), TargetInfo::ArmStreamingKind::NotStreaming);
 
   unsigned NumElts = VT->getNumElements();
   llvm::Type *EltType = llvm::Type::getInt1Ty(getVMContext());

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1668,30 +1668,40 @@ void Clang::AddAArch64TargetArgs(const ArgList &Args,
   }
 
   // Handle -msve_vector_bits=<bits>
-  if (Arg *A = Args.getLastArg(options::OPT_msve_vector_bits_EQ)) {
+  auto HandleVectorBits = [&](Arg *A, StringRef VScaleMin,
+                              StringRef VScaleMax) {
     StringRef Val = A->getValue();
     const Driver &D = getToolChain().getDriver();
     if (Val == "128" || Val == "256" || Val == "512" || Val == "1024" ||
         Val == "2048" || Val == "128+" || Val == "256+" || Val == "512+" ||
         Val == "1024+" || Val == "2048+") {
       unsigned Bits = 0;
       if (!Val.consume_back("+")) {
-        bool Invalid = Val.getAsInteger(10, Bits); (void)Invalid;
+        bool Invalid = Val.getAsInteger(10, Bits);
+        (void)Invalid;
         assert(!Invalid && "Failed to parse value");
         CmdArgs.push_back(
-            Args.MakeArgString("-mvscale-max=" + llvm::Twine(Bits / 128)));
+            Args.MakeArgString(VScaleMax + llvm::Twine(Bits / 128)));
       }
 
-      bool Invalid = Val.getAsInteger(10, Bits); (void)Invalid;
+      bool Invalid = Val.getAsInteger(10, Bits);
+      (void)Invalid;
       assert(!Invalid && "Failed to parse value");
+
       CmdArgs.push_back(
-          Args.MakeArgString("-mvscale-min=" + llvm::Twine(Bits / 128)));
-    // Silently drop requests for vector-length agnostic code as it's implied.
-    } else if (Val != "scalable")
+          Args.MakeArgString(VScaleMin + llvm::Twine(Bits / 128)));
+    } else if (Val == "scalable") {
+      // Silently drop requests for vector-length agnostic code as it's implied.
+    } else {
       // Handle the unsupported values passed to msve-vector-bits.
       D.Diag(diag::err_drv_unsupported_option_argument)
           << A->getSpelling() << Val;
-  }
+    }
+  };
+  if (Arg *A = Args.getLastArg(options::OPT_msve_vector_bits_EQ))
+    HandleVectorBits(A, "-mvscale-min=", "-mvscale-max=");
+  if (Arg *A = Args.getLastArg(options::OPT_msve_streaming_vector_bits_EQ))
+    HandleVectorBits(A, "-mvscale-streaming-min=", "-mvscale-streaming-max=");
 
   AddAAPCSVolatileBitfieldArgs(Args, CmdArgs);
 

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4560,6 +4560,11 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
     if (StringRef(A->getValue()).getAsInteger(10, VScaleMin) || VScaleMin == 0)
       Diags.Report(diag::err_cc1_unbounded_vscale_min);
   }
+  if (Arg *A = Args.getLastArg(options::OPT_mvscale_streaming_min_EQ)) {
+    unsigned VScaleMin;
+    if (StringRef(A->getValue()).getAsInteger(10, VScaleMin) || VScaleMin == 0)
+      Diags.Report(diag::err_cc1_unbounded_vscale_min);
+  }
 
   if (const Arg *A = Args.getLastArg(OPT_frandomize_layout_seed_file_EQ)) {
     std::ifstream SeedFile(A->getValue(0));

diff --git a/clang/lib/Sema/Sema.cpp b/clang/lib/Sema/Sema.cpp
@@ -2261,6 +2261,24 @@ void Sema::checkTypeSupport(QualType Ty, SourceLocation Loc, ValueDecl *D) {
         }
       }
     }
+
+    if (auto *VT = Ty->getAs<VectorType>();
+        VT && FD &&
+        (VT->getVectorKind() == VectorKind::SveFixedLengthData ||
+         VT->getVectorKind() == VectorKind::SveFixedLengthPredicate) &&
+        (LangOpts.VScaleMin != LangOpts.VScaleStreamingMin ||
+         LangOpts.VScaleMax != LangOpts.VScaleStreamingMax)) {
+      if (IsArmStreamingFunction(FD, /*IncludeLocallyStreaming=*/true)) {
+        Diag(Loc, diag::err_sve_fixed_vector_in_streaming_function)
+            << Ty << /*Streaming*/ 0;
+      } else if (const auto *FTy = FD->getType()->getAs<FunctionProtoType>()) {
+        if (FTy->getAArch64SMEAttributes() &
+            FunctionType::SME_PStateSMCompatibleMask) {
+          Diag(Loc, diag::err_sve_fixed_vector_in_streaming_function)
+              << Ty << /*StreamingCompatible*/ 1;
+        }
+      }
+    }
   };
 
   CheckType(Ty);

diff --git a/clang/lib/Sema/SemaARM.cpp b/clang/lib/Sema/SemaARM.cpp
@@ -1410,29 +1410,49 @@ void SemaARM::CheckSMEFunctionDefAttributes(const FunctionDecl *FD) {
 }
 
 /// getSVETypeSize - Return SVE vector or predicate register size.
-static uint64_t getSVETypeSize(ASTContext &Context, const BuiltinType *Ty) {
+static uint64_t getSVETypeSize(ASTContext &Context, const BuiltinType *Ty,
+                               bool IsStreaming) {
   assert(Ty->isSveVLSBuiltinType() && "Invalid SVE Type");
+  uint64_t VScale = IsStreaming ? Context.getLangOpts().VScaleStreamingMin
+                                : Context.getLangOpts().VScaleMin;
   if (Ty->getKind() == BuiltinType::SveBool ||
       Ty->getKind() == BuiltinType::SveCount)
-    return (Context.getLangOpts().VScaleMin * 128) / Context.getCharWidth();
-  return Context.getLangOpts().VScaleMin * 128;
+    return (VScale * 128) / Context.getCharWidth();
+  return VScale * 128;
 }
 
 bool SemaARM::areCompatibleSveTypes(QualType FirstType, QualType SecondType) {
-  auto IsValidCast = [this](QualType FirstType, QualType SecondType) {
+  bool IsStreaming = false;
+  if (getLangOpts().VScaleMin != getLangOpts().VScaleStreamingMin ||
+      getLangOpts().VScaleMax != getLangOpts().VScaleStreamingMax) {
+    if (const FunctionDecl *FD =
+            SemaRef.getCurFunctionDecl(/*AllowLambda=*/true)) {
+      // For streaming-compatible functions, we don't know vector length.
+      if (const auto *T = FD->getType()->getAs<FunctionProtoType>()) {
+        if (T->getAArch64SMEAttributes() &
+            FunctionType::SME_PStateSMCompatibleMask)
+          return false;
+      }
+
+      if (IsArmStreamingFunction(FD, /*IncludeLocallyStreaming=*/true))
+        IsStreaming = true;
+    }
+  }
+
+  auto IsValidCast = [&](QualType FirstType, QualType SecondType) {
     if (const auto *BT = FirstType->getAs<BuiltinType>()) {
       if (const auto *VT = SecondType->getAs<VectorType>()) {
-        ASTContext &Context = getASTContext();
         // Predicates have the same representation as uint8 so we also have to
         // check the kind to make these types incompatible.
+        ASTContext &Context = getASTContext();
         if (VT->getVectorKind() == VectorKind::SveFixedLengthPredicate)
           return BT->getKind() == BuiltinType::SveBool;
         else if (VT->getVectorKind() == VectorKind::SveFixedLengthData)
           return VT->getElementType().getCanonicalType() ==
                  FirstType->getSveEltType(Context);
         else if (VT->getVectorKind() == VectorKind::Generic)
           return Context.getTypeSize(SecondType) ==
-                     getSVETypeSize(Context, BT) &&
+                     getSVETypeSize(Context, BT, IsStreaming) &&
                  Context.hasSameType(
                      VT->getElementType(),
                      Context.getBuiltinVectorTypeInfo(BT).ElementType);
@@ -1447,7 +1467,23 @@ bool SemaARM::areCompatibleSveTypes(QualType FirstType, QualType SecondType) {
 
 bool SemaARM::areLaxCompatibleSveTypes(QualType FirstType,
                                        QualType SecondType) {
-  auto IsLaxCompatible = [this](QualType FirstType, QualType SecondType) {
+  bool IsStreaming = false;
+  if (getLangOpts().VScaleMin != getLangOpts().VScaleStreamingMin ||
+      getLangOpts().VScaleMax != getLangOpts().VScaleStreamingMax) {
+    if (const FunctionDecl *FD =
+            SemaRef.getCurFunctionDecl(/*AllowLambda=*/true)) {
+      // For streaming-compatible functions, we don't know vector length.
+      if (const auto *T = FD->getType()->getAs<FunctionProtoType>())
+        if (T->getAArch64SMEAttributes() &
+            FunctionType::SME_PStateSMCompatibleMask)
+          return false;
+
+      if (IsArmStreamingFunction(FD, /*IncludeLocallyStreaming=*/true))
+        IsStreaming = true;
+    }
+  }
+
+  auto IsLaxCompatible = [&](QualType FirstType, QualType SecondType) {
     const auto *BT = FirstType->getAs<BuiltinType>();
     if (!BT)
       return false;
@@ -1471,7 +1507,8 @@ bool SemaARM::areLaxCompatibleSveTypes(QualType FirstType,
       // ACLE Spec Version 00bet6, 3.7.3.2. Behavior common to vectors and
       // predicates.
       if (VecTy->getVectorKind() == VectorKind::Generic &&
-          Context.getTypeSize(SecondType) != getSVETypeSize(Context, BT))
+          Context.getTypeSize(SecondType) !=
+              getSVETypeSize(Context, BT, IsStreaming))
         return false;
 
       // If -flax-vector-conversions=all is specified, the types are

diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
@@ -8522,8 +8522,8 @@ static void HandleRISCVRVVVectorBitsTypeAttr(QualType &CurType,
     return;
   }
 
-  auto VScale =
-      S.Context.getTargetInfo().getVScaleRange(S.getLangOpts(), false);
+  auto VScale = S.Context.getTargetInfo().getVScaleRange(
+      S.getLangOpts(), TargetInfo::ArmStreamingKind::NotStreaming);
   if (!VScale || !VScale->first || VScale->first != VScale->second) {
     S.Diag(Attr.getLoc(), diag::err_attribute_riscv_rvv_bits_unsupported)
         << Attr;