[AArch64][SME] Add diagnostics for SME attributes on lambda functions (#121777)

CheckFunctionDeclaration emits diagnostics if any SME attributes are used
by a function definition without the required +sme or +sme2 target features.
This patch moves these diagnostics to a new function in SemaARM and
also adds a call to this from ActOnStartOfLambdaDefinition.

Author: kmclaughlin-arm

clang/include/clang/Sema/SemaARM.h

@@ -79,6 +79,8 @@ class SemaARM : public SemaBase {
   void handleNewAttr(Decl *D, const ParsedAttr &AL);
   void handleCmseNSEntryAttr(Decl *D, const ParsedAttr &AL);
   void handleInterruptAttr(Decl *D, const ParsedAttr &AL);
+
+  void CheckSMEFunctionDefAttributes(const FunctionDecl *FD);
 };
 
 SemaARM::ArmStreamingType getArmStreamingFnType(const FunctionDecl *FD);

clang/lib/Sema/SemaARM.cpp

@@ -1328,4 +1328,57 @@ void SemaARM::handleInterruptAttr(Decl *D, const ParsedAttr &AL) {
                  ARMInterruptAttr(getASTContext(), AL, Kind));
 }
 
+// Check if the function definition uses any AArch64 SME features without
+// having the '+sme' feature enabled and warn user if sme locally streaming
+// function returns or uses arguments with VL-based types.
+void SemaARM::CheckSMEFunctionDefAttributes(const FunctionDecl *FD) {
+  const auto *Attr = FD->getAttr<ArmNewAttr>();
+  bool UsesSM = FD->hasAttr<ArmLocallyStreamingAttr>();
+  bool UsesZA = Attr && Attr->isNewZA();
+  bool UsesZT0 = Attr && Attr->isNewZT0();
+
+  if (FD->hasAttr<ArmLocallyStreamingAttr>()) {
+    if (FD->getReturnType()->isSizelessVectorType())
+      Diag(FD->getLocation(),
+           diag::warn_sme_locally_streaming_has_vl_args_returns)
+          << /*IsArg=*/false;
+    if (llvm::any_of(FD->parameters(), [](ParmVarDecl *P) {
+          return P->getOriginalType()->isSizelessVectorType();
+        }))
+      Diag(FD->getLocation(),
+           diag::warn_sme_locally_streaming_has_vl_args_returns)
+          << /*IsArg=*/true;
+  }
+  if (const auto *FPT = FD->getType()->getAs<FunctionProtoType>()) {
+    FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
+    UsesSM |= EPI.AArch64SMEAttributes & FunctionType::SME_PStateSMEnabledMask;
+    UsesZA |= FunctionType::getArmZAState(EPI.AArch64SMEAttributes) !=
+              FunctionType::ARM_None;
+    UsesZT0 |= FunctionType::getArmZT0State(EPI.AArch64SMEAttributes) !=
+               FunctionType::ARM_None;
+  }
+
+  ASTContext &Context = getASTContext();
+  if (UsesSM || UsesZA) {
+    llvm::StringMap<bool> FeatureMap;
+    Context.getFunctionFeatureMap(FeatureMap, FD);
+    if (!FeatureMap.contains("sme")) {
+      if (UsesSM)
+        Diag(FD->getLocation(),
+             diag::err_sme_definition_using_sm_in_non_sme_target);
+      else
+        Diag(FD->getLocation(),
+             diag::err_sme_definition_using_za_in_non_sme_target);
+    }
+  }
+  if (UsesZT0) {
+    llvm::StringMap<bool> FeatureMap;
+    Context.getFunctionFeatureMap(FeatureMap, FD);
+    if (!FeatureMap.contains("sme2")) {
+      Diag(FD->getLocation(),
+           diag::err_sme_definition_using_zt0_in_non_sme2_target);
+    }
+  }
+}
+
 } // namespace clang

clang/lib/Sema/SemaDecl.cpp

@@ -45,6 +45,7 @@
 #include "clang/Sema/ParsedTemplate.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
+#include "clang/Sema/SemaARM.h"
 #include "clang/Sema/SemaCUDA.h"
 #include "clang/Sema/SemaHLSL.h"
 #include "clang/Sema/SemaInternal.h"
@@ -12297,58 +12298,8 @@ bool Sema::CheckFunctionDeclaration(Scope *S, FunctionDecl *NewFD,
     }
   }
 
-  // Check if the function definition uses any AArch64 SME features without
-  // having the '+sme' feature enabled and warn user if sme locally streaming
-  // function returns or uses arguments with VL-based types.
-  if (DeclIsDefn) {
-    const auto *Attr = NewFD->getAttr<ArmNewAttr>();
-    bool UsesSM = NewFD->hasAttr<ArmLocallyStreamingAttr>();
-    bool UsesZA = Attr && Attr->isNewZA();
-    bool UsesZT0 = Attr && Attr->isNewZT0();
-
-    if (NewFD->hasAttr<ArmLocallyStreamingAttr>()) {
-      if (NewFD->getReturnType()->isSizelessVectorType())
-        Diag(NewFD->getLocation(),
-             diag::warn_sme_locally_streaming_has_vl_args_returns)
-            << /*IsArg=*/false;
-      if (llvm::any_of(NewFD->parameters(), [](ParmVarDecl *P) {
-            return P->getOriginalType()->isSizelessVectorType();
-          }))
-        Diag(NewFD->getLocation(),
-             diag::warn_sme_locally_streaming_has_vl_args_returns)
-            << /*IsArg=*/true;
-    }
-    if (const auto *FPT = NewFD->getType()->getAs<FunctionProtoType>()) {
-      FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
-      UsesSM |=
-          EPI.AArch64SMEAttributes & FunctionType::SME_PStateSMEnabledMask;
-      UsesZA |= FunctionType::getArmZAState(EPI.AArch64SMEAttributes) !=
-                FunctionType::ARM_None;
-      UsesZT0 |= FunctionType::getArmZT0State(EPI.AArch64SMEAttributes) !=
-                 FunctionType::ARM_None;
-    }
-
-    if (UsesSM || UsesZA) {
-      llvm::StringMap<bool> FeatureMap;
-      Context.getFunctionFeatureMap(FeatureMap, NewFD);
-      if (!FeatureMap.contains("sme")) {
-        if (UsesSM)
-          Diag(NewFD->getLocation(),
-               diag::err_sme_definition_using_sm_in_non_sme_target);
-        else
-          Diag(NewFD->getLocation(),
-               diag::err_sme_definition_using_za_in_non_sme_target);
-      }
-    }
-    if (UsesZT0) {
-      llvm::StringMap<bool> FeatureMap;
-      Context.getFunctionFeatureMap(FeatureMap, NewFD);
-      if (!FeatureMap.contains("sme2")) {
-        Diag(NewFD->getLocation(),
-             diag::err_sme_definition_using_zt0_in_non_sme2_target);
-      }
-    }
-  }
+  if (DeclIsDefn && Context.getTargetInfo().getTriple().isAArch64())
+    ARM().CheckSMEFunctionDefAttributes(NewFD);
 
   return Redeclaration;
 }

clang/lib/Sema/SemaLambda.cpp

@@ -21,6 +21,7 @@
 #include "clang/Sema/Lookup.h"
 #include "clang/Sema/Scope.h"
 #include "clang/Sema/ScopeInfo.h"
+#include "clang/Sema/SemaARM.h"
 #include "clang/Sema/SemaCUDA.h"
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/SemaOpenMP.h"
@@ -1455,6 +1456,9 @@ void Sema::ActOnStartOfLambdaDefinition(LambdaIntroducer &Intro,
   // Attributes on the lambda apply to the method.
   ProcessDeclAttributes(CurScope, Method, ParamInfo);
 
+  if (Context.getTargetInfo().getTriple().isAArch64())
+    ARM().CheckSMEFunctionDefAttributes(Method);
+
   // CUDA lambdas get implicit host and device attributes.
   if (getLangOpts().CUDA)
     CUDA().SetLambdaAttrs(Method);

clang/test/Sema/aarch64-sme-func-attrs-without-target-feature.cpp

@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -fsyntax-only -verify %s
+// RUN: %clang_cc1 -triple aarch64-none-linux-gnu -std=c++23 -fsyntax-only -verify %s
 
 // This test is testing the diagnostics that Clang emits when compiling without '+sme'.
 
@@ -48,3 +48,9 @@ void streaming_compatible_def2(void (*streaming_fn_ptr)(void) __arm_streaming,
 // Also test when call-site is not a function.
 int streaming_decl_ret_int() __arm_streaming;
 int x = streaming_decl_ret_int(); // expected-error {{call to a streaming function requires 'sme'}}
+
+void sme_attrs_lambdas() {
+  [] __arm_locally_streaming () { return; }();  // expected-error {{function executed in streaming-SVE mode requires 'sme'}}
+  [] __arm_new("za") () { return; }();  // expected-error {{function using ZA state requires 'sme'}}
+  [] __arm_new("zt0") () { return; }();  // expected-error {{function using ZT0 state requires 'sme2'}}
+}