[clang][patch][NFC] Refactor calculation of FunctionDecl to avoid duplicate code

Author: Melanie Blower

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -710,9 +710,9 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
 
   DidCallStackSave = false;
   CurCodeDecl = D;
-  if (const auto *FD = dyn_cast_or_null<FunctionDecl>(D))
-    if (FD->usesSEHTry())
-      CurSEHParent = FD;
+  const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
+  if (FD && FD->usesSEHTry())
+    CurSEHParent = FD;
   CurFuncDecl = (D ? D->getNonClosureContext() : nullptr);
   FnRetTy = RetTy;
   CurFn = Fn;
@@ -803,10 +803,9 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
   // are not aware of how to move the extra UBSan instructions across the split
   // coroutine boundaries.
   if (D && SanOpts.has(SanitizerKind::Null))
-    if (const auto *FD = dyn_cast<FunctionDecl>(D))
-      if (FD->getBody() &&
-          FD->getBody()->getStmtClass() == Stmt::CoroutineBodyStmtClass)
-        SanOpts.Mask &= ~SanitizerKind::Null;
+    if (FD && FD->getBody() &&
+        FD->getBody()->getStmtClass() == Stmt::CoroutineBodyStmtClass)
+      SanOpts.Mask &= ~SanitizerKind::Null;
 
   // Apply xray attributes to the function (as a string, for now)
   bool AlwaysXRayAttr = false;
@@ -896,32 +895,27 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
   if (D && D->hasAttr<NoProfileFunctionAttr>())
     Fn->addFnAttr(llvm::Attribute::NoProfile);
 
-  if (getLangOpts().OpenCL) {
+  if (FD && getLangOpts().OpenCL) {
     // Add metadata for a kernel function.
-    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
-      EmitOpenCLKernelMetadata(FD, Fn);
+    EmitOpenCLKernelMetadata(FD, Fn);
   }
 
   // If we are checking function types, emit a function type signature as
   // prologue data.
-  if (getLangOpts().CPlusPlus && SanOpts.has(SanitizerKind::Function)) {
-    if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
-      if (llvm::Constant *PrologueSig = getPrologueSignature(CGM, FD)) {
-        // Remove any (C++17) exception specifications, to allow calling e.g. a
-        // noexcept function through a non-noexcept pointer.
-        auto ProtoTy =
-          getContext().getFunctionTypeWithExceptionSpec(FD->getType(),
-                                                        EST_None);
-        llvm::Constant *FTRTTIConst =
-            CGM.GetAddrOfRTTIDescriptor(ProtoTy, /*ForEH=*/true);
-        llvm::Constant *FTRTTIConstEncoded =
-            EncodeAddrForUseInPrologue(Fn, FTRTTIConst);
-        llvm::Constant *PrologueStructElems[] = {PrologueSig,
-                                                 FTRTTIConstEncoded};
-        llvm::Constant *PrologueStructConst =
-            llvm::ConstantStruct::getAnon(PrologueStructElems, /*Packed=*/true);
-        Fn->setPrologueData(PrologueStructConst);
-      }
+  if (FD && getLangOpts().CPlusPlus && SanOpts.has(SanitizerKind::Function)) {
+    if (llvm::Constant *PrologueSig = getPrologueSignature(CGM, FD)) {
+      // Remove any (C++17) exception specifications, to allow calling e.g. a
+      // noexcept function through a non-noexcept pointer.
+      auto ProtoTy = getContext().getFunctionTypeWithExceptionSpec(
+          FD->getType(), EST_None);
+      llvm::Constant *FTRTTIConst =
+          CGM.GetAddrOfRTTIDescriptor(ProtoTy, /*ForEH=*/true);
+      llvm::Constant *FTRTTIConstEncoded =
+          EncodeAddrForUseInPrologue(Fn, FTRTTIConst);
+      llvm::Constant *PrologueStructElems[] = {PrologueSig, FTRTTIConstEncoded};
+      llvm::Constant *PrologueStructConst =
+          llvm::ConstantStruct::getAnon(PrologueStructElems, /*Packed=*/true);
+      Fn->setPrologueData(PrologueStructConst);
     }
   }
 
@@ -948,25 +942,22 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
   //     kernels cannot include RTTI information, exception classes,
   //     recursive code, virtual functions or make use of C++ libraries that
   //     are not compiled for the device.
-  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
-    if ((getLangOpts().CPlusPlus && FD->isMain()) || getLangOpts().OpenCL ||
-        getLangOpts().SYCLIsDevice ||
-        (getLangOpts().CUDA && FD->hasAttr<CUDAGlobalAttr>()))
-      Fn->addFnAttr(llvm::Attribute::NoRecurse);
-  }
+  if (FD && ((getLangOpts().CPlusPlus && FD->isMain()) ||
+             getLangOpts().OpenCL || getLangOpts().SYCLIsDevice ||
+             (getLangOpts().CUDA && FD->hasAttr<CUDAGlobalAttr>())))
+    Fn->addFnAttr(llvm::Attribute::NoRecurse);
 
-  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
+  if (FD) {
     Builder.setIsFPConstrained(FD->hasAttr<StrictFPAttr>());
     if (FD->hasAttr<StrictFPAttr>())
       Fn->addFnAttr(llvm::Attribute::StrictFP);
   }
 
   // If a custom alignment is used, force realigning to this alignment on
   // any main function which certainly will need it.
-  if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
-    if ((FD->isMain() || FD->isMSVCRTEntryPoint()) &&
-        CGM.getCodeGenOpts().StackAlignment)
-      Fn->addFnAttr("stackrealign");
+  if (FD && ((FD->isMain() || FD->isMSVCRTEntryPoint()) &&
+             CGM.getCodeGenOpts().StackAlignment))
+    Fn->addFnAttr("stackrealign");
 
   llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
 
@@ -993,7 +984,7 @@ void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
     // such as 'this' and 'vtt', show up in the debug info. Preserve the calling
     // convention.
     CallingConv CC = CallingConv::CC_C;
-    if (auto *FD = dyn_cast_or_null<FunctionDecl>(D))
+    if (FD)
       if (const auto *SrcFnTy = FD->getType()->getAs<FunctionType>())
         CC = SrcFnTy->getCallConv();
     SmallVector<QualType, 16> ArgTypes;