Add a spelling of pass_object_size that uses __builtin_dynamic_object_size

The attribute pass_dynamic_object_size(n) behaves exactly like
pass_object_size(n), but instead of evaluating __builtin_object_size on calls,
it evaluates __builtin_dynamic_object_size, which has the potential to produce
runtime code when the object size can't be determined statically.

Differential revision: https://reviews.llvm.org/D58757

llvm-svn: 356515

4 files changed, 13 insertions, 7 deletions

diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 5d5d857c44f..3357756466f 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -2833,7 +2833,10 @@ void CXXNameMangler::mangleBareFunctionType(const FunctionProtoType *Proto,
       if (auto *Attr = FD->getParamDecl(I)->getAttr<PassObjectSizeAttr>()) {
         // Attr can only take 1 character, so we can hardcode the length below.
         assert(Attr->getType() <= 9 && Attr->getType() >= 0);
-        Out << "U17pass_object_size" << Attr->getType();
+        if (Attr->isDynamic())
+          Out << "U25pass_dynamic_object_size" << Attr->getType();
+        else
+          Out << "U17pass_object_size" << Attr->getType();
       }
     }
   }
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index 9112af30666..c5db936b861 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -267,7 +267,7 @@ class MicrosoftCXXNameMangler {
   typedef llvm::DenseMap<const void *, unsigned> ArgBackRefMap;
   ArgBackRefMap TypeBackReferences;
 
-  typedef std::set<int> PassObjectSizeArgsSet;
+  typedef std::set<std::pair<int, bool>> PassObjectSizeArgsSet;
   PassObjectSizeArgsSet PassObjectSizeArgs;
 
   ASTContext &getASTContext() const { return Context.getASTContext(); }
@@ -1761,14 +1761,16 @@ void MicrosoftCXXNameMangler::mangleArgumentType(QualType T,
 void MicrosoftCXXNameMangler::manglePassObjectSizeArg(
     const PassObjectSizeAttr *POSA) {
   int Type = POSA->getType();
+  bool Dynamic = POSA->isDynamic();
 
-  auto Iter = PassObjectSizeArgs.insert(Type).first;
+  auto Iter = PassObjectSizeArgs.insert({Type, Dynamic}).first;
   auto *TypePtr = (const void *)&*Iter;
   ArgBackRefMap::iterator Found = TypeBackReferences.find(TypePtr);
 
   if (Found == TypeBackReferences.end()) {
-    mangleArtificialTagType(TTK_Enum, "__pass_object_size" + llvm::utostr(Type),
-                           {"__clang"});
+    std::string Name =
+        Dynamic ? "__pass_dynamic_object_size" : "__pass_object_size";
+    mangleArtificialTagType(TTK_Enum, Name + llvm::utostr(Type), {"__clang"});
 
     if (TypeBackReferences.size() < 10) {
       size_t Size = TypeBackReferences.size();
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index 626578ad84f..73a87a4933d 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -3452,7 +3452,7 @@ void CodeGenFunction::EmitCallArgs(
     assert(EmittedArg.getScalarVal() && "We emitted nothing for the arg?");
     llvm::Value *V = evaluateOrEmitBuiltinObjectSize(Arg, PS->getType(), T,
                                                      EmittedArg.getScalarVal(),
-                                                     /*IsDynamic=*/false);
+                                                     PS->isDynamic());
     Args.add(RValue::get(V), SizeTy);
     // If we're emitting args in reverse, be sure to do so with
     // pass_object_size, as well.
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 9fa7f48d8d2..2f8295aa977 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -2935,7 +2935,8 @@ static bool hasIdenticalPassObjectSizeAttrs(const FunctionDecl *A,
     const auto *AttrB = B->getAttr<PassObjectSizeAttr>();
     if (AttrA == AttrB)
       return true;
-    return AttrA && AttrB && AttrA->getType() == AttrB->getType();
+    return AttrA && AttrB && AttrA->getType() == AttrB->getType() &&
+           AttrA->isDynamic() == AttrB->isDynamic();
   };
 
   return std::equal(A->param_begin(), A->param_end(), B->param_begin(), AttrEq);