Reimplement the parameter attributes support, phase #1. hilights:

1. There is now a "PAListPtr" class, which is a smart pointer around
   the underlying uniqued parameter attribute list object, and manages
   its refcount.  It is now impossible to mess up the refcount.
2. PAListPtr is now the main interface to the underlying object, and
   the underlying object is now completely opaque.
3. Implementation details like SmallVector and FoldingSet are now no
   longer part of the interface.
4. You can create a PAListPtr with an arbitrary sequence of
   ParamAttrsWithIndex's, no need to make a SmallVector of a specific 
   size (you can just use an array or scalar or vector if you wish).
5. All the client code that had to check for a null pointer before
   dereferencing the pointer is simplified to just access the 
   PAListPtr directly.
6. The interfaces for adding attrs to a list and removing them is a
   bit simpler.

Phase #2 will rename some stuff (e.g. PAListPtr) and do other less 
invasive changes.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48289 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 31 deletions

diff --git a/lib/VMCore/Function.cpp b/lib/VMCore/Function.cpp
index f5712e7561..5a69c099f6 100644
--- a/lib/VMCore/Function.cpp
+++ b/lib/VMCore/Function.cpp
@@ -14,7 +14,6 @@
 #include "llvm/Module.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/IntrinsicInst.h"
-#include "llvm/ParamAttrsList.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/Support/LeakDetector.h"
 #include "llvm/Support/StringPool.h"
@@ -140,12 +139,12 @@ void Function::eraseFromParent() {
 
 /// @brief Determine whether the function has the given attribute.
 bool Function::paramHasAttr(uint16_t i, ParameterAttributes attr) const {
-  return ParamAttrs && ParamAttrs->paramHasAttr(i, attr);
+  return ParamAttrs.paramHasAttr(i, attr);
 }
 
 /// @brief Extract the alignment for a call or parameter (0=unknown).
 uint16_t Function::getParamAlignment(uint16_t i) const {
-  return ParamAttrs ? ParamAttrs->getParamAlignment(i) : 0;
+  return ParamAttrs.getParamAlignment(i);
 }
 
 /// @brief Determine if the function cannot return.
@@ -181,8 +180,7 @@ bool Function::hasStructRetAttr() const {
 Function::Function(const FunctionType *Ty, LinkageTypes Linkage,
                    const std::string &name, Module *ParentModule)
   : GlobalValue(PointerType::getUnqual(Ty), 
-                Value::FunctionVal, 0, 0, Linkage, name),
-    ParamAttrs(0) {
+                Value::FunctionVal, 0, 0, Linkage, name) {
   SymTab = new ValueSymbolTable();
 
   assert((getReturnType()->isFirstClassType() ||getReturnType() == Type::VoidTy
@@ -207,10 +205,6 @@ Function::~Function() {
   ArgumentList.clear();
   delete SymTab;
 
-  // Drop our reference to the parameter attributes, if any.
-  if (ParamAttrs)
-    ParamAttrs->dropRef();
-  
   // Remove the function from the on-the-side collector table.
   clearCollector();
 }
@@ -243,24 +237,6 @@ void Function::setParent(Module *parent) {
     LeakDetector::removeGarbageObject(this);
 }
 
-void Function::setParamAttrs(const ParamAttrsList *attrs) {
-  // Avoid deleting the ParamAttrsList if they are setting the
-  // attributes to the same list.
-  if (ParamAttrs == attrs)
-    return;
-
-  // Drop reference on the old ParamAttrsList
-  if (ParamAttrs)
-    ParamAttrs->dropRef();
-
-  // Add reference to the new ParamAttrsList
-  if (attrs)
-    attrs->addRef();
-
-  // Set the new ParamAttrsList.
-  ParamAttrs = attrs; 
-}
-
 // dropAllReferences() - This function causes all the subinstructions to "let
 // go" of all references that they are maintaining.  This allows one to
 // 'delete' a whole class at a time, even though there may be circular
@@ -370,8 +346,7 @@ const FunctionType *Intrinsic::getType(ID id, const Type **Tys,
   return FunctionType::get(ResultTy, ArgTys, IsVarArg); 
 }
 
-const ParamAttrsList *Intrinsic::getParamAttrs(ID id) {
-  ParamAttrsVector Attrs;
+PAListPtr Intrinsic::getParamAttrs(ID id) {
   ParameterAttributes Attr = ParamAttr::None;
 
 #define GET_INTRINSIC_ATTRIBUTES
@@ -381,8 +356,8 @@ const ParamAttrsList *Intrinsic::getParamAttrs(ID id) {
   // Intrinsics cannot throw exceptions.
   Attr |= ParamAttr::NoUnwind;
 
-  Attrs.push_back(ParamAttrsWithIndex::get(0, Attr));
-  return ParamAttrsList::get(Attrs);
+  ParamAttrsWithIndex PAWI = ParamAttrsWithIndex::get(0, Attr);
+  return PAListPtr::get(&PAWI, 1);
 }
 
 Function *Intrinsic::getDeclaration(Module *M, ID id, const Type **Tys,