commit 855243789cb44799c03f4c7216d3d6308805f549
author Benjamin Kramer <benny.kra@googlemail.com> Thu Jun 07 15:09:51 2012 +0000
committer Benjamin Kramer <benny.kra@googlemail.com> Thu Jun 07 15:09:51 2012 +0000
tree ddfaf2e09c5404dd1a1caa9447984cdc7382dd97
parent 575b66a8e07984ff21c1d3ed0da704043b9390bd

Plug a long standing memory leak in TemplateArgument.

The integral APSInt value is now stored in a decomposed form and the backing
store for large values is allocated via the ASTContext. This way its not
leaked as TemplateArguments are never destructed when they are allocated in
the ASTContext. Since the integral data is immutable it is now shared between
instances, making copying TemplateArguments a trivial operation.

Currently getting the integral data out of a TemplateArgument requires creating
a new APSInt object. This is cheap when the value is small but can be expensive
if it's not. If this turns out to be an issue a more efficient accessor could
be added.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@158150 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AST/TemplateBase.cpp

diff --git a/lib/AST/TemplateBase.cpp b/lib/AST/TemplateBase.cpp
index 531e03e..284c1b5 100644
--- a/lib/AST/TemplateBase.cpp
+++ b/lib/AST/TemplateBase.cpp
@@ -36,17 +36,17 @@
 static void printIntegral(const TemplateArgument &TemplArg,
                           raw_ostream &Out) {
   const ::clang::Type *T = TemplArg.getIntegralType().getTypePtr();
-  const llvm::APSInt *Val = TemplArg.getAsIntegral();
+  const llvm::APSInt &Val = TemplArg.getAsIntegral();
 
   if (T->isBooleanType()) {
-    Out << (Val->getBoolValue() ? "true" : "false");
+    Out << (Val.getBoolValue() ? "true" : "false");
   } else if (T->isCharType()) {
-    const char Ch = Val->getZExtValue();
+    const char Ch = Val.getZExtValue();
     Out << ((Ch == '\'') ? "'\\" : "'");
     Out.write_escaped(StringRef(&Ch, 1), /*UseHexEscapes=*/ true);
     Out << "'";
   } else {
-    Out << Val->toString(10);
+    Out << Val;
   }
 }
 
@@ -54,6 +54,24 @@
 // TemplateArgument Implementation
 //===----------------------------------------------------------------------===//
 
+TemplateArgument::TemplateArgument(ASTContext &Ctx, const llvm::APSInt &Value,
+                                   QualType Type)
+  : Kind(Integral) {
+  // Copy the APSInt value into our decomposed form.
+  Integer.BitWidth = Value.getBitWidth();
+  Integer.IsUnsigned = Value.isUnsigned();
+  // If the value is large, we have to get additional memory from the ASTContext
+  if (Integer.BitWidth > 64) {
+    void *Mem = Ctx.Allocate(Integer.BitWidth / 8);
+    std::memcpy(Mem, Value.getRawData(), Integer.BitWidth / 8);
+    Integer.pVal = static_cast<uint64_t *>(Mem);
+  } else {
+    Integer.VAL = Value.getZExtValue();
+  }
+
+  Integer.Type = Type.getAsOpaquePtr();
+}
+
 TemplateArgument TemplateArgument::CreatePackCopy(ASTContext &Context,
                                                   const TemplateArgument *Args,
                                                   unsigned NumArgs) {
@@ -246,7 +264,7 @@
   }
       
   case Integral:
-    getAsIntegral()->Profile(ID);
+    getAsIntegral().Profile(ID);
     getIntegralType().Profile(ID);
     break;
 
@@ -275,7 +293,7 @@
 
   case Integral:
     return getIntegralType() == Other.getIntegralType() &&
-           *getAsIntegral() == *Other.getAsIntegral();
+           getAsIntegral() == Other.getAsIntegral();
 
   case Pack:
     if (Args.NumArgs != Other.Args.NumArgs) return false;
@@ -498,7 +516,7 @@
     return DB << "nullptr";
       
   case TemplateArgument::Integral:
-    return DB << Arg.getAsIntegral()->toString(10);
+    return DB << Arg.getAsIntegral().toString(10);
       
   case TemplateArgument::Template:
     return DB << Arg.getAsTemplate();