Twines: Support numeric conversion directly (uitostr, etc).

- Provides static constructors for doing number to string conversions without
   using temporaries.

 - There are several ways to do this, I think given the Twine constraints this
   is the simplest one.

 - One FIXME for fast number -> hex conversion.

 - Added another comment on one last major bit of perf work Twines need, which
   is to make raw_svector_ostream more efficient.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77445 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/ADT/Twine.h

@@ -86,6 +86,9 @@ namespace llvm {
       /// The empty string.
       EmptyKind,
 
+      /// A pointer to a Twine instance.
+      TwineKind,
+
       /// A pointer to a C string instance.
       CStringKind,
 
@@ -95,8 +98,16 @@ namespace llvm {
       /// A pointer to a StringRef instance.
       StringRefKind,
 
-      /// A pointer to a Twine instance.
-      TwineKind
+      /// A pointer to a uint64_t value, to render as an unsigned decimal
+      /// integer.
+      UDecKind,
+
+      /// A pointer to a uint64_t value, to render as an unsigned hexadecimal
+      /// integer.
+      UHexKind,
+
+      /// A pointer to a uint64_t value, to render as a signed decimal integer.
+      SDecKind
     };
 
   private:
@@ -232,12 +243,6 @@ namespace llvm {
       assert(isValid() && "Invalid twine!");
     }
 
-    /// Create a 'null' string, which is an empty string that always
-    /// concatenates to form another empty string.
-    static Twine createNull() {
-      return Twine(NullKind);
-    }
-
     // FIXME: Unfortunately, to make sure this is as efficient as possible we
     // need extra binary constructors from particular types. We can't rely on
     // the compiler to be smart enough to fold operator+()/concat() down to the
@@ -255,6 +260,38 @@ namespace llvm {
       assert(isValid() && "Invalid twine!");
     }
 
+    /// Create a 'null' string, which is an empty string that always
+    /// concatenates to form another empty string.
+    static Twine createNull() {
+      return Twine(NullKind);
+    }
+
+    /// @}
+    /// @name Numeric Conversions
+    /// @{
+
+    /// Construct a twine to print \arg Val as an unsigned decimal integer.
+    static Twine utostr(const uint64_t &Val) {
+      return Twine(&Val, UDecKind, 0, EmptyKind);
+    }
+
+    /// Construct a twine to print \arg Val as a signed decimal integer.
+    static Twine itostr(const int64_t &Val) {
+      return Twine(&Val, SDecKind, 0, EmptyKind);
+    }
+
+    // Construct a twine to print \arg Val as an unsigned hexadecimal integer.
+    static Twine utohexstr(const uint64_t &Val) {
+      return Twine(&Val, UHexKind, 0, EmptyKind);
+    }
+
+    // Construct a twine to print \arg Val as an unsigned hexadecimal
+    // integer. This routine is provided as a convenience to sign extend values
+    // before printing.
+    static Twine itohexstr(const int64_t &Val) {
+      return Twine(&Val, UHexKind, 0, EmptyKind);
+    }
+
     /// @}
     /// @name String Operations
     /// @{

lib/Support/Twine.cpp

@@ -19,6 +19,13 @@ std::string Twine::str() const {
 }
 
 void Twine::toVector(SmallVectorImpl<char> &Out) const {
+  // FIXME: This is very inefficient, since we are creating a large raw_ostream
+  // buffer -- hitting malloc, which we were supposed to avoid -- all when we
+  // have this pretty little small vector available.
+  //
+  // The best way to fix this is to make raw_svector_ostream do the right thing
+  // and be efficient, by augmenting the base raw_ostream with the ability to
+  // have the buffer managed by a concrete implementation.
   raw_svector_ostream OS(Out);
   print(OS);
 }
@@ -28,6 +35,9 @@ void Twine::printOneChild(raw_ostream &OS, const void *Ptr,
   switch (Kind) {
   case Twine::NullKind: break;
   case Twine::EmptyKind: break;
+  case Twine::TwineKind:
+    static_cast<const Twine*>(Ptr)->print(OS); 
+    break;
   case Twine::CStringKind: 
     OS << static_cast<const char*>(Ptr); 
     break;
@@ -37,8 +47,15 @@ void Twine::printOneChild(raw_ostream &OS, const void *Ptr,
   case Twine::StringRefKind:
     OS << *static_cast<const StringRef*>(Ptr); 
     break;
-  case Twine::TwineKind:
-    static_cast<const Twine*>(Ptr)->print(OS); 
+  case Twine::UDecKind:
+    OS << *static_cast<const uint64_t*>(Ptr);
+    break;
+  case Twine::SDecKind:
+    OS << *static_cast<const int64_t*>(Ptr);
+    break;
+  case Twine::UHexKind:
+    // FIXME: Add raw_ostream functionality for this.
+    OS << ::utohexstr(*static_cast<const uint64_t*>(Ptr));
     break;
   }
 }
@@ -50,22 +67,31 @@ void Twine::printOneChildRepr(raw_ostream &OS, const void *Ptr,
     OS << "null"; break;
   case Twine::EmptyKind:
     OS << "empty"; break;
-  case Twine::CStringKind:
-    OS << "cstring:\"" 
-       << static_cast<const char*>(Ptr) << "\""; 
-    break;
-  case Twine::StdStringKind:
-    OS << "std::string:\"" 
-       << *static_cast<const std::string*>(Ptr) << "\""; 
-    break;
-  case Twine::StringRefKind:
-    OS << "stringref:\"" 
-       << *static_cast<const StringRef*>(Ptr) << "\""; 
-    break;
   case Twine::TwineKind:
     OS << "rope:";
     static_cast<const Twine*>(Ptr)->printRepr(OS);
     break;
+  case Twine::CStringKind:
+    OS << "cstring:\""
+       << static_cast<const char*>(Ptr) << "\"";
+    break;
+  case Twine::StdStringKind:
+    OS << "std::string:\""
+       << static_cast<const std::string*>(Ptr) << "\"";
+    break;
+  case Twine::StringRefKind:
+    OS << "stringref:\""
+       << static_cast<const StringRef*>(Ptr) << "\"";
+    break;
+  case Twine::UDecKind:
+    OS << "udec:" << static_cast<const uint64_t*>(Ptr) << "\"";
+    break;
+  case Twine::SDecKind:
+    OS << "sdec:" << static_cast<const int64_t*>(Ptr) << "\"";
+    break;
+  case Twine::UHexKind:
+    OS << "uhex:" << static_cast<const uint64_t*>(Ptr) << "\"";
+    break;
   }
 }
 

unittests/ADT/TwineTest.cpp

@@ -30,6 +30,18 @@ TEST(TwineTest, Construction) {
   EXPECT_EQ("hi", Twine(StringRef("hithere", 2)).str());
 }
 
+TEST(TwineTest, Numbers) {
+  EXPECT_EQ("123", Twine::utostr(123).str());
+  EXPECT_EQ("-123", Twine::itostr(-123).str());
+  EXPECT_EQ("123", Twine::utostr(123).str());
+  EXPECT_EQ("-123", Twine::itostr(-123).str());
+  EXPECT_EQ("123", Twine::utostr((char) 123).str());
+  EXPECT_EQ("-123", Twine::itostr((char) -123).str());
+
+  EXPECT_EQ("7B", Twine::utohexstr(123).str());
+  EXPECT_EQ("FFFFFFFFFFFFFF85", Twine::itohexstr(-123).str());
+}
+
 TEST(TwineTest, Concat) {
   // Check verse repr, since we care about the actual representation not just
   // the result.