[llvm-commits] [llvm] r52995 - in /llvm/trunk: include/llvm/ADT/FoldingSet.h lib/Support/FoldingSet.cpp

[Owen Anderson]

Author: resistor
Date: Tue Jul  1 18:49:59 2008
New Revision: 52995

URL: http://llvm.org/viewvc/llvm-project?rev=52995&view=rev
Log:
Add a version of AddString that takes a const char* so we can avoid extraneous
conversions to std::string.

Modified:
    llvm/trunk/include/llvm/ADT/FoldingSet.h
    llvm/trunk/lib/Support/FoldingSet.cpp

Modified: llvm/trunk/include/llvm/ADT/FoldingSet.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/FoldingSet.h?rev=52995&r1=52994&r2=52995&view=diff

==============================================================================
--- llvm/trunk/include/llvm/ADT/FoldingSet.h (original)
+++ llvm/trunk/include/llvm/ADT/FoldingSet.h Tue Jul  1 18:49:59 2008
@@ -220,6 +220,7 @@
   void AddFloat(float F);
   void AddDouble(double D);
   void AddString(const std::string &String);
+  void AddString(const char* String);
   
   template <typename T>
   inline void Add(const T& x) { FoldingSetTrait<T>::Profile(x, *this); }

Modified: llvm/trunk/lib/Support/FoldingSet.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/FoldingSet.cpp?rev=52995&r1=52994&r2=52995&view=diff

==============================================================================
--- llvm/trunk/lib/Support/FoldingSet.cpp (original)
+++ llvm/trunk/lib/Support/FoldingSet.cpp Tue Jul  1 18:49:59 2008
@@ -57,6 +57,44 @@
 void FoldingSetNodeID::AddDouble(double D) {
  AddInteger(DoubleToBits(D));
 }
+
+void FoldingSetNodeID::AddString(const char *String) {
+  unsigned Size = static_cast<unsigned>(strlen(String));
+  Bits.push_back(Size);
+  if (!Size) return;
+
+  unsigned Units = Size / 4;
+  unsigned Pos = 0;
+  const unsigned *Base = (const unsigned *)String;
+  
+  // If the string is aligned do a bulk transfer.
+  if (!((intptr_t)Base & 3)) {
+    Bits.append(Base, Base + Units);
+    Pos = (Units + 1) * 4;
+  } else {
+    // Otherwise do it the hard way.
+    for ( Pos += 4; Pos <= Size; Pos += 4) {
+      unsigned V = ((unsigned char)String[Pos - 4] << 24) |
+                   ((unsigned char)String[Pos - 3] << 16) |
+                   ((unsigned char)String[Pos - 2] << 8) |
+                    (unsigned char)String[Pos - 1];
+      Bits.push_back(V);
+    }
+  }
+  
+  // With the leftover bits.
+  unsigned V = 0;
+  // Pos will have overshot size by 4 - #bytes left over. 
+  switch (Pos - Size) {
+  case 1: V = (V << 8) | (unsigned char)String[Size - 3]; // Fall thru.
+  case 2: V = (V << 8) | (unsigned char)String[Size - 2]; // Fall thru.
+  case 3: V = (V << 8) | (unsigned char)String[Size - 1]; break;
+  default: return; // Nothing left.
+  }
+
+  Bits.push_back(V);
+}
+
 void FoldingSetNodeID::AddString(const std::string &String) {
   unsigned Size = static_cast<unsigned>(String.size());
   Bits.push_back(Size);