From acbceeae4d7bdfbbc3437c60a5a3e26449888a15 Mon Sep 17 00:00:00 2001
From: Daniel Dunbar <daniel@zuster.org>
Date: Wed, 29 Feb 2012 20:31:09 +0000
Subject: [PATCH] BitstreamWriter: Change primary output buffer to be a
 SmallVector instead of an std::vector.  - Good for 1-2% speedup on writing
 PCH for Cocoa.h.  - Clang side API match to follow shortly, there wasn't an
 easy way to make this    non-breaking.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@151750 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Bitcode/BitstreamWriter.h | 5 +++--
 lib/Bitcode/Writer/BitcodeWriter.cpp   | 7 +++----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/llvm/Bitcode/BitstreamWriter.h b/include/llvm/Bitcode/BitstreamWriter.h
index 56b20c8474a..55e3cd390b1 100644
--- a/include/llvm/Bitcode/BitstreamWriter.h
+++ b/include/llvm/Bitcode/BitstreamWriter.h
@@ -16,13 +16,14 @@
 #define BITSTREAM_WRITER_H
 
 #include "llvm/ADT/StringRef.h"
+#include "llvm/ADT/SmallVector.h"
 #include "llvm/Bitcode/BitCodes.h"
 #include <vector>
 
 namespace llvm {
 
 class BitstreamWriter {
-  std::vector<unsigned char> &Out;
+  SmallVectorImpl<char> &Out;
 
   /// CurBit - Always between 0 and 31 inclusive, specifies the next bit to use.
   unsigned CurBit;
@@ -90,7 +91,7 @@ class BitstreamWriter {
   }
 
 public:
-  explicit BitstreamWriter(std::vector<unsigned char> &O)
+  explicit BitstreamWriter(SmallVectorImpl<char> &O)
     : Out(O), CurBit(0), CurValue(0), CurCodeSize(2) {}
 
   ~BitstreamWriter() {
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index c6c7fb7dcb2..93769906801 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1774,8 +1774,7 @@ enum {
   DarwinBCHeaderSize = 5*4
 };
 
-static void WriteInt32ToBuffer(uint32_t Value,
-                               std::vector<unsigned char> &Buffer,
+static void WriteInt32ToBuffer(uint32_t Value, SmallVectorImpl<char> &Buffer,
                                uint32_t &Position) {
   Buffer[Position + 0] = (unsigned char) (Value >>  0);
   Buffer[Position + 1] = (unsigned char) (Value >>  8);
@@ -1784,7 +1783,7 @@ static void WriteInt32ToBuffer(uint32_t Value,
   Position += 4;
 }
 
-static void EmitDarwinBCHeaderAndTrailer(std::vector<unsigned char> &Buffer,
+static void EmitDarwinBCHeaderAndTrailer(SmallVectorImpl<char> &Buffer,
                                          const Triple &TT) {
   unsigned CPUType = ~0U;
 
@@ -1833,7 +1832,7 @@ static void EmitDarwinBCHeaderAndTrailer(std::vector<unsigned char> &Buffer,
 /// WriteBitcodeToFile - Write the specified module to the specified output
 /// stream.
 void llvm::WriteBitcodeToFile(const Module *M, raw_ostream &Out) {
-  std::vector<unsigned char> Buffer;
+  SmallVector<char, 1024> Buffer;
   Buffer.reserve(256*1024);
 
   // If this is darwin or another generic macho target, reserve space for the