Improve performance of PadToColumn by eliminating flushes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77397 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/FormattedStream.cpp

@@ -19,11 +19,11 @@ using namespace llvm;
 /// ComputeColumn - Examine the current output and figure out which
 /// column we end up in after output.
 ///
-void formatted_raw_ostream::ComputeColumn(const char *Ptr, size_t Size) {
+void formatted_raw_ostream::ComputeColumn(unsigned &Column) {
   // Keep track of the current column by scanning the string for
   // special characters
 
-  for (const char *epos = Ptr + Size; Ptr != epos; ++Ptr) {
+  for (const char *Ptr = begin(); Ptr != end(); ++Ptr) {
     ++Column;
     if (*Ptr == '\n' || *Ptr == '\r')
       Column = 0;
@@ -38,8 +38,13 @@ void formatted_raw_ostream::ComputeColumn(const char *Ptr, size_t Size) {
 /// \param MinPad - The minimum space to give after the most recent
 /// I/O, even if the current column + minpad > newcol.
 ///
-void formatted_raw_ostream::PadToColumn(unsigned NewCol, unsigned MinPad) {
-  flush();
+void formatted_raw_ostream::PadToColumn(unsigned NewCol, unsigned MinPad) { 
+  // Start out from the last flush position.
+  unsigned Column = ColumnFlushed;
+
+  // Now figure out what's in the buffer and add it to the column
+  // count.
+  ComputeColumn(Column);
 
   // Output spaces until we reach the desired column.
   unsigned num = NewCol - Column;