Support: Add a raw_ostream::write_zeros() function. NFCI.

This will eventually replace MCObjectWriter::WriteZeros.

Part of PR37466.

Differential Revision: https://reviews.llvm.org/D47033

llvm-svn: 332675

1 files changed, 26 insertions, 14 deletions

diff --git a/llvm/lib/Support/raw_ostream.cpp b/llvm/lib/Support/raw_ostream.cpp
index 68f2f7ac714..a4ab75c2735 100644
--- a/llvm/lib/Support/raw_ostream.cpp
+++ b/llvm/lib/Support/raw_ostream.cpp
@@ -455,23 +455,35 @@ raw_ostream &raw_ostream::operator<<(const FormattedBytes &FB) {
   return *this;
 }
 
-/// indent - Insert 'NumSpaces' spaces.
-raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
-  static const char Spaces[] = "                                "
-                               "                                "
-                               "                ";
+template <char C>
+static raw_ostream &write_padding(raw_ostream &OS, unsigned NumChars) {
+  static const char Chars[] = {C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C,
+                               C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C,
+                               C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C,
+                               C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C,
+                               C, C, C, C, C, C, C, C, C, C, C, C, C, C, C, C};
 
   // Usually the indentation is small, handle it with a fastpath.
-  if (NumSpaces < array_lengthof(Spaces))
-    return write(Spaces, NumSpaces);
-
-  while (NumSpaces) {
-    unsigned NumToWrite = std::min(NumSpaces,
-                                   (unsigned)array_lengthof(Spaces)-1);
-    write(Spaces, NumToWrite);
-    NumSpaces -= NumToWrite;
+  if (NumChars < array_lengthof(Chars))
+    return OS.write(Chars, NumChars);
+
+  while (NumChars) {
+    unsigned NumToWrite = std::min(NumChars,
+                                   (unsigned)array_lengthof(Chars)-1);
+    OS.write(Chars, NumToWrite);
+    NumChars -= NumToWrite;
   }
-  return *this;
+  return OS;
+}
+
+/// indent - Insert 'NumSpaces' spaces.
+raw_ostream &raw_ostream::indent(unsigned NumSpaces) {
+  return write_padding<' '>(*this, NumSpaces);
+}
+
+/// write_zeros - Insert 'NumZeros' nulls.
+raw_ostream &raw_ostream::write_zeros(unsigned NumZeros) {
+  return write_padding<'\0'>(*this, NumZeros);
 }
 
 void raw_ostream::anchor() {}