From fa2757ca10d3562cc98882f8480dd7e2ee73a646 Mon Sep 17 00:00:00 2001
From: Peter Collingbourne <peter@pcc.me.uk>
Date: Thu, 17 May 2018 22:11:43 +0000
Subject: [PATCH] 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
---
 include/llvm/Support/raw_ostream.h |  3 +++
 lib/Support/raw_ostream.cpp        | 38 ++++++++++++++++++++----------
 2 files changed, 28 insertions(+), 13 deletions(-)

diff --git a/include/llvm/Support/raw_ostream.h b/include/llvm/Support/raw_ostream.h
index 14212017d04..83037a9b02c 100644
--- a/include/llvm/Support/raw_ostream.h
+++ b/include/llvm/Support/raw_ostream.h
@@ -242,6 +242,9 @@ public:
   /// indent - Insert 'NumSpaces' spaces.
   raw_ostream &indent(unsigned NumSpaces);
 
+  /// write_zeros - Insert 'NumZeros' nulls.
+  raw_ostream &write_zeros(unsigned NumZeros);
+
   /// Changes the foreground color of text that will be output from this point
   /// forward.
   /// @param Color ANSI color to use, the special SAVEDCOLOR can be used to
diff --git a/lib/Support/raw_ostream.cpp b/lib/Support/raw_ostream.cpp
index 68f2f7ac714..a4ab75c2735 100644
--- a/lib/Support/raw_ostream.cpp
+++ b/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);
+  if (NumChars < array_lengthof(Chars))
+    return OS.write(Chars, NumChars);
 
-  while (NumSpaces) {
-    unsigned NumToWrite = std::min(NumSpaces,
-                                   (unsigned)array_lengthof(Spaces)-1);
-    write(Spaces, NumToWrite);
-    NumSpaces -= NumToWrite;
+  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() {}