Introduce a string_ostream string builder facilty

string_ostream is a safe and efficient string builder that combines opaque
stack storage with a built-in ostream interface.

small_string_ostream<bytes> additionally permits an explicit stack storage size
other than the default 128 bytes to be provided. Beyond that, storage is
transferred to the heap.

This convenient class can be used in most places an
std::string+raw_string_ostream pair or SmallString<>+raw_svector_ostream pair
would previously have been used, in order to guarantee consistent access
without byte truncation.

The patch also converts much of LLVM to use the new facility. These changes
include several probable bug fixes for truncated output, a programming error
that's no longer possible with the new interface.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211749 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 8 deletions

diff --git a/tools/llvm-objdump/llvm-objdump.cpp b/tools/llvm-objdump/llvm-objdump.cpp
index d98691b4b0..d9886c10ae 100644
--- a/tools/llvm-objdump/llvm-objdump.cpp
+++ b/tools/llvm-objdump/llvm-objdump.cpp
@@ -222,8 +222,7 @@ static void emitDOTFile(const char *FileName, const MCFunction &f,
         Out << "<o>";
 
       // Escape special chars and print the instruction in mnemonic form.
-      std::string Str;
-      raw_string_ostream OS(Str);
+      string_ostream OS;
       IP->printInst(&(*i)->getInsts()->at(ii).Inst, OS, "");
       Out << DOT::EscapeString(OS.str());
     }
@@ -473,9 +472,7 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
     if (Symbols.empty())
       Symbols.push_back(std::make_pair(0, name));
 
-
-    SmallString<40> Comments;
-    raw_svector_ostream CommentStream(Comments);
+    small_string_ostream<40> Comments;
 
     StringRef Bytes;
     if (error(Section.getContents(Bytes)))
@@ -513,15 +510,14 @@ static void DisassembleObject(const ObjectFile *Obj, bool InlineRelocs) {
         MCInst Inst;
 
         if (DisAsm->getInstruction(Inst, Size, memoryObject,
-                                   SectionAddr + Index,
-                                   DebugOut, CommentStream)) {
+                                   SectionAddr + Index, DebugOut, Comments)) {
           outs() << format("%8" PRIx64 ":", SectionAddr + Index);
           if (!NoShowRawInsn) {
             outs() << "\t";
             DumpBytes(StringRef(Bytes.data() + Index, Size));
           }
           IP->printInst(&Inst, outs(), "");
-          outs() << CommentStream.str();
+          outs() << Comments.str();
           Comments.clear();
           outs() << "\n";
         } else {