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

2 files changed, 3 insertions, 4 deletions

diff --git a/tools/llvm-readobj/ARMWinEHPrinter.cpp b/tools/llvm-readobj/ARMWinEHPrinter.cpp
index f6675bdcfe..7138438ca2 100644
--- a/tools/llvm-readobj/ARMWinEHPrinter.cpp
+++ b/tools/llvm-readobj/ARMWinEHPrinter.cpp
@@ -95,8 +95,7 @@ raw_ostream &operator<<(raw_ostream &OS, const ARM::WinEH::ReturnType &RT) {
 
 static std::string formatSymbol(StringRef Name, uint64_t Address,
                                 uint64_t Offset = 0) {
-  std::string Buffer;
-  raw_string_ostream OS(Buffer);
+  string_ostream OS;
 
   if (!Name.empty())
     OS << Name << " ";
diff --git a/tools/llvm-readobj/Win64EHDumper.cpp b/tools/llvm-readobj/Win64EHDumper.cpp
index f058632a8c..2d67843486 100644
--- a/tools/llvm-readobj/Win64EHDumper.cpp
+++ b/tools/llvm-readobj/Win64EHDumper.cpp
@@ -115,8 +115,7 @@ static unsigned getNumUsedSlots(const UnwindCode &UnwindCode) {
 static std::string formatSymbol(const Dumper::Context &Ctx,
                                 const coff_section *Section, uint64_t Offset,
                                 uint32_t Displacement) {
-  std::string Buffer;
-  raw_string_ostream OS(Buffer);
+  string_ostream OS;
 
   StringRef Name;
   SymbolRef Symbol;
@@ -131,6 +130,7 @@ static std::string formatSymbol(const Dumper::Context &Ctx,
     OS << format(" +0x%X (0x%" PRIX64 ")", Displacement, Offset);
   else
     OS << format(" (0x%" PRIX64 ")", Offset);
+
   return OS.str();
 }