[Sanitizer] Print symbolized stack frame using a single Printf() call.

This reduces the number of "write" syscalls performed to print a single
stack frame description, and makes sanitizer output less intermixed with
program output. Also, add a number of unit tests.

llvm-svn: 194686

1 files changed, 9 insertions, 0 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_printf.cc b/compiler-rt/lib/sanitizer_common/sanitizer_printf.cc
index 4f3968ad258..bbdb24b685d 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_printf.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_printf.cc
@@ -294,4 +294,13 @@ int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
   return needed_length;
 }
 
+void InternalScopedString::append(const char *format, ...) {
+  CHECK_LT(length_, size());
+  va_list args;
+  va_start(args, format);
+  VSNPrintf(data() + length_, size() - length_, format, args);
+  va_end(args);
+  length_ += internal_strlen(data() + length_);
+}
+
 }  // namespace __sanitizer