Minimal runtime for UBSan.

Summary:
An implementation of ubsan runtime library suitable for use in production.

Minimal attack surface.
* No stack traces.
* Definitely no C++ demangling.
* No UBSAN_OPTIONS=log_file=/path (very suid-unfriendly). And no UBSAN_OPTIONS in general.
* as simple as possible

Minimal CPU and RAM overhead.
* Source locations unnecessary in the presence of (split) debug info.
* Values and types (as in A+B overflows T) can be reconstructed from register/stack dumps, once you know what type of error you are looking at.
* above two items save 3% binary size.

When UBSan is used with -ftrap-function=abort, sometimes it is hard to reason about failures. This library replaces abort with a slightly more informative message without much extra overhead. Since ubsan interface in not stable, this code must reside in compiler-rt.

Reviewers: pcc, kcc

Subscribers: srhines, mgorny, aprantl, krytarowski, llvm-commits

Differential Revision: https://reviews.llvm.org/D36810

llvm-svn: 312029

1 files changed, 8 insertions, 3 deletions

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 690f3b3a96b..d052bb2001c 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -555,6 +555,7 @@ collectSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
   if (SanArgs.needsAsanRt() && SanArgs.needsSharedAsanRt()) {
     SharedRuntimes.push_back("asan");
   }
+
   // The stats_client library is also statically linked into DSOs.
   if (SanArgs.needsStatsRt())
     StaticRuntimes.push_back("stats_client");
@@ -588,9 +589,13 @@ collectSanitizerRuntimes(const ToolChain &TC, const ArgList &Args,
       StaticRuntimes.push_back("tsan_cxx");
   }
   if (SanArgs.needsUbsanRt()) {
-    StaticRuntimes.push_back("ubsan_standalone");
-    if (SanArgs.linkCXXRuntimes())
-      StaticRuntimes.push_back("ubsan_standalone_cxx");
+    if (SanArgs.requiresMinimalRuntime()) {
+      StaticRuntimes.push_back("ubsan_minimal");
+    } else {
+      StaticRuntimes.push_back("ubsan_standalone");
+      if (SanArgs.linkCXXRuntimes())
+        StaticRuntimes.push_back("ubsan_standalone_cxx");
+    }
   }
   if (SanArgs.needsSafeStackRt()) {
     NonWholeStaticRuntimes.push_back("safestack");