[UBSan] Embed UBSan into ASan runtime (compiler-rt part).

Summary:
Change the way we use ASan and UBSan together. Instead of keeping two
separate runtimes (libclang_rt.asan and libclang_rt.ubsan), embed UBSan
into ASan and get rid of libclang_rt.ubsan. If UBSan is not supported on
a platform, all UBSan sources are just compiled into dummy empty object
files. UBSan initialization code (e.g. flag parsing) is directly called
from ASan initialization, so we are able to enforce correct
initialization order.

This mirrors the approach we already use for ASan+LSan. This change
doesn't modify the way we use standalone UBSan.

Test Plan: regression test suite

Reviewers: kubabrecka, zaks.anna, rsmith, kcc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8646

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@233861 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 19 deletions

diff --git a/lib/ubsan/ubsan_flags.cc b/lib/ubsan/ubsan_flags.cc
index 49ada8a26..eda7557a0 100644
--- a/lib/ubsan/ubsan_flags.cc
+++ b/lib/ubsan/ubsan_flags.cc
@@ -20,7 +20,7 @@
 
 namespace __ubsan {
 
-static const char *MaybeCallUbsanDefaultOptions() {
+const char *MaybeCallUbsanDefaultOptions() {
   return (&__ubsan_default_options) ? __ubsan_default_options() : "";
 }
 
@@ -39,31 +39,22 @@ void RegisterUbsanFlags(FlagParser *parser, Flags *f) {
 #undef UBSAN_FLAG
 }
 
-void InitializeFlags(bool standalone) {
-  Flags *f = flags();
-  FlagParser parser;
-  RegisterUbsanFlags(&parser, f);
-
-  if (standalone) {
-    RegisterCommonFlags(&parser);
-
-    SetCommonFlagsDefaults();
+void InitializeFlags() {
+  SetCommonFlagsDefaults();
+  {
     CommonFlags cf;
     cf.CopyFrom(*common_flags());
     cf.print_summary = false;
     OverrideCommonFlags(cf);
-  } else {
-    // Ignore common flags if not standalone.
-    // This is inconsistent with LSan, which allows common flags in LSAN_FLAGS.
-    // This is caused by undefined initialization order between ASan and UBsan,
-    // which makes it impossible to make sure that common flags from ASAN_OPTIONS
-    // have not been used (in __asan_init) before they are overwritten with flags
-    // from UBSAN_OPTIONS.
-    CommonFlags cf_ignored;
-    RegisterCommonFlags(&parser, &cf_ignored);
   }
 
+  Flags *f = flags();
   f->SetDefaults();
+
+  FlagParser parser;
+  RegisterCommonFlags(&parser);
+  RegisterUbsanFlags(&parser, f);
+
   // Override from user-specified string.
   parser.ParseString(MaybeCallUbsanDefaultOptions());
   // Override from environment variable.