[ASan] Linker-initialize static ScopedInErrorReport::current_error_.

Summary:
Static ScopedInErrorReport::current_error_ can be linker initialized to
shave one global ctor call on application startup and be __asan_init-safe.

Global constructors in ASan runtime are bad because __asan_init runs
from preinit_array, before any such constructors.

Issue: https://github.com/google/sanitizers/issues/194

Reviewers: eugenis, morehouse

Subscribers: kubamracek, delcypher, #sanitizers, llvm-commits

Differential Revision: https://reviews.llvm.org/D48141

llvm-svn: 334748

2 files changed, 2 insertions, 1 deletions

diff --git a/compiler-rt/lib/asan/asan_errors.h b/compiler-rt/lib/asan/asan_errors.h
index 512d2537bd0..574197ebff8 100644
--- a/compiler-rt/lib/asan/asan_errors.h
+++ b/compiler-rt/lib/asan/asan_errors.h
@@ -414,6 +414,7 @@ struct ErrorDescription {
   };
 
   ErrorDescription() { internal_memset(this, 0, sizeof(*this)); }
+  explicit ErrorDescription(LinkerInitialized) {}
   ASAN_FOR_EACH_ERROR_KIND(ASAN_ERROR_DESCRIPTION_CONSTRUCTOR)
 
   bool IsValid() { return kind != kErrorKindInvalid; }
diff --git a/compiler-rt/lib/asan/asan_report.cc b/compiler-rt/lib/asan/asan_report.cc
index 18daace3990..b1762c6974e 100644
--- a/compiler-rt/lib/asan/asan_report.cc
+++ b/compiler-rt/lib/asan/asan_report.cc
@@ -206,7 +206,7 @@ class ScopedInErrorReport {
   bool halt_on_error_;
 };
 
-ErrorDescription ScopedInErrorReport::current_error_;
+ErrorDescription ScopedInErrorReport::current_error_(LINKER_INITIALIZED);
 
 void ReportDeadlySignal(const SignalContext &sig) {
   ScopedInErrorReport in_report(/*fatal*/ true);