[PATCH] [UBSan] Embed UBSan into ASan runtime (Clang part).

[Alexey Samsonov]

Hi kubabrecka, zaks.anna, kcc, rsmith,

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.

http://reviews.llvm.org/D8645

Files:
  lib/Driver/SanitizerArgs.cpp
  lib/Driver/ToolChains.cpp
  lib/Driver/Tools.cpp
  test/Driver/sanitizer-ld.c

Index: lib/Driver/SanitizerArgs.cpp
===================================================================
--- lib/Driver/SanitizerArgs.cpp
+++ lib/Driver/SanitizerArgs.cpp
@@ -159,7 +159,8 @@
 }
 
 bool SanitizerArgs::needsUbsanRt() const {
-  return !UbsanTrapOnError && hasOneOf(Sanitizers, NeedsUbsanRt);
+  return !UbsanTrapOnError && hasOneOf(Sanitizers, NeedsUbsanRt) &&
+         !Sanitizers.has(SanitizerKind::Address);
 }
 
 bool SanitizerArgs::requiresPIE() const {
Index: lib/Driver/ToolChains.cpp
===================================================================
--- lib/Driver/ToolChains.cpp
+++ lib/Driver/ToolChains.cpp
@@ -338,6 +338,9 @@
                                     OS + "_dynamic.dylib").str(),
                     /*AlwaysLink*/ true, /*IsEmbedded*/ false,
                     /*AddRPath*/ true);
+  // Add explicit dependcy on -lc++abi, as -lc++ doesn't re-export
+  // all RTTI-related symbols that UBSan uses.
+  CmdArgs.push_back("-lc++abi");
 }
 
 void DarwinClang::AddLinkRuntimeLibArgs(const ArgList &Args,
@@ -401,9 +404,6 @@
           << "-fsanitize=undefined";
     } else {
       AddLinkSanitizerLibArgs(Args, CmdArgs, "ubsan");
-      // Add explicit dependcy on -lc++abi, as -lc++ doesn't re-export
-      // all RTTI-related symbols that UBSan uses.
-      CmdArgs.push_back("-lc++abi");
     }
   }
 
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -2281,18 +2281,10 @@
     StaticRuntimes.push_back("msan");
   if (SanArgs.needsTsanRt())
     StaticRuntimes.push_back("tsan");
-  // WARNING: UBSan should always go last.
   if (SanArgs.needsUbsanRt()) {
-    // Check if UBSan is combined with another sanitizers.
-    if (StaticRuntimes.empty()) {
-      StaticRuntimes.push_back("ubsan_standalone");
-      if (SanArgs.linkCXXRuntimes())
-        StaticRuntimes.push_back("ubsan_standalone_cxx");
-    } else {
-      StaticRuntimes.push_back("ubsan");
-      if (SanArgs.linkCXXRuntimes())
-        StaticRuntimes.push_back("ubsan_cxx");
-    }
+    StaticRuntimes.push_back("ubsan_standalone");
+    if (SanArgs.linkCXXRuntimes())
+      StaticRuntimes.push_back("ubsan_standalone_cxx");
   }
 }
 
Index: test/Driver/sanitizer-ld.c
===================================================================
--- test/Driver/sanitizer-ld.c
+++ test/Driver/sanitizer-ld.c
@@ -227,8 +227,7 @@
 // RUN:   | FileCheck --check-prefix=CHECK-ASAN-UBSAN-LINUX %s
 // CHECK-ASAN-UBSAN-LINUX: "{{.*}}ld{{(.exe)?}}"
 // CHECK-ASAN-UBSAN-LINUX: "-whole-archive" "{{.*}}libclang_rt.asan-i386.a" "-no-whole-archive"
-// CHECK-ASAN-UBSAN-LINUX: "-whole-archive" "{{.*}}libclang_rt.ubsan-i386.a" "-no-whole-archive"
-// CHECK-ASAN-UBSAN-LINUX-NOT: libclang_rt.ubsan_cxx
+// CHECK-ASAN-UBSAN-LINUX-NOT: libclang_rt.ubsan
 // CHECK-ASAN-UBSAN-LINUX-NOT: "-lstdc++"
 // CHECK-ASAN-UBSAN-LINUX: "-lpthread"
 
@@ -238,8 +237,8 @@
 // RUN:   | FileCheck --check-prefix=CHECK-ASAN-UBSAN-LINUX-CXX %s
 // CHECK-ASAN-UBSAN-LINUX-CXX: "{{.*}}ld{{(.exe)?}}"
 // CHECK-ASAN-UBSAN-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.asan-i386.a" "-no-whole-archive"
-// CHECK-ASAN-UBSAN-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.ubsan-i386.a" "-no-whole-archive"
-// CHECK-ASAN-UBSAN-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.ubsan_cxx-i386.a" "-no-whole-archive"
+// CHECK-ASAN-UBSAN-LINUX-CXX: "-whole-archive" "{{.*}}libclang_rt.asan_cxx-i386.a" "-no-whole-archive"
+// CHECK-ASAN-UBSAN-LINUX-CXX-NOT: libclang_rt.ubsan
 // CHECK-ASAN-UBSAN-LINUX-CXX: "-lstdc++"
 // CHECK-ASAN-UBSAN-LINUX-CXX: "-lpthread"

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