From b5b2ffe3be103325db681e671cbbde7c7d89e768 Mon Sep 17 00:00:00 2001
From: Dan Albert <danalbert@google.com>
Date: Thu, 16 Apr 2015 18:07:07 -0700
Subject: [PATCH] Add support for a partial ubsan build.

Some of the ubsan checks expose a few pathological performance cases
in clang, and thus aren't suited to be used in SANITIZE_HOST.

This mode is also supported on the target despite not having the
target runtime libraries for ubsan by generating traps.

Change-Id: I0b0f0a08ca84d72e44e2174a66726b1c5e5cad7e
---
 core/clang/config.mk      | 26 ++++++++++++++++++++++++++
 core/config_sanitizers.mk | 12 ++++++++----
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/core/clang/config.mk b/core/clang/config.mk
index e2a4c088cd..24c06b63c7 100644
--- a/core/clang/config.mk
+++ b/core/clang/config.mk
@@ -98,6 +98,32 @@ CLANG_CONFIG_TARGET_EXTRA_CFLAGS := -nostdlibinc
 CLANG_CONFIG_TARGET_EXTRA_CPPFLAGS := -nostdlibinc
 CLANG_CONFIG_TARGET_EXTRA_LDFLAGS :=
 
+CLANG_DEFAULT_UB_CHECKS := \
+  bool \
+  integer-divide-by-zero \
+  return \
+  returns-nonnull-attribute \
+  shift-exponent \
+  unreachable \
+  vla-bound \
+
+# TODO(danalbert): The following checks currently have compiler performance
+# issues.
+# CLANG_DEFAULT_UB_CHECKS += alignment
+# CLANG_DEFAULT_UB_CHECKS += bounds
+# CLANG_DEFAULT_UB_CHECKS += enum
+# CLANG_DEFAULT_UB_CHECKS += float-cast-overflow
+# CLANG_DEFAULT_UB_CHECKS += float-divide-by-zero
+# CLANG_DEFAULT_UB_CHECKS += nonnull-attribute
+# CLANG_DEFAULT_UB_CHECKS += null
+# CLANG_DEFAULT_UB_CHECKS += shift-base
+# CLANG_DEFAULT_UB_CHECKS += signed-integer-overflow
+
+# TODO(danalbert): Fix UB in libc++'s __tree so we can turn this on.
+# https://llvm.org/PR19302
+# http://reviews.llvm.org/D6974
+# CLANG_DEFAULT_UB_CHECKS += object-size
+
 # HOST config
 clang_2nd_arch_prefix :=
 include $(BUILD_SYSTEM)/clang/HOST_$(HOST_ARCH).mk
diff --git a/core/config_sanitizers.mk b/core/config_sanitizers.mk
index b433712305..210d442409 100644
--- a/core/config_sanitizers.mk
+++ b/core/config_sanitizers.mk
@@ -50,11 +50,15 @@ ifneq ($(my_clang),true)
   endif
 endif
 
-unknown_sanitizers := $(filter-out address, \
-                      $(filter-out undefined,$(my_sanitize)))
+ifneq ($(filter default-ub,$(my_sanitize)),)
+  my_sanitize := $(CLANG_DEFAULT_UB_CHECKS)
+  my_ldlibs += -ldl
 
-ifneq ($(unknown_sanitizers),)
-  $(error Unknown sanitizers: $(unknown_sanitizers))
+  ifdef LOCAL_IS_HOST_MODULE
+    my_cflags += -fno-sanitize-recover=all
+  else
+    my_cflags += -fsanitize-undefined-trap-on-error
+  endif
 endif
 
 ifneq ($(my_sanitize),)