[UBSan] Add returns-nonnull sanitizer.

Summary:
This patch adds a runtime check verifying that functions
annotated with "returns_nonnull" attribute do in fact return nonnull pointers.
It is based on suggestion by Jakub Jelinek:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140623/223693.html.

Test Plan: regression test suite

Reviewers: rsmith

Reviewed By: rsmith

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D4849

llvm-svn: 215485

1 files changed, 16 insertions, 2 deletions

diff --git a/clang/test/CodeGen/catch-undef-behavior.c b/clang/test/CodeGen/catch-undef-behavior.c
index 00962e40f66..2b9aedd4b5b 100644
--- a/clang/test/CodeGen/catch-undef-behavior.c
+++ b/clang/test/CodeGen/catch-undef-behavior.c
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
-// RUN: %clang_cc1 -fsanitize-undefined-trap-on-error -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-TRAP
+// RUN: %clang_cc1 -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool,returns-nonnull-attribute -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
+// RUN: %clang_cc1 -fsanitize-undefined-trap-on-error -fsanitize=alignment,null,object-size,shift,return,signed-integer-overflow,vla-bound,float-cast-overflow,integer-divide-by-zero,bool,returns-nonnull-attribute -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-TRAP
 // RUN: %clang_cc1 -fsanitize=null -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-NULL
 // RUN: %clang_cc1 -fsanitize=signed-integer-overflow -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-OVERFLOW
 
@@ -432,6 +432,20 @@ _Bool sour_bool(_Bool *p) {
   return *p;
 }
 
+// CHECK-LABEL: @ret_nonnull
+__attribute__((returns_nonnull))
+int *ret_nonnull(int *a) {
+  // CHECK: [[OK:%.*]] = icmp ne i32* {{.*}}, null
+  // CHECK: br i1 [[OK]]
+  // CHECK: call void @__ubsan_handle_nonnull_return
+
+  // CHECK-TRAP: [[OK:%.*]] = icmp ne i32* {{.*}}, null
+  // CHECK-TRAP: br i1 [[OK]]
+  // CHECK-TRAP: call void @llvm.trap() [[NR_NUW]]
+  // CHECK-TRAP: unreachable
+  return a;
+}
+
 // CHECK: ![[WEIGHT_MD]] = metadata !{metadata !"branch_weights", i32 1048575, i32 1}
 
 // CHECK-TRAP: attributes [[NR_NUW]] = { noreturn nounwind }