[ubsan] Improve diagnostics for return value checks (clang)

This patch makes ubsan's nonnull return value diagnostics more precise,
which makes the diagnostics more useful when there are multiple return
statements in a function. Example:

1 |__attribute__((returns_nonnull)) char *foo() {
2 |  if (...) {
3 |    return expr_which_might_evaluate_to_null();
4 |  } else {
5 |    return another_expr_which_might_evaluate_to_null();
6 |  }
7 |} // <- The current diagnostic always points here!

runtime error: Null returned from Line 7, Column 2!
With this patch, the diagnostic would point to either Line 3, Column 5
or Line 5, Column 5.

This is done by emitting source location metadata for each return
statement in a sanitized function. The runtime is passed a pointer to
the appropriate metadata so that it can prepare and deduplicate reports.

Compiler-rt patch (with more tests): https://reviews.llvm.org/D34298

Differential Revision: https://reviews.llvm.org/D34299

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@306163 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 51 insertions, 15 deletions

diff --git a/test/CodeGenObjC/ubsan-nonnull-and-nullability.m b/test/CodeGenObjC/ubsan-nonnull-and-nullability.m
index b927f55cd4..db6588dac3 100644
--- a/test/CodeGenObjC/ubsan-nonnull-and-nullability.m
+++ b/test/CodeGenObjC/ubsan-nonnull-and-nullability.m
@@ -7,16 +7,26 @@
 // CHECK-LABEL: define nonnull i32* @f1
 __attribute__((returns_nonnull)) int *_Nonnull f1(int *_Nonnull p) {
   // CHECK: entry:
+  // CHECK-NEXT: [[SLOC_PTR:%.*]] = alloca i8*
   // CHECK-NEXT: [[ADDR:%.*]] = alloca i32*
+  // CHECK-NEXT: store i8* null, i8** [[SLOC_PTR]]
   // CHECK-NEXT: store i32* [[P:%.*]], i32** [[ADDR]]
+  // CHECK-NEXT: store {{.*}} [[SLOC_PTR]]
   // CHECK-NEXT: [[ARG:%.*]] = load i32*, i32** [[ADDR]]
+  // CHECK-NEXT: [[SLOC:%.*]] = load {{.*}} [[SLOC_PTR]]
+  // CHECK-NEXT: [[SLOC_NONNULL:%.*]] = icmp ne i8* [[SLOC]], null
+  // CHECK-NEXT: br i1 [[SLOC_NONNULL]], label %nullcheck
+  // 
+  // CHECK: nullcheck:
   // CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32* [[ARG]], null, !nosanitize
   // CHECK-NEXT: br i1 [[ICMP]], label %[[CONT:.+]], label %[[HANDLE:[^,]+]]
   // CHECK: [[HANDLE]]:
-  // CHECK-NEXT:   call void @__ubsan_handle_nonnull_return_abort
+  // CHECK:      call void @__ubsan_handle_nonnull_return
   // CHECK-NEXT:   unreachable, !nosanitize
   // CHECK: [[CONT]]:
-  // CHECK-NEXT:   ret i32*
+  // CHECK-NEXT:   br label %no.nullcheck
+  // CHECK: no.nullcheck:
+  // CHECK-NEXT: ret i32* [[ARG]]
   return p;
 }
 
@@ -29,3 +39,23 @@ void call_f2() {
   // CHECK-NOT: call void @__ubsan_handle_nonnull_arg_abort
   f2((void *)0);
 }
+
+// If the return value isn't meant to be checked, make sure we don't check it.
+// CHECK-LABEL: define i32* @f3
+int *f3(int *p) {
+  // CHECK-NOT: return.sloc
+  // CHECK-NOT: call{{.*}}ubsan
+  return p;
+}
+
+// Check for a valid "return" source location, even when there is no return
+// statement, to avoid accidentally calling the runtime.
+
+// CHECK-LABEL: define nonnull i32* @f4
+__attribute__((returns_nonnull)) int *f4() {
+  // CHECK: store i8* null, i8** [[SLOC_PTR:%.*]]
+  // CHECK: [[SLOC:%.*]] = load {{.*}} [[SLOC_PTR]]
+  // CHECK: [[SLOC_NONNULL:%.*]] = icmp ne i8* [[SLOC]], null
+  // CHECK: br i1 [[SLOC_NONNULL]], label %nullcheck
+  // CHECK: nullcheck:
+}
diff --git a/test/CodeGenObjC/ubsan-nullability.m b/test/CodeGenObjC/ubsan-nullability.m
index 7f53ea6292..eeb24b03c8 100644
--- a/test/CodeGenObjC/ubsan-nullability.m
+++ b/test/CodeGenObjC/ubsan-nullability.m
@@ -2,7 +2,7 @@
 // RUN: %clang_cc1 -x objective-c -emit-llvm -triple x86_64-apple-macosx10.10.0 -fsanitize=nullability-arg,nullability-assign,nullability-return -w %s -o - | FileCheck %s
 // RUN: %clang_cc1 -x objective-c++ -emit-llvm -triple x86_64-apple-macosx10.10.0 -fsanitize=nullability-arg,nullability-assign,nullability-return -w %s -o - | FileCheck %s
 
-// CHECK: [[NONNULL_RV_LOC1:@.*]] = private unnamed_addr global {{.*}} i32 109, i32 1 {{.*}} i32 100, i32 6
+// CHECK: [[NONNULL_RV_LOC1:@.*]] = private unnamed_addr global {{.*}} i32 100, i32 6
 // CHECK: [[NONNULL_ARG_LOC:@.*]] = private unnamed_addr global {{.*}} i32 204, i32 15 {{.*}} i32 190, i32 23
 // CHECK: [[NONNULL_ASSIGN1_LOC:@.*]] = private unnamed_addr global {{.*}} i32 305, i32 9
 // CHECK: [[NONNULL_ASSIGN2_LOC:@.*]] = private unnamed_addr global {{.*}} i32 405, i32 10
@@ -10,7 +10,7 @@
 // CHECK: [[NONNULL_INIT1_LOC:@.*]] = private unnamed_addr global {{.*}} i32 604, i32 25
 // CHECK: [[NONNULL_INIT2_LOC1:@.*]] = private unnamed_addr global {{.*}} i32 707, i32 26
 // CHECK: [[NONNULL_INIT2_LOC2:@.*]] = private unnamed_addr global {{.*}} i32 707, i32 29
-// CHECK: [[NONNULL_RV_LOC2:@.*]] = private unnamed_addr global {{.*}} i32 817, i32 1 {{.*}} i32 800, i32 6
+// CHECK: [[NONNULL_RV_LOC2:@.*]] = private unnamed_addr global {{.*}} i32 800, i32 6
 
 #define NULL ((void *)0)
 #define INULL ((int *)NULL)
@@ -19,14 +19,11 @@
 // CHECK-LABEL: define i32* @{{.*}}nonnull_retval1
 #line 100
 int *_Nonnull nonnull_retval1(int *p) {
-  // CHECK: br i1 true, label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
-  // CHECK: [[NULL]]:
   // CHECK: [[ICMP:%.*]] = icmp ne i32* {{.*}}, null, !nosanitize
-  // CHECK-NEXT: br i1 [[ICMP]], {{.*}}, !nosanitize
+  // CHECK: br i1 [[ICMP]], {{.*}}, !nosanitize
   // CHECK: call void @__ubsan_handle_nullability_return{{.*}}[[NONNULL_RV_LOC1]]
   return p;
-  // CHECK: [[NONULL]]:
-  // CHECK-NEXT: ret i32*
+  // CHECK: ret i32*
 }
 
 #line 190
@@ -108,10 +105,13 @@ int *_Nonnull nonnull_retval2(int *_Nonnull arg1,  //< Test this.
   // CHECK-NEXT: [[DO_RV_CHECK_1:%.*]] = and i1 true, [[ARG1CMP]], !nosanitize
   // CHECK: [[ARG2CMP:%.*]] = icmp ne i32* %arg2, null, !nosanitize
   // CHECK-NEXT: [[DO_RV_CHECK_2:%.*]] = and i1 [[DO_RV_CHECK_1]], [[ARG2CMP]]
-  // CHECK: br i1 [[DO_RV_CHECK_2]], label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
+  // CHECK: [[SLOC_PTR:%.*]] = load i8*, i8** %return.sloc.ptr
+  // CHECK-NEXT: [[SLOC_NONNULL:%.*]] = icmp ne i8* [[SLOC_PTR]], null
+  // CHECK-NEXT: [[DO_RV_CHECK_3:%.*]] = and i1 [[SLOC_NONNULL]], [[DO_RV_CHECK_2]]
+  // CHECK: br i1 [[DO_RV_CHECK_3]], label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
   // CHECK: [[NULL]]:
   // CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32* {{.*}}, null, !nosanitize
-  // CHECK-NEXT: br i1 [[ICMP]], {{.*}}, !nosanitize
+  // CHECK: br i1 [[ICMP]], {{.*}}, !nosanitize
   // CHECK: call void @__ubsan_handle_nullability_return{{.*}}[[NONNULL_RV_LOC2]]
   return arg1;
   // CHECK: [[NONULL]]:
@@ -129,10 +129,13 @@ int *_Nonnull nonnull_retval2(int *_Nonnull arg1,  //< Test this.
 +(int *_Nonnull) objc_clsmethod: (int *_Nonnull) arg1 {
   // CHECK: [[ARG1CMP:%.*]] = icmp ne i32* %arg1, null, !nosanitize
   // CHECK-NEXT: [[DO_RV_CHECK:%.*]] = and i1 true, [[ARG1CMP]]
-  // CHECK: br i1 [[DO_RV_CHECK]], label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
+  // CHECK: [[SLOC_PTR:%.*]] = load i8*, i8** %return.sloc.ptr
+  // CHECK-NEXT: [[SLOC_NONNULL:%.*]] = icmp ne i8* [[SLOC_PTR]], null
+  // CHECK-NEXT: [[DO_RV_CHECK_2:%.*]] = and i1 [[SLOC_NONNULL]], [[DO_RV_CHECK]]
+  // CHECK: br i1 [[DO_RV_CHECK_2]], label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
   // CHECK: [[NULL]]:
   // CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32* {{.*}}, null, !nosanitize
-  // CHECK-NEXT: br i1 [[ICMP]], {{.*}}, !nosanitize
+  // CHECK: br i1 [[ICMP]], {{.*}}, !nosanitize
   // CHECK: call void @__ubsan_handle_nullability_return{{.*}}
   return arg1;
   // CHECK: [[NONULL]]:
@@ -143,10 +146,13 @@ int *_Nonnull nonnull_retval2(int *_Nonnull arg1,  //< Test this.
 -(int *_Nonnull) objc_method: (int *_Nonnull) arg1 {
   // CHECK: [[ARG1CMP:%.*]] = icmp ne i32* %arg1, null, !nosanitize
   // CHECK-NEXT: [[DO_RV_CHECK:%.*]] = and i1 true, [[ARG1CMP]]
-  // CHECK: br i1 [[DO_RV_CHECK]], label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
+  // CHECK: [[SLOC_PTR:%.*]] = load i8*, i8** %return.sloc.ptr
+  // CHECK-NEXT: [[SLOC_NONNULL:%.*]] = icmp ne i8* [[SLOC_PTR]], null
+  // CHECK-NEXT: [[DO_RV_CHECK_2:%.*]] = and i1 [[SLOC_NONNULL]], [[DO_RV_CHECK]]
+  // CHECK: br i1 [[DO_RV_CHECK_2]], label %[[NULL:.*]], label %[[NONULL:.*]], !nosanitize
   // CHECK: [[NULL]]:
   // CHECK-NEXT: [[ICMP:%.*]] = icmp ne i32* {{.*}}, null, !nosanitize
-  // CHECK-NEXT: br i1 [[ICMP]], {{.*}}, !nosanitize
+  // CHECK: br i1 [[ICMP]], {{.*}}, !nosanitize
   // CHECK: call void @__ubsan_handle_nullability_return{{.*}}
   return arg1;
   // CHECK: [[NONULL]]: