r283249 - [ubsan] Disable bounds-check for flexible array ivars

[Vedant Kumar via cfe-commits]

Author: vedantk
Date: Tue Oct  4 15:36:04 2016
New Revision: 283249

URL: http://llvm.org/viewvc/llvm-project?rev=283249&view=rev
Log:
[ubsan] Disable bounds-check for flexible array ivars

This eliminates a class of false positives for -fsanitize=array-bounds
on instrumented ObjC projects.

Differential Revision: https://reviews.llvm.org/D22227

Added:
    cfe/trunk/test/CodeGenObjC/ubsan-array-bounds.m
Modified:
    cfe/trunk/lib/CodeGen/CGExpr.cpp

Modified: cfe/trunk/lib/CodeGen/CGExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExpr.cpp?rev=283249&r1=283248&r2=283249&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExpr.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExpr.cpp Tue Oct  4 15:36:04 2016
@@ -708,6 +708,8 @@ static bool isFlexibleArrayMemberExpr(co
           DeclContext::decl_iterator(const_cast<FieldDecl *>(FD)));
       return ++FI == FD->getParent()->field_end();
     }
+  } else if (const auto *IRE = dyn_cast<ObjCIvarRefExpr>(E)) {
+    return IRE->getDecl()->getNextIvar() == nullptr;
   }
 
   return false;

Added: cfe/trunk/test/CodeGenObjC/ubsan-array-bounds.m
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenObjC/ubsan-array-bounds.m?rev=283249&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenObjC/ubsan-array-bounds.m (added)
+++ cfe/trunk/test/CodeGenObjC/ubsan-array-bounds.m Tue Oct  4 15:36:04 2016
@@ -0,0 +1,59 @@
+// RUN: %clang_cc1 -x objective-c -emit-llvm -triple x86_64-apple-macosx10.10.0 -Wno-objc-root-class -fsanitize=array-bounds %s -o - | FileCheck %s
+
+ at interface FlexibleArray1 {
+ at public
+  char chars[0];
+}
+ at end
+ at implementation FlexibleArray1
+ at end
+
+// CHECK-LABEL: test_FlexibleArray1
+char test_FlexibleArray1(FlexibleArray1 *FA1) {
+  // CHECK-NOT: !nosanitize
+  return FA1->chars[1];
+  // CHECK: }
+}
+
+ at interface FlexibleArray2 {
+ at public
+  char chars[0];
+}
+ at end
+ at implementation FlexibleArray2 {
+ at public
+  char chars2[0];
+}
+ at end
+
+// CHECK-LABEL: test_FlexibleArray2_1
+char test_FlexibleArray2_1(FlexibleArray2 *FA2) {
+  // CHECK: !nosanitize
+  return FA2->chars[1];
+  // CHECK: }
+}
+
+// CHECK-LABEL: test_FlexibleArray2_2
+char test_FlexibleArray2_2(FlexibleArray2 *FA2) {
+  // CHECK-NOT: !nosanitize
+  return FA2->chars2[1];
+  // CHECK: }
+}
+
+ at interface FlexibleArray3 {
+ at public
+  char chars[0];
+}
+ at end
+ at implementation FlexibleArray3 {
+ at public
+  int i;
+}
+ at end
+
+// CHECK-LABEL: test_FlexibleArray3
+char test_FlexibleArray3(FlexibleArray3 *FA3) {
+  // CHECK: !nosanitize
+  return FA3->chars[1];
+  // CHECK: }
+}