r220708 - Do not insert asan paddings after fields that have flexible arrays.
Kostya Serebryany
kcc at google.com
Mon Oct 27 12:34:10 PDT 2014
Author: kcc
Date: Mon Oct 27 14:34:10 2014
New Revision: 220708
URL: http://llvm.org/viewvc/llvm-project?rev=220708&view=rev
Log:
Do not insert asan paddings after fields that have flexible arrays.
Summary:
We should avoid a tail padding not only if the last field
has zero size but also if the last field is a struct with a flexible array.
If/when http://reviews.llvm.org/D5478 is committed,
this will also handle the case of structs with zero-sized arrays.
Reviewers: majnemer, rsmith
Reviewed By: rsmith
Subscribers: cfe-commits
Differential Revision: http://reviews.llvm.org/D5924
Modified:
cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
cfe/trunk/test/CodeGen/sanitize-address-field-padding.cpp
Modified: cfe/trunk/lib/AST/RecordLayoutBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/RecordLayoutBuilder.cpp?rev=220708&r1=220707&r2=220708&view=diff
==============================================================================
--- cfe/trunk/lib/AST/RecordLayoutBuilder.cpp (original)
+++ cfe/trunk/lib/AST/RecordLayoutBuilder.cpp Mon Oct 27 14:34:10 2014
@@ -1331,8 +1331,13 @@ void RecordLayoutBuilder::LayoutFields(c
// Layout each field, for now, just sequentially, respecting alignment. In
// the future, this will need to be tweakable by targets.
bool InsertExtraPadding = D->mayInsertExtraPadding(/*EmitRemark=*/true);
- for (const auto *Field : D->fields())
- LayoutField(Field, InsertExtraPadding);
+ bool HasFlexibleArrayMember = D->hasFlexibleArrayMember();
+ for (auto I = D->field_begin(), End = D->field_end(); I != End; ++I) {
+ auto Next(I);
+ ++Next;
+ LayoutField(*I,
+ InsertExtraPadding && (Next != End || !HasFlexibleArrayMember));
+ }
}
// Rounds the specified size to have it a multiple of the char size.
@@ -1750,7 +1755,7 @@ void RecordLayoutBuilder::LayoutField(co
Context.toBits(UnpackedFieldOffset),
Context.toBits(UnpackedFieldAlign), FieldPacked, D);
- if (InsertExtraPadding && !FieldSize.isZero()) {
+ if (InsertExtraPadding) {
CharUnits ASanAlignment = CharUnits::fromQuantity(8);
CharUnits ExtraSizeForAsan = ASanAlignment;
if (FieldSize % ASanAlignment)
Modified: cfe/trunk/test/CodeGen/sanitize-address-field-padding.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/sanitize-address-field-padding.cpp?rev=220708&r1=220707&r2=220708&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/sanitize-address-field-padding.cpp (original)
+++ cfe/trunk/test/CodeGen/sanitize-address-field-padding.cpp Mon Oct 27 14:34:10 2014
@@ -55,6 +55,36 @@ class ClassWithVirtualBase : public virt
ClassWithVirtualBase class_with_virtual_base;
+class WithFlexibleArray1 {
+ public:
+ WithFlexibleArray1() {}
+ ~WithFlexibleArray1() {}
+ int make_it_non_standard_layout;
+ private:
+ char private1[33];
+ int flexible[]; // Don't insert padding after this field.
+};
+
+WithFlexibleArray1 with_flexible_array1;
+// CHECK: %class.WithFlexibleArray1 = type { i32, [12 x i8], [33 x i8], [15 x i8], [0 x i32] }
+
+class WithFlexibleArray2 {
+ public:
+ char x[21];
+ WithFlexibleArray1 flex1; // Don't insert padding after this field.
+};
+
+WithFlexibleArray2 with_flexible_array2;
+// CHECK: %class.WithFlexibleArray2 = type { [21 x i8], [11 x i8], %class.WithFlexibleArray1 }
+
+class WithFlexibleArray3 {
+ public:
+ char x[13];
+ WithFlexibleArray2 flex2; // Don't insert padding after this field.
+};
+
+WithFlexibleArray3 with_flexible_array3;
+
class Negative1 {
public:
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