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The -fstrict-flex-arrays=3 is the most restrictive type of flex arrays.
No number, including 0, is allowed in the FAM. In the cases where a "0"
is used, the resulting size is the same as if a zero-sized object were
substituted.
This is needed for proper _FORTIFY_SOURCE coverage in the Linux kernel,
among other reasons. So while the only reason for specifying a
zero-length array at the end of a structure is for specify a FAM,
treating it as such will cause _FORTIFY_SOURCE not to work correctly.
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D134902
Files:
clang/include/clang/Driver/Options.td
clang/lib/AST/ExprConstant.cpp
clang/lib/CodeGen/CGExpr.cpp
clang/test/CodeGen/bounds-checking-fam.c
clang/test/CodeGen/object-size-flex-array.c
clang/test/Sema/array-bounds-ptr-arith.c
clang/test/SemaCXX/array-bounds-strict-flex-arrays.cpp
Index: clang/test/SemaCXX/array-bounds-strict-flex-arrays.cpp
===================================================================
--- clang/test/SemaCXX/array-bounds-strict-flex-arrays.cpp
+++ clang/test/SemaCXX/array-bounds-strict-flex-arrays.cpp
@@ -1,5 +1,6 @@
// RUN: %clang_cc1 -verify=relaxed -fstrict-flex-arrays=1 %s
// RUN: %clang_cc1 -verify=relaxed,strict -fstrict-flex-arrays=2 %s
+// RUN: %clang_cc1 -verify=relaxed,strict -fstrict-flex-arrays=3 %s
// We cannot know for sure the size of a flexible array.
struct t {
Index: clang/test/Sema/array-bounds-ptr-arith.c
===================================================================
--- clang/test/Sema/array-bounds-ptr-arith.c
+++ clang/test/Sema/array-bounds-ptr-arith.c
@@ -1,6 +1,7 @@
// RUN: %clang_cc1 -verify=expected -Warray-bounds-pointer-arithmetic %s
// RUN: %clang_cc1 -verify=expected -Warray-bounds-pointer-arithmetic %s -fstrict-flex-arrays=0
// RUN: %clang_cc1 -verify=expected,strict -Warray-bounds-pointer-arithmetic %s -fstrict-flex-arrays=2
+// RUN: %clang_cc1 -verify=expected,strict -Warray-bounds-pointer-arithmetic %s -fstrict-flex-arrays=3
// Test case from PR10615
struct ext2_super_block{
Index: clang/test/CodeGen/object-size-flex-array.c
===================================================================
--- clang/test/CodeGen/object-size-flex-array.c
+++ clang/test/CodeGen/object-size-flex-array.c
@@ -1,6 +1,8 @@
-// RUN: %clang -fstrict-flex-arrays=2 -target x86_64-apple-darwin -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-2 %s
-// RUN: %clang -fstrict-flex-arrays=1 -target x86_64-apple-darwin -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-1 %s
-// RUN: %clang -fstrict-flex-arrays=0 -target x86_64-apple-darwin -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-0 %s
+// RUN: %clang -target x86_64 -O2 -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-NO-STRICT %s
+// RUN: %clang -fstrict-flex-arrays=0 -target x86_64 -O2 -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-0 %s
+// RUN: %clang -fstrict-flex-arrays=1 -target x86_64 -O2 -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-1 %s
+// RUN: %clang -fstrict-flex-arrays=2 -target x86_64 -O2 -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-2 %s
+// RUN: %clang -fstrict-flex-arrays=3 -target x86_64 -O2 -S -emit-llvm %s -o - 2>&1 | FileCheck --check-prefixes=CHECK,CHECK-STRICT-3 %s
#define OBJECT_SIZE_BUILTIN __builtin_object_size
@@ -26,36 +28,86 @@
// CHECK-LABEL: @bar(
unsigned bar(foo_t *f) {
- // CHECK-STRICT-0: ret i32 %
- // CHECK-STRICT-1: ret i32 %
- // CHECK-STRICT-2: ret i32 %
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 -1
+ // CHECK-STRICT-2: ret i32 -1
+ // CHECK-STRICT-3: ret i32 -1
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
// CHECK-LABEL: @bar0(
unsigned bar0(foo0_t *f) {
- // CHECK-STRICT-0: ret i32 %
- // CHECK-STRICT-1: ret i32 %
- // CHECK-STRICT-2: ret i32 %
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 -1
+ // CHECK-STRICT-2: ret i32 -1
+ // CHECK-STRICT-3: ret i32 0
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
// CHECK-LABEL: @bar1(
unsigned bar1(foo1_t *f) {
- // CHECK-STRICT-0: ret i32 %
- // CHECK-STRICT-1: ret i32 %
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 -1
// CHECK-STRICT-2: ret i32 8
+ // CHECK-STRICT-3: ret i32 8
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
// CHECK-LABEL: @bar2(
unsigned bar2(foo2_t *f) {
- // CHECK-STRICT-0: ret i32 %
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
// CHECK-STRICT-1: ret i32 16
// CHECK-STRICT-2: ret i32 16
+ // CHECK-STRICT-3: ret i32 16
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
+#define DYNAMIC_OBJECT_SIZE_BUILTIN __builtin_dynamic_object_size
+
+// CHECK-LABEL: @dyn_bar(
+unsigned dyn_bar(foo_t *f) {
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 -1
+ // CHECK-STRICT-2: ret i32 -1
+ // CHECK-STRICT-3: ret i32 -1
+ return DYNAMIC_OBJECT_SIZE_BUILTIN(f->c, 1);
+}
+
+// CHECK-LABEL: @dyn_bar0(
+unsigned dyn_bar0(foo0_t *f) {
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 -1
+ // CHECK-STRICT-2: ret i32 -1
+ // CHECK-STRICT-3: ret i32 0
+ return DYNAMIC_OBJECT_SIZE_BUILTIN(f->c, 1);
+}
+
+// CHECK-LABEL: @dyn_bar1(
+unsigned dyn_bar1(foo1_t *f) {
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 -1
+ // CHECK-STRICT-2: ret i32 8
+ // CHECK-STRICT-3: ret i32 8
+ return DYNAMIC_OBJECT_SIZE_BUILTIN(f->c, 1);
+}
+
+// CHECK-LABEL: @dyn_bar2(
+unsigned dyn_bar2(foo2_t *f) {
+ // CHECK-NO-STRICT: ret i32 -1
+ // CHECK-STRICT-0: ret i32 -1
+ // CHECK-STRICT-1: ret i32 16
+ // CHECK-STRICT-2: ret i32 16
+ // CHECK-STRICT-3: ret i32 16
+ return DYNAMIC_OBJECT_SIZE_BUILTIN(f->c, 1);
+}
+
// Also checks for non-trailing flex-array like members
typedef struct {
@@ -75,24 +127,30 @@
// CHECK-LABEL: @babar0(
unsigned babar0(foofoo0_t *f) {
+ // CHECK-NO-STRICT: ret i32 0
// CHECK-STRICT-0: ret i32 0
// CHECK-STRICT-1: ret i32 0
// CHECK-STRICT-2: ret i32 0
+ // CHECK-STRICT-3: ret i32 0
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
// CHECK-LABEL: @babar1(
unsigned babar1(foofoo1_t *f) {
+ // CHECK-NO-STRICT: ret i32 8
// CHECK-STRICT-0: ret i32 8
// CHECK-STRICT-1: ret i32 8
// CHECK-STRICT-2: ret i32 8
+ // CHECK-STRICT-3: ret i32 8
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
// CHECK-LABEL: @babar2(
unsigned babar2(foofoo2_t *f) {
+ // CHECK-NO-STRICT: ret i32 16
// CHECK-STRICT-0: ret i32 16
// CHECK-STRICT-1: ret i32 16
// CHECK-STRICT-2: ret i32 16
+ // CHECK-STRICT-3: ret i32 16
return OBJECT_SIZE_BUILTIN(f->c, 1);
}
Index: clang/test/CodeGen/bounds-checking-fam.c
===================================================================
--- clang/test/CodeGen/bounds-checking-fam.c
+++ clang/test/CodeGen/bounds-checking-fam.c
@@ -1,10 +1,12 @@
// REQUIRES: x86-registered-target
-// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=0 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-0
-// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=0 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-0,CXX,CXX-STRICT-0
-// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=1 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-1
-// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=1 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-1,CXX
-// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=2 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-2
-// RUN: %clang_cc1 -emit-llvm -triple x86_64 -fstrict-flex-arrays=2 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-2,CXX
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=0 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-0
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=0 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-0,CXX,CXX-STRICT-0
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=1 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-1
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=1 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-1,CXX
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=2 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-2
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=2 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-2,CXX
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=3 -fsanitize=array-bounds %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-3
+// RUN: %clang_cc1 -O2 -emit-llvm -triple x86_64 -fstrict-flex-arrays=3 -fsanitize=array-bounds -x c++ %s -o - | FileCheck %s --check-prefixes=CHECK,CHECK-STRICT-3,CXX
// Before flexible array member was added to C99, many projects use a
// one-element array as the last member of a structure as an alternative.
// E.g. https://github.com/python/cpython/issues/84301
@@ -24,6 +26,7 @@
// CHECK-STRICT-0-NOT: @__ubsan
// CHECK-STRICT-1-NOT: @__ubsan
// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
+ // CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
return p->a[i] + (p->a)[i];
}
@@ -32,6 +35,7 @@
// CHECK-STRICT-0: call void @__ubsan_handle_out_of_bounds_abort(
// CHECK-STRICT-1: call void @__ubsan_handle_out_of_bounds_abort(
// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
+ // CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
return p->a[i] + (p->a)[i];
}
@@ -53,6 +57,7 @@
// CHECK-STRICT-0-NOT: @__ubsan
// CHECK-STRICT-1-NOT: @__ubsan
// CHECK-STRICT-2-NOT: @__ubsan
+ // CHECK-STRICT-3: @__ubsan
return p->a[i] + (p->a)[i];
}
@@ -61,6 +66,7 @@
// CHECK-STRICT-0-NOT: @__ubsan
// CHECK-STRICT-1-NOT: @__ubsan
// CHECK-STRICT-2: @__ubsan
+ // CHECK-STRICT-3: @__ubsan
return p->a[i] + (p->a)[i];
}
@@ -69,6 +75,7 @@
// CHECK-STRICT-0: @__ubsan
// CHECK-STRICT-1: @__ubsan
// CHECK-STRICT-2: @__ubsan
+ // CHECK-STRICT-3: @__ubsan
return p->a[i] + (p->a)[i];
}
@@ -77,6 +84,7 @@
// CHECK-STRICT-0: @__ubsan
// CHECK-STRICT-1: @__ubsan
// CHECK-STRICT-2: @__ubsan
+ // CHECK-STRICT-3: @__ubsan
return p->a[i] + (p->a)[i];
}
@@ -85,6 +93,7 @@
// CHECK-STRICT-0: call void @__ubsan_handle_out_of_bounds_abort(
// CHECK-STRICT-1: call void @__ubsan_handle_out_of_bounds_abort(
// CHECK-STRICT-2: call void @__ubsan_handle_out_of_bounds_abort(
+ // CHECK-STRICT-3: call void @__ubsan_handle_out_of_bounds_abort(
return p->a[i] + (p->a)[i];
}
Index: clang/lib/CodeGen/CGExpr.cpp
===================================================================
--- clang/lib/CodeGen/CGExpr.cpp
+++ clang/lib/CodeGen/CGExpr.cpp
@@ -885,17 +885,24 @@
// the two mechanisms.
const ArrayType *AT = E->getType()->castAsArrayTypeUnsafe();
if (const auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
+ // At -fstrict-flex-arrays=3, only IncompleteArrayTypes are considered
+ // FAMs.
+ if (StrictFlexArraysLevel == 3)
+ return false;
+
// FIXME: Sema doesn't treat [1] as a flexible array member if the bound
// was produced by macro expansion.
- if (StrictFlexArraysLevel >= 2 && CAT->getSize().ugt(0))
+ if (StrictFlexArraysLevel == 2 && CAT->getSize().ugt(0))
return false;
+
// FIXME: While the default -fstrict-flex-arrays=0 permits Size>1 trailing
// arrays to be treated as flexible-array-members, we still emit ubsan
// checks as if they are not.
if (CAT->getSize().ugt(1))
return false;
- } else if (!isa<IncompleteArrayType>(AT))
+ } else if (!isa<IncompleteArrayType>(AT)) {
return false;
+ }
E = E->IgnoreParens();
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -11618,7 +11618,8 @@
Designator.Entries.size() == Designator.MostDerivedPathLength &&
Designator.MostDerivedIsArrayElement &&
(Designator.isMostDerivedAnUnsizedArray() ||
- Designator.getMostDerivedArraySize() == 0 ||
+ (Designator.getMostDerivedArraySize() == 0 &&
+ StrictFlexArraysLevel < 3) ||
(Designator.getMostDerivedArraySize() == 1 &&
StrictFlexArraysLevel < 2) ||
StrictFlexArraysLevel == 0) &&
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1141,7 +1141,7 @@
HelpText<"Use Apple's kernel extensions ABI">,
MarshallingInfoFlag<LangOpts<"AppleKext">>;
def fstrict_flex_arrays_EQ : Joined<["-"], "fstrict-flex-arrays=">, Group<f_Group>,
- MetaVarName<"<n>">, Values<"0,1,2">,
+ MetaVarName<"<n>">, Values<"0,1,2,3">,
LangOpts<"StrictFlexArrays">,
Flags<[CC1Option]>,
HelpText<"Enable optimizations based on the strict definition of flexible arrays">,
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