Hello,
The following patch adds __attribute__((no_address_safety_analysis)) which
will allow to disable
address safety analysis (such as e.g. AddressSanitizer or SAFECode) for a
specific function.
When building with AddressSanitizer, add AddressSafety function attribute
to every generated function
except for those that have __attribute__((no_address_safety_analysis)).
With this patch we will be able to
1. disable AddressSanitizer for a particular function
2. disable AddressSanitizer-hostile optimizations (such as some cases of
load widening) when AddressSanitizer is on.
http://codereview.appspot.com/5561050/
Thanks,
--kcc
Index: test/CodeGen/address-safety-attr.c
===================================================================
--- test/CodeGen/address-safety-attr.c (revision 0)
+++ test/CodeGen/address-safety-attr.c (revision 0)
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -emit-llvm -o - %s -faddress-sanitizer | FileCheck -check-prefix ASAN %s
+
+// The address_safety attribute should be attached to functions
+// when AddressSanitizer is enabled, unless no_address_safety_analysis attribute
+// is present.
+
+// CHECK-NOT: NoAddressSafety1{{.*}} address_safety
+// ASAN-NOT: NoAddressSafety1{{.*}} address_safety
+__attribute__((no_address_safety_analysis))
+int NoAddressSafety1(int *a) { return *a; }
+
+// CHECK-NOT: NoAddressSafety2{{.*}} address_safety
+// ASAN-NOT: NoAddressSafety2{{.*}} address_safety
+__attribute__((no_address_safety_analysis))
+int NoAddressSafety2(int *a);
+int NoAddressSafety2(int *a) { return *a; }
+
+// CHECK-NOT: AddressSafetyOk{{.*}} address_safety
+// ASAN: AddressSafetyOk{{.*}} address_safety
+int AddressSafetyOk(int *a) { return *a; }
Index: include/clang/Basic/Attr.td
===================================================================
--- include/clang/Basic/Attr.td (revision 148551)
+++ include/clang/Basic/Attr.td (working copy)
@@ -574,6 +574,10 @@
let Spellings = [];
}
+// AddressSafety attribute (e.g. for AddressSanitizer)
+def NoAddressSafetyAnalysis : InheritableAttr {
+ let Spellings = ["no_address_safety_analysis"];
+}
// C/C++ Thread safety attributes (e.g. for deadlock, data race checking)
Index: include/clang/Sema/AttributeList.h
===================================================================
--- include/clang/Sema/AttributeList.h (revision 148551)
+++ include/clang/Sema/AttributeList.h (working copy)
@@ -218,6 +218,7 @@
AT_naked,
AT_neon_polyvector_type, // Clang-specific.
AT_neon_vector_type, // Clang-specific.
+ AT_no_address_safety_analysis,
AT_no_instrument_function,
AT_no_thread_safety_analysis,
AT_nocommon,
Index: docs/LanguageExtensions.html
===================================================================
--- docs/LanguageExtensions.html (revision 148551)
+++ docs/LanguageExtensions.html (working copy)
@@ -1453,6 +1453,10 @@
to check if the code is being built with <a
href="AddressSanitizer.html">AddressSanitizer</a>.
</p>
+<p>Use <tt>__attribute__((no_address_safety_analysis))</tt> on a function
+declaration to specify that address safety instrumentation (e.g.
+AddressSanitizer) should not be applied to that function.
+</p>
<!-- ======================================================================= -->
<h2 id="threadsafety">Thread-Safety Annotation Checking</h2>
Index: lib/Sema/SemaDeclAttr.cpp
===================================================================
--- lib/Sema/SemaDeclAttr.cpp (revision 148551)
+++ lib/Sema/SemaDeclAttr.cpp (working copy)
@@ -446,6 +446,23 @@
S.Context));
}
+static void handleNoAddressSafetyAttr(Sema &S, Decl *D,
+ const AttributeList &Attr) {
+ assert(!Attr.isInvalid());
+
+ if (!checkAttributeNumArgs(S, Attr, 0))
+ return;
+
+ if (!isa<FunctionDecl>(D) && !isa<FunctionTemplateDecl>(D)) {
+ S.Diag(Attr.getLoc(), diag::warn_attribute_wrong_decl_type)
+ << Attr.getName() << ExpectedFunctionOrMethod;
+ return;
+ }
+
+ D->addAttr(::new (S.Context) NoAddressSafetyAnalysisAttr(Attr.getRange(),
+ S.Context));
+}
+
static void handleAcquireOrderAttr(Sema &S, Decl *D, const AttributeList &Attr,
bool before) {
assert(!Attr.isInvalid());
@@ -3680,6 +3697,9 @@
case AttributeList::AT_scoped_lockable:
handleLockableAttr(S, D, Attr, /*scoped = */true);
break;
+ case AttributeList::AT_no_address_safety_analysis:
+ handleNoAddressSafetyAttr(S, D, Attr);
+ break;
case AttributeList::AT_no_thread_safety_analysis:
handleNoThreadSafetyAttr(S, D, Attr);
break;
Index: lib/Sema/AttributeList.cpp
===================================================================
--- lib/Sema/AttributeList.cpp (revision 148551)
+++ lib/Sema/AttributeList.cpp (working copy)
@@ -218,6 +218,7 @@
.Case("pt_guarded_var", AT_pt_guarded_var)
.Case("scoped_lockable", AT_scoped_lockable)
.Case("lockable", AT_lockable)
+ .Case("no_address_safety_analysis", AT_no_address_safety_analysis)
.Case("no_thread_safety_analysis", AT_no_thread_safety_analysis)
.Case("guarded_by", AT_guarded_by)
.Case("pt_guarded_by", AT_pt_guarded_by)
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp (revision 148551)
+++ lib/CodeGen/CodeGenModule.cpp (working copy)
@@ -1020,6 +1020,14 @@
if (ExtraAttrs != llvm::Attribute::None)
F->addFnAttr(ExtraAttrs);
+ if (Features.AddressSanitizer) {
+ // When AddressSanitizer is enabled, set AddressSafety attribute
+ // unless __attribute__((no_address_safety_analysis)) is used.
+ const FunctionDecl *FD = cast_or_null<FunctionDecl>(D.getDecl());
+ if (!FD || !FD->hasAttr<NoAddressSafetyAnalysisAttr>())
+ F->addFnAttr(llvm::Attribute::AddressSafety);
+ }
+
// This is the first use or definition of a mangled name. If there is a
// deferred decl with this name, remember that we need to emit it at the end
// of the file.
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