Hi rsmith,
This change adds description of globals created by UBSan
instrumentation (UBSan handlers, type descriptors, filenames) to
llvm.asan.globals metadata, effectively "blacklisting" them. This can
dramatically decrease the data section in binaries built with UBSan+ASan,
as UBSan tends to create a lot of handlers, and ASan instrumentation
increases the global size to at least 64 bytes.
http://reviews.llvm.org/D4575
Files:
lib/CodeGen/CGExpr.cpp
lib/CodeGen/CodeGenModule.cpp
lib/CodeGen/CodeGenModule.h
test/CodeGenCXX/catch-undef-behavior.cpp
Index: lib/CodeGen/CodeGenModule.h
===================================================================
--- lib/CodeGen/CodeGenModule.h
+++ lib/CodeGen/CodeGenModule.h
@@ -1018,7 +1018,11 @@
void reportGlobalToASan(llvm::GlobalVariable *GV, const VarDecl &D,
bool IsDynInit = false);
void reportGlobalToASan(llvm::GlobalVariable *GV, SourceLocation Loc,
- StringRef Name, bool IsDynInit = false);
+ StringRef Name, bool IsDynInit = false,
+ bool IsBlacklisted = false);
+
+ /// Disable sanitizer instrumentation for this global.
+ void disableSanitizerForGlobal(llvm::GlobalVariable *GV);
void addDeferredVTable(const CXXRecordDecl *RD) {
DeferredVTables.push_back(RD);
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -1962,11 +1962,11 @@
void CodeGenModule::reportGlobalToASan(llvm::GlobalVariable *GV,
SourceLocation Loc, StringRef Name,
- bool IsDynInit) {
+ bool IsDynInit, bool IsBlacklisted) {
if (!LangOpts.Sanitize.Address)
return;
IsDynInit &= !SanitizerBL.isIn(*GV, "init");
- bool IsBlacklisted = SanitizerBL.isIn(*GV);
+ IsBlacklisted |= SanitizerBL.isIn(*GV);
llvm::GlobalVariable *LocDescr = nullptr;
llvm::GlobalVariable *GlobalName = nullptr;
@@ -2019,6 +2019,13 @@
reportGlobalToASan(GV, D.getLocation(), OS.str(), IsDynInit);
}
+void CodeGenModule::disableSanitizerForGlobal(llvm::GlobalVariable *GV) {
+ // For now, just make sure the global is not modified by the ASan
+ // instrumentation.
+ if (LangOpts.Sanitize.Address)
+ reportGlobalToASan(GV, SourceLocation(), "", false, true);
+}
+
static bool isVarDeclStrongDefinition(const VarDecl *D, bool NoCommon) {
// Don't give variables common linkage if -fno-common was specified unless it
// was overridden by a NoCommon attribute.
Index: lib/CodeGen/CGExpr.cpp
===================================================================
--- lib/CodeGen/CGExpr.cpp
+++ lib/CodeGen/CGExpr.cpp
@@ -2127,6 +2127,7 @@
CGM.getModule(), Descriptor->getType(),
/*isConstant=*/true, llvm::GlobalVariable::PrivateLinkage, Descriptor);
GV->setUnnamedAddr(true);
+ CGM.disableSanitizerForGlobal(GV);
// Remember the descriptor for this type.
CGM.setTypeDescriptorInMap(T, GV);
@@ -2170,14 +2171,23 @@
/// \endcode
/// For an invalid SourceLocation, the Filename pointer is null.
llvm::Constant *CodeGenFunction::EmitCheckSourceLocation(SourceLocation Loc) {
+ llvm::Constant *Filename;
+ int Line, Column;
+
PresumedLoc PLoc = getContext().getSourceManager().getPresumedLoc(Loc);
+ if (PLoc.isValid()) {
+ auto FilenameGV = CGM.GetAddrOfConstantCString(PLoc.getFilename(), ".src");
+ CGM.disableSanitizerForGlobal(FilenameGV);
+ Filename = FilenameGV;
+ Line = PLoc.getLine();
+ Column = PLoc.getColumn();
+ } else {
+ Filename = llvm::Constant::getNullValue(Int8PtrTy);
+ Line = Column = 0;
+ }
- llvm::Constant *Data[] = {
- PLoc.isValid() ? CGM.GetAddrOfConstantCString(PLoc.getFilename(), ".src")
- : llvm::Constant::getNullValue(Int8PtrTy),
- Builder.getInt32(PLoc.isValid() ? PLoc.getLine() : 0),
- Builder.getInt32(PLoc.isValid() ? PLoc.getColumn() : 0)
- };
+ llvm::Constant *Data[] = {Filename, Builder.getInt32(Line),
+ Builder.getInt32(Column)};
return llvm::ConstantStruct::getAnon(Data);
}
@@ -2214,6 +2224,7 @@
new llvm::GlobalVariable(CGM.getModule(), Info->getType(), false,
llvm::GlobalVariable::PrivateLinkage, Info);
InfoPtr->setUnnamedAddr(true);
+ CGM.disableSanitizerForGlobal(InfoPtr);
SmallVector<llvm::Value *, 4> Args;
SmallVector<llvm::Type *, 4> ArgTypes;
Index: test/CodeGenCXX/catch-undef-behavior.cpp
===================================================================
--- test/CodeGenCXX/catch-undef-behavior.cpp
+++ test/CodeGenCXX/catch-undef-behavior.cpp
@@ -1,11 +1,18 @@
// RUN: %clang_cc1 -std=c++11 -fsanitize=signed-integer-overflow,integer-divide-by-zero,float-divide-by-zero,shift,unreachable,return,vla-bound,alignment,null,vptr,object-size,float-cast-overflow,bool,enum,array-bounds,function -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s
+// RUN: %clang_cc1 -std=c++11 -fsanitize=vptr,address -emit-llvm %s -o - -triple x86_64-linux-gnu | FileCheck %s --check-prefix=CHECK-ASAN
struct S {
double d;
int a, b;
virtual int f();
};
+// Check that type descriptor global is not modified by ASan.
+// CHECK-ASAN: [[TYPE_DESCR:@[0-9]+]] = private unnamed_addr constant { i16, i16, [4 x i8] } { i16 -1, i16 0, [4 x i8] c"'S'\00" }
+
+// Check that type mismatch handler is not modified by ASan.
+// CHECK-ASAN: private unnamed_addr global { { [{{.*}} x i8]*, i32, i32 }, { i16, i16, [4 x i8] }*, i8*, i8 } { {{.*}}, { i16, i16, [4 x i8] }* [[TYPE_DESCR]], {{.*}} }
+
struct T : S {};
// CHECK-LABEL: @_Z17reference_binding
@@ -31,6 +38,7 @@
}
// CHECK-LABEL: @_Z13member_access
+// CHECK-ASAN-LABEL: @_Z13member_access
void member_access(S *p) {
// (1a) Check 'p' is appropriately sized and aligned for member access.
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