Author: vedantk
Date: Wed Dec 20 16:10:25 2017
New Revision: 321231
URL: http://llvm.org/viewvc/llvm-project?rev=321231&view=rev
Log:
[ubsan] Diagnose noreturn functions which return
Diagnose 'unreachable' UB when a noreturn function returns.
1. Insert a check at the end of functions marked noreturn.
2. A decl may be marked noreturn in the caller TU, but not marked in
the TU where it's defined. To diagnose this scenario, strip away the
noreturn attribute on the callee and insert check after calls to it.
Testing: check-clang, check-ubsan, check-ubsan-minimal, D40700
rdar://33660464
Differential Revision: https://reviews.llvm.org/D40698
Added:
cfe/trunk/test/CodeGen/ubsan-noreturn.c
cfe/trunk/test/CodeGenCXX/ubsan-unreachable.cpp
Modified:
cfe/trunk/docs/UndefinedBehaviorSanitizer.rst
cfe/trunk/lib/CodeGen/CGBuiltin.cpp
cfe/trunk/lib/CodeGen/CGCall.cpp
cfe/trunk/lib/CodeGen/CGExpr.cpp
cfe/trunk/lib/CodeGen/CGExprCXX.cpp
cfe/trunk/lib/CodeGen/CodeGenFunction.h
Modified: cfe/trunk/docs/UndefinedBehaviorSanitizer.rst
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/docs/UndefinedBehaviorSanitizer.rst?rev=321231&r1=321230&r2=321231&view=diff
==============================================================================
--- cfe/trunk/docs/UndefinedBehaviorSanitizer.rst (original)
+++ cfe/trunk/docs/UndefinedBehaviorSanitizer.rst Wed Dec 20 16:10:25 2017
@@ -124,8 +124,8 @@ Available checks are:
- ``-fsanitize=signed-integer-overflow``: Signed integer overflow,
including all the checks added by ``-ftrapv``, and checking for
overflow in signed division (``INT_MIN / -1``).
- - ``-fsanitize=unreachable``: If control flow reaches
- ``__builtin_unreachable``.
+ - ``-fsanitize=unreachable``: If control flow reaches an unreachable
+ program point.
- ``-fsanitize=unsigned-integer-overflow``: Unsigned integer
overflows. Note that unlike signed integer overflow, unsigned integer
is not undefined behavior. However, while it has well-defined semantics,
Modified: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGBuiltin.cpp?rev=321231&r1=321230&r2=321231&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGBuiltin.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp Wed Dec 20 16:10:25 2017
@@ -1432,14 +1432,7 @@ RValue CodeGenFunction::EmitBuiltinExpr(
case Builtin::BI__debugbreak:
return RValue::get(EmitTrapCall(Intrinsic::debugtrap));
case Builtin::BI__builtin_unreachable: {
- if (SanOpts.has(SanitizerKind::Unreachable)) {
- SanitizerScope SanScope(this);
- EmitCheck(std::make_pair(static_cast<llvm::Value *>(Builder.getFalse()),
- SanitizerKind::Unreachable),
- SanitizerHandler::BuiltinUnreachable,
- EmitCheckSourceLocation(E->getExprLoc()), None);
- } else
- Builder.CreateUnreachable();
+ EmitUnreachable(E->getExprLoc());
// We do need to preserve an insertion point.
EmitBlock(createBasicBlock("unreachable.cont"));
Modified: cfe/trunk/lib/CodeGen/CGCall.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGCall.cpp?rev=321231&r1=321230&r2=321231&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGCall.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGCall.cpp Wed Dec 20 16:10:25 2017
@@ -2758,6 +2758,12 @@ static llvm::StoreInst *findDominatingSt
void CodeGenFunction::EmitFunctionEpilog(const CGFunctionInfo &FI,
bool EmitRetDbgLoc,
SourceLocation EndLoc) {
+ if (FI.isNoReturn()) {
+ // Noreturn functions don't return.
+ EmitUnreachable(EndLoc);
+ return;
+ }
+
if (CurCodeDecl && CurCodeDecl->hasAttr<NakedAttr>()) {
// Naked functions don't have epilogues.
Builder.CreateUnreachable();
@@ -3718,7 +3724,8 @@ RValue CodeGenFunction::EmitCall(const C
const CGCallee &Callee,
ReturnValueSlot ReturnValue,
const CallArgList &CallArgs,
- llvm::Instruction **callOrInvoke) {
+ llvm::Instruction **callOrInvoke,
+ SourceLocation Loc) {
// FIXME: We no longer need the types from CallArgs; lift up and simplify.
assert(Callee.isOrdinary());
@@ -4241,7 +4248,15 @@ RValue CodeGenFunction::EmitCall(const C
EmitLifetimeEnd(llvm::ConstantInt::get(Int64Ty, UnusedReturnSize),
SRetPtr.getPointer());
- Builder.CreateUnreachable();
+ // Strip away the noreturn attribute to better diagnose unreachable UB.
+ if (SanOpts.has(SanitizerKind::Unreachable)) {
+ if (auto *F = CS.getCalledFunction())
+ F->removeFnAttr(llvm::Attribute::NoReturn);
+ CS.removeAttribute(llvm::AttributeList::FunctionIndex,
+ llvm::Attribute::NoReturn);
+ }
+
+ EmitUnreachable(Loc);
Builder.ClearInsertionPoint();
// FIXME: For now, emit a dummy basic block because expr emitters in
Modified: cfe/trunk/lib/CodeGen/CGExpr.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExpr.cpp?rev=321231&r1=321230&r2=321231&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExpr.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExpr.cpp Wed Dec 20 16:10:25 2017
@@ -3076,6 +3076,17 @@ void CodeGenFunction::EmitCfiCheckFail()
CGM.addUsedGlobal(F);
}
+void CodeGenFunction::EmitUnreachable(SourceLocation Loc) {
+ if (SanOpts.has(SanitizerKind::Unreachable)) {
+ SanitizerScope SanScope(this);
+ EmitCheck(std::make_pair(static_cast<llvm::Value *>(Builder.getFalse()),
+ SanitizerKind::Unreachable),
+ SanitizerHandler::BuiltinUnreachable,
+ EmitCheckSourceLocation(Loc), None);
+ }
+ Builder.CreateUnreachable();
+}
+
void CodeGenFunction::EmitTrapCheck(llvm::Value *Checked) {
llvm::BasicBlock *Cont = createBasicBlock("cont");
@@ -4616,7 +4627,7 @@ RValue CodeGenFunction::EmitCall(QualTyp
Callee.setFunctionPointer(CalleePtr);
}
- return EmitCall(FnInfo, Callee, ReturnValue, Args);
+ return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr, E->getExprLoc());
}
LValue CodeGenFunction::
Modified: cfe/trunk/lib/CodeGen/CGExprCXX.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprCXX.cpp?rev=321231&r1=321230&r2=321231&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprCXX.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprCXX.cpp Wed Dec 20 16:10:25 2017
@@ -89,7 +89,8 @@ RValue CodeGenFunction::EmitCXXMemberOrO
*this, MD, This, ImplicitParam, ImplicitParamTy, CE, Args, RtlArgs);
auto &FnInfo = CGM.getTypes().arrangeCXXMethodCall(
Args, FPT, CallInfo.ReqArgs, CallInfo.PrefixSize);
- return EmitCall(FnInfo, Callee, ReturnValue, Args);
+ return EmitCall(FnInfo, Callee, ReturnValue, Args, nullptr,
+ CE ? CE->getExprLoc() : SourceLocation());
}
RValue CodeGenFunction::EmitCXXDestructorCall(
@@ -446,7 +447,7 @@ CodeGenFunction::EmitCXXMemberPointerCal
EmitCallArgs(Args, FPT, E->arguments());
return EmitCall(CGM.getTypes().arrangeCXXMethodCall(Args, FPT, required,
/*PrefixSize=*/0),
- Callee, ReturnValue, Args);
+ Callee, ReturnValue, Args, nullptr, E->getExprLoc());
}
RValue
Modified: cfe/trunk/lib/CodeGen/CodeGenFunction.h
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CodeGenFunction.h?rev=321231&r1=321230&r2=321231&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CodeGenFunction.h (original)
+++ cfe/trunk/lib/CodeGen/CodeGenFunction.h Wed Dec 20 16:10:25 2017
@@ -3288,11 +3288,15 @@ public:
/// LLVM arguments and the types they were derived from.
RValue EmitCall(const CGFunctionInfo &CallInfo, const CGCallee &Callee,
ReturnValueSlot ReturnValue, const CallArgList &Args,
- llvm::Instruction **callOrInvoke = nullptr);
-
+ llvm::Instruction **callOrInvoke, SourceLocation Loc);
+ RValue EmitCall(const CGFunctionInfo &CallInfo, const CGCallee &Callee,
+ ReturnValueSlot ReturnValue, const CallArgList &Args,
+ llvm::Instruction **callOrInvoke = nullptr) {
+ return EmitCall(CallInfo, Callee, ReturnValue, Args, callOrInvoke,
+ SourceLocation());
+ }
RValue EmitCall(QualType FnType, const CGCallee &Callee, const CallExpr *E,
- ReturnValueSlot ReturnValue,
- llvm::Value *Chain = nullptr);
+ ReturnValueSlot ReturnValue, llvm::Value *Chain = nullptr);
RValue EmitCallExpr(const CallExpr *E,
ReturnValueSlot ReturnValue = ReturnValueSlot());
RValue EmitSimpleCallExpr(const CallExpr *E, ReturnValueSlot ReturnValue);
@@ -3747,6 +3751,10 @@ public:
llvm::ConstantInt *TypeId, llvm::Value *Ptr,
ArrayRef<llvm::Constant *> StaticArgs);
+ /// Emit a reached-unreachable diagnostic if \p Loc is valid and runtime
+ /// checking is enabled. Otherwise, just emit an unreachable instruction.
+ void EmitUnreachable(SourceLocation Loc);
+
/// \brief Create a basic block that will call the trap intrinsic, and emit a
/// conditional branch to it, for the -ftrapv checks.
void EmitTrapCheck(llvm::Value *Checked);
Added: cfe/trunk/test/CodeGen/ubsan-noreturn.c
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/ubsan-noreturn.c?rev=321231&view=auto
==============================================================================
--- cfe/trunk/test/CodeGen/ubsan-noreturn.c (added)
+++ cfe/trunk/test/CodeGen/ubsan-noreturn.c Wed Dec 20 16:10:25 2017
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 %s -emit-llvm -fsanitize=unreachable -o - | FileCheck %s
+
+// CHECK-LABEL: @f(
+void __attribute__((noreturn)) f() {
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+}
Added: cfe/trunk/test/CodeGenCXX/ubsan-unreachable.cpp
URL:
http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/ubsan-unreachable.cpp?rev=321231&view=auto
==============================================================================
--- cfe/trunk/test/CodeGenCXX/ubsan-unreachable.cpp (added)
+++ cfe/trunk/test/CodeGenCXX/ubsan-unreachable.cpp Wed Dec 20 16:10:25 2017
@@ -0,0 +1,81 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -emit-llvm -o - %s
-fsanitize=unreachable | FileCheck %s
+
+extern void __attribute__((noreturn)) abort();
+
+// CHECK-LABEL: define void @_Z14calls_noreturnv
+void calls_noreturn() {
+ abort();
+
+ // Check that there are no attributes on the call site.
+ // CHECK-NOT: call void @_Z5abortv{{.*}}#
+
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+}
+
+struct A {
+ // CHECK: declare void @_Z5abortv{{.*}} [[ABORT_ATTR:#[0-9]+]]
+
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A5call1Ev
+ void call1() {
+ // CHECK-NOT: call void @_ZN1A16does_not_return2Ev{{.*}}#
+ does_not_return2();
+
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+
+ // Test static members.
+ static void __attribute__((noreturn)) does_not_return1() {
+ // CHECK-NOT: call void @_Z5abortv{{.*}}#
+ abort();
+ }
+
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A5call2Ev
+ void call2() {
+ // CHECK-NOT: call void @_ZN1A16does_not_return1Ev{{.*}}#
+ does_not_return1();
+
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+
+ // Test calls through pointers to non-static member functions.
+ typedef void __attribute__((noreturn)) (A::*MemFn)();
+
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A5call3Ev
+ void call3() {
+ MemFn MF = &A::does_not_return2;
+ (this->*MF)();
+
+ // CHECK-NOT: call void %{{.*}}#
+ // CHECK: __ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+
+ // Test regular members.
+ // CHECK-LABEL: define linkonce_odr void @_ZN1A16does_not_return2Ev({{.*}})
+ // CHECK-SAME: [[DOES_NOT_RETURN_ATTR:#[0-9]+]]
+ void __attribute__((noreturn)) does_not_return2() {
+ // CHECK-NOT: call void @_Z5abortv(){{.*}}#
+ abort();
+
+ // CHECK: call void @__ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+
+ // CHECK: call void @__ubsan_handle_builtin_unreachable
+ // CHECK: unreachable
+ }
+};
+
+// CHECK: define linkonce_odr void @_ZN1A16does_not_return1Ev()
[[DOES_NOT_RETURN_ATTR]]
+
+void force_irgen() {
+ A a;
+ a.call1();
+ a.call2();
+ a.call3();
+}
+
+// CHECK-NOT: [[ABORT_ATTR]] = {{[^}]+}}noreturn
+// CHECK-NOT: [[DOES_NOT_RETURN_ATTR]] = {{[^}]+}}noreturn
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