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Implement runtime checks for undefined behavior. WIP. 

This implements a new flag -fcatch-undefined-behavior.  The flag turns
on additional runtime checks for:

  T a[I];

  a[i]    abort when i < 0 or i >= I.

Future stuff includes shifts by >= bitwidth amounts.

llvm-svn: 91198
This commit is contained in:
Mike Stump 2009-12-12 01:27:46 +00:00
parent 7cc35b76c3
commit d954638f02
10 changed files with 83 additions and 1 deletions
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2
clang/include/clang/Basic/LangOptions.h
View File

@ -92,6 +92,7 @@ public:
unsigned ElideConstructors : 1; // Whether C++ copy constructors should be
// elided if possible.
unsigned CatchUndefined :1; // Generate code to check for undefined ops.
private:
unsigned GC : 2; // Objective-C Garbage Collection modes. We
// declare this enum as unsigned because MSVC
@ -160,6 +161,7 @@ public:
CharIsSigned = 1;
ShortWChar = 0;
CatchUndefined = 0;
}
GCMode getGCMode() const { return (GCMode) GC; }

2
clang/include/clang/Driver/CC1Options.td
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@ -105,6 +105,8 @@ def disable_llvm_optzns : Flag<"-disable-llvm-optzns">,
def disable_red_zone : Flag<"-disable-red-zone">,
HelpText<"Do not emit code that uses the red zone.">;
def g : Flag<"-g">, HelpText<"Generate source level debug information">;
def fcatch_undefined_behavior : Flag<"-fcatch-undefined-behavior">,
HelpText<"Generate runtime checks for undefined behavior.">;
def fno_common : Flag<"-fno-common">,
HelpText<"Compile common globals like normal definitions">;
def no_implicit_float : Flag<"-no-implicit-float">,

2
clang/include/clang/Driver/Options.td
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@ -236,6 +236,8 @@ def fbootclasspath_EQ : Joined<"-fbootclasspath=">, Group<f_Group>;
def fbuiltin_strcat : Flag<"-fbuiltin-strcat">, Group<f_Group>;
def fbuiltin_strcpy : Flag<"-fbuiltin-strcpy">, Group<f_Group>;
def fbuiltin : Flag<"-fbuiltin">, Group<f_Group>;
def fcatch_undefined_behavior : Flag<"-fcatch-undefined-behavior">,
Group<f_Group>, HelpText<"Generate runtime checks for undefined behavior.">;
def fclasspath_EQ : Joined<"-fclasspath=">, Group<f_Group>;
def fcolor_diagnostics : Flag<"-fcolor-diagnostics">, Group<f_Group>;
def fcommon : Flag<"-fcommon">, Group<f_Group>;

61
clang/lib/CodeGen/CGExpr.cpp
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@ -1012,6 +1012,36 @@ LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
}
}
static llvm::Constant *getAbortFn(CodeGenFunction &CGF) {
// void abort();
const llvm::FunctionType *FTy =
llvm::FunctionType::get(llvm::Type::getVoidTy(CGF.getLLVMContext()), false);
return CGF.CGM.CreateRuntimeFunction(FTy, "abort");
}
llvm::BasicBlock*CodeGenFunction::getAbortBB() {
if (AbortBB)
return AbortBB;
llvm::BasicBlock *Cont = 0;
if (HaveInsertPoint()) {
Cont = createBasicBlock("cont");
EmitBranch(Cont);
}
AbortBB = createBasicBlock("abort");
EmitBlock(AbortBB);
llvm::CallInst *AbortCall = Builder.CreateCall(getAbortFn(*this));
AbortCall->setDoesNotReturn();
AbortCall->setDoesNotThrow();
Builder.CreateUnreachable();
if (Cont)
EmitBlock(Cont);
return AbortBB;
}
LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
// The index must always be an integer, which is not an aggregate. Emit it.
llvm::Value *Idx = EmitScalarExpr(E->getIdx());
@ -1040,6 +1070,37 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E) {
llvm::IntegerType::get(VMContext, LLVMPointerWidth),
IdxSigned, "idxprom");
if (CatchUndefined) {
if (const ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(E->getBase())) {
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ICE->getSubExpr())) {
if (ICE->getCastKind() == CastExpr::CK_ArrayToPointerDecay) {
if (const ConstantArrayType *CAT
= getContext().getAsConstantArrayType(DRE->getType())) {
llvm::APInt Size = CAT->getSize();
llvm::BasicBlock *Cont = createBasicBlock("cont");
if (IdxSigned) {
Builder.CreateCondBr(Builder.CreateICmpSGE(Idx,
llvm::ConstantInt::get(Idx->getType(), 0)),
Cont, getAbortBB());
EmitBlock(Cont);
Cont = createBasicBlock("cont");
Builder.CreateCondBr(Builder.CreateICmpSLT(Idx,
llvm::ConstantInt::get(Idx->getType(), Size)),
Cont, getAbortBB());
EmitBlock(Cont);
} else {
llvm::BasicBlock *Cont = createBasicBlock("cont");
Builder.CreateCondBr(Builder.CreateICmpULT(Idx,
llvm::ConstantInt::get(Idx->getType(), Size)),
Cont, getAbortBB());
EmitBlock(Cont);
}
}
}
}
}
}
// We know that the pointer points to a type of the correct size, unless the
// size is a VLA or Objective-C interface.
llvm::Value *Address = 0;

3
clang/lib/CodeGen/CodeGenFunction.cpp
View File

@ -32,10 +32,11 @@ CodeGenFunction::CodeGenFunction(CodeGenModule &cgm)
SwitchInsn(0), CaseRangeBlock(0), InvokeDest(0),
CXXThisDecl(0), CXXVTTDecl(0),
ConditionalBranchLevel(0), TerminateHandler(0),
UniqueAggrDestructorCount(0) {
UniqueAggrDestructorCount(0), AbortBB(0) {
LLVMIntTy = ConvertType(getContext().IntTy);
LLVMPointerWidth = Target.getPointerWidth(0);
Exceptions = getContext().getLangOptions().Exceptions;
CatchUndefined = getContext().getLangOptions().CatchUndefined;
}
ASTContext &CodeGenFunction::getContext() const {

6
clang/lib/CodeGen/CodeGenFunction.h
View File

@ -108,6 +108,7 @@ public:
uint32_t LLVMPointerWidth;
bool Exceptions;
bool CatchUndefined;
public:
/// ObjCEHValueStack - Stack of Objective-C exception values, used for
/// rethrows.
@ -1266,6 +1267,11 @@ private:
ArgType));
}
}
llvm::BasicBlock *AbortBB;
/// getAbortBB - Create a basic block that will call abort. We'll generate
/// a branch around the created basic block as necessary.
llvm::BasicBlock* getAbortBB();
};

1
clang/lib/Driver/Tools.cpp
View File

@ -895,6 +895,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
}
// Forward -f (flag) options which we can pass directly.
Args.AddLastArg(CmdArgs, options::OPT_fcatch_undefined_behavior);
Args.AddLastArg(CmdArgs, options::OPT_femit_all_decls);
Args.AddLastArg(CmdArgs, options::OPT_ffreestanding);
Args.AddLastArg(CmdArgs, options::OPT_fheinous_gnu_extensions);

3
clang/lib/Frontend/CompilerInvocation.cpp
View File

@ -447,6 +447,8 @@ static void LangOptsToArgs(const LangOptions &Opts,
Res.push_back("-fno-operator-names");
if (Opts.PascalStrings)
Res.push_back("-fpascal-strings");
if (Opts.CatchUndefined)
Res.push_back("-fcatch-undefined-behavior");
if (Opts.WritableStrings)
Res.push_back("-fwritable-strings");
if (!Opts.LaxVectorConversions)
@ -1151,6 +1153,7 @@ static void ParseLangArgs(LangOptions &Opts, ArgList &Args,
Opts.ObjCConstantStringClass = getLastArgValue(Args,
OPT_fconstant_string_class);
Opts.ObjCNonFragileABI = Args.hasArg(OPT_fobjc_nonfragile_abi);
Opts.CatchUndefined = Args.hasArg(OPT_fcatch_undefined_behavior);
Opts.EmitAllDecls = Args.hasArg(OPT_femit_all_decls);
Opts.PICLevel = getLastArgIntValue(Args, OPT_pic_level, 0, Diags);
Opts.Static = Args.hasArg(OPT_static_define);

3
clang/lib/Frontend/PCHReader.cpp
View File

@ -116,6 +116,7 @@ PCHValidator::ReadLanguageOptions(const LangOptions &LangOpts) {
diag::warn_pch_stack_protector);
PARSE_LANGOPT_BENIGN(InstantiationDepth);
PARSE_LANGOPT_IMPORTANT(OpenCL, diag::warn_pch_opencl);
PARSE_LANGOPT_BENIGN(CatchUndefined);
PARSE_LANGOPT_IMPORTANT(ElideConstructors, diag::warn_pch_elide_constructors);
#undef PARSE_LANGOPT_IRRELEVANT
#undef PARSE_LANGOPT_BENIGN
@ -1719,6 +1720,8 @@ bool PCHReader::ParseLanguageOptions(
++Idx;
PARSE_LANGOPT(InstantiationDepth);
PARSE_LANGOPT(OpenCL);
PARSE_LANGOPT(CatchUndefined);
// FIXME: Missing ElideConstructors?!
#undef PARSE_LANGOPT
return Listener->ReadLanguageOptions(LangOpts);

1
clang/lib/Frontend/PCHWriter.cpp
View File

@ -781,6 +781,7 @@ void PCHWriter::WriteLanguageOptions(const LangOptions &LangOpts) {
Record.push_back(LangOpts.getStackProtectorMode());
Record.push_back(LangOpts.InstantiationDepth);
Record.push_back(LangOpts.OpenCL);
Record.push_back(LangOpts.CatchUndefined);
Record.push_back(LangOpts.ElideConstructors);
Stream.EmitRecord(pch::LANGUAGE_OPTIONS, Record);
}