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[WinEH] Make setjmp work correctly with EH

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32-bit X86 EH on Windows utilizes a stack of registration nodes
allocated and deallocated on entry/exit.  A registration node contains a
bunch of EH personality specific information like which try-state we are
currently in.

Because a setjmp target allows control flow from arbitrary program
points, there is no way to ensure that the try-state we are in is
correctly updated once we transfer control.

MSVC compatible compilers, like MSVC and ICC, utilize runtime helpers to
reinitialize the try-state when a longjmp occurs.  This is implemented
by adding additional arguments to _setjmp3: the desired try-state and
a helper routine to update the try-state.

Differential Revision: http://reviews.llvm.org/D17721

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@262241 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2016-02-29 19:16:03 +00:00
parent eb295ed84e
commit ace061bc34
2 changed files with 211 additions and 20 deletions
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156
lib/Target/X86/X86WinEHState.cpp
View File

@ -73,6 +73,14 @@ private:
Function *generateLSDAInEAXThunk(Function *ParentFunc);
bool isStateStoreNeeded(EHPersonality Personality, CallSite CS);
void rewriteSetJmpCallSite(IRBuilder<> &Builder, Function &F, CallSite CS,
Value *State);
int getBaseStateForBB(DenseMap<BasicBlock *, ColorVector> &BlockColors,
WinEHFuncInfo &FuncInfo, BasicBlock *BB);
int getStateForCallSite(DenseMap<BasicBlock *, ColorVector> &BlockColors,
WinEHFuncInfo &FuncInfo, CallSite CS);
// Module-level type getters.
Type *getEHLinkRegistrationType();
Type *getSEHRegistrationType();
@ -83,15 +91,16 @@ private:
StructType *EHLinkRegistrationTy = nullptr;
StructType *CXXEHRegistrationTy = nullptr;
StructType *SEHRegistrationTy = nullptr;
Function *FrameRecover = nullptr;
Function *FrameAddress = nullptr;
Function *FrameEscape = nullptr;
Constant *SetJmp3 = nullptr;
Constant *CxxLongjmpUnwind = nullptr;
// Per-function state
EHPersonality Personality = EHPersonality::Unknown;
Function *PersonalityFn = nullptr;
bool UseStackGuard = false;
int ParentBaseState;
Constant *SehLongjmpUnwind = nullptr;
Constant *Cookie = nullptr;
/// The stack allocation containing all EH data, including the link in the
/// fs:00 chain and the current state.
@ -123,9 +132,10 @@ bool WinEHStatePass::doFinalization(Module &M) {
EHLinkRegistrationTy = nullptr;
CXXEHRegistrationTy = nullptr;
SEHRegistrationTy = nullptr;
FrameEscape = nullptr;
FrameRecover = nullptr;
FrameAddress = nullptr;
SetJmp3 = nullptr;
CxxLongjmpUnwind = nullptr;
SehLongjmpUnwind = nullptr;
Cookie = nullptr;
return false;
}
@ -159,9 +169,12 @@ bool WinEHStatePass::runOnFunction(Function &F) {
if (!HasPads)
return false;
FrameEscape = Intrinsic::getDeclaration(TheModule, Intrinsic::localescape);
FrameRecover = Intrinsic::getDeclaration(TheModule, Intrinsic::localrecover);
FrameAddress = Intrinsic::getDeclaration(TheModule, Intrinsic::frameaddress);
Type *Int8PtrType = Type::getInt8PtrTy(TheModule->getContext());
SetJmp3 = TheModule->getOrInsertFunction(
"_setjmp3", FunctionType::get(
Type::getInt32Ty(TheModule->getContext()),
{Int8PtrType, Type::getInt32Ty(TheModule->getContext())},
/*isVarArg=*/true));
// Disable frame pointer elimination in this function.
// FIXME: Do the nested handlers need to keep the parent ebp in ebp, or can we
@ -276,6 +289,13 @@ void WinEHStatePass::emitExceptionRegistrationRecord(Function *F) {
Function *Trampoline = generateLSDAInEAXThunk(F);
Link = Builder.CreateStructGEP(RegNodeTy, RegNode, 1);
linkExceptionRegistration(Builder, Trampoline);
CxxLongjmpUnwind = TheModule->getOrInsertFunction(
"__CxxLongjmpUnwind",
FunctionType::get(Type::getVoidTy(TheModule->getContext()), Int8PtrType,
/*isVarArg=*/false));
cast<Function>(CxxLongjmpUnwind->stripPointerCasts())
->setCallingConv(CallingConv::X86_StdCall);
} else if (Personality == EHPersonality::MSVC_X86SEH) {
// If _except_handler4 is in use, some additional guard checks and prologue
// stuff is required.
@ -292,22 +312,26 @@ void WinEHStatePass::emitExceptionRegistrationRecord(Function *F) {
ParentBaseState = UseStackGuard ? -2 : -1;
insertStateNumberStore(&*Builder.GetInsertPoint(), ParentBaseState);
// ScopeTable = llvm.x86.seh.lsda(F)
Value *FI8 = Builder.CreateBitCast(F, Int8PtrType);
Value *LSDA = Builder.CreateCall(
Intrinsic::getDeclaration(TheModule, Intrinsic::x86_seh_lsda), FI8);
Value *LSDA = emitEHLSDA(Builder, F);
Type *Int32Ty = Type::getInt32Ty(TheModule->getContext());
LSDA = Builder.CreatePtrToInt(LSDA, Int32Ty);
// If using _except_handler4, xor the address of the table with
// __security_cookie.
if (UseStackGuard) {
Value *Cookie =
TheModule->getOrInsertGlobal("__security_cookie", Int32Ty);
Cookie = TheModule->getOrInsertGlobal("__security_cookie", Int32Ty);
Value *Val = Builder.CreateLoad(Int32Ty, Cookie);
LSDA = Builder.CreateXor(LSDA, Val);
}
Builder.CreateStore(LSDA, Builder.CreateStructGEP(RegNodeTy, RegNode, 3));
Link = Builder.CreateStructGEP(RegNodeTy, RegNode, 2);
linkExceptionRegistration(Builder, PersonalityFn);
SehLongjmpUnwind = TheModule->getOrInsertFunction(
UseStackGuard ? "_seh_longjmp_unwind4" : "_seh_longjmp_unwind",
FunctionType::get(Type::getVoidTy(TheModule->getContext()), Int8PtrType,
/*isVarArg=*/false));
cast<Function>(SehLongjmpUnwind->stripPointerCasts())
->setCallingConv(CallingConv::X86_StdCall);
} else {
llvm_unreachable("unexpected personality function");
}
@ -402,10 +426,67 @@ void WinEHStatePass::unlinkExceptionRegistration(IRBuilder<> &Builder) {
Builder.CreateStore(Next, FSZero);
}
// Calls to setjmp(p) are lowered to _setjmp3(p, 0) by the frontend.
// The idea behind _setjmp3 is that it takes an optional number of personality
// specific parameters to indicate how to restore the personality-specific frame
// state when longjmp is initiated. Typically, the current TryLevel is saved.
void WinEHStatePass::rewriteSetJmpCallSite(IRBuilder<> &Builder, Function &F,
CallSite CS, Value *State) {
// Don't rewrite calls with a weird number of arguments.
if (CS.getNumArgOperands() != 2)
return;
Instruction *Inst = CS.getInstruction();
SmallVector<OperandBundleDef, 1> OpBundles;
CS.getOperandBundlesAsDefs(OpBundles);
SmallVector<Value *, 3> OptionalArgs;
if (Personality == EHPersonality::MSVC_CXX) {
OptionalArgs.push_back(CxxLongjmpUnwind);
OptionalArgs.push_back(State);
OptionalArgs.push_back(emitEHLSDA(Builder, &F));
} else if (Personality == EHPersonality::MSVC_X86SEH) {
OptionalArgs.push_back(SehLongjmpUnwind);
OptionalArgs.push_back(State);
if (UseStackGuard)
OptionalArgs.push_back(Cookie);
} else {
llvm_unreachable("unhandled personality!");
}
SmallVector<Value *, 5> Args;
Args.push_back(
Builder.CreateBitCast(CS.getArgOperand(0), Builder.getInt8PtrTy()));
Args.push_back(Builder.getInt32(OptionalArgs.size()));
Args.append(OptionalArgs.begin(), OptionalArgs.end());
CallSite NewCS;
if (CS.isCall()) {
auto *CI = cast<CallInst>(Inst);
CallInst *NewCI = Builder.CreateCall(SetJmp3, Args, OpBundles);
NewCI->setTailCallKind(CI->getTailCallKind());
NewCS = NewCI;
} else {
auto *II = cast<InvokeInst>(Inst);
NewCS = Builder.CreateInvoke(
SetJmp3, II->getNormalDest(), II->getUnwindDest(), Args, OpBundles);
}
NewCS.setCallingConv(CS.getCallingConv());
NewCS.setAttributes(CS.getAttributes());
NewCS->setDebugLoc(CS->getDebugLoc());
Instruction *NewInst = NewCS.getInstruction();
NewInst->takeName(Inst);
Inst->replaceAllUsesWith(NewInst);
Inst->eraseFromParent();
}
// Figure out what state we should assign calls in this block.
static int getBaseStateForBB(DenseMap<BasicBlock *, ColorVector> &BlockColors,
WinEHFuncInfo &FuncInfo, BasicBlock *BB) {
int BaseState = -1;
int WinEHStatePass::getBaseStateForBB(
DenseMap<BasicBlock *, ColorVector> &BlockColors, WinEHFuncInfo &FuncInfo,
BasicBlock *BB) {
int BaseState = ParentBaseState;
auto &BBColors = BlockColors[BB];
assert(BBColors.size() == 1 && "multi-color BB not removed by preparation");
@ -421,8 +502,9 @@ static int getBaseStateForBB(DenseMap<BasicBlock *, ColorVector> &BlockColors,
}
// Calculate the state a call-site is in.
static int getStateForCallSite(DenseMap<BasicBlock *, ColorVector> &BlockColors,
WinEHFuncInfo &FuncInfo, CallSite CS) {
int WinEHStatePass::getStateForCallSite(
DenseMap<BasicBlock *, ColorVector> &BlockColors, WinEHFuncInfo &FuncInfo,
CallSite CS) {
if (auto *II = dyn_cast<InvokeInst>(CS.getInstruction())) {
// Look up the state number of the EH pad this unwinds to.
assert(FuncInfo.InvokeStateMap.count(II) && "invoke has no state!");
@ -510,13 +592,16 @@ static int getSuccState(DenseMap<BasicBlock *, int> &InitialStates, Function &F,
return CommonState;
}
static bool isStateStoreNeeded(EHPersonality Personality, CallSite CS) {
bool WinEHStatePass::isStateStoreNeeded(EHPersonality Personality,
CallSite CS) {
if (!CS)
return false;
// If the function touches memory, it needs a state store.
if (isAsynchronousEHPersonality(Personality))
return !CS.doesNotAccessMemory();
// If the function throws, it needs a state store.
return !CS.doesNotThrow();
}
@ -636,6 +721,37 @@ void WinEHStatePass::addStateStores(Function &F, WinEHFuncInfo &FuncInfo) {
if (EndState->second != PrevState)
insertStateNumberStore(BB->getTerminator(), EndState->second);
}
SmallVector<CallSite, 1> SetJmp3CallSites;
for (BasicBlock *BB : RPOT) {
for (Instruction &I : *BB) {
CallSite CS(&I);
if (!CS)
continue;
if (CS.getCalledValue()->stripPointerCasts() !=
SetJmp3->stripPointerCasts())
continue;
SetJmp3CallSites.push_back(CS);
}
}
for (CallSite CS : SetJmp3CallSites) {
auto &BBColors = BlockColors[CS->getParent()];
BasicBlock *FuncletEntryBB = BBColors.front();
bool InCleanup = isa<CleanupPadInst>(FuncletEntryBB->getFirstNonPHI());
IRBuilder<> Builder(CS.getInstruction());
Value *State;
if (InCleanup) {
Value *StateField =
Builder.CreateStructGEP(nullptr, RegNode, StateFieldIndex);
State = Builder.CreateLoad(StateField);
} else {
State = Builder.getInt32(getStateForCallSite(BlockColors, FuncInfo, CS));
}
rewriteSetJmpCallSite(Builder, F, CS, State);
}
}
void WinEHStatePass::insertStateNumberStore(Instruction *IP, int State) {

75
test/CodeGen/WinEH/wineh-setjmp.ll Normal file
View File

@ -0,0 +1,75 @@
; RUN: opt -mtriple=i686-pc-windows-msvc -S -x86-winehstate < %s | FileCheck %s
target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
target triple = "i686-pc-windows-msvc"
@jb = external global i8
define i32 @test1() personality i32 (...)* @__CxxFrameHandler3 {
entry:
; CHECK-LABEL: define i32 @test1(
; CHECK: %[[eh_reg:.*]] = alloca
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 2
; CHECK: store i32 -1, i32* %[[gep]]
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 2
; CHECK: store i32 0, i32* %[[gep]]
; CHECK: %[[lsda:.*]] = call i8* @llvm.x86.seh.lsda(i8* bitcast (i32 ()* @test1 to i8*))
; CHECK: invoke i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 3, void (i8*)* @__CxxLongjmpUnwind, i32 0, i8* %[[lsda]])
%inv = invoke i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 0) #2
to label %invoke.cont unwind label %ehcleanup
invoke.cont:
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 2
; CHECK: store i32 -1, i32* %[[gep]]
; CHECK: %[[lsda:.*]] = call i8* @llvm.x86.seh.lsda(i8* bitcast (i32 ()* @test1 to i8*))
; CHECK: call i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 3, void (i8*)* @__CxxLongjmpUnwind, i32 -1, i8* %[[lsda]])
call i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 0)
call void @cleanup()
ret i32 %inv
ehcleanup:
%cp = cleanuppad within none []
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 2
; CHECK: %[[load:.*]] = load i32, i32* %[[gep]]
; CHECK: %[[lsda:.*]] = call i8* @llvm.x86.seh.lsda(i8* bitcast (i32 ()* @test1 to i8*))
; CHECK: call i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 3, void (i8*)* @__CxxLongjmpUnwind, i32 %[[load]], i8* %[[lsda]]) [ "funclet"(token %cp) ]
%cal = call i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 0) [ "funclet"(token %cp) ]
call void @cleanup() [ "funclet"(token %cp) ]
cleanupret from %cp unwind to caller
}
define i32 @test2() personality i32 (...)* @_except_handler3 {
entry:
; CHECK-LABEL: define i32 @test2(
; CHECK: %[[eh_reg:.*]] = alloca
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 4
; CHECK: store i32 -1, i32* %[[gep]]
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 4
; CHECK: store i32 0, i32* %[[gep]]
; CHECK: invoke i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 2, void (i8*)* @_seh_longjmp_unwind, i32 0)
%inv = invoke i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 0) #2
to label %invoke.cont unwind label %ehcleanup
invoke.cont:
; CHECK: %[[gep:.*]] = getelementptr inbounds {{.*}}, {{.*}} %[[eh_reg]], i32 0, i32 4
; CHECK: store i32 -1, i32* %[[gep]]
; CHECK: call i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 2, void (i8*)* @_seh_longjmp_unwind, i32 -1)
call i32 (i8*, i32, ...) @_setjmp3(i8* @jb, i32 0)
call void @cleanup()
ret i32 %inv
ehcleanup:
%cp = cleanuppad within none []
call void @cleanup() [ "funclet"(token %cp) ]
cleanupret from %cp unwind to caller
}
; Function Attrs: returns_twice
declare i32 @_setjmp3(i8*, i32, ...) #2
declare i32 @__CxxFrameHandler3(...)
declare i32 @_except_handler3(...)
declare void @cleanup()
attributes #2 = { returns_twice }