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//===-- trycatchfinally.cpp -------------------------------------*- C++ -*-===//
//
// LDC the LLVM D compiler
//
// This file is distributed under the BSD-style LDC license. See the LICENSE
// file for details.
//
//===----------------------------------------------------------------------===//
#include "gen/trycatchfinally.h"
#include "statement.h"
#include "target.h"
#include "gen/classes.h"
#include "gen/funcgenstate.h"
#include "gen/llvmhelpers.h"
#include "gen/mangling.h"
#include "gen/ms-cxx-helper.h"
#include "gen/rttibuilder.h"
#include "gen/runtime.h"
#include "gen/tollvm.h"
#include "ir/irfunction.h"
#include "ir/irtypeclass.h"
////////////////////////////////////////////////////////////////////////////////
TryCatchScope::TryCatchScope(IRState &irs, llvm::Value *ehPtrSlot,
TryCatchStatement *stmt, llvm::BasicBlock *endbb)
: stmt(stmt), endbb(endbb) {
assert(stmt->catches);
cleanupScope = irs.funcGen().scopes.currentCleanupScope();
catchesNonExceptions =
std::any_of(stmt->catches->begin(), stmt->catches->end(), [](Catch *c) {
for (auto cd = c->type->toBasetype()->isClassHandle(); cd;
cd = cd->baseClass) {
if (cd == ClassDeclaration::exception)
return false;
}
return true;
});
#if LDC_LLVM_VER >= 308
if (useMSVCEH()) {
emitCatchBodiesMSVC(irs, ehPtrSlot);
return;
}
#endif
emitCatchBodies(irs, ehPtrSlot);
}
const std::vector<TryCatchScope::CatchBlock> &
TryCatchScope::getCatchBlocks() const {
assert(!catchBlocks.empty());
return catchBlocks;
}
void TryCatchScope::emitCatchBodies(IRState &irs, llvm::Value *ehPtrSlot) {
assert(catchBlocks.empty());
auto &PGO = irs.funcGen().pgo;
const auto entryCount = PGO.setCurrentStmt(stmt);
struct CBPrototype {
ClassDeclaration *cd;
llvm::BasicBlock *catchBB;
uint64_t catchCount;
uint64_t uncaughtCount;
};
llvm::SmallVector<CBPrototype, 8> cbPrototypes;
cbPrototypes.reserve(stmt->catches->dim);
for (auto c : *stmt->catches) {
auto catchBB =
irs.insertBBBefore(endbb, llvm::Twine("catch.") + c->type->toChars());
irs.scope() = IRScope(catchBB);
irs.DBuilder.EmitBlockStart(c->loc);
PGO.emitCounterIncrement(c);
const auto cd = c->type->toBasetype()->isClassHandle();
const bool isCPPclass = cd->isCPPclass();
const auto enterCatchFn = getRuntimeFunction(
c->loc, irs.module,
isCPPclass ? "__cxa_begin_catch" : "_d_eh_enter_catch");
const auto ptr = DtoLoad(ehPtrSlot);
const auto throwableObj = irs.ir->CreateCall(enterCatchFn, ptr);
// For catches that use the Throwable object, create storage for it.
// We will set it in the code that branches from the landing pads
// (there might be more than one) to catchBB.
if (c->var) {
// This will alloca if we haven't already and take care of nested refs
// if there are any.
DtoDeclarationExp(c->var);
// Copy the exception reference over from the _d_eh_enter_catch return
// value.
DtoStore(DtoBitCast(throwableObj, DtoType(c->var->type)),
getIrLocal(c->var)->value);
}
// Emit handler, if there is one. The handler is zero, for instance,
// when building 'catch { debug foo(); }' in non-debug mode.
if (isCPPclass) {
// from DMD:
/* C++ catches need to end with call to __cxa_end_catch().
* Create:
* try { handler } finally { __cxa_end_catch(); }
* Note that this is worst case code because it always sets up an
* exception handler. At some point should try to do better.
*/
FuncDeclaration *fdend =
FuncDeclaration::genCfunc(nullptr, Type::tvoid, "__cxa_end_catch");
Expression *efunc = VarExp::create(Loc(), fdend);
Expression *ecall = CallExp::create(Loc(), efunc);
ecall->type = Type::tvoid;
Statement *call = ExpStatement::create(Loc(), ecall);
Statement *stmt =
c->handler ? TryFinallyStatement::create(Loc(), c->handler, call)
: call;
Statement_toIR(stmt, &irs);
} else {
if (c->handler)
Statement_toIR(c->handler, &irs);
}
if (!irs.scopereturned())
irs.ir->CreateBr(endbb);
irs.DBuilder.EmitBlockEnd();
// PGO information, currently unused
auto catchCount = PGO.getRegionCount(c);
// uncaughtCount is handled in a separate pass below
cbPrototypes.push_back({cd, catchBB, catchCount, 0});
}
// Total number of uncaught exceptions is equal to the execution count at
// the start of the try block minus the one after the continuation.
// uncaughtCount keeps track of the exception type mismatch count while
// iterating through the catch block prototypes in reversed order.
auto uncaughtCount = entryCount - PGO.getRegionCount(stmt);
for (auto it = cbPrototypes.rbegin(), end = cbPrototypes.rend(); it != end;
++it) {
it->uncaughtCount = uncaughtCount;
// Add this catch block's match count to the uncaughtCount, because these
// failed to match the remaining (lexically preceding) catch blocks.
uncaughtCount += it->catchCount;
}
catchBlocks.reserve(stmt->catches->dim);
for (const auto &p : cbPrototypes) {
auto branchWeights =
PGO.createProfileWeights(p.catchCount, p.uncaughtCount);
DtoResolveClass(p.cd);
LLGlobalVariable *ci;
if (p.cd->isCPPclass()) {
// Wrap std::type_info pointers inside a __cpp_type_info_ptr class
// instance so that the personality routine may differentiate C++ catch
// clauses from D ones.
OutBuffer wrapperMangleBuf;
wrapperMangleBuf.writestring("_D");
mangleToBuffer(p.cd, &wrapperMangleBuf);
wrapperMangleBuf.printf("%d%s", 18, "_cpp_type_info_ptr");
const auto wrapperMangle =
getIRMangledVarName(wrapperMangleBuf.peekString(), LINKd);
ci = irs.module.getGlobalVariable(wrapperMangle);
if (!ci) {
const char *name = Target::cppTypeInfoMangle(p.cd);
auto cpp_ti =
declareGlobal(p.cd->loc, irs.module, getVoidPtrType(), name,
/*isConstant=*/true);
const auto cppTypeInfoPtrType = getCppTypeInfoPtrType();
RTTIBuilder b(cppTypeInfoPtrType);
b.push(cpp_ti);
auto wrapperType = llvm::cast<llvm::StructType>(
static_cast<IrTypeClass *>(cppTypeInfoPtrType->ctype)
->getMemoryLLType());
auto wrapperInit = b.get_constant(wrapperType);
ci = defineGlobal(p.cd->loc, irs.module, wrapperMangle, wrapperInit,
LLGlobalValue::LinkOnceODRLinkage,
/*isConstant=*/true);
}
} else {
ci = getIrAggr(p.cd)->getClassInfoSymbol();
}
catchBlocks.push_back({ci, p.catchBB, branchWeights});
}
}
#if LDC_LLVM_VER >= 308
namespace {
void emitBeginCatchMSVC(IRState &irs, Catch *ctch,
llvm::CatchSwitchInst *catchSwitchInst) {
VarDeclaration *var = ctch->var;
// The MSVC/x86 build uses C++ exception handling
// This needs a series of catch pads to match the exception
// and the catch handler must be terminated by a catch return instruction
LLValue *exnObj = nullptr;
LLValue *cpyObj = nullptr;
LLValue *typeDesc = nullptr;
LLValue *clssInfo = nullptr;
if (var) {
// alloca storage for the variable, it always needs a place on the stack
// do not initialize, this will be done by the C++ exception handler
var->_init = nullptr;
// redirect scope to avoid the generation of debug info before the
// catchpad
IRScope save = irs.scope();
irs.scope() = IRScope(gIR->topallocapoint()->getParent());
irs.scope().builder.SetInsertPoint(gIR->topallocapoint());
DtoDeclarationExp(var);
// catch handler will be outlined, so always treat as a nested reference
exnObj = getIrValue(var);
if (var->nestedrefs.dim) {
// if variable needed in a closure, use a stack temporary and copy it
// when caught
cpyObj = exnObj;
exnObj = DtoAlloca(var->type, "exnObj");
}
irs.scope() = save;
irs.DBuilder.EmitStopPoint(ctch->loc); // re-set debug loc after the
// SetInsertPoint(allocaInst) call
} else if (ctch->type) {
// catch without var
exnObj = DtoAlloca(ctch->type, "exnObj");
} else {
// catch all
exnObj = LLConstant::getNullValue(getVoidPtrType());
}
bool isCPPclass = false;
if (ctch->type) {
ClassDeclaration *cd = ctch->type->toBasetype()->isClassHandle();
typeDesc = getTypeDescriptor(irs, cd);
isCPPclass = cd->isCPPclass();
if (!isCPPclass)
clssInfo = getIrAggr(cd)->getClassInfoSymbol();
} else {
// catch all
typeDesc = LLConstant::getNullValue(getVoidPtrType());
clssInfo = LLConstant::getNullValue(DtoType(getClassInfoType()));
}
// "catchpad within %switch [TypeDescriptor, 0, &caughtObject]" must be
// first instruction
int flags = var ? (isCPPclass ? 8 : 0) : 64; // just mimicking clang here
LLValue *args[] = {typeDesc, DtoConstUint(flags), exnObj};
auto catchpad = irs.ir->CreateCatchPad(catchSwitchInst, args, "");
catchSwitchInst->addHandler(irs.scopebb());
if (cpyObj) {
// assign the caught exception to the location in the closure
auto val = irs.ir->CreateLoad(exnObj);
irs.ir->CreateStore(val, cpyObj);
exnObj = cpyObj;
}
// Exceptions are never rethrown by D code (but thrown again), so
// we can leave the catch handler right away and continue execution
// outside the catch funclet
llvm::BasicBlock *catchhandler = irs.insertBB("catchhandler");
llvm::CatchReturnInst::Create(catchpad, catchhandler, irs.scopebb());
irs.scope() = IRScope(catchhandler);
irs.funcGen().pgo.emitCounterIncrement(ctch);
if (!isCPPclass) {
auto enterCatchFn =
getRuntimeFunction(ctch->loc, irs.module, "_d_eh_enter_catch");
irs.CreateCallOrInvoke(enterCatchFn, DtoBitCast(exnObj, getVoidPtrType()),
clssInfo);
}
}
}
void TryCatchScope::emitCatchBodiesMSVC(IRState &irs, llvm::Value *) {
assert(catchBlocks.empty());
auto &scopes = irs.funcGen().scopes;
auto catchSwitchBlock = irs.insertBBBefore(endbb, "catch.dispatch");
llvm::BasicBlock *unwindto =
scopes.currentCleanupScope() > 0 ? scopes.getLandingPad() : nullptr;
auto catchSwitchInst = llvm::CatchSwitchInst::Create(
llvm::ConstantTokenNone::get(irs.context()), unwindto, stmt->catches->dim,
"", catchSwitchBlock);
for (auto c : *stmt->catches) {
auto catchBB =
irs.insertBBBefore(endbb, llvm::Twine("catch.") + c->type->toChars());
irs.scope() = IRScope(catchBB);
irs.DBuilder.EmitBlockStart(c->loc);
emitBeginCatchMSVC(irs, c, catchSwitchInst);
// Emit handler, if there is one. The handler is zero, for instance,
// when building 'catch { debug foo(); }' in non-debug mode.
if (c->handler)
Statement_toIR(c->handler, &irs);
if (!irs.scopereturned())
irs.ir->CreateBr(endbb);
irs.DBuilder.EmitBlockEnd();
}
scopes.pushCleanup(catchSwitchBlock, catchSwitchBlock);
// if no landing pad is created, the catch blocks are unused, but
// the verifier complains if there are catchpads without personality
// so we can just set it unconditionally
if (!irs.func()->hasLLVMPersonalityFn()) {
const char *personality = "__CxxFrameHandler3";
irs.func()->setLLVMPersonalityFn(
getRuntimeFunction(stmt->loc, irs.module, personality));
}
}
#endif // LDC_LLVM_VER >= 308
////////////////////////////////////////////////////////////////////////////////
CleanupScope::CleanupScope(llvm::BasicBlock *beginBlock,
llvm::BasicBlock *endBlock) {
#if LDC_LLVM_VER >= 308
if (useMSVCEH()) {
findSuccessors(blocks, beginBlock, endBlock);
return;
}
#endif
blocks.push_back(beginBlock);
if (endBlock != beginBlock)
blocks.push_back(endBlock);
}
llvm::BasicBlock *CleanupScope::run(IRState &irs, llvm::BasicBlock *sourceBlock,
llvm::BasicBlock *continueWith) {
#if LDC_LLVM_VER >= 308
if (useMSVCEH())
return runCopying(irs, sourceBlock, continueWith);
#endif
if (exitTargets.empty() || (exitTargets.size() == 1 &&
exitTargets[0].branchTarget == continueWith)) {
// We didn't need a branch selector before and still don't need one.
assert(!branchSelector);
// Set up the unconditional branch at the end of the cleanup if we have
// not done so already.
if (exitTargets.empty()) {
exitTargets.emplace_back(continueWith);
llvm::BranchInst::Create(continueWith, endBlock());
}
exitTargets.front().sourceBlocks.push_back(sourceBlock);
return beginBlock();
}
// We need a branch selector if we are here...
if (!branchSelector) {
// ... and have not created one yet, so do so now.
branchSelector = new llvm::AllocaInst(llvm::Type::getInt32Ty(irs.context()),
#if LDC_LLVM_VER >= 500
irs.module.getDataLayout().getAllocaAddrSpace(),
#endif
llvm::Twine("branchsel.") +
beginBlock()->getName(),
irs.topallocapoint());
// Now we also need to store 0 to it to keep the paths that go to the
// only existing branch target the same.
for (auto bb : exitTargets.front().sourceBlocks) {
new llvm::StoreInst(DtoConstUint(0), branchSelector, bb->getTerminator());
}
// And convert the BranchInst to the existing branch target to a
// SelectInst so we can append the other cases to it.
endBlock()->getTerminator()->eraseFromParent();
llvm::Value *sel = new llvm::LoadInst(branchSelector, "", endBlock());
llvm::SwitchInst::Create(
sel, exitTargets[0].branchTarget,
1, // Expected number of branches, only for pre-allocating.
endBlock());
}
// If we already know this branch target, figure out the branch selector
// value and simply insert the store into the source block (prior to the
// last instruction, which is the branch to the first cleanup).
for (unsigned i = 0; i < exitTargets.size(); ++i) {
CleanupExitTarget &t = exitTargets[i];
if (t.branchTarget == continueWith) {
new llvm::StoreInst(DtoConstUint(i), branchSelector,
sourceBlock->getTerminator());
// Note: Strictly speaking, keeping this up to date would not be
// needed right now, because we never to any optimizations that
// require changes to the source blocks after the initial conversion
// from one to two branch targets. Keeping this around for now to
// ease future development, but may be removed to save some work.
t.sourceBlocks.push_back(sourceBlock);
return beginBlock();
}
}
// We don't know this branch target yet, so add it to the SwitchInst...
llvm::ConstantInt *const selectorVal = DtoConstUint(exitTargets.size());
llvm::cast<llvm::SwitchInst>(endBlock()->getTerminator())
->addCase(selectorVal, continueWith);
// ... insert the store into the source block...
new llvm::StoreInst(selectorVal, branchSelector,
sourceBlock->getTerminator());
// ... and keep track of it (again, this is unnecessary right now as
// discussed in the above note).
exitTargets.emplace_back(continueWith);
exitTargets.back().sourceBlocks.push_back(sourceBlock);
return beginBlock();
}
#if LDC_LLVM_VER >= 308
llvm::BasicBlock *CleanupScope::runCopying(IRState &irs,
llvm::BasicBlock *sourceBlock,
llvm::BasicBlock *continueWith,
llvm::BasicBlock *unwindTo,
llvm::Value *funclet) {
if (isCatchSwitchBlock(beginBlock()))
return continueWith;
if (exitTargets.empty()) {
if (!endBlock()->getTerminator())
// Set up the unconditional branch at the end of the cleanup
llvm::BranchInst::Create(continueWith, endBlock());
} else {
// check whether we have an exit target with the same continuation
for (CleanupExitTarget &tgt : exitTargets)
if (tgt.branchTarget == continueWith) {
tgt.sourceBlocks.push_back(sourceBlock);
return tgt.cleanupBlocks.front();
}
}
// reuse the original IR if not unwinding and not already used
bool useOriginal = unwindTo == nullptr && funclet == nullptr;
for (CleanupExitTarget &tgt : exitTargets) {
if (tgt.cleanupBlocks.front() == beginBlock()) {
useOriginal = false;
break;
}
}
// append new target
exitTargets.emplace_back(continueWith);
auto &exitTarget = exitTargets.back();
exitTarget.sourceBlocks.push_back(sourceBlock);
if (useOriginal) {
// change the continuation target if the initial branch was created
// by another instance with unwinding
if (continueWith)
if (auto term = endBlock()->getTerminator())
if (auto succ = term->getSuccessor(0))
if (succ != continueWith)
remapBlocksValue(blocks, succ, continueWith);
exitTarget.cleanupBlocks = blocks;
} else {
// clone the code
cloneBlocks(blocks, exitTarget.cleanupBlocks, continueWith, unwindTo,
funclet);
}
return exitTarget.cleanupBlocks.front();
}
#endif
////////////////////////////////////////////////////////////////////////////////
TryCatchFinallyScopes::TryCatchFinallyScopes(IRState &irs) : irs(irs) {
// create top-level stacks
unresolvedGotosPerCleanupScope.emplace_back();
landingPadsPerCleanupScope.emplace_back();
}
TryCatchFinallyScopes::~TryCatchFinallyScopes() {
assert(currentCleanupScope() == 0);
// If there are still unresolved gotos left, it means that they were either
// down or "sideways" (i.e. down another branch) of the tree of all
// cleanup scopes, both of which are not allowed in D.
if (!currentUnresolvedGotos().empty()) {
for (const auto &i : currentUnresolvedGotos()) {
error(i.sourceLoc, "`goto` into `try`/`finally` scope is not allowed");
}
fatal();
}
}
void TryCatchFinallyScopes::pushTryCatch(TryCatchStatement *stmt,
llvm::BasicBlock *endbb) {
TryCatchScope scope(irs, getOrCreateEhPtrSlot(), stmt, endbb);
// Only after emitting all the catch bodies, register the catch scopes.
// This is so that (re)throwing inside a catch does not match later
// catches.
tryCatchScopes.push_back(scope);
if (!useMSVCEH())
landingPadsPerCleanupScope[currentCleanupScope()].push_back(nullptr);
}
void TryCatchFinallyScopes::popTryCatch() {
tryCatchScopes.pop_back();
if (useMSVCEH()) {
#if LDC_LLVM_VER >= 308
assert(isCatchSwitchBlock(cleanupScopes.back().beginBlock()));
#endif
popCleanups(currentCleanupScope() - 1);
} else {
landingPadsPerCleanupScope[currentCleanupScope()].pop_back();
}
}
bool TryCatchFinallyScopes::isCatchingNonExceptions() const {
return std::any_of(
tryCatchScopes.begin(), tryCatchScopes.end(),
[](const TryCatchScope &tc) { return tc.isCatchingNonExceptions(); });
}
////////////////////////////////////////////////////////////////////////////////
void TryCatchFinallyScopes::pushCleanup(llvm::BasicBlock *beginBlock,
llvm::BasicBlock *endBlock) {
cleanupScopes.emplace_back(beginBlock, endBlock);
unresolvedGotosPerCleanupScope.emplace_back();
landingPadsPerCleanupScope.emplace_back();
}
void TryCatchFinallyScopes::popCleanups(CleanupCursor targetScope) {
assert(targetScope <= currentCleanupScope());
if (targetScope == currentCleanupScope())
return;
for (CleanupCursor i = currentCleanupScope(); i-- > targetScope;) {
// Any gotos that are still unresolved necessarily leave this scope.
// Thus, the cleanup needs to be executed.
for (const auto &gotoJump : currentUnresolvedGotos()) {
// Replace all branches to the tentative target by branches to the cleanup
// and continue with the tentative target (we simply reuse it because
// there is no reason not to).
llvm::BasicBlock *tentative = gotoJump.tentativeTarget;
// 1) Replace all branches to the tentative target by branches to a
// temporary placeholder BB.
llvm::BasicBlock *dummy = irs.insertBB("");
tentative->replaceAllUsesWith(dummy);
// 2) We need a cleanup instance which continues execution with the
// tentative target.
auto startCleanup =
cleanupScopes[i].run(irs, gotoJump.sourceBlock, tentative);
// 3) Replace all branches to the placeholder BB by branches to the
// cleanup.
dummy->replaceAllUsesWith(startCleanup);
dummy->eraseFromParent();
}
Gotos &nextUnresolved = unresolvedGotosPerCleanupScope[i];
nextUnresolved.insert(nextUnresolved.end(),
currentUnresolvedGotos().begin(),
currentUnresolvedGotos().end());
cleanupScopes.pop_back();
unresolvedGotosPerCleanupScope.pop_back();
landingPadsPerCleanupScope.pop_back();
}
}
void TryCatchFinallyScopes::runCleanups(CleanupCursor targetScope,
llvm::BasicBlock *continueWith) {
runCleanups(currentCleanupScope(), targetScope, continueWith);
}
void TryCatchFinallyScopes::runCleanups(CleanupCursor sourceScope,
CleanupCursor targetScope,
llvm::BasicBlock *continueWith) {
#if LDC_LLVM_VER >= 308
if (useMSVCEH()) {
runCleanupCopies(sourceScope, targetScope, continueWith);
return;
}
#endif
assert(targetScope <= sourceScope);
if (targetScope == sourceScope) {
// No cleanups to run, just branch to the next block.
irs.ir->CreateBr(continueWith);
return;
}
// Insert the unconditional branch to the first cleanup block.
irs.ir->CreateBr(cleanupScopes[sourceScope - 1].beginBlock());
// Update all the control flow in the cleanups to make sure we end up where
// we want.
for (CleanupCursor i = sourceScope; i-- > targetScope;) {
llvm::BasicBlock *nextBlock =
(i > targetScope) ? cleanupScopes[i - 1].beginBlock() : continueWith;
cleanupScopes[i].run(irs, irs.scopebb(), nextBlock);
}
}
#if LDC_LLVM_VER >= 308
void TryCatchFinallyScopes::runCleanupCopies(CleanupCursor sourceScope,
CleanupCursor targetScope,
llvm::BasicBlock *continueWith) {
assert(targetScope <= sourceScope);
// work through the blocks in reverse execution order, so we
// can merge cleanups that end up at the same continuation target
for (CleanupCursor i = targetScope; i < sourceScope; ++i)
continueWith =
cleanupScopes[i].runCopying(irs, irs.scopebb(), continueWith);
// Insert the unconditional branch to the first cleanup block.
irs.ir->CreateBr(continueWith);
}
#endif
////////////////////////////////////////////////////////////////////////////////
std::vector<GotoJump> &TryCatchFinallyScopes::currentUnresolvedGotos() {
return unresolvedGotosPerCleanupScope[currentCleanupScope()];
}
void TryCatchFinallyScopes::registerUnresolvedGoto(Loc loc,
Identifier *labelName) {
llvm::BasicBlock *target = irs.insertBB("goto.unresolved");
irs.ir->CreateBr(target);
currentUnresolvedGotos().push_back({loc, irs.scopebb(), target, labelName});
}
void TryCatchFinallyScopes::tryResolveGotos(Identifier *labelName,
llvm::BasicBlock *targetBlock) {
auto &unresolved = currentUnresolvedGotos();
size_t i = 0;
while (i < unresolved.size()) {
if (unresolved[i].targetLabel != labelName) {
++i;
continue;
}
unresolved[i].tentativeTarget->replaceAllUsesWith(targetBlock);
unresolved[i].tentativeTarget->eraseFromParent();
unresolved.erase(unresolved.begin() + i);
}
}
////////////////////////////////////////////////////////////////////////////////
llvm::BasicBlock *TryCatchFinallyScopes::getLandingPad() {
llvm::BasicBlock *&landingPad = getLandingPadRef(currentCleanupScope());
if (!landingPad)
landingPad = emitLandingPad();
return landingPad;
}
llvm::BasicBlock *&
TryCatchFinallyScopes::getLandingPadRef(CleanupCursor scope) {
auto &pads = landingPadsPerCleanupScope[scope];
if (pads.empty()) {
// Have not encountered any catches (for which we would push a scope) or
// calls to throwing functions (where we would have already executed
// this if) in this cleanup scope yet.
pads.push_back(nullptr);
}
return pads.back();
}
namespace {
llvm::LandingPadInst *createLandingPadInst(IRState &irs) {
LLType *retType =
LLStructType::get(LLType::getInt8PtrTy(irs.context()),
LLType::getInt32Ty(irs.context())
#if LDC_LLVM_VER < 500
, nullptr
#endif
);
if (!irs.func()->hasLLVMPersonalityFn()) {
irs.func()->setLLVMPersonalityFn(
getRuntimeFunction(Loc(), irs.module, "_d_eh_personality"));
}
return irs.ir->CreateLandingPad(retType, 0);
}
}
llvm::BasicBlock *TryCatchFinallyScopes::emitLandingPad() {
#if LDC_LLVM_VER >= 308
if (useMSVCEH()) {
assert(currentCleanupScope() > 0);
return emitLandingPadMSVC(currentCleanupScope() - 1);
}
#endif
// save and rewrite scope
IRScope savedIRScope = irs.scope();
// insert landing pads at the end of the function, in emission order,
// to improve human-readability of the IR
llvm::BasicBlock *beginBB = irs.insertBBBefore(nullptr, "landingPad");
irs.scope() = IRScope(beginBB);
llvm::LandingPadInst *landingPad = createLandingPadInst(irs);
// Stash away the exception object pointer and selector value into their
// stack slots.
llvm::Value *ehPtr = DtoExtractValue(landingPad, 0);
irs.ir->CreateStore(ehPtr, getOrCreateEhPtrSlot());
llvm::Value *ehSelector = DtoExtractValue(landingPad, 1);
if (!ehSelectorSlot)
ehSelectorSlot = DtoRawAlloca(ehSelector->getType(), 0, "eh.selector");
irs.ir->CreateStore(ehSelector, ehSelectorSlot);
// Add landingpad clauses, emit finallys and 'if' chain to catch the
// exception.
CleanupCursor lastCleanup = currentCleanupScope();
for (auto it = tryCatchScopes.rbegin(), end = tryCatchScopes.rend();
it != end; ++it) {
const auto &tryCatchScope = *it;
// Insert any cleanups in between the previous (inner-more) try-catch scope
// and this one.
const auto newCleanup = tryCatchScope.getCleanupScope();
assert(lastCleanup >= newCleanup);
if (lastCleanup > newCleanup) {
landingPad->setCleanup(true);
llvm::BasicBlock *afterCleanupBB =
irs.insertBB(beginBB->getName() + llvm::Twine(".after.cleanup"));
runCleanups(lastCleanup, newCleanup, afterCleanupBB);
irs.scope() = IRScope(afterCleanupBB);
lastCleanup = newCleanup;
}
for (const auto &cb : tryCatchScope.getCatchBlocks()) {
// Add the ClassInfo reference to the landingpad instruction so it is
// emitted to the EH tables.
landingPad->addClause(cb.classInfoPtr);
llvm::BasicBlock *mismatchBB =
irs.insertBB(beginBB->getName() + llvm::Twine(".mismatch"));
// "Call" llvm.eh.typeid.for, which gives us the eh selector value to
// compare the landing pad selector value with.
llvm::Value *ehTypeId =
irs.ir->CreateCall(GET_INTRINSIC_DECL(eh_typeid_for),
DtoBitCast(cb.classInfoPtr, getVoidPtrType()));
// Compare the selector value from the unwinder against the expected
// one and branch accordingly.
irs.ir->CreateCondBr(
irs.ir->CreateICmpEQ(irs.ir->CreateLoad(ehSelectorSlot), ehTypeId),
cb.bodyBB, mismatchBB, cb.branchWeights);
irs.scope() = IRScope(mismatchBB);
}
}
// No catch matched. Execute all finallys and resume unwinding.
auto resumeUnwindBlock = getOrCreateResumeUnwindBlock();
if (lastCleanup > 0) {
landingPad->setCleanup(true);
runCleanups(lastCleanup, 0, resumeUnwindBlock);
} else if (!tryCatchScopes.empty()) {
// Directly convert the last mismatch branch into a branch to the
// unwind resume block.
irs.scopebb()->replaceAllUsesWith(resumeUnwindBlock);
irs.scopebb()->eraseFromParent();
} else {
irs.ir->CreateBr(resumeUnwindBlock);
}
irs.scope() = savedIRScope;
return beginBB;
}
llvm::AllocaInst *TryCatchFinallyScopes::getOrCreateEhPtrSlot() {
if (!ehPtrSlot)
ehPtrSlot = DtoRawAlloca(getVoidPtrType(), 0, "eh.ptr");
return ehPtrSlot;
}
llvm::BasicBlock *TryCatchFinallyScopes::getOrCreateResumeUnwindBlock() {
if (!resumeUnwindBlock) {
resumeUnwindBlock = irs.insertBB("eh.resume");
llvm::BasicBlock *oldBB = irs.scopebb();
irs.scope() = IRScope(resumeUnwindBlock);
llvm::Function *resumeFn = getUnwindResumeFunction(Loc(), irs.module);
irs.ir->CreateCall(resumeFn, DtoLoad(getOrCreateEhPtrSlot()));
irs.ir->CreateUnreachable();
irs.scope() = IRScope(oldBB);
}
return resumeUnwindBlock;
}
#if LDC_LLVM_VER >= 308
llvm::BasicBlock *
TryCatchFinallyScopes::emitLandingPadMSVC(CleanupCursor cleanupScope) {
if (!irs.func()->hasLLVMPersonalityFn()) {
const char *personality = "__CxxFrameHandler3";
irs.func()->setLLVMPersonalityFn(
getRuntimeFunction(Loc(), irs.module, personality));
}
if (cleanupScope == 0)
return runCleanupPad(cleanupScope, nullptr);
llvm::BasicBlock *&pad = getLandingPadRef(cleanupScope);
if (!pad)
pad = emitLandingPadMSVC(cleanupScope - 1);
return runCleanupPad(cleanupScope, pad);
}
llvm::BasicBlock *
TryCatchFinallyScopes::runCleanupPad(CleanupCursor scope,
llvm::BasicBlock *unwindTo) {
// a catch switch never needs to be cloned and is an unwind target itself
if (isCatchSwitchBlock(cleanupScopes[scope].beginBlock()))
return cleanupScopes[scope].beginBlock();
// each cleanup block is bracketed by a pair of cleanuppad/cleanupret
// instructions, any unwinding should also just continue at the next
// cleanup block, e.g.:
//
// cleanuppad:
// %0 = cleanuppad within %funclet[]
// %frame = nullptr
// if (!_d_enter_cleanup(%frame)) br label %cleanupret
// else br label %copy
//
// copy:
// invoke _dtor to %cleanupret unwind %unwindTo [ "funclet"(token %0) ]
//
// cleanupret:
// _d_leave_cleanup(%frame)
// cleanupret %0 unwind %unwindTo
//
llvm::BasicBlock *cleanupbb = irs.insertBB("cleanuppad");
auto funcletToken = llvm::ConstantTokenNone::get(irs.context());
auto cleanuppad =
llvm::CleanupPadInst::Create(funcletToken, {}, "", cleanupbb);
llvm::BasicBlock *cleanupret = irs.insertBBAfter(cleanupbb, "cleanupret");
// preparation to allocate some space on the stack where _d_enter_cleanup
// can place an exception frame (but not done here)
auto frame = getNullPtr(getVoidPtrType());
auto savedInsertBlock = irs.ir->GetInsertBlock();
auto savedInsertPoint = irs.ir->GetInsertPoint();
auto savedDbgLoc = irs.DBuilder.GetCurrentLoc();
auto endFn = getRuntimeFunction(Loc(), irs.module, "_d_leave_cleanup");
irs.ir->SetInsertPoint(cleanupret);
irs.DBuilder.EmitStopPoint(irs.func()->decl->loc);
irs.ir->CreateCall(endFn, frame,
{llvm::OperandBundleDef("funclet", cleanuppad)}, "");
llvm::CleanupReturnInst::Create(cleanuppad, unwindTo, cleanupret);
auto copybb = cleanupScopes[scope].runCopying(irs, cleanupbb, cleanupret,
unwindTo, cleanuppad);
auto beginFn = getRuntimeFunction(Loc(), irs.module, "_d_enter_cleanup");
irs.ir->SetInsertPoint(cleanupbb);
irs.DBuilder.EmitStopPoint(irs.func()->decl->loc);
auto exec = irs.ir->CreateCall(
beginFn, frame, {llvm::OperandBundleDef("funclet", cleanuppad)}, "");
llvm::BranchInst::Create(copybb, cleanupret, exec, cleanupbb);
irs.ir->SetInsertPoint(savedInsertBlock, savedInsertPoint);
irs.DBuilder.EmitStopPoint(savedDbgLoc);
return cleanupbb;
}
#endif
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