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[SILGen] Unified Entry Point Emission #67747

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Merged
merged 8 commits into from
Aug 8, 2023
Merged

[SILGen] Unified Entry Point Emission #67747

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7dae2e6
[SILGen] Implement SILGenTopLevel
Jul 20, 2023
3b4e94f
[SILGen] Emit toplevel code through `emitFunctionDefinition`
Jul 20, 2023
441a356
[SILGen] Emit toplevel code through `emitFunctionDefinition`
Jul 20, 2023
3657cba
[SILGen] Move all top-level emission code to `SILGenTopLevel.cpp`
Aug 4, 2023
03526c3
[SILGen] Remove TODO referring to unified entry point emission
Aug 4, 2023
41cd9fb
[Test] Fix test `IRGen/objc_ns_enum.swift`
Aug 7, 2023
a459c97
[SILGen] [Test] Address code review comments
Aug 8, 2023
db1cdbd
[SILGen] Refactor use of removed `forEachMemberToLower`
Aug 8, 2023
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1 change: 1 addition & 0 deletions lib/SILGen/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -35,6 +35,7 @@ add_swift_host_library(swiftSILGen STATIC
SILGenRequests.cpp
SILGenStmt.cpp
SILGenThunk.cpp
SILGenTopLevel.cpp
SILGenType.cpp)
target_link_libraries(swiftSILGen PRIVATE
swiftSerialization
Expand Down
280 changes: 14 additions & 266 deletions lib/SILGen/SILGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@
#include "RValue.h"
#include "SILGenFunction.h"
#include "SILGenFunctionBuilder.h"
#include "SILGenTopLevel.h"
#include "Scope.h"
#include "swift/AST/Decl.h"
#include "swift/AST/DiagnosticsSIL.h"
Expand Down Expand Up @@ -51,7 +52,7 @@ using namespace Lowering;
//===----------------------------------------------------------------------===//

SILGenModule::SILGenModule(SILModule &M, ModuleDecl *SM)
: M(M), Types(M.Types), SwiftModule(SM), TopLevelSGF(nullptr),
: M(M), Types(M.Types), SwiftModule(SM),
FileIDsByFilePath(SM->computeFileIDMap(/*shouldDiagnose=*/true)) {
const SILOptions &Opts = M.getOptions();
if (!Opts.UseProfile.empty()) {
Expand All @@ -70,7 +71,6 @@ SILGenModule::SILGenModule(SILModule &M, ModuleDecl *SM)
}

SILGenModule::~SILGenModule() {
assert(!TopLevelSGF && "active source file lowering!?");

// Update the linkage of external private functions to public_external,
// because there is no private_external linkage. External private functions
Expand Down Expand Up @@ -962,7 +962,6 @@ void SILGenModule::emitFunctionDefinition(SILDeclRef constant, SILFunction *f) {
auto *pbd = var->getParentPatternBinding();
unsigned idx = pbd->getPatternEntryIndexForVarDecl(var);
auto *initDC = pbd->getInitContext(idx);
auto captureInfo = pbd->getCaptureInfo(idx);
auto *init = constant.getInitializationExpr();
assert(init);

Expand All @@ -971,17 +970,6 @@ void SILGenModule::emitFunctionDefinition(SILDeclRef constant, SILFunction *f) {
PrettyStackTraceSILFunction X("silgen emitStoredPropertyInitialization", f);
f->createProfiler(constant);
SILGenFunction SGF(*this, *f, initDC);

// If this is a stored property initializer inside a type at global scope,
// it may close over a global variable. If we're emitting top-level code,
// then emit a "mark_function_escape" that lists the captured global
// variables so that definite initialization can reason about this
// escape point.
if (!var->getDeclContext()->isLocalContext() && TopLevelSGF &&
TopLevelSGF->B.hasValidInsertionPoint()) {
emitMarkFunctionEscapeForTopLevelCodeGlobals(var, captureInfo);
}

SGF.emitGeneratorFunction(constant, init, /*EmitProfilerIncrement=*/true);
postEmitFunction(constant, f);
break;
Expand Down Expand Up @@ -1107,9 +1095,15 @@ void SILGenModule::emitFunctionDefinition(SILDeclRef constant, SILFunction *f) {
case SILDeclRef::Kind::AsyncEntryPoint:
case SILDeclRef::Kind::EntryPoint: {
f->setBare(IsBare);
if (constant.hasFileUnit()) {
auto *File = constant.getFileUnit();
// In script mode
assert(isa<SourceFile>(File) && "Emitting entry-point of non source file?!");
auto *SF = cast<SourceFile>(File);
emitEntryPoint(SF, f);
return;
}

// TODO: Handle main SourceFile emission (currently done by
// SourceFileScope).
auto loc = constant.getAsRegularLocation();
preEmitFunction(constant, f, loc);
auto *decl = constant.getDecl();
Expand Down Expand Up @@ -1363,41 +1357,10 @@ void SILGenModule::emitDifferentiabilityWitness(
vjp);
}

void SILGenModule::
emitMarkFunctionEscapeForTopLevelCodeGlobals(SILLocation loc,
CaptureInfo captureInfo) {
assert(TopLevelSGF && TopLevelSGF->B.hasValidInsertionPoint()
&& "no valid code generator for top-level function?!");

SmallVector<SILValue, 4> Captures;

for (auto capture : captureInfo.getCaptures()) {
// Decls captured by value don't escape.
auto It = TopLevelSGF->VarLocs.find(capture.getDecl());
if (It == TopLevelSGF->VarLocs.end() ||
!It->getSecond().value->getType().isAddress())
continue;

Captures.push_back(It->second.value);
}

if (!Captures.empty())
TopLevelSGF->B.createMarkFunctionEscape(loc, Captures);
}

void SILGenModule::emitAbstractFuncDecl(AbstractFunctionDecl *AFD) {
// Emit default arguments and property wrapper initializers.
emitArgumentGenerators(AFD, AFD->getParameters());

// If this is a function at global scope, it may close over a global variable.
// If we're emitting top-level code, then emit a "mark_function_escape" that
// lists the captured global variables so that definite initialization can
// reason about this escape point.
if (!AFD->getDeclContext()->isLocalContext() &&
TopLevelSGF && TopLevelSGF->B.hasValidInsertionPoint()) {
emitMarkFunctionEscapeForTopLevelCodeGlobals(AFD, AFD->getCaptureInfo());
}

// If the declaration is exported as a C function, emit its native-to-foreign
// thunk too, if it wasn't already forced.
if (AFD->getAttrs().hasAttribute<CDeclAttr>()) {
Expand Down Expand Up @@ -1770,7 +1733,6 @@ void SILGenModule::emitObjCDestructorThunk(DestructorDecl *destructor) {
}

void SILGenModule::visitPatternBindingDecl(PatternBindingDecl *pd) {
assert(!TopLevelSGF && "script mode PBDs should be in TopLevelCodeDecls");
for (auto i : range(pd->getNumPatternEntries()))
if (pd->getExecutableInit(i))
emitGlobalInitialization(pd, i);
Expand Down Expand Up @@ -1964,225 +1926,8 @@ void SILGenModule::visitPoundDiagnosticDecl(PoundDiagnosticDecl *PDD) {
// Nothing to do for #error/#warning; they've already been emitted.
}

void SILGenModule::visitTopLevelCodeDecl(TopLevelCodeDecl *td) {
assert(TopLevelSGF && "top-level code in a non-main source file!");

if (!TopLevelSGF->B.hasValidInsertionPoint())
return;

TopLevelSGF->emitProfilerIncrement(td->getBody());

DebugScope DS(*TopLevelSGF, CleanupLocation(td));

for (auto &ESD : td->getBody()->getElements()) {
if (!TopLevelSGF->B.hasValidInsertionPoint()) {
if (auto *S = ESD.dyn_cast<Stmt*>()) {
if (S->isImplicit())
continue;
} else if (auto *E = ESD.dyn_cast<Expr*>()) {
if (E->isImplicit())
continue;
}

diagnose(ESD.getStartLoc(), diag::unreachable_code);
// There's no point in trying to emit anything else.
return;
}

if (auto *S = ESD.dyn_cast<Stmt*>()) {
TopLevelSGF->emitStmt(S);
} else if (auto *E = ESD.dyn_cast<Expr*>()) {
TopLevelSGF->emitIgnoredExpr(E);
} else {
TopLevelSGF->visit(ESD.get<Decl*>());
}
}
}

namespace {

/// An RAII class to scope source file codegen.
class SourceFileScope {
SILGenModule &sgm;
SILDeclRef EntryRef;
llvm::Optional<Scope> scope;
bool isAsyncTopLevel = false;
public:
SourceFileScope(SILGenModule &sgm, SourceFile *sf) : sgm(sgm) {
// If this is the script-mode file for the module, create a toplevel.
// TODO: We need to unify emission of the entry point such that we walk
// all of the TopLevelCodeDecls in one shot. This will be needed in order
// to requestify entry point emission.
if (sf->isScriptMode()) {
assert(!sgm.TopLevelSGF && "already emitted toplevel?!");
assert(!sgm.M.lookUpFunction(
sgm.getASTContext().getEntryPointFunctionName()) &&
"already emitted toplevel?!");

auto mainEntryRef = SILDeclRef::getMainFileEntryPoint(sf);
SILFunction * toplevel = sgm.getFunction(mainEntryRef, ForDefinition);
toplevel->setBare(IsBare);
EntryRef = mainEntryRef;

if (sf->isAsyncContext()) {
isAsyncTopLevel = true;
auto asyncEntryRef = SILDeclRef::getAsyncMainFileEntryPoint(sf);
auto *asyncTopLevel = sgm.getFunction(asyncEntryRef, ForDefinition);
SILGenFunction(sgm, *toplevel, sf).emitAsyncMainThreadStart(asyncEntryRef);
toplevel = asyncTopLevel;
EntryRef = asyncEntryRef;
}

toplevel->createProfiler(EntryRef);

sgm.TopLevelSGF = new SILGenFunction(sgm, *toplevel, sf);
sgm.TopLevelSGF->MagicFunctionName = sgm.SwiftModule->getName();
auto moduleCleanupLoc = CleanupLocation::getModuleCleanupLocation();

sgm.TopLevelSGF->prepareEpilog(llvm::None, true, moduleCleanupLoc);

auto prologueLoc = RegularLocation::getModuleLocation();
prologueLoc.markAsPrologue();
if (sf->isAsyncContext()) {
// emitAsyncMainThreadStart will create argc and argv.
// Just set the main actor as the expected executor; we should
// already be running on it.
SILValue executor = sgm.TopLevelSGF->emitMainExecutor(prologueLoc);
sgm.TopLevelSGF->ExpectedExecutor =
sgm.TopLevelSGF->B.createOptionalSome(
prologueLoc, executor,
SILType::getOptionalType(executor->getType()));
} else {
// Create the argc and argv arguments.
auto entry = sgm.TopLevelSGF->B.getInsertionBB();
auto context = sgm.TopLevelSGF->getTypeExpansionContext();
auto paramTypeIter = sgm.TopLevelSGF->F.getConventions()
.getParameterSILTypes(context)
.begin();

entry->createFunctionArgument(*paramTypeIter);
entry->createFunctionArgument(*std::next(paramTypeIter));
}
scope.emplace(sgm.TopLevelSGF->Cleanups, moduleCleanupLoc);
}
}

~SourceFileScope() {
if (sgm.TopLevelSGF) {
scope.reset();

// Unregister the top-level function emitter.
auto &SGF = *sgm.TopLevelSGF;
sgm.TopLevelSGF = nullptr;

// Write out the epilog.
auto moduleLoc = RegularLocation::getModuleLocation();
moduleLoc.markAutoGenerated();
auto returnInfo = SGF.emitEpilogBB(moduleLoc);
auto returnLoc = returnInfo.second;
returnLoc.markAutoGenerated();

SILFunction *exitFunc = nullptr;

SILType returnType;
if (isAsyncTopLevel) {
FuncDecl *exitFuncDecl = sgm.getExit();
assert(exitFuncDecl && "Failed to find exit function declaration");
exitFunc = sgm.getFunction(
SILDeclRef(exitFuncDecl, SILDeclRef::Kind::Func, /*isForeign*/true),
NotForDefinition);
SILFunctionType & funcType = *exitFunc->getLoweredType().getAs<SILFunctionType>();
returnType = SILType::getPrimitiveObjectType(
funcType.getParameters().front().getInterfaceType());
} else {
returnType = SGF.F.getConventions().getSingleSILResultType(
SGF.getTypeExpansionContext());
}

auto emitTopLevelReturnValue = [&](unsigned value) -> SILValue {
// Create an integer literal for the value.
auto litType = SILType::getBuiltinIntegerType(32, sgm.getASTContext());
SILValue retValue =
SGF.B.createIntegerLiteral(moduleLoc, litType, value);

// Wrap that in a struct if necessary.
if (litType != returnType) {
retValue = SGF.B.createStruct(moduleLoc, returnType, retValue);
}
return retValue;
};

// Fallthrough should signal a normal exit by returning 0.
SILValue returnValue;
if (SGF.B.hasValidInsertionPoint())
returnValue = emitTopLevelReturnValue(0);

// Handle the implicit rethrow block.
auto rethrowBB = SGF.ThrowDest.getBlock();
SGF.ThrowDest = JumpDest::invalid();

// If the rethrow block wasn't actually used, just remove it.
if (rethrowBB->pred_empty()) {
SGF.eraseBasicBlock(rethrowBB);

// Otherwise, we need to produce a unified return block.
} else {
auto returnBB = SGF.createBasicBlock();
if (SGF.B.hasValidInsertionPoint())
SGF.B.createBranch(returnLoc, returnBB, returnValue);
returnValue =
returnBB->createPhiArgument(returnType, OwnershipKind::Owned);
SGF.B.emitBlock(returnBB);

// Emit the rethrow block.
SILGenSavedInsertionPoint savedIP(SGF, rethrowBB,
FunctionSection::Postmatter);

// Log the error.
SILValue error = rethrowBB->getArgument(0);
SGF.B.createBuiltin(moduleLoc,
sgm.getASTContext().getIdentifier("errorInMain"),
sgm.Types.getEmptyTupleType(), {}, {error});

// Then end the lifetime of the error.
//
// We do this to appease the ownership verifier. We do not care about
// actually destroying the value since we are going to immediately exit,
// so this saves us a slight bit of code-size since end_lifetime is
// stripped out after ownership is removed.
SGF.B.createEndLifetime(moduleLoc, error);

// Signal an abnormal exit by returning 1.
SGF.Cleanups.emitCleanupsForReturn(CleanupLocation(moduleLoc),
IsForUnwind);
SGF.B.createBranch(returnLoc, returnBB, emitTopLevelReturnValue(1));
}

// Return.
if (SGF.B.hasValidInsertionPoint()) {

if (isAsyncTopLevel) {
SILValue exitCall = SGF.B.createFunctionRef(moduleLoc, exitFunc);
SGF.B.createApply(moduleLoc, exitCall, {}, {returnValue});
SGF.B.createUnreachable(moduleLoc);
} else {
SGF.B.createReturn(returnLoc, returnValue);
}
}

// Okay, we're done emitting the top-level function; destroy the
// emitter and verify the result.
SILFunction *toplevel = &SGF.getFunction();
delete &SGF;

LLVM_DEBUG(llvm::dbgs() << "lowered toplevel sil:\n";
toplevel->print(llvm::dbgs()));
toplevel->verifyIncompleteOSSA();
sgm.emitLazyConformancesForFunction(toplevel);
}
}
};

// An RAII object that constructs a \c SILGenModule instance.
// On destruction, delayed definitions are automatically emitted.
class SILGenModuleRAII {
Expand All @@ -2193,7 +1938,10 @@ class SILGenModuleRAII {
// Type-check the file if we haven't already.
performTypeChecking(*sf);

SourceFileScope scope(SGM, sf);
if (sf->isScriptMode()) {
SGM.emitEntryPoint(sf);
}

for (auto *D : sf->getTopLevelDecls()) {
// Emit auxiliary decls.
D->visitAuxiliaryDecls([&](Decl *auxiliaryDecl) {
Expand Down
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