Merge pull request #67747 from zachary0kent/sil-gen-top-level

[SILGen] Unified Entry Point Emission

Author: zachary-kent

lib/SILGen/CMakeLists.txt

@@ -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

lib/SILGen/SILGen.cpp

@@ -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"
@@ -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()) {
@@ -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
@@ -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);
 
@@ -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;
@@ -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();
@@ -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>()) {
@@ -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);
@@ -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 {
@@ -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) {