[CodeGen] Stop creating fake FunctionDecls when generating IR for

functions implicitly generated by the compiler

These fake functions would cause clang to crash if the changes proposed
in https://reviews.llvm.org/D98799 were made.

clang/lib/CodeGen/CGBuiltin.cpp

@@ -1681,7 +1681,6 @@ llvm::Function *CodeGenFunction::generateBuiltinOSLogHelperFunction(
   }
 
   QualType ReturnTy = Ctx.VoidTy;
-  QualType FuncionTy = Ctx.getFunctionType(ReturnTy, ArgTys, {});
 
   // The helper function has linkonce_odr linkage to enable the linker to merge
   // identical functions. To ensure the merging always happens, 'noinline' is
@@ -1701,14 +1700,7 @@ llvm::Function *CodeGenFunction::generateBuiltinOSLogHelperFunction(
     Fn->addFnAttr(llvm::Attribute::NoInline);
 
   auto NL = ApplyDebugLocation::CreateEmpty(*this);
-  IdentifierInfo *II = &Ctx.Idents.get(Name);
-  FunctionDecl *FD = FunctionDecl::Create(
-      Ctx, Ctx.getTranslationUnitDecl(), SourceLocation(), SourceLocation(), II,
-      FuncionTy, nullptr, SC_PrivateExtern, false, false);
-  // Avoid generating debug location info for the function.
-  FD->setImplicit();
-
-  StartFunction(FD, ReturnTy, Fn, FI, Args);
+  StartFunction(GlobalDecl(), ReturnTy, Fn, FI, Args);
 
   // Create a scope with an artificial location for the body of this function.
   auto AL = ApplyDebugLocation::CreateArtificial(*this);

clang/lib/CodeGen/CGNonTrivialStruct.cpp

@@ -472,14 +472,10 @@ template <class Derived> struct GenFuncBase {
     F->setVisibility(llvm::GlobalValue::HiddenVisibility);
     CGM.SetLLVMFunctionAttributes(GlobalDecl(), FI, F, /*IsThunk=*/false);
     CGM.SetLLVMFunctionAttributesForDefinition(nullptr, F);
-    IdentifierInfo *II = &Ctx.Idents.get(FuncName);
-    FunctionDecl *FD = FunctionDecl::Create(
-        Ctx, Ctx.getTranslationUnitDecl(), SourceLocation(), SourceLocation(),
-        II, Ctx.getFunctionType(Ctx.VoidTy, llvm::None, {}), nullptr,
-        SC_PrivateExtern, false, false);
     CodeGenFunction NewCGF(CGM);
     setCGF(&NewCGF);
-    CGF->StartFunction(FD, Ctx.VoidTy, F, FI, Args);
+    CGF->StartFunction(GlobalDecl(), Ctx.VoidTy, F, FI, Args);
+    auto AL = ApplyDebugLocation::CreateArtificial(*CGF);
     std::array<Address, N> Addrs =
         getParamAddrs<N>(std::make_index_sequence<N>{}, Alignments, Args, CGF);
     asDerived().visitStructFields(QT, CharUnits::Zero(), Addrs);

clang/lib/CodeGen/ItaniumCXXABI.cpp

@@ -2611,15 +2611,6 @@ static llvm::Function *createGlobalInitOrCleanupFn(CodeGen::CodeGenModule &CGM,
   return GlobalInitOrCleanupFn;
 }
 
-static FunctionDecl *
-createGlobalInitOrCleanupFnDecl(CodeGen::CodeGenModule &CGM, StringRef FnName) {
-  ASTContext &Ctx = CGM.getContext();
-  QualType FunctionTy = Ctx.getFunctionType(Ctx.VoidTy, llvm::None, {});
-  return FunctionDecl::Create(
-      Ctx, Ctx.getTranslationUnitDecl(), SourceLocation(), SourceLocation(),
-      &Ctx.Idents.get(FnName), FunctionTy, nullptr, SC_Static, false, false);
-}
-
 void CodeGenModule::unregisterGlobalDtorsWithUnAtExit() {
   for (const auto &I : DtorsUsingAtExit) {
     int Priority = I.first;
@@ -2629,13 +2620,11 @@ void CodeGenModule::unregisterGlobalDtorsWithUnAtExit() {
     llvm::Function *GlobalCleanupFn =
         createGlobalInitOrCleanupFn(*this, GlobalCleanupFnName);
 
-    FunctionDecl *GlobalCleanupFD =
-        createGlobalInitOrCleanupFnDecl(*this, GlobalCleanupFnName);
-
     CodeGenFunction CGF(*this);
-    CGF.StartFunction(GlobalDecl(GlobalCleanupFD), getContext().VoidTy,
-                      GlobalCleanupFn, getTypes().arrangeNullaryFunction(),
-                      FunctionArgList(), SourceLocation(), SourceLocation());
+    CGF.StartFunction(GlobalDecl(), getContext().VoidTy, GlobalCleanupFn,
+                      getTypes().arrangeNullaryFunction(), FunctionArgList(),
+                      SourceLocation(), SourceLocation());
+    auto AL = ApplyDebugLocation::CreateArtificial(CGF);
 
     // Get the destructor function type, void(*)(void).
     llvm::FunctionType *dtorFuncTy = llvm::FunctionType::get(CGF.VoidTy, false);
@@ -2688,13 +2677,12 @@ void CodeGenModule::registerGlobalDtorsWithAtExit() {
         std::string("__GLOBAL_init_") + llvm::to_string(Priority);
     llvm::Function *GlobalInitFn =
         createGlobalInitOrCleanupFn(*this, GlobalInitFnName);
-    FunctionDecl *GlobalInitFD =
-        createGlobalInitOrCleanupFnDecl(*this, GlobalInitFnName);
 
     CodeGenFunction CGF(*this);
-    CGF.StartFunction(GlobalDecl(GlobalInitFD), getContext().VoidTy,
-                      GlobalInitFn, getTypes().arrangeNullaryFunction(),
-                      FunctionArgList(), SourceLocation(), SourceLocation());
+    CGF.StartFunction(GlobalDecl(), getContext().VoidTy, GlobalInitFn,
+                      getTypes().arrangeNullaryFunction(), FunctionArgList(),
+                      SourceLocation(), SourceLocation());
+    auto AL = ApplyDebugLocation::CreateArtificial(CGF);
 
     // Since constructor functions are run in non-descending order of their
     // priorities, destructors are registered in non-descending order of their

clang/test/CodeGen/constructor-attribute.c

@@ -1,5 +1,5 @@
 // RUN: %clang_cc1 -triple x86_64-apple-darwin -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=WITHOUTATEXIT %s
-// RUN: %clang_cc1 -triple x86_64-apple-darwin -fregister-global-dtors-with-atexit -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=CXAATEXIT --check-prefix=WITHATEXIT %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin -fregister-global-dtors-with-atexit -debug-info-kind=line-tables-only -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=CXAATEXIT --check-prefix=WITHATEXIT %s
 // RUN: %clang_cc1 -triple x86_64-apple-darwin -fno-use-cxa-atexit -fregister-global-dtors-with-atexit -emit-llvm -o - %s | FileCheck --check-prefix=CHECK --check-prefix=ATEXIT --check-prefix=WITHATEXIT %s
 
 // WITHOUTATEXIT: global_ctors{{.*}}@A{{.*}}@C
@@ -19,8 +19,9 @@
 // CHECK: define internal i32 @foo()
 // WITHOUTATEXIT-NOT: define
 
-// WITHATEXIT: define internal void @__GLOBAL_init_123(){{.*}}section "__TEXT,__StaticInit,regular,pure_instructions"
-// CXAATEXIT: call i32 @__cxa_atexit(void (i8*)* bitcast (void ()* @E to void (i8*)*), i8* null, i8* @__dso_handle)
+// CXAATEXIT: define internal void @__GLOBAL_init_123(){{.*}}section "__TEXT,__StaticInit,regular,pure_instructions" !dbg ![[GLOBAL_INIT_SP:.*]] {
+// ATEXIT: define internal void @__GLOBAL_init_123(){{.*}}section "__TEXT,__StaticInit,regular,pure_instructions"
+// CXAATEXIT: call i32 @__cxa_atexit(void (i8*)* bitcast (void ()* @E to void (i8*)*), i8* null, i8* @__dso_handle) {{.*}}, !dbg ![[GLOBAL_INIT_LOC:.*]]
 // CXAATEXIT: call i32 @__cxa_atexit(void (i8*)* bitcast (void ()* @G to void (i8*)*), i8* null, i8* @__dso_handle)
 // ATEXIT: call i32 @atexit(void ()* @E)
 // ATEXIT: call i32 @atexit(void ()* @G)
@@ -82,3 +83,6 @@ static void D() {
 int main() {
   return 0;
 }
+
+// CXAATEXIT: ![[GLOBAL_INIT_SP]] = distinct !DISubprogram(linkageName: "__GLOBAL_init_123",
+// CXAATEXIT: ![[GLOBAL_INIT_LOC]] = !DILocation(line: 0, scope: ![[GLOBAL_INIT_SP]])

clang/test/CodeGen/debug-info-oslog.c

@@ -10,6 +10,6 @@ void test_builtin_os_log(void *buf, int i, const char *data) {
 // This helper is going to be uniqued, so it should not have a line
 // number between file and type.
 
-// CHECK: distinct !DISubprogram(name: "__os_log_helper_1_0_1_4_0",
+// CHECK: distinct !DISubprogram(linkageName: "__os_log_helper_1_0_1_4_0",
 // CHECK-SAME:                   file: !{{.*}}, type
 // CHECK-SAME:                   flags: DIFlagArtificial

clang/test/CodeGenObjC/nontrivial-c-struct-exception.m

@@ -54,6 +54,9 @@ void testStrongException(void) {
 
 // CHECK: resume
 
+// CHECK: define{{.*}} void @__destructor_8_w8({{.*}} !dbg ![[DTOR_SP:.*]] {
+// CHECK: load i8**, i8*** {{.*}}, !dbg ![[DTOR_LOC:.*]]
+
 Weak genWeak(void);
 void calleeWeak(Weak, Weak);
 
@@ -63,3 +66,5 @@ void testWeakException(void) {
 
 // CHECK-DAG: [[ARTIFICIAL_LOC_1]] = !DILocation(line: 0
 // CHECK-DAG: [[ARTIFICIAL_LOC_2]] = !DILocation(line: 0
+// CHECK: ![[DTOR_SP]] = distinct !DISubprogram(linkageName: "__destructor_8_w8",
+// CHECK: ![[DTOR_LOC]] = !DILocation(line: 0, scope: ![[DTOR_SP]])