forked from OSchip/llvm-project
[Windows] Put init_seg(compiler/lib) in llvm.global_ctors
Currently we treat initializers with init_seg(compiler/lib) as similar
to any other init_seg, they simply have a global variable in the proper
section (".CRT$XCC" for compiler/".CRT$XCL" for lib) and are added to
llvm.used. However, this doesn't match with how LLVM sees normal (or
init_seg(user)) initializers via llvm.global_ctors. This
causes issues like incorrect init_seg(compiler) vs init_seg(user)
ordering due to GlobalOpt evaluating constructors, and the
ability to remove init_seg(compiler/lib) initializers at all.
Currently we use 'A' for priorities less than 200. Use 200 for
init_seg(compiler) (".CRT$XCC") and 400 for init_seg(lib) (".CRT$XCL"),
which do not append the priority to the section name. Priorities
between 200 and 400 use ".CRT$XCC${Priority}". This allows for
some wiggle room for people/future extensions that want to add
initializers between compiler and lib.
Fixes #56922
Reviewed By: rnk
Differential Revision: https://reviews.llvm.org/D131910
This commit is contained in:
Arthur Eubanks
parent
ba1c396e09
commit
9181ce623f
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@ -127,6 +127,10 @@ relative ordering of values is important. For example:
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``Obj2`` will be initialized *before* ``Obj1`` despite the usual order of
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initialization being the opposite.
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On Windows, ``init_seg(compiler)`` is represented with a priority of 200 and
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``init_seg(library)`` is represented with a priority of 400. ``init_seg(user)``
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uses the default 65535 priority.
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This attribute is only supported for C++ and Objective-C++ and is ignored in
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other language modes. Currently, this attribute is not implemented on z/OS.
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}];
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@ -553,7 +553,18 @@ CodeGenModule::EmitCXXGlobalVarDeclInitFunc(const VarDecl *D,
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CXXThreadLocalInits.push_back(Fn);
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CXXThreadLocalInitVars.push_back(D);
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} else if (PerformInit && ISA) {
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EmitPointerToInitFunc(D, Addr, Fn, ISA);
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// Contract with backend that "init_seg(compiler)" corresponds to priority
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// 200 and "init_seg(lib)" corresponds to priority 400.
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int Priority = -1;
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if (ISA->getSection() == ".CRT$XCC")
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Priority = 200;
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else if (ISA->getSection() == ".CRT$XCL")
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Priority = 400;
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if (Priority != -1)
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AddGlobalCtor(Fn, Priority, COMDATKey);
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else
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EmitPointerToInitFunc(D, Addr, Fn, ISA);
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} else if (auto *IPA = D->getAttr<InitPriorityAttr>()) {
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OrderGlobalInitsOrStermFinalizers Key(IPA->getPriority(),
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PrioritizedCXXGlobalInits.size());
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@ -10,12 +10,12 @@ namespace simple_init {
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#pragma init_seg(compiler)
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int x = f();
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// CHECK: @"?x@simple_init@@3HA" = dso_local global i32 0, align 4
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// CHECK: @__cxx_init_fn_ptr = private constant ptr @"??__Ex@simple_init@@YAXXZ", section ".CRT$XCC"
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// No function pointer! This one goes on @llvm.global_ctors.
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#pragma init_seg(lib)
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int y = f();
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// CHECK: @"?y@simple_init@@3HA" = dso_local global i32 0, align 4
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// CHECK: @__cxx_init_fn_ptr.1 = private constant ptr @"??__Ey@simple_init@@YAXXZ", section ".CRT$XCL"
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// No function pointer! This one goes on @llvm.global_ctors.
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#pragma init_seg(user)
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int z = f();
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@ -29,14 +29,14 @@ namespace internal_init {
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namespace {
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int x = f();
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// CHECK: @"?x@?A0x{{[^@]*}}@internal_init@@3HA" = internal global i32 0, align 4
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// CHECK: @__cxx_init_fn_ptr.2 = private constant ptr @"??__Ex@?A0x{{[^@]*}}@internal_init@@YAXXZ", section ".asdf"
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// CHECK: @__cxx_init_fn_ptr = private constant ptr @"??__Ex@?A0x{{[^@]*}}@internal_init@@YAXXZ", section ".asdf"
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}
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}
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namespace selectany_init {
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int __declspec(selectany) x = f();
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// CHECK: @"?x@selectany_init@@3HA" = weak_odr dso_local global i32 0, comdat, align 4
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// CHECK: @__cxx_init_fn_ptr.3 = private constant ptr @"??__Ex@selectany_init@@YAXXZ", section ".asdf", comdat($"?x@selectany_init@@3HA")
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// CHECK: @__cxx_init_fn_ptr.1 = private constant ptr @"??__Ex@selectany_init@@YAXXZ", section ".asdf", comdat($"?x@selectany_init@@3HA")
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}
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namespace explicit_template_instantiation {
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@ -44,7 +44,7 @@ template <typename T> struct A { static const int x; };
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template <typename T> const int A<T>::x = f();
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template struct A<int>;
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// CHECK: @"?x@?$A@H@explicit_template_instantiation@@2HB" = weak_odr dso_local global i32 0, comdat, align 4
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// CHECK: @__cxx_init_fn_ptr.4 = private constant ptr @"??__E?x@?$A@H@explicit_template_instantiation@@2HB@@YAXXZ", section ".asdf", comdat($"?x@?$A@H@explicit_template_instantiation@@2HB")
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// CHECK: @__cxx_init_fn_ptr.2 = private constant ptr @"??__E?x@?$A@H@explicit_template_instantiation@@2HB@@YAXXZ", section ".asdf", comdat($"?x@?$A@H@explicit_template_instantiation@@2HB")
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}
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namespace implicit_template_instantiation {
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@ -52,21 +52,19 @@ template <typename T> struct A { static const int x; };
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template <typename T> const int A<T>::x = f();
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int g() { return A<int>::x; }
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// CHECK: @"?x@?$A@H@implicit_template_instantiation@@2HB" = linkonce_odr dso_local global i32 0, comdat, align 4
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// CHECK: @__cxx_init_fn_ptr.5 = private constant ptr @"??__E?x@?$A@H@implicit_template_instantiation@@2HB@@YAXXZ", section ".asdf", comdat($"?x@?$A@H@implicit_template_instantiation@@2HB")
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// CHECK: @__cxx_init_fn_ptr.3 = private constant ptr @"??__E?x@?$A@H@implicit_template_instantiation@@2HB@@YAXXZ", section ".asdf", comdat($"?x@?$A@H@implicit_template_instantiation@@2HB")
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}
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// ... and here's where we emitted user level ctors.
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// CHECK: @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }]
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// CHECK: [{ i32, ptr, ptr } { i32 65535, ptr @_GLOBAL__sub_I_pragma_init_seg.cpp, ptr null }]
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// CHECK: @llvm.global_ctors = appending global [3 x { i32, ptr, ptr }]
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// CHECK: [{ i32, ptr, ptr } { i32 200, ptr @"??__Ex@simple_init@@YAXXZ", ptr @"?x@simple_init@@3HA" }, { i32, ptr, ptr } { i32 400, ptr @"??__Ey@simple_init@@YAXXZ", ptr @"?y@simple_init@@3HA" }, { i32, ptr, ptr } { i32 65535, ptr @_GLOBAL__sub_I_pragma_init_seg.cpp, ptr null }]
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// We have to mark everything used so we can survive globalopt, even through
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// LTO. There's no way LLVM could really understand if data in the .asdf
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// section is really used or dead.
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//
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// CHECK: @llvm.used = appending global [6 x ptr]
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// CHECK: @llvm.used = appending global [4 x ptr]
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// CHECK: [ptr @__cxx_init_fn_ptr,
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// CHECK: ptr @__cxx_init_fn_ptr.1,
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// CHECK: ptr @__cxx_init_fn_ptr.2,
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// CHECK: ptr @__cxx_init_fn_ptr.3,
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// CHECK: ptr @__cxx_init_fn_ptr.4,
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// CHECK: ptr @__cxx_init_fn_ptr.5], section "llvm.metadata"
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// CHECK: ptr @__cxx_init_fn_ptr.3], section "llvm.metadata"
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@ -1889,11 +1889,24 @@ static MCSectionCOFF *getCOFFStaticStructorSection(MCContext &Ctx,
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// string that sorts between .CRT$XCA and .CRT$XCU. In the general case, we
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// make a name like ".CRT$XCT12345", since that runs before .CRT$XCU. Really
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// low priorities need to sort before 'L', since the CRT uses that
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// internally, so we use ".CRT$XCA00001" for them.
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// internally, so we use ".CRT$XCA00001" for them. We have a contract with
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// the frontend that "init_seg(compiler)" corresponds to priority 200 and
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// "init_seg(lib)" corresponds to priority 400, and those respectively use
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// 'C' and 'L' without the priority suffix. Priorities between 200 and 400
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// use 'C' with the priority as a suffix.
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SmallString<24> Name;
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char LastLetter = 'T';
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bool AddPrioritySuffix = Priority != 200 && Priority != 400;
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if (Priority < 200)
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LastLetter = 'A';
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else if (Priority < 400)
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LastLetter = 'C';
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else if (Priority == 400)
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LastLetter = 'L';
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raw_svector_ostream OS(Name);
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OS << ".CRT$X" << (IsCtor ? "C" : "T") <<
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(Priority < 200 ? 'A' : 'T') << format("%05u", Priority);
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OS << ".CRT$X" << (IsCtor ? "C" : "T") << LastLetter;
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if (AddPrioritySuffix)
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OS << format("%05u", Priority);
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MCSectionCOFF *Sec = Ctx.getCOFFSection(
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Name, COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
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SectionKind::getReadOnly());
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@ -6,6 +6,15 @@
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; CHECK: .section .CRT$XCA00042,"dr"
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; CHECK: .p2align 3
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; CHECK: .quad f
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; CHECK: .section .CRT$XCC,"dr"
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; CHECK: .p2align 3
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; CHECK: .quad i
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; CHECK: .section .CRT$XCC00250,"dr"
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; CHECK: .p2align 3
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; CHECK: .quad k
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; CHECK: .section .CRT$XCL,"dr"
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; CHECK: .p2align 3
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; CHECK: .quad j
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; CHECK: .section .CRT$XCT12345,"dr"
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; CHECK: .p2align 3
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; CHECK: .quad g
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@ -24,10 +33,13 @@ $h = comdat any
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@str1 = private dso_local unnamed_addr constant [6 x i8] c"first\00", align 1
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@str2 = private dso_local unnamed_addr constant [5 x i8] c"main\00", align 1
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@llvm.global_ctors = appending global [3 x { i32, ptr, ptr }] [
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@llvm.global_ctors = appending global [6 x { i32, ptr, ptr }] [
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{ i32, ptr, ptr } { i32 12345, ptr @g, ptr null },
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{ i32, ptr, ptr } { i32 42, ptr @f, ptr null },
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{ i32, ptr, ptr } { i32 23456, ptr @init_h, ptr @h }
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{ i32, ptr, ptr } { i32 23456, ptr @init_h, ptr @h },
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{ i32, ptr, ptr } { i32 200, ptr @i, ptr null },
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{ i32, ptr, ptr } { i32 400, ptr @j, ptr null },
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{ i32, ptr, ptr } { i32 250, ptr @k, ptr null }
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]
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declare dso_local i32 @puts(ptr nocapture readonly) local_unnamed_addr
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@ -50,6 +62,23 @@ entry:
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ret void
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}
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define dso_local void @i() {
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entry:
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store i8 43, ptr @h
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ret void
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}
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define dso_local void @j() {
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entry:
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store i8 44, ptr @h
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ret void
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}
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define dso_local void @k() {
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entry:
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store i8 45, ptr @h
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ret void
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}
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; Function Attrs: nounwind uwtable
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define dso_local i32 @main() local_unnamed_addr {
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