[PATCH] D137107: Allow MS extension: support of constexpr with __declspec(dllimport).

[Zahira Ammarguellat via Phabricator via cfe-commits]

zahiraam marked an inline comment as done.
zahiraam added inline comments.


================
Comment at: clang/lib/CodeGen/CodeGenModule.cpp:5009
+  if (isStaticInit(D, getLangOpts()) && NeedsGlobalCtor && NeedsGlobalDtor) {
+    EmitCXXCtorInit(D, GV, true, 201, llvm::StringLiteral("ctor"), false);
+    EmitCXXCtorInit(D, GV, false, 65535, llvm::StringLiteral("dtor"), true);
----------------
efriedma wrote:
> zahiraam wrote:
> > efriedma wrote:
> > > I think you want to use priority 201 whether or not there's a destructor.
> > Is that what you mean?
> I think it should look something more like this:
> 
> ```
> if (isStaticInit(D, getLangOpts()) {
>   if (NeedsGlobalCtor)
>     EmitCXXCtorInit(D, GV, true, 201, llvm::StringLiteral("ctor"), false);
>   if (NeedsGlobalDtor)
>     EmitCXXCtorInit(D, GV, false, 65535, llvm::StringLiteral("dtor"), true);
>   DelayedCXXInitPosition[D] = ~0U;
> } else {
>   EmitCXXGlobalVarDeclInitFunc(D, GV, NeedsGlobalCtor);
> }
If you agree with the generated IR for this case, then I will start editing the LIT tests accordingly.

  // CHECK: @"?b@@3UB@@A" = dso_local global %struct.B undef
  // CHECK: @llvm.global_ctors = appending global [1 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr @dtor, ptr null }]

  // CHECK: define internal void @dtor()
  // CHECK: entry:
  // CHECK:     %0 = call i32 @atexit(ptr @"??__Fb@@YAXXZ")
  // CHECK:   ret void

  // CHECk: define linkonce_odr dso_local x86_thiscallcc void @"??1B@@QAE at XZ"
  // CHECK: entry:
  // CHECK:  %this.addr = alloca ptr, align 4
  // CHECK:  store ptr %this, ptr %this.addr, align 4
  // CHECK:  %this1 = load ptr, ptr %this.addr, align 4
  // CHECK:  ret void


  // CHECK: define internal void @"??__Fb@@YAXXZ"() #0 {
  // CHECK: entry:
  // CHECK:   call x86_thiscallcc void @"??1B@@QAE at XZ"(ptr @"?b@@3UB@@A")
  // CHECK:   ret void


  struct B {
    constexpr B() {}
    ~B() {};
  };
  constinit B b;


The ctor with priority 201 is generated only when tryEmitForInitializer returns a nullptr (that's the only time when NeedsGlobalCtor is set to true). Correct?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D137107/new/

https://reviews.llvm.org/D137107