efriedma added a comment.
> is this an ABI breaking change
It only affects the order of initialization within a file, so it doesn't really
have any implications for the binary ABI. It might break code, of course, but
that's a different issue.
If we want a flag to maintain the old behavior, we need to define what the
"old" order is. Not sure that's worthwhile.
================
Comment at: clang/lib/CodeGen/CGDeclCXX.cpp:580
+ I = DelayedCXXInitPosition.find(D);
+ unsigned LexOrder = I == DelayedCXXInitPosition.end() ? ~0U : I->second;
+ AddGlobalCtor(Fn, 65535, LexOrder, COMDATKey);
----------------
This ensures delayed initialization calls are ordered relative to each other...
but are they ordered correctly relative to non-delayed initialization calls?
I'm skeptical that using a LexOrder of "~0U" is really correct. (For example,
if you change the variable "b" in your testcase to a struct with a destructor.)
================
Comment at: clang/lib/CodeGen/CodeGenModule.cpp:544
}
+ llvm::stable_sort(GlobalCtors, [](const Structor &L, const Structor &R) {
+ return L.LexOrder < R.LexOrder;
----------------
ychen wrote:
> rnk wrote:
> > Please move this sorting into EmitCtorList and apply it to destructors. I
> > believe they are currently emitted in source order, and the loader executes
> > them in reverse order, so we get the desired reverse source order cleanup
> > behavior.
> I looked into this. They are indeed "currently emitted in source order".
> However, if a dtor ever uses an entry in `llvm.global_dtors`, it must have
> bailed out of deferred emission here
> (https://github.com/llvm/llvm-project/blob/69c09d11f877a35655e285cda96ec0699e385fc9/clang/lib/CodeGen/CodeGenModule.cpp#L3256-L3263),
> which is to say, the corresponding ctor is also in lexing order. So the
> situation is either the ctor/dtor pair both use lexing order, or there is no
> dtor (like `inline int` with an initializer) and the ctor is
> deferred/reordered where this patch kicks in.
>
Is MayBeEmittedEagerly always true for variables with destructors?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D127233/new/
https://reviews.llvm.org/D127233
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