[PATCH] [ms-cxxabi] Implement guard variables for static initialization

[Reid Kleckner]

On Thu, Sep 5, 2013 at 4:26 PM, Eli Friedman <eli.friedman at gmail.com> wrote:

> On Wed, Sep 4, 2013 at 10:10 AM, Reid Kleckner <rnk at google.com> wrote:
>
>> On Fri, Aug 30, 2013 at 10:45 AM, Reid Kleckner <rnk at google.com> wrote:
>>
>>>
>>>
>>> ================
>>> Comment at: lib/Sema/SemaLambda.cpp:101
>>> @@ -98,1 +100,3 @@
>>> +        (isa<FunctionDecl>(CurContext) &&
>>> +         Context.getTargetInfo().getCXXABI().isMicrosoft())) {
>>>        ManglingContextDecl = 0;
>>> ----------------
>>> Eli Friedman wrote:
>>> > Why do you need to number anything in a function which isn't inline?
>>>  CodeGen can mangle static variables etc.  however it wants because they
>>> aren't externally visible.
>>> I'm using these to number bits in a bitfield, not to mangle.  I have to
>>> use this mechanism to number the bits of inline functions, so it makes
>>> sense to use it to number bits of non inline functions too.  Otherwise I
>>> have to add back the CXXABIFunctionState code I had in the first version of
>>> this patch.
>>>
>>> I'm having a very hard time extracting this function from Sema and
>>> moving it over to AST/ItaniumCXXABI.cpp as John suggested.  It accesses a
>>> bunch of Sema fields.  Do you have any thoughts on how this should look in
>>> the long run?
>>>
>>
>> Any thoughts on this?  This is needed to avoid double initialization of
>> llvm::outs/errs(), and factoring this one check out will require a massive
>> migration of Eli's Itanium logic from Sema to AST.
>>
>>
> The Itanium ABI code actually uses two numbering schemes: one for
> externally-visible stuff, and one for non-exernally visible stuff.  Not
> sure if you want to go that route.  See the beginning of the definition of
> "class ItaniumMangleContext" for how it numbers non-externally-visible
> stuff.  The idea is that we can avoid tracking the numbering in the AST for
> declarations where the numbers don't matter.  (Also, it involved changing
> less code when I implemented it.)
>

That makes sense.  I'll number non-externally visible things in CodeGen and
commit without the check in SemaLambda.

Thanks John for the review!


> If you want to, I'm fine with leaving that check as-is.
>
> (I haven't actually reviewed the rest of the patch.)
>
> -Eli
>
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