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

[Eli Friedman]

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.)

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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