[PATCH] D103304: Update and improve compiler-rt tests for -mllvm -asan_use_after_return=(never|[runtime]|always).

[Vitaly Buka via Phabricator via llvm-commits]

vitalybuka added a comment.

In D103304#2800789 <https://reviews.llvm.org/D103304#2800789>, @kda wrote:

> Regarding below, I had this previously: https://reviews.llvm.org/differential/changeset/?ref=2601358

Correct, at that time I thought we are doing WEAK __asan_use_after_return_mode, for which new fictions are not needed.
Sorry, we'd save some time if I asked to drop __asan_use_after_return_mode instead.
If you are going to recover that one I'd recommencement Flagless -> Always to be consistent with naming?

> The problem I don't know how to navigate is that GetFakeStackFast is only called from one place (at runtime, the other is for testing only).
> That call is in OnMalloc.  Which, in turn, is only called from one place: __asan_stack_malloc_<##class_id>
>
> How do I have the runtime code pick the Always version of GetFakeStackFast without examining the global?
> Do I inject the function ptr when generating the call to __asan_stack_malloc?

No, AddressSanitizer Always branch will call only __asan_stack_malloc_always_<##class_id> functions
Runtime branch will continue to call __asan_stack_malloc_<##class_id>

> In D103304#2800596 <https://reviews.llvm.org/D103304#2800596>, @vitalybuka wrote:
>
>> I looked at Lazy approach and it's simpler then I thought. Asan already contains all needed pieces.
>> Considering that we have not idea how to handle Windows and Darwin we should do that in this patch.
>>
>> Cloning of GetFakeStackFast -> GetFakeStackFastAlways which does not check __asan_option_detect_stack_use_after_return should be enough.
>>
>>   static FakeStack *GetFakeStackFast() {
>>     if (FakeStack *fs = GetTLSFakeStack())
>>       return fs;
>>     if (!__asan_option_detect_stack_use_after_return)
>>       return nullptr;
>>     return GetFakeStack();
>>   }
>>   
>>   
>>   static FakeStack *GetFakeStackFastAlways() {
>>     if (FakeStack *fs = GetTLSFakeStack())
>>       return fs;
>>     return GetFakeStack();
>>   }
>>
>> And same for all callers.
>> Anything __asan_detect_use_after_return_always related can be reverted.




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