[PATCH] D140166: [IR] return nullptr in Instruction::getInsertionPointAfterDef for CallBrInst

[Chuanqi Xu via Phabricator via llvm-commits]

ChuanqiXu added a comment.

In D140166#4018476 <https://reviews.llvm.org/D140166#4018476>, @dblaikie wrote:

>> Note that there is only a coroutine `a()` in the above example. The frontend generated code (with -g) will consist of 1144 lines of IR codes. I get it by:
>>
>>   clang++ -std=c++20 src.cpp -O3 -S -emit-llvm -g -Xclang -disable-llvm-passes -o frontend-generated.ll
>>
>> And for the optimized (but before coroutine splitting) IR, it'll still consist of 645 lines of IR code. (I get it by inserting codes in CoroSplit.cpp). So I feel it is too lengthy for a lit test.
>
> That's with all LLVM passes disabled - it might be interesting if there's something more manageable with some optimization passes applied? (I guess if you don't disable them from clang, -O3 ends up lowering the IR beyond the coroutine abstracitons - so you'd have to do this manually with opt or something to only apply some optimizations and stop before the coroutines were lowered too far/beyond what's needed for this test)

As far as I know, I don't the method to generate the IR before Coro-splitting automatically. In the past I always tried to insert codes in CoroSplit pass manually. I didn't feel tired for it.

> Though, yeah, it still wouldn't surprise me if it's infeasibly long.
>
> That said - I'm still confused about the CHECK-NOT for the label - that looked roughly OK to me/didn't seem too brittle (at least with checking for the end of line, if that's practical)

In the test, we don't care about the inserted instructions. We only care about that the `@llvm.dbg.declare` lives in the `DEFAULT_DEST` BB. So it is slightly better to me if we only check the interesting part. The good part if one day someone else made a similar change (insert some instructions to the BB or remove some instructions in the BB), then he probably don't need to worry about the test. Personally, I feel bad when I made a change and I ran the test and many test failed but I found they are not related to my change. So I feel better to add `CHECK-NOT` to skip these tests.


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