Gate this optimization under optimization level and put the optimization code into a helper class.

In D87596#2272955, @lxfind wrote:

In D87596#2272950, @ChuanqiXu wrote:

In D87596#2271942, @lxfind wrote:

Thank you for working on this optimization!

This type of optimizations is typically not enabled in O0, and we probably don't want to either. Should we gate it under the optimization level?

This optimization depends on lifetime markers, which would not be produced in O0. So this optimization won't be enabled in O0.

That's not entirely true though. lifetime markers could be enabled with ASAN in O0 for instance.

In D87596#2271942, @lxfind wrote:

Thank you for working on this optimization!

This type of optimizations is typically not enabled in O0, and we probably don't want to either. Should we gate it under the optimization level?

In D86672#2240988, @vitalybuka wrote:

isPointerOffset is not what I need

In D85399#2225025, @vitalybuka wrote:

LGTM with some updates

In D85399#2223329, @vitalybuka wrote:

The test is still could be useful
Maybe something like this llvm/test/Analysis/StackSafetyAnalysis/lifetime.ll ?

In D85399#2223309, @vitalybuka wrote:

This function was changed
Is this issue still relevant?
If this is still needed, could you please make this a regular lit test?

@RKSimon , gentle ping~

In D85399#2199566, @RKSimon wrote:

test case?

Update test case

In D85279#2195758, @junparser wrote:

LGTM，Thank you, Please merge the testcases into one file.

Create BitCastInst directly instead of using IRBuilder

Due to my mistake, the diff updated before is a draft. It is terribly sorry if it confuses any one...

In D84821#2183795, @ChuanqiXu wrote:

In D84821#2183027, @nikic wrote:

I don't think this is the right approach to the problem. Can you give some more information on which places in LLVM assume that only bitcasts feed into lifetime intrinsics?

From the CodeExtractor.cpp, CoroFrame.cpp and StackLifetime.cpp, I find such assumptions. I also find that there are other methods to collect lifetime marker of an instruction. For example, in the Inline Module, it finds among all the users of the instruction I to find which is used by lifetime marker. And in the InstCombineLoadStore.cpp, I find it collects lifetime marker by calculates the users with kind BitCast, GEP and AddrSpaceCastInst (which means there are cases which are not covered by this patch). What I want to say here is that the style of collecting lifetime marker seems a little out-of-order.

In D84821#2183271, @lebedev.ri wrote:

I'm not sure any such assumption being made is sane. Those passes should be fixed instead.

Yes. We can fix this problem by either fixing other passes or fixing this pass. We need find out that which one is more natural. In my thought, when I want to collect lifetime marker as a newbie here, I will go to see how the lifetime marker is created. So I find CreateLifetimeStart and CreateLifetimeEnd in LLVM and CreateCall ('lifetime_start' or lifetime_end`') in clang's CodeGen` module. In all of the methods, the logic is to judge whether the type of the source value is i8*. If the type of the source value is i8*, the Create* methods will create a direct call to lifetime intrinsics. Otherwise, the Create* methods will create a BitCast to convert the type of source value to i8*. So from the process, I think it is natural for code reader who is not so familiar with LLVM to think that he can collect lifetime marker by judge the instruction itself and the users who is BitCastInst.

In D84821#2183027, @nikic wrote:

I don't think this is the right approach to the problem. Can you give some more information on which places in LLVM assume that only bitcasts feed into lifetime intrinsics?

In D84135#2162478, @MaskRay wrote:

For NFC changes please tag so (you can find plenty of examples in the history). Please upload the full diff (arc diff or git diff 'HEAD^' -U9999).

---

When you commit, please drop Reviewers: Subscribers: Tags: and the text Summary: from the git commit with the following script:

arcfilter () {
        arc amend
        git log -1 --pretty=%B | awk '/Reviewers:|Subscribers:/{p=1} /Reviewed By:|Differential Revision:/{p=0} !p && !/^Summary:$/ {sub(/^Summary: /,"");print}' | git commit --amend --date=now -F -
}

Reviewed By: is considered important by some people. Please keep the tag. (--date=now is my personal preference (author dates are usually not useful. Using committer dates can make log almost monotonic in time))

llvm/utils/git/pre-push.py can validate the message does not include unneeded tags.

Hi @modocache ，may I ask for your option about this patch?

re-upload the patch due to previous misuse of Phabricator , sorry..

Because of D82029, the promise_type::final_suspend() should declare with noexcept specifier .