It allows more than two, right? like {vex}{vex2}{vex3} instruction. I think it should be a bug for att.

2. Delete IsPrefix parameter, and delete 'break'

1. Check prefix, ignoring case
2. Delete IsPrefix parameter, and delete 'break', so that we won't check prefix again. I am not sure if this is right. Att format can allow two prefix and using the last one as the finally encoding prefix. I think this may not be the original intention of the design.
3. Change the test: checking the IR istead of checking the assembly.
4. Made some format adjustments.

Ping?

Rebase.
Adding the '{}' to prefix when generate IR.

1. Address comments;
2. Only support parsing vex/vex2/vex3/evex prefix for MASM

Thanks for all of your review!

In D89105#2363927, @pengfei wrote:

LGTM. Thanks. Better to wait one day or two to see if others object.

1. Move the testcase from avx-vnni/ to test/CodeGen/X86/.
2. Refine the Run line in avx_vnni-intrinsics.ll

Address comments

In D89184#2363591, @echristo wrote:

Let's go ahead and unblock you, but getting a lot of this refactored would be great if you can. I think it's hitting the limits of the original design. :)

In D89184#2360846, @echristo wrote:

I'll take a look tomorrow, sorry for the delay.

Ping?

In D90009#2354849, @kiranchandramohan wrote:

I have added a fix to run the test only when the X86 target is available. Please feel free to change if it is not the correct fix.
https://github.com/llvm/llvm-project/commit/c551ba0e90bd2b49ef501d591f8362ba44e5484d

Address comments.

Adding avxvnni to Alder Lake.

1. move the commonvnniintrin.h to the avx512vlvnniintrin.h.
2. move the testcase avxvnni-builtins.c to X86 subdirectory.

Hi, @echristo. What's your opinion here?

Address comments

Address comments

In D89184#2346453, @pengfei wrote:

LGTM. But I suggest you waiting for 1 or 2 days to see if other reviewers object.

Adding an option compatible with old abi is good method. Looks good for me.

Rebase.

ping?

Add a line of comment on unit test.

Address comments.

Thanks for all of your help!

D89105 appears to use only "avx512vl , avx512vnni | avxvnni".
Does it mean (avx512vl , avx512vnni) | avxvnni or avx512vl , (avx512vnni | avxvnni) ?

In D78699#2328541, @dyung wrote:

Hi, the test you added seems to pass both before and after your change, is this intended?

In D89184#2326818, @pengfei wrote:

LGTM with nit. I'd like to see if others have objection.

Address comments

Address comments.

In D89184#2325597, @tra wrote:

Would it make sense to add a negation, too?

Address comments.

In D78699#2320678, @bruno wrote:

LGTM

In D60748#2310148, @RKSimon wrote:

@wxiao3 @LiuChen3 Are you still looking at this or should it be abandoned?

Address comments.

Include the context.

It has been a long time to remember details, but I share @rjmccall concerns.

Address comments

Ping?

Hi, @majnemer, @bruno. I saw that both of you have modified this logic. What's your opinion here?

Ping?

Address comments: Replacing the bool argument with an enum argument

Address the comments

Remove redundant variables

Remove default arguments.

I used gcc and clang cross-compilation for testing, and currently found no problems.
main.c:

Restricting this change to varargs function calls and address comments.

In D78564#2102121, @efriedma wrote:

Can you provide a few C testcases comparing gcc and clang, where clang currently misaligns an argument? I briefly tried a few testcases with __m256i vectors, and clang seemed to do the right thing.

ping?

Address the comment.

Determine whether the type is m128/m256/__m512 by type alignment rather than type size.
Since I am not familiar with front-end, adding diagnostics will take some effort. I think it would be better to foucus on this calling-convention for now.