[llvm] [SLP] The order of store chains needs to consider the size of the values. (PR #101810)

[via llvm-commits]

tcwzxx wrote:

> I don't see test update

The existing test cases are fine.

There is a new pattern :
```
; RUN: opt -S --passes=slp-vectorizer -mtriple=x86_64-unknown-linux < %s | FileCheck %s
define void @test(ptr %p) {
entry:
    %idx1 = getelementptr i8, ptr %p, i64 1
    store i8 0, ptr %idx1, align 4
    %idx.64.9 = getelementptr i64, ptr %p, i64 9
    store i64 1, ptr %idx.64.9, align 8
    %idx2 = getelementptr i8, ptr %p, i64 2
    store i8 0, ptr %idx2, align 4
    %idx3 = getelementptr i8, ptr %p, i64 3
    store i8 0, ptr %idx3, align 4
    %idx4 = getelementptr i8, ptr %p, i64 4
    store i8 0, ptr %idx4, align 4
    %idx5 = getelementptr i8, ptr %p, i64 5
    store i8 0, ptr %idx5, align 4
    %idx6 = getelementptr i8, ptr %p, i64 6
    store i8 0, ptr %idx6, align 4
    %idx7 = getelementptr i8, ptr %p, i64 7
    store i8 0, ptr %idx7, align 4
    %idx8 = getelementptr i8, ptr %p, i64 8
    store i8 0, ptr %idx8, align 4
    ret void
}

```

Before the patch:

```
define void @test(ptr %p) {
entry:
    %idx1 = getelementptr i8, ptr %p, i64 1
    store i8 0, ptr %idx1, align 4
    %idx.64.9 = getelementptr i64, ptr %p, i64 9
    store i64 1, ptr %idx.64.9, align 8
    %idx2 = getelementptr i8, ptr %p, i64 2
    store <4 x i8> zeroinitializer, ptr %idx2, align 4
    %idx6 = getelementptr i8, ptr %p, i64 6
    store i8 0, ptr %idx6, align 4
    %idx7 = getelementptr i8, ptr %p, i64 7
    store i8 0, ptr %idx7, align 4
    %idx8 = getelementptr i8, ptr %p, i64 8
    store i8 0, ptr %idx8, align 4
    ret void
}
```

After the patch:

```
define void @test(ptr %p) {
entry:
    %idx1 = getelementptr i8, ptr %p, i64 1
    %idx.64.9 = getelementptr i64, ptr %p, i64 9
    store i64 1, ptr %idx.64.9, align 8
    store <8 x i8> zeroinitializer, ptr %idx1, align 4
    ret void
}
```



> Add a test in a separate patch

I will commit the above test case in a different PR.

https://github.com/llvm/llvm-project/pull/101810