[Attributor] Loop-aware attribute handling? (alignment)

[LebedevRI]

Bugzilla Link	44604
Version	trunk
OS	Linux
CC	@jdoerfert,@jdoerfert,@Ralender,@uenoku

Extended Description

Given

// Type your code here, or load an example.
void test(int* dst, int count) {
    dst = (int*)__builtin_assume_aligned(dst, 1024);
    for(int i = 0; i != count; ++i) 
        dst[i] = 42;
}

normal clang -O3 -fno-unroll-loops does result in propagating of alignment
to store. But attributor fails to do that.

https://godbolt.org/z/dncWmz

[jdoerfert]

The Attributor doesn't utilize llvm.assume yet. We are working on a more powerful version which we will integrate and switch to. This will take a few more weeks but is in the works already.

[LebedevRI]

The Attributor doesn't utilize llvm.assume yet. We are working on a more
powerful version which we will integrate and switch to. This will take a few
more weeks but is in the works already.

Hm, looks like i didn't update the godbolt link..
I anticipated that question, and checked without @​llvm.assume,
and that isn't the problem: https://godbolt.org/z/Zivvvy