recreate this patch from
https://github.com/llvm/llvm-project/pull/153894

It seems ISel sliently ignore the `i64 = zext i16` with a chained
`reg_sequence` pattern and thus this is causing a selection failure in
hip test. Recreate a new patch with an alternative pattern, and added a
ll test global-extload-gfx11plus.ll

This reverts commit 7c53c6162bd43d952546a3ef7d019babd5244c29.

This patch hit an issue in hip test. revert and will reopen later

Update true16 mode with zext patterns using vgpr16 for 16bit data types.
This stop isel from inserting invalid "vgpr32 = copy vgpr16"

Recent upstream trends have moved away from explicitly using `-verify-machineinstrs`, as it's already covered by the expensive checks. This PR removes almost all `-verify-machineinstrs` from tests in `llvm/test/CodeGen/AMDGPU/*.ll`, leaving only those tests where its removal currently causes failures.

Some of the packed build_vector use vgpr_32 for i16/f16/bf16. 

In gfx11, bf16 arithmetic get promoted to f32 and this is done via v2i16
pack. In true16 mode this v2i16 pack is selected to a
build_vector/v_lshlrev pattern which only accepts VGPR32. This causes
isel to insert an illegal copy "vgpr32 = copy vgpr16" between def and
use. In the end this illegal copy confuses cse pass and trigger wrong
code elimination.

Remove the packed build_vector pattern from true16. After removal, ISel
will use vgpr16 build_vector patterns instead.

For the majority of cases, this is a neutral or positive change.
There are even testcases that greatly benefit from it, but some regressions are possible.
There is #140040 for GlobalISel that'd need to be fixed but it's only a one instruction regression and I think it can be fixed later.

Solves #64591

Fixes UB in tests due to mismatched CC (definition and callsite).

This is a NFC patch.

This patch run a bulk update on CodeGen tests that are impacted by the
true16 features. This patch applies:
1. duplicate GFX11plus runlines and apply them with
"+mattr=+real-true16" and "+mattr=-real-true16"
2. update the test with the update script

For some GISEL runlines, the current CodeGen do not fully support the
true16 version. Still update the runlines, but comment out the failing
one, and added a "FIXME-TRUE16" comment to that test for easier
tracking. These test will be fixed in the following patches.

This is in a transition state that we support both
"+real-true16/-real-true16" in our code base. We plan to move to
"+real-true16" as default, and finally remove "-real-true16" mode and
test lines.

Many tests use store to undef as a placeholder use, so just replace
all of these with poison.