This PR improves general validity of emitted code between passes due to
generation of `TargetOpcode::PHI` instead of `SPIRV::OpPhi` after
Instruction Selection, fixing generation of OpTypePointer instructions
and using of proper virtual register classes.
Using `TargetOpcode::PHI` instead of `SPIRV::OpPhi` after Instruction
Selection has a benefit to support existing optimization passes
immediately, as an alternative path to disable those passes that use
`MI.isPHI()`. This PR makes it possible thus to revert
https://github.com/llvm/llvm-project/pull/116060 actions and get back to
use the `MachineSink` pass.
This PR is a solution of the problem discussed in details in
https://github.com/llvm/llvm-project/pull/110507. It accepts an advice
from code reviewers of the PR #110507 to postpone generation of OpPhi
rather than to patch CodeGen. This solution allows to unblock
improvements wrt. expensive checks and makes it unrelated to the general
points of the discussion about OpPhi vs. G_PHI/PHI.
This PR contains numerous small patches of emitted code validity that
allows to substantially pass rate with expensive checks. Namely, the
test suite with expensive checks set ON now has only 12 fails out of 569
total test cases.
FYI @bogner
This PR resolved the following issues:
(1) There are rare but possible cases when there are bitcasts between
pointers intertwined in a sophisticated way with loads, stores, function
calls and other instructions that are part of type deduction. In this
case we must account for inserted bitcasts between pointers rather than
just ignore them.
(2) Null pointers have the same constant representation but different
types. Type info from Intrinsic::spv_track_constant() refers to the
opaque (untyped) pointer, so that each MF/v-reg pair would fall into the
same Const record in Duplicate Tracker and would be represented by a
single OpConstantNull instruction, unless we use precise pointee type
info. We must be able to distinguish one constant (null) pointer from
another to avoid generating invalid code with inconsistent types of
operands.
This patch introduces a new spv_ptrcast intrinsic for tracking expected
pointer types. The change fixes multiple OpenCL CTS regressions due the
switch to opaque pointers (e.g. basic/hiloeo).
