This reverts commit ca907bfb57.
According to michel.daenzer,
> This completely broke the Mesa radeonsi driver on Navi 14. Xorg +
> xterm come up with major corruption & psychedelic colours.
When memory operations are outstanding on function calls, either the
caller or the callee can insert a waitcnt to ensure that all reads are
finished.
Calls need some time to be executed, so if the callee inserts the
waitcnt, filling the instruction buffer and waiting for memory will be
interleaved, hiding some latency. This comes at the cost of having a
waitcnt inside functions that may not be needed as no memory operations
are outstanding.
For function calls, this is already implemented. The same principal
applies to returns: If the caller inserts a waitcnt after the call, the
callee does not have to wait and the return and memory operation can be
run in parallel.
This commit implements waiting in the caller after returning from a
function call.
Differential Revision: https://reviews.llvm.org/D87674
Summary:
- `dead-mi-elimination` assumes MIR in the SSA form and cannot be
arranged after phi elimination or DeSSA. It's enhanced to handle the
dead register definition by skipping use check on it. Once a register
def is `dead`, all its uses, if any, should be `undef`.
- Re-arrange the DIE in RA phase for AMDGPU by placing it directly after
`detect-dead-lanes`.
- Many relevant tests are refined due to different register assignment.
Reviewers: rampitec, qcolombet, sunfish
Subscribers: arsenm, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D72709
This reverts commit 7a6ef3004655dd86d722199c471ae78c28e31bb4.
We discovered some internal test failures, so reverting for now.
Differential Revision: https://reviews.llvm.org/D61213
llvm-svn: 359363
One of out of tree targets has regressed with this patch. Reverting
it for now and let liveness to be fully reconstructed in case pass
was used after the LIS is created to resolve the regression.
Differential Revision: https://reviews.llvm.org/D60466
llvm-svn: 358015
Relying on no spill or other code being inserted before this was
precarious. It relied on code diligently checking isBasicBlockPrologue
which is likely to be forgotten.
Ideally this could be done earlier, but this doesn't work because of
phis. Any other instruction can't be placed before them, so we have to
accept the position being incorrect during SSA.
This avoids regressions in the fast register allocator rewrite from
inverting the direction.
llvm-svn: 357634
Sebastian Neubauer