Commit Graph

13 Commits

Author SHA1 Message Date
Roman Lebedev 4b80647367
[AMDGPU][SimplifyCFG] Teach AMDGPUUnifyDivergentExitNodes to preserve {,Post}DomTree
This is a (last big?) part of the patch series to make SimplifyCFG
preserve DomTree. Currently, it still does not actually preserve it,
even thought it is pretty much fully updated to preserve it.

Once the default is flipped, a valid DomTree must be passed into
simplifyCFG, which means that whatever pass calls simplifyCFG,
should also be smart about DomTree's.

As far as i can see from `check-llvm` with default flipped,
this is the last LLVM test batch (other than bugpoint tests)
that needed fixes to not break with default flipped.

The changes here are boringly identical to the ones i did
over 42+ times/commits recently already,
so while AMDGPU is outside of my normal ecosystem,
i'm going to go for post-commit review here,
like in all the other 42+ changes.

Note that while the pass is taught to preserve {,Post}DomTree,
it still doesn't do that by default, because simplifycfg
still doesn't do that by default, and flipping default
in this pass will implicitly flip the default for simplifycfg.
That will happen, but not right now.
2021-01-02 01:01:20 +03:00
Roman Lebedev b23b1bcc26
[NFC][CodeGen][Tests] Mark all tests that fail to preserve DomTree for SimplifyCFG as such
These tests start to fail when the SimplifyCFG's default regarding DomTree
updating is switched on, so mark them as needing changes.
2021-01-02 01:01:19 +03:00
cdevadas e53a9d96e6 Resubmit: [AMDGPU] Invert the handling of skip insertion.
The current implementation of skip insertion (SIInsertSkip) makes it a
mandatory pass required for correctness. Initially, the idea was to
have an optional pass. This patch inserts the s_cbranch_execz upfront
during SILowerControlFlow to skip over the sections of code when no
lanes are active. Later, SIRemoveShortExecBranches removes the skips
for short branches, unless there is a sideeffect and the skip branch is
really necessary.

This new pass will replace the handling of skip insertion in the
existing SIInsertSkip Pass.

Differential revision: https://reviews.llvm.org/D68092
2020-01-22 13:18:32 +09:00
Nicolai Hähnle a80291ce10 Revert "[AMDGPU] Invert the handling of skip insertion."
This reverts commit 0dc6c249bf.

The commit is reported to cause a regression in piglit/bin/glsl-vs-loop for
Mesa.
2020-01-21 09:17:25 +01:00
cdevadas 0dc6c249bf [AMDGPU] Invert the handling of skip insertion.
The current implementation of skip insertion (SIInsertSkip) makes it a
mandatory pass required for correctness. Initially, the idea was to
have an optional pass. This patch inserts the s_cbranch_execz upfront
during SILowerControlFlow to skip over the sections of code when no
lanes are active. Later, SIRemoveShortExecBranches removes the skips
for short branches, unless there is a sideeffect and the skip branch is
really necessary.

This new pass will replace the handling of skip insertion in the
existing SIInsertSkip Pass.

Differential revision: https://reviews.llvm.org/D68092
2020-01-15 15:18:16 +05:30
Stanislav Mekhanoshin a9487d92d7 [AMDGPU] Eliminate no effect instructions before s_endpgm
Differential Revision: https://reviews.llvm.org/D36585

llvm-svn: 310987
2017-08-16 04:43:49 +00:00
Matt Arsenault b8f8dbc227 AMDGPU: Unify divergent function exits.
StructurizeCFG can't handle cases with multiple
returns creating regions with multiple exits.
Create a copy of UnifyFunctionExitNodes that only
unifies exit nodes that skips exit nodes
with uniform branch sources.

llvm-svn: 298729
2017-03-24 19:52:05 +00:00
Matt Arsenault 3dbeefa978 AMDGPU: Mark all unspecified CC functions in tests as amdgpu_kernel
Currently the default C calling convention functions are treated
the same as compute kernels. Make this explicit so the default
calling convention can be changed to a non-kernel.

Converted with perl -pi -e 's/define void/define amdgpu_kernel void/'
on the relevant test directories (and undoing in one place that actually
wanted a non-kernel).

llvm-svn: 298444
2017-03-21 21:39:51 +00:00
Kyle Butt efe56fed12 Revert "CodeGen: Allow small copyable blocks to "break" the CFG."
This reverts commit ada6595a526d71df04988eb0a4b4fe84df398ded.

This needs a simple probability check because there are some cases where it is
not profitable.

llvm-svn: 291695
2017-01-11 19:55:19 +00:00
Kyle Butt df27aa8c89 CodeGen: Allow small copyable blocks to "break" the CFG.
When choosing the best successor for a block, ordinarily we would have preferred
a block that preserves the CFG unless there is a strong probability the other
direction. For small blocks that can be duplicated we now skip that requirement
as well.

Differential revision: https://reviews.llvm.org/D27742

llvm-svn: 291609
2017-01-10 23:04:30 +00:00
Matt Arsenault 327188aa15 AMDGPU: Select branch on undef to uniform scc branch
llvm-svn: 289877
2016-12-15 21:57:11 +00:00
Matt Arsenault f530e8b3f0 AMDGPU: Remove unnecessary and on conditional branch
The comment explaining why this was necessary is incorrect
in its description of v_cmp's behavior for inactive workitems.

llvm-svn: 286134
2016-11-07 19:09:33 +00:00
Changpeng Fang 26fb9d268b AMDGPU/SI: Don't handle a loop if there is no loop at all for a terminator BB.
Differential Revision: http://reviews.llvm.org/D22021

Reviewed by: arsenm

llvm-svn: 277073
2016-07-28 23:01:45 +00:00