The code in fixLdsBranchVmemWARHazard looks for patterns of a vmem/lds
access followed by a branch, followed by an lds/vmem access.
The handling of the hazard requires an arbitrary number of instructions
to process. In the worst case where a function has a vmem access, but no lds
accesses, all instructions are examined only to conclude that the hazard
cannot occur.
Add the pre-processing stage which detects if there is both lds and vmem
present in the function and only then does the more costly search.
This patch significantly improves compilation time in the cases the hazard
cannot happen. In one pathological case I looked at IsHazardInst is needlesly
called 88.6 milions times.
The numbers could also be improved by introducing a map around the
inner calls to ::getWaitStatesSince in fixLdsBranchVmemWARHazard, but
nothing will beat not running fixLdsBranchVmemWARHazard at all in the cases
detected by shouldRunLdsBranchVmemWARHazardFixup().
Differential Revision: https://reviews.llvm.org/D104219
Refactor IsHazardFn and IsExpiredFn to use constant references as these should not be mutating the instructions visited and the instruction can never be null.
Reviewed By: foad
Differential Revision: https://reviews.llvm.org/D101430
Reset the tracked emitted instructions when starting scheduling on a new
region.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D90347
MFMA instructions shall not be scheduled back to back
to avoid MAI SIMD stall. Tell post-RA schedule we would
prefer some other instruction instead.
Differential Revision: https://reviews.llvm.org/D84883
When called from the post-RA scheduler, hazards have already been
handled by getHazardType returning NoopHazard, so PreEmitNoops always
returns zero. Remove it. NFC.
Historical note: PreEmitNoops was added to the hazard recognizer
interface as an optional feature to support dispatch group formation on
the POWER target:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20131202/197470.html
So it seems right that we shouldn't need to implement it.
We do still implement the other overload PreEmitNoops(MachineInstr *)
because that is used by the PostRAHazardRecognizer pass.
Differential Revision: https://reviews.llvm.org/D79476
Summary: GCNHazardRecognizer fails to identify hazards that are in and around bundles. This patch allows the hazard recognizer to consider bundled instructions in both scheduler and hazard recognizer mode. We ignore “bundledness” for the purpose of detecting hazards and examine the instructions individually.
Reviewers: arsenm, msearles, rampitec
Reviewed By: rampitec
Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61564
llvm-svn: 360199
Fixes two problems with GCNHazardRecognizer:
1. It only scans up to 5 instructions emitted earlier.
2. It does not take control flow into account. An earlier instruction
from the previous basic block is not necessarily a predecessor.
At the same time a real predecessor block is not scanned.
The patch provides a way to distinguish between scheduler and
hazard recognizer mode. It is OK to work with emitted instructions
in the scheduler because we do not really know what will be emitted
later and its order. However, when pass works as a hazard recognizer
the schedule is already finalized, and we have full access to the
instructions for the whole function, so we can properly traverse
predecessors and their instructions.
Differential Revision: https://reviews.llvm.org/D56923
llvm-svn: 351759
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
llvm-svn: 351636
Summary:
This is a follow-up to r335942.
- Merge SISubtarget into AMDGPUSubtarget and rename to GCNSubtarget
- Rename AMDGPUCommonSubtarget to AMDGPUSubtarget
- Merge R600Subtarget::Generation and GCNSubtarget::Generation into
AMDGPUSubtarget::Generation.
Reviewers: arsenm, jvesely
Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D49037
llvm-svn: 336851
This is mostly moving VMEM clause breaking into
the hazard recognizer. Also move another hazard
currently handled in the waitcnt pass.
Also stops breaking clauses unless xnack is enabled.
llvm-svn: 318557
Split AMDGPUSubtarget into amdgcn/r600 specific subclasses.
This removes most of the static_casting of the basic codegen
classes everywhere, and tries to restrict the features
visible on the wrong target.
llvm-svn: 273652
Summary:
Add support for detecting hazards in SMEM soft clauses, so that we only
break the clauses when necessary, either by adding s_nop or re-ordering
other alu instructions.
Reviewers: arsenm
Subscribers: arsenm, llvm-commits
Differential Revision: http://reviews.llvm.org/D18870
llvm-svn: 268260
Summary:
This includes a hazard recognizer implementation to replace some of
the hazard handling we had during frame index elimination.
Reviewers: arsenm
Subscribers: qcolombet, arsenm, llvm-commits
Differential Revision: http://reviews.llvm.org/D18602
llvm-svn: 268143
