For the pattern of IR (%if terminates with a divergent branch.),
divergence analysis will report %phi as uniform to help optimal code
generation.
```
%if
| \
| %then
| /
%endif: %phi = phi [ %uniform, %if ], [ %undef, %then ]
```
In the backend, %phi and %uniform will be assigned a scalar register.
But the %undef from %then will make the scalar register dead in %then.
This will likely cause the register being over-written in %then. To fix
the issue, we will rewrite %undef as %uniform. For details, please refer
the comment in AMDGPURewriteUndefForPHI.cpp. Currently there is no test
changes shown, but this is mandatory for later changes.
Reviewed by: sameerds
Differential Revision: https://reviews.llvm.org/D133840
We form VOPD instructions in the GCNCreateVOPD pass by combining
back-to-back component instructions. There are strict register
constraints for creating a legal VOPD, namely that the matching operands
(e.g. src0x and src0y, src1x and src1y) must be in different register
banks. We add a PostRA scheduler
mutation to put possible VOPD components back-to-back.
Depends on D128442, D128270
Reviewed By: #amdgpu, rampitec
Differential Revision: https://reviews.llvm.org/D128656
GFX11 has a new message type MSG_DEALLOC_VGPRS which can be used to
release a shader's VGPRs. Sending this at the end of a shader (just
before the s_endpgm) can help overall system performance in cases where
the s_endpgm would have to wait for outstanding VMEM stores to complete
before releasing the VGPRs.
Differential Revision: https://reviews.llvm.org/D128442
The sched_barrier builtin allow the scheduler's behavior to be shaped by users
when very specific codegen is needed in order to create highly optimized code.
This patch adds more granular control over the types of instructions that are
allowed to be reordered with respect to one or multiple sched_barriers. A mask
is used to specify groups of instructions that should be allowed to be scheduled
around a sched_barrier. The details about this mask may be used can be found in
llvm/include/llvm/IR/IntrinsicsAMDGPU.td.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D127123
This patch implements a DAG mutation which adds edges between different groups of instructions. The purpose is to try to generate code that conforms to a pipeline (groupA instructions occur before groupB, groupB -> groupC, and so on). Currently the pipeline order is hardcoded as VMEM->DSRead->MFMA->DSWrite, but the patch was designed to be easily extensible. Alias analysis is problematic for pipelining as memory instructions will usually not be able to be reordered w.r.t one another.
Differential Revision: https://reviews.llvm.org/D125997
This patch adds cluster edges between independent MFMA instructions. Additionally, it propogates all predecessors of cluster insts to the root of the cluster(s), and all successors to the leaf(ves) of the cluster(s) -- this is done to remove the possibility that those insts will be interspersed within the cluster.
Reviewed By: kerbowa
Differential Revision: https://reviews.llvm.org/D124678
As older waves execute long sequences of VALU instructions, this may
prevent younger waves from address calculation and then issuing their
VMEM loads, which in turn leads the VALU unit to idle. This patch tries
to prevent this by temporarily raising the wave's priority.
Reviewed By: foad
Differential Revision: https://reviews.llvm.org/D124246
Previously the name of the class (AMDGPUCFGStructurizer) did not
match the name of the file (AMDILCFGStructurizer).
Standardize on the name R600MachineCFGStructurizer by analogy with
AMDGPUMachineCFGStructurizer.
Differential Revision: https://reviews.llvm.org/D120128
This was a workaround for not supporting indirect calls when
instcombine didn't eliminate constant expression casts of the callee
at -O0. Indirect calls are supposed to work now, so drop the hack.
If possible fold fneg into instruction above if users cannot fold mods and we
know it will decrease instruction count.
Follows same logic as SDAG combiner in choosing opportunities to combine.
Differential Revision: https://reviews.llvm.org/D112827
The new pass walks kernel's pointer arguments, then loads from them.
If a loaded value is a pointer and loaded pointer is unmodified in
the kernel before the load, then promote loaded pointer to global.
Then recursively continue.
Differential Revision: https://reviews.llvm.org/D111464
1. Splitted out some parts of R600 target to separate modules/headers.
2. Reduced some include lists in headers.
3. Minor forward declarations, redundant includes and flags in GCNSubtarget
cleanup.
Reviewed By: foad
Differential Revision: https://reviews.llvm.org/D109351
1. Splitted out some parts of R600 target to separate modules/headers.
2. Reduced some include lists in headers.
3. Found and fixed issue with override `GCNTargetMachine::getSubtargetImpl()`
and `R600TargetMachine::getSubtargetImpl()` had different return value type
than base class.
4. Minor forward declarations cleanup.
Reviewed By: foad
Differential Revision: https://reviews.llvm.org/D108596
This patch introduces a new code object metadata field, ".kind"
which is used to add support for init and fini kernels.
HSAStreamer will use function attributes, "device-init" and
"device-fini" to distinguish between init and fini kernels from
the regular kernels and will emit metadata with ".kind" set to
"init" and "fini" respectively.
To reduce the number of init and fini kernels, the ctors and
dtors present in the llvm's global.ctors and global.dtors lists
are called from a single init and fini kernel respectively.
Reviewed by: yaxunl
Differential Revision: https://reviews.llvm.org/D105682
This patch introduces a new code object metadata field, ".kind"
which is used to add support for init and fini kernels.
HSAStreamer will use function attributes, "device-init" and
"device-fini" to distinguish between init and fini kernels from
the regular kernels and will emit metadata with ".kind" set to
"init" and "fini" respectively.
To reduce the number of init and fini kernels, the ctors and
dtors present in the llvm's global.ctors and global.dtors lists
are called from a single init and fini kernel respectively.
Reviewed by: yaxunl
Differential Revision: https://reviews.llvm.org/D105682
This patch introduces a pass that uses the Attributor to deduce AMDGPU specific attributes.
Reviewed By: jdoerfert, arsenm
Differential Revision: https://reviews.llvm.org/D104997
First, collect the register usage in each function, then apply the
maximum register usage of all functions to functions with indirect
calls.
This is more accurate than guessing the maximum register usage without
looking at the actual usage.
As before, assume that indirect calls will hit a function in the
current module.
Differential Revision: https://reviews.llvm.org/D105839
This is to allow 64 bit constant rematerialization. If a constant
is split into two separate moves initializing sub0 and sub1 like
now RA cannot rematerizalize a 64 bit register.
This gives 10-20% uplift in a set of huge apps heavily using double
precession math.
Fixes: SWDEV-292645
Differential Revision: https://reviews.llvm.org/D104874
This pass aims to optimize VGPR live-range in a typical divergent if-else
control flow. For example:
def(a)
if(cond)
use(a)
... // A
else
use(a)
As AMDGPU access vgpr with respect to active-mask, we can mark `a` as
dead in region A. For details, please refer to the comments in
implementation file.
The pass is enabled by default, the frontend can disable it through
"-amdgpu-opt-vgpr-liverange=false".
Differential Revision: https://reviews.llvm.org/D102212
The main motivation behind pointer replacement of LDS use within non-kernel
functions is - to *avoid* subsequent LDS lowering pass from directly packing
LDS (assume large LDS) into a struct type which would otherwise cause allocating
huge memory for struct instance within every kernel.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D103225
the compilation time and there is no case for which we see any improvement in
performance. This patch removes this pass and its associated test cases from
the tree.
Differential Revision: https://reviews.llvm.org/D101313
Change-Id: I0599169a7609c19a887f8d847a71e664030cc141
Pass no longer handles skips. Pass now removes unnecessary
unconditional branches and lowers early termination branches.
Hence rename to SILateBranchLowering.
Move code to handle returns to epilog from SIPreEmitPeephole
into SILateBranchLowering. This means SIPreEmitPeephole only
contains optional optimisations, and all required transforms
are in SILateBranchLowering.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D98915
SIRemoveShortExecBranches is an optimisation so fits well in the
context of SIPreEmitPeephole.
Test changes relate to early termination from kills which have now
been lowered prior to considering branches for removal.
As these use s_cbranch the execz skips are now retained instead.
Currently either behaviour is valid as kill with EXEC=0 is a nop;
however, if early termination is used differently in future then
the new behaviour is the correct one.
Reviewed By: foad
Differential Revision: https://reviews.llvm.org/D98917
[amdgpu] Implement lower function LDS pass
Local variables are allocated at kernel launch. This pass collects global
variables that are used from non-kernel functions, moves them into a new struct
type, and allocates an instance of that type in every kernel. Uses are then
replaced with a constantexpr offset.
Prior to this pass, accesses from a function are compiled to trap. With this
pass, most such accesses are removed before reaching codegen. The trap logic
is left unchanged by this pass. It is still reachable for the cases this pass
misses, notably the extern shared construct from hip and variables marked
constant which survive the optimizer.
This is of interest to the openmp project because the deviceRTL runtime library
uses cuda shared variables from functions that cannot be inlined. Trunk llvm
therefore cannot compile some openmp kernels for amdgpu. In addition to the
unit tests attached, this patch applied to ROCm llvm with fixed-abi enabled
and the function pointer hashing scheme deleted passes the openmp suite.
This lowering will use more LDS than strictly necessary. It is intended to be
a functionally correct fallback for cases that are difficult to target from
future optimisation passes.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D94648
Allow parsing generated mir with custom pseudo source value tokens.
Also rename pseudo source values to have more meaningful names.
Relands ba7dcd8542, which had memory leaks.
Differential Revision: https://reviews.llvm.org/D95215
Having a custom inliner doesn't really fit in with the new PM's
pipeline. It's also extra technical debt.
amdgpu-inline only does a couple of custom things compared to the normal
inliner:
1) It disables inlining if the number of BBs in a function would exceed
some limit
2) It increases the threshold if there are pointers to private arrays(?)
These can all be handled as TTI inliner hooks.
There already exists a hook for backends to multiply the inlining
threshold.
This way we can remove the custom amdgpu-inline pass.
This caused inline-hint.ll to fail, and after some investigation, it
looks like getInliningThresholdMultiplier() was previously getting
applied twice in amdgpu-inline (https://reviews.llvm.org/D62707 fixed it
not applying at all, so some later inliner change must have fixed
something), so I had to change the threshold in the test.
Reviewed By: rampitec
Differential Revision: https://reviews.llvm.org/D94153
Allow parsing generated mir with custom pseudo source value tokens.
Also rename pseudo source values to have more meaningful names.
Differential Revision: https://reviews.llvm.org/D94768
And add them to the pipeline via
AMDGPUTargetMachine::registerPassBuilderCallbacks(), which mirrors
AMDGPUTargetMachine::adjustPassManager().
These passes can't be unconditionally added to PassRegistry.def since
they are only present when the AMDGPU backend is enabled. And there are
no target-specific headers in llvm/include, so parsing these pass names
must occur somewhere in the AMDGPU directory. I decided the best place
was inside the TargetMachine, since the PassBuilder invokes
TargetMachine::registerPassBuilderCallbacks() anyway. If we come up with
a cleaner solution for target-specific passes in the future that's fine,
but there aren't too many target-specific IR passes living in
target-specific directories so it shouldn't be too bad to change in the
future.
Reviewed By: ychen, arsenm
Differential Revision: https://reviews.llvm.org/D93863
No longer rely on an external tool to build the llvm component layout.
Instead, leverage the existing `add_llvm_componentlibrary` cmake function and
introduce `add_llvm_component_group` to accurately describe component behavior.
These function store extra properties in the created targets. These properties
are processed once all components are defined to resolve library dependencies
and produce the header expected by llvm-config.
Differential Revision: https://reviews.llvm.org/D90848
This was only used for matching the saddr addressing mode of global
instructions, but this was not implemented correctly. The instruction
definitions aren't even correct, and are defined as using a 64-bit
VGPR component. Eliminate this pass to enable correcting the
instruction definitions. A new matching implementation can work in
GlobalISel or relying on DAG divergence information for the base
address.
For a long time, the InstCombine pass handled target specific
intrinsics. Having target specific code in general passes was noted as
an area for improvement for a long time.
D81728 moves most target specific code out of the InstCombine pass.
Applying the target specific combinations in an extra pass would
probably result in inferior optimizations compared to the current
fixed-point iteration, therefore the InstCombine pass resorts to newly
introduced functions in the TargetTransformInfo when it encounters
unknown intrinsics.
The patch should not have any effect on generated code (under the
assumption that code never uses intrinsics from a foreign target).
This introduces three new functions:
TargetTransformInfo::instCombineIntrinsic
TargetTransformInfo::simplifyDemandedUseBitsIntrinsic
TargetTransformInfo::simplifyDemandedVectorEltsIntrinsic
A few target specific parts are left in the InstCombine folder, where
it makes sense to share code. The largest left-over part in
InstCombineCalls.cpp is the code shared between arm and aarch64.
This allows to move about 3000 lines out from InstCombine to the targets.
Differential Revision: https://reviews.llvm.org/D81728
Enable clausing of memory loads on gfx10 by adding a new pass to insert
the s_clause instructions that mark the start of each hard clause.
Differential Revision: https://reviews.llvm.org/D79792
This pass can handle all the optimization
opportunities found just before code emission.
Presently it includes the handling of vcc branch
optimization that was handled earlier in SIInsertSkips.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D76712
The current set of custom combines are only really useful after
legalization, so move them there. There is a lot of overlap in the
boilerplate here, but I think we do want a pretty different set of
combines before and after legalize. I think we will want a lot of
overlap between the post-legalize and a post-regbankselect combiner.
We are relying on atrificial DAG edges inserted by the
MemOpClusterMutation to keep loads and stores together in the
post-RA scheduler. This does not work all the time since it
allows to schedule a completely independent instruction in the
middle of the cluster.
Removed the DAG mutation and added pass to bundle already
clustered instructions. These bundles are unpacked before the
memory legalizer because it does not work with bundles but also
because it allows to insert waitcounts in the middle of a store
cluster.
Removing artificial edges also allows a more relaxed scheduling.
Differential Revision: https://reviews.llvm.org/D72737
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
Ruiling Song