We are using `PostMachineScheduler` instead of `PostRAScheduler`
since #68696.
The hook `getPostRAMutations` is only used in `PostRAScheduler` so
it is actually dead code for RISC-V now.
This is based on other targets like PPC/AArch64 and some experiments.
This PR will only enable bidirectional scheduling and tracking register
pressure.
Disclaimer: I haven't tested it on many cores, maybe we should make
some options being features. I believe downstreams must have tried
this before, so feedbacks are welcome.
Fixed length vectors use scalable vector containers. With Zve32* and not
Zvl64b, vscale is a 0.5 due RVVBitsPerBlock being 64.
To support this correctly we need to lower RVVBitsPerBlock to 32 and
change our type mapping. But we need to RVVBitsPerBlock to alway be
>= ELEN. This means we need two different mapping depending on ELEN.
That is a non-trivial amount of work so disable fixed lenght vectors
without Zvl64b for now.
We had almost no tests for Zve32x without Zvl64b which is probably why
we never realized that it was broken.
Fixes#102352.
Instead of std::unique_ptr<RegisterBankInfo>. This allows us to return a
RISCVRegisterBankInfo* from getRegBankInfo so we can avoid a
static_cast.
This does require an additional header file to be included in
RISCVSubtarget.h, but I don't think it's a big deal.
Prior to this commit, we created the GlobalISel objects in the
RISCVSubtarget constructor, even if we are not running GlobalISel. This
patch moves creation of the GlobalISel objects into their getters, which
ensures that we only create these objects if they are actually needed.
This helps since some of the constructors of the GlobalISel objects have
a significant amount of code.
We make the `unique_ptr`s `mutable` since GlobalISel passes only have
access to `const TargetSubtargetInfo` through `MF.getSubtarget()`.
This patch is tested by the fact that all existing RISC-V GlobalISel
tests remain passing.
This removes the uses of target flags to disable subreg liveness,
relying on the `-enable-subreg-liveness` flag instead. The
`-enable-subreg-liveness` flag has been changed to take precedence over
the subtarget if set, and one use of `Subtarget->enableSubRegLiveness()`
has been changed to `MRI->subRegLivenessEnabled()` to make sure the
option properly applies.
We convert existed macro fusions to TableGen.
Bacause `Fusion` depend on `Instruction` definitions which is defined
below `RISCVFeatures.td`, so we recommend user to add fusion features
when defining new processor.
There are many information that can be used for tuning, like
alignments, cache line size, etc. But we can't make all of them
`SubtargetFeature` because some of them are not with enumerable
value, for example, `PrefetchDistance` used by `LoopDataPrefetch`.
In this patch, a searchable table `RISCVTuneInfoTable` is added,
in which each entry contains the CPU name and all tune information
defined in `RISCVTuneInfo`. Each field of `RISCVTuneInfo` should
have a default value and processor definitions can override the
default value via `let` statements.
We don't need to define a `RISCVTuneInfo` for each processor and
it will use the default value (which is for `generic`) if no
`RISCVTuneInfo` defined.
For processors in the same series, a subclass can inherit from
`RISCVTuneInfo` and override the fields. And we can also override
the fields in processor definitions if there are some differences
in the same processor series.
When initilizing `RISCVSubtarget`, we will use `TuneCPU` as the
key to serach the tune info table. So, the behavior here is if
we don't specify the tune CPU, we will use specified `CPU`, which
is expected I think.
This patch almost undoes 61ab106, in which I added tune features
of preferred function/loop alignments. More tune information can
be added in the future.
We're already tracking XLen, we can compute XLenVt from that. Note that XLen itself should probably be driven from IsRV64 (the processor flag), but I'm leaving that to a separate change (with review).
In llvm alias analysis is off by default now.
This patch enable alias analysis on RISCV target during code generation by default,
and this makes more chances for improving performance.
Modified related test cases.
Differential Revision: https://reviews.llvm.org/D157250
This patch adds logic for determining RegisterBank size to RegisterBankInfo, which allows accounting for the HwMode of the target. Individual RegisterBanks cannot be constructed with HwMode information as construction is generated by TableGen, but a RegisterBankInfo subclass can provide the HwMode as a constructor argument. The HwMode is used to select the appropriate RegisterBank size from an array relating sizes to RegisterBanks.
Targets simply need to provide the HwMode argument to the <target>GenRegisterBankInfo constructor. The RISC-V RegisterBankInfo constructor has been updated accordingly (plus an unused argument removed).
Reviewed By: simoncook, craig.topper
Differential Revision: https://reviews.llvm.org/D76007
Fuchsia's ABI always reserves the x18 (s2) register for the
ShadowCallStack ABI, even when -fsanitize=shadow-call-stack is
not enabled.
Reviewed By: phosek
Differential Revision: https://reviews.llvm.org/D143355
This change enables the use of RISCV's variable length vector registers for fixed length vectors in the IR, and implicitly enables various IR transforms which generate fixed length vectors if legal (e.g. LoopVectorize). Specifically, this enables fixed length vectors which are known to be inbounds of the underlying variable hardware size.
For context, remember that the +V extension provides a minimum VLEN of 128. The embedded variants provide lower minimums. The analogy here is essentially vectorizing for SSE on a machine which may or may not include AVX2/AVX512. We won't get full utilization by default, but we will get some benefit. And of course, with an explicit mcpu we can vectorize to the exact target hardware.
The LV impact is mostly related to vectorizer robustness. In cases we haven't yet fully implemented scalable vectorization support, we can fall back to fixed length vectorization.
SLP has been disabled for now, even when fixed vectors are enabled. See a310637 and associated review. There are a few addiitional code quality issues which need worked through before turning SLP on would be reasonable.
Differential Revision: https://reviews.llvm.org/D131508
Saves a heap allocation and avoids an explicit call to the BitVector constructor.
Reviewed By: reames, myhsu
Differential Revision: https://reviews.llvm.org/D132674
We previously enabled subregister liveness by default when compiling
with RVV. This has been shown to cause miscompilations where RVV
register operand constraints are not met. A test was added for this in
D129639 which explains the issue in more detail.
Until this issue is fixed in some way, we should not be enabling
subregister liveness unless the user asks for it.
Reviewed By: craig.topper, rogfer01, kito-cheng
Differential Revision: https://reviews.llvm.org/D129646
This adds the macrofusion plumbing and support fusing LUI+ADDI(W).
This is similar to D73643, but handles a different case. Other cases
can be added in the future.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D128393
The failure that caused the previous revert has been fixed
by https://reviews.llvm.org/D126048
Original commit message:
RVV makes heavy use of subregisters due to LMUL>1 and segment
load/store tuples. Enabling subregister liveness tracking improves the quality
of the register allocation.
I've added a command line that can be used to turn it off if it causes compile
time or functional issues. I used the command line to keep the old behavior
for one interesting test case that was testing register allocation.
Reviewed By: kito-cheng
Differential Revision: https://reviews.llvm.org/D128016
This reverts most of ed242b54c9c2aa84a47f66af5b8497d93646b68d
I'm seeing failures in our intrinsic testing on qemu that seem
related to this. Reverting while I investigate.
I've left the command line option in place for directed testing.
It defaults to off.
RVV makes heavy use of subregisters due to LMUL>1 and segment
load/store tuples. Enabling subregister liveness tracking improves the quality
of the register allocation.
I've added a command line that can be used to turn it off if it causes compile
time or functional issues. I used the command line to keep the old behavior
for one interesting test case that was testing register allocation.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D125108
riscv-v-vector-bits-min is primarily used to opt-in to the
autovectorizer. The vector width can be determined from Zvl*b.
This patch adds support treating -1 as meaning use Zvl*b so we can
still opt-in to autovectorization without needing to repeat a
vector width already given by Zvl*b or -mcpu.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D124960
This was added before Zve extensions were defined. I think users
should use Zve32x or Zve32f now. Though we will lose support for limiting
ELEN to 16 or 8, but I hope no one was using that.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D123418
Most other targets support 'generic', but RISCV issues an error.
This can require a special case in tools that use LLVM that aren't
clang.
This patch treats "generic" the same as an empty string and remaps
it to generic-rv/rv64 based on the triple. Unfortunately, it has to
be added to RISCV.td because MCSubtargetInfo is constructed and
parses the CPU before RISCVSubtarget's constructor gets a chance
to remap it. The CPU will then reparsed and the state in the
MCSubtargetInfo subclass will be updated again.
Fixes PR54146.
Reviewed By: khchen
Differential Revision: https://reviews.llvm.org/D121149
In the Zve* extensions, the vlen could be 64. This patch change the vlen constraint of low bound to 64.
Differential Revision: https://reviews.llvm.org/D118217
This is needed to properly limit fractional LMULs for Zve32.
Add new RUN Zve32 RUN lines to the existing tests for the
-riscv-v-fixed-length-vector-elen-max command line option.
`zvl` is the new standard vector extension that specifies the minimum vector length of the vector extension.
The `zvl` extension is related to the `zve` extension and other updates that are added in v1.0.
According to https://github.com/riscv-non-isa/riscv-c-api-doc/pull/21,
Clang defines macro `__riscv_v_min_vlen` for `zvl` and it can be used for applications that uses the vector extension.
LLVM checks whether the option `riscv-v-vector-bits-min` (if specified) matches the `zvl*` extension specified.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D108694
For large integers (for example, magic numbers generated by
TargetLowering::BuildSDIV when dividing by constant), we may
need about 4~8 instructions to build them.
In the same time, it just takes two instructions to load
constants (with extra cycles to access memory), so it may be
profitable to put these integers into constant pool.
Reviewed By: asb, craig.topper
Differential Revision: https://reviews.llvm.org/D114950
Add new hasVInstructions() which is currently equivalent.
Replace vector uses of hasStdExtZfh/F/D with new vector specific
versions. The vector spec no longer requires that the vectors implement the
same types as scalar. It only requires that the scalar type is
the maximum size the vectors can support. This is currently
implemented using the scalar rule we were using before.
Add new hasVInstructionsI64() begin using to qualify code that
requires i64 vector elements.
This is all NFC for now, but we can start using this to better
implement D112408 which introduces the Zve extensions.
Reviewed By: frasercrmck, eopXD
Differential Revision: https://reviews.llvm.org/D112496
This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
This adds an ELEN limit for fixed length vectors. This will scalarize
any elements larger than this. It will also disable some fractional
LMULs. For example, if ELEN=32 then mf8 becomes illegal, i32/f32
vectors can't use any fractional LMULs, i16/f16 can only use mf2,
and i8 can use mf2 and mf4.
We may also need something for the scalable vectors, but that has
interactions with the intrinsics and we can't scalarize a scalable
vector.
Longer term this should come from one of the Zve* features
Make it a static function RISCVISelLowering, the only place it
is used.
I think I'm going to make this return a fractional LMULs in some
cases so I'm sorting out where it should live before I start
making changes.
I encountered a project that uses llvm that passes "generic" by
default. While I could fix that project, I wouldn't be surprised
if other projects did something similar. So it seems like
a good idea to provide a better error here.
I've also added validation of the 64Bit feature against the
triple so that we can catch a mismatched CPU before failing in
a mysterious way. We can make it pretty far in isel because we
calculate XLenVT from the triple and use that to set up the legal
integer type.
Reviewed By: luismarques, khchen
Differential Revision: https://reviews.llvm.org/D98307
This refines how we determine which masks types are legal and adds
support for loads, stores, and all ones/zeros splats.
I left a fixme in store handling where I think we need to zero
extra bits if the type isn't a multiple of a byte. If I remember
right from X86 there was some case we could have a store of a
1, 2, or 4 bit mask and have a scalar zextload that then expected the
bits to be 0. Its tricky to zero the bits with RVV. We need to do
something like round VL up, zero a register, lower the VL back down,
then do a tail undisturbed move into the zero register. Another
option might be to generate a mask of 1/2/4 bits set with a VL of 8
and use that to mask off the bits.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D96468
Define an option -riscv-vector-bits-max to specify the maximum vector
bits for vectorizer. Loop vectorizer will use the value to check if it
is safe to use the whole vector registers to vectorize the loop.
It is not the optimum solution for loop vectorizing for scalable vector.
It assumed the whole vector registers will be used to vectorize the code.
If it is possible, we should configure vl to do vectorize instead of
using whole vector registers.
We only consider LMUL = 1 in this patch.
This patch just an initial work for loop vectorizer for RISC-V Vector.
Differential Revision: https://reviews.llvm.org/D95659
This is an alternative to D95563.
This is modeled after a similar feature for AArch64's SVE that uses
predicated scalable vector instructions.a
Rather than use predication, this patch uses an explicit VL operand.
I've limited it to always use LMUL=1 for now, but we can improve this
in the future.
This requires a bunch of new ISD opcodes to carry the VL operand.
I think we can probably lower intrinsics to these ISD opcodes to
cut down on the size of the isel table. Which is why I've added
patterns for all integer/float types and not just LMUL=1.
I'm only testing one vector width right now, but the width is
programmable via the command line.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D95705
- The goal of this patch is improve option compatible with RISCV-V GCC,
-mcpu support on GCC side will sent patch in next few days.
- -mtune only affect the pipeline model and non-arch/extension related
target feature, e.g. instruction fusion; in td file it called
TuneFeatures, which is introduced by X86 back-end[1].
- -mtune accept all valid option for -mcpu and extra alias processor
option, e.g. `generic`, `rocket` and `sifive-7-series`, the purpose is
option compatible with RISCV-V GCC.
- Processor alias for -mtune will resolve according the current target arch,
rv32 or rv64, e.g. `rocket` will resolve to `rocket-rv32` or `rocket-rv64`.
- Interaction between -mcpu and -mtune:
* -mtune has higher priority than -mcpu for pipeline model and
TuneFeatures.
[1] https://reviews.llvm.org/D85165
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D89025
This patch implements initial backend support for a -mtune CPU controlled by a "tune-cpu" function attribute. If the attribute is not present X86 will use the resolved CPU from target-cpu attribute or command line.
This patch adds MC layer support a tune CPU. Each CPU now has two sets of features stored in their GenSubtargetInfo.inc tables . These features lists are passed separately to the Processor and ProcessorModel classes in tablegen. The tune list defaults to an empty list to avoid changes to non-X86. This annoyingly increases the size of static tables on all target as we now store 24 more bytes per CPU. I haven't quantified the overall impact, but I can if we're concerned.
One new test is added to X86 to show a few tuning features with mismatched tune-cpu and target-cpu/target-feature attributes to demonstrate independent control. Another new test is added to demonstrate that the scheduler model follows the tune CPU.
I have not added a -mtune to llc/opt or MC layer command line yet. With no attributes we'll just use the -mcpu for both. MC layer tools will always follow the normal CPU for tuning.
Differential Revision: https://reviews.llvm.org/D85165
This reverts commit e9f22fd4293a65bcdcf1b18b91c72f63e5e9e45b.
When building with -DLLVM_USE_SANITIZER="Thread", check-llvm has 70
failing tests with this revision, and 29 without this revision.
This patch generates TableGen descriptions for the specified register
banks which contain a list of register sizes corresponding to the
available HwModes. The appropriate size is used during codegen according
to the current HwMode. As this HwMode was not available on generation,
it is set upon construction of the RegisterBankInfo class. Targets
simply need to provide the HwMode argument to the
<target>GenRegisterBankInfo constructor.
The RISC-V RegisterBankInfo constructor has been updated accordingly
(plus an unused argument removed).
Differential Revision: https://reviews.llvm.org/D76007
