This can avoid a loss of decoupling with the scalar unit on cores
with decoupled scalar and vector units.
We should support FP too, but those use extract_element and not a
custom ISD node so it is a little different. I also left a FIXME
in the test for i64 extract and store on RV32.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D109482
If one input of a fixed vector multiply is a sign/zero extend and
the other operand is a splat of a scalar, we can use a widening
multiply if the scalar value has sufficient sign/zero bits.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D110028
This particular case was creating a `VMSET_VL` using the old
fixed-length type in order to pass a mask to other custom nodes
operating on the scalable container type. This kind of thing wasn't
caught for us; I only noticed when experimenting with odd-length
vectors, where it was trying to generate an invalid `v3i1` MVT.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D110420
Add the tail policy argument to LLVM IR intrinsics. There are two policies for tail elements. Tail agnostic means users do not care about the values in the tail elements and tail undisturbed means the values in the tail elements need to be kept after the operation. In order to let users control the tail policy, we add an additional argument at the end of the argument list.
For unmasked operations, we have no maskedoff and the tail policy is always tail agnostic. If users want to keep tail elements under unmasked operations, they could use all one mask in the masked operations to do it. So, we only add the additional argument for masked operations for most cases. There are exceptions listed below.
In this patch, we do not handle the following cases to reduce the complexity of the patch. There could be two separate patches for them.
* Use dest argument to control tail policy
vmerge.vvm/vmerge.vxm/vmerge.vim (add _t builtins with additional dest argument)
vfmerge.vfm (add _t builtins with additional dest argument)
vmv.v.v (add _t builtins with additional dest argument)
vmv.v.x (add _t builtins with additional dest argument)
vmv.v.i (add _t builtins with additional dest argument)
vfmv.v.f (add _t builtins with additional dest argument)
vadc.vvm/vadc.vxm/vadc.vim (add _t builtins with additional dest argument)
vsbc.vvm/vsbc.vxm (add _t builtins with additional dest argument)
* Always has tail argument for masked/unmasked intrinsics
Vector Single-Width Integer Multiply-Add Instructions (add _t and _mt builtins)
Vector Widening Integer Multiply-Add Instructions (add _t and _mt builtins)
Vector Single-Width Floating-Point Fused Multiply-Add Instructions (add _t and _mt builtins)
Vector Widening Floating-Point Fused Multiply-Add Instructions (add _t and _mt builtins)
Vector Reduction Operations (add _t and _mt builtins)
Vector Slideup Instructions (add _t and _mt builtins)
Vector Slidedown Instructions (add _t and _mt builtins)
Discussion: https://github.com/riscv/rvv-intrinsic-doc/pull/101
Differential Revision: https://reviews.llvm.org/D105092
This patch adds codegen support for lowering the vector-predicated
reduction intrinsics to RVV instructions. The process is similar to that
of the other reduction intrinsics, save for the fact that every VP
reduction has a start value. We reuse the existing custom "VL" nodes,
adding extra patterns where required to handle non-true masks.
To support these nodes, the `RISCVISD::VECREDUCE_*_VL` nodes have been
given an explicit "merge" operand. This is to faciliate the VP
reductions, where we must be careful to ensure that even if no operation
is performed (when VL=0) we still produce the start value. The RVV
reductions don't update the destination register under these conditions,
so we tie the splatted start value to the output register.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D107657
We can use riscv_vse intrinsic instead of riscv_vse_mask. The code here
is based on similar code for handling masked.scatter and vp.scatter.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D110206
This requires a minor change to CodeGenPrepare to ensure that
shouldSinkOperands will be called for And.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D110106
Optimize (add (mul x, c0), c1) -> (ADDI (MUL (ADDI, c1/c0), c0), c1%c0),
if c1/c0 and c1%c0 are simm12, while c1 is not.
Optimize (add (mul x, c0), c1) -> (MUL (ADDI, c1/c0), c0),
if c1%c0 is zero, and c1/c0 is simm12 while c1 is not.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D108607
For strided accesses the loop vectorizer seems to prefer creating a
vector induction variable with a start value of the form
<i32 0, i32 1, i32 2, ...>. This value will be incremented each
loop iteration by a splat constant equal to the length of the vector.
Within the loop, arithmetic using splat values will be done on this
vector induction variable to produce indices for a vector GEP.
This pass attempts to dig through the arithmetic back to the phi
to create a new scalar induction variable and a stride. We push
all of the arithmetic out of the loop by folding it into the start,
step, and stride values. Then we create a scalar GEP to use as the
base pointer for a strided load or store using the computed stride.
Loop strength reduce will run after this pass and can do some
cleanups to the scalar GEP and induction variable.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D107790
LICM may have pulled out a splat, but with .vx instructions we
can fold it into an operation.
This patch enables CGP to reverse the LICM transform and move the
splat back into the loop.
I've started with the commutable integer operations and shifts, but we can
extend this with more operations in future patches.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D109394
Since i128 isn't a legal C type on RV32, I don't believe
libgcc implements these functions for RV32. compiler-rt
does implement them because i128 support is enabled
in order to handle long double.
This is consistent with 32-bit X86 and ARM.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D109383
This patch adds support for the vector-predicated `VP_STORE` and
`VP_LOAD` nodes. We do this in the same way we lower `MSTORE` and
`MLOAD`: to regular load/store instructions via intrinsics.
One necessary change was made to `SelectionDAGLegalize` so that
`VP_STORE` nodes' operation actions are taken from the stored "value"
operands, in the same vein as `STORE` or `MSTORE`.
Reviewed By: craig.topper, rogfer01
Differential Revision: https://reviews.llvm.org/D108999
This patch adds support for the `VP_SCATTER` and `VP_GATHER` nodes by
lowering them to RVV's `vsox`/`vlux` instructions, respectively. This
process is almost identical to the existing `MSCATTER`/`MGATHER` support.
One extra change was made to `SelectionDAGLegalize` so that
`VP_SCATTER`'s operation action is derived from its stored "value"
operand rather than its return type (which is always the chain).
Reviewed By: craig.topper, rogfer01
Differential Revision: https://reviews.llvm.org/D108987
This patch changes the register class to avoid accidentally setting
the AVL operand to X0 through MachineIR optimizations.
There are cases where we really want to use X0, but we can't get that
past the MachineVerifier with the register class as GPRNoX0. So I've
use a 64-bit -1 as a sentinel for X0. All other immediate values should
be uimm5. I convert it to X0 at the earliest possible point in the VSETVLI
insertion pass to avoid touching the rest of the algorithm. In
SelectionDAG lowering I'm using a -1 TargetConstant to hide it from
instruction selection and treat it differently than if the user
used -1. A user -1 should be selected to a register since it doesn't
fit in uimm5.
This is the rest of the changes started in D109110. As mentioned there,
I don't have a failing test from MachineIR optimizations anymore.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D109116
If the true and false values are the same, we don't need a SELECT_CC.
This would normally be folded before a select is legalized to
select_cc. The test case exploits the late legalization of vscale
to trigger a case where they become identical after legalization.
This works around an issue found on a test case in D107957. In that
case the true/false values were both eventually 0 and the select was
used by a vector AVL operand. The select_cc got expanded to control
flow and a phi, but the phi inputs were both copies from X0. MachineIR
optimizations simplified this to a single copy from X0 going into the
vector instruction. This became the input of a vsetvli after vsetvli
insertion. Then register coalescing folded the copy into the vsetvli.
X0 as the source of a vsetvli is a special encoding and should not be
created by coalesing. We need to fix our vsetvli handling to make sure
this can never happen any other way, but removing the unneeded select
is still a worthwhile optimization.
Similar to D108842, D108844, D108926, D108928, and D108936.
__has_builtin(builtin_mul_overflow) returns true for 32b RISCV targets,
but Clang is deferring to compiler RT when encountering long long types.
If the semantics of __has_builtin mean "the compiler resolves these,
always" then we shouldn't conditionally emit a libcall.
Link: https://bugs.llvm.org/show_bug.cgi?id=28629
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D108939
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
Similar to what we do for add/sub/mul.
This can help remove some sext.w. There are some regressions on
some bswap tests, but I have an idea how to fix that for a follow up.
A new PACKW pattern is added to handle the new sext_inreg placement.
Differential Revision: https://reviews.llvm.org/D108663
This encapsulates the APInt creation and worklist management into
a helper function.
To keep one common interface I've use Log2_32 in places that
previously created a mask by subtracting 1 from a power of 2.
Differential Revision: https://reviews.llvm.org/D108324
We already do this for non-constants RHS. This just removes the
special case. I believe the special case may have been needed
because the ANY_EXTEND of a constant used to create zero extended
constants, but we recently changed that to produce sign extended
constants.
D107658 is needed to prevent some regressions.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D107697
Similar for sub except sub isn't commutative.
Modify the existing and/or/xor folds to also work on ISD::SELECT
and not just RISCVISD::SELECT_CC. This is needed to make sure
we do this transform before type legalization turns i32 add/sub
into add/sub+sign_extend_inreg on RV64. If we don't do this before
that, the sign_extend_inreg will still be after the select.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D107603
Shuffles which are broken into separate halves reveal splats in which
a half is accessed via one index; such operations can be optimized to
use "vrgather.vi".
This optimization could be achieved by adding extra patterns to match
`vrgather_vv_vl` which uses a splat as an index operand, but this patch
instead identifies splat earlier. This way, future optimizations can
build on top of the data gathered here, e.g., to splat-gather dominant
indices and insert any leftovers.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D107449
Previously we converted ISD condition codes to integers and stored
them directly in our MIR instructions. The ISD enum kind of belongs
to SelectionDAG so that seems like incorrect layering.
This patch instead uses a CondCode node on RISCV::SELECT_CC until
isel and then converts it from ISD encoding to a RISCV specific value.
This value can be converted to/from the RISCV branch opcodes in the
RISCV namespace.
My larger motivation is to possibly support a microarchitectural
feature of some CPUs where a short forward branch over a single
instruction can be predicated internally. This will require a new
pseudo instruction for select that needs to carry a branch condition
and live probably until RISCVExpandPseudos. At that point it can be
expanded to control flow without other instructions ending up in the
predicated basic block. Using an ISD encoding in RISCVExpandPseudos
doesn't seem like correct layering.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D107400
The fcvt fp to integer instructions saturate if their input is
infinity or out of range, but the instructions produce a maximum
integer for nan instead of 0 required for the ISD opcodes.
This means we can use the instructions to do the saturating
conversion, but we'll need to fix up the nan case at the end.
We can probably improve the i8 and i16 default codegen as well,
but I'll leave that for a follow up.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D107230
This patch extends the optimization of VID-sequence BUILD_VECTORs
introduced in D104921 to include simple fractional steps composed of a
separated integer numerator and denominator.
A notable limitation in this sequence detection is that only sequences
with steps N/1 or 1/D are found, meaning that the step between elements
and the frequency with which it changes is consistent across the whole
sequence. Fractional steps such as 2/3 won't be matched as those would
involve more complex tracking of state or some level of backtracking.
As is stands, however, this patch is sufficient to match common
interleave-type shuffle indices, for example matching `<0,0,1,1>` (or
commonly `<0,u,1,u>` or `<u,0,u,1>`) to an index sequence divided by 2.
While the optimization is relatively `undef`-tolerant, due to greedy
pattern-matching there even are some simple patterns which confuse the
sequence detection into identifying either a suboptimal sequence or no
sequence at all.
Currently only fractional-step sequences identified as having a
power-of-two denominator are actually lowered to RVV instructions. This
is to avoid introducing divisions into the generated code.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D106533
This patch aims to improve the performance of BUILD_VECTORs which are
identified as containing a dominant element. Given that most
floating-point constants themselves require a load from the constant
pool, it was possible for the optimization to actually increase the
number of individual loads on small vectors. The exception is the zero
constant -- +0.0 -- which can be materialized efficiently.
While this optimization could do with a proper cost model to weigh the
benfits of a single vector load vs. the manipulation of individual
elements -- even for integer vectors which often require several
instructions to materialize -- without a concrete RVV implementation to
work with any heuristic is likely to be both more obtuse and inaccurate.
Until then, this patch fixes at least one known obvious deficiency.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D106963
The sign_extend we insert here can get turned into a zero_extend if
the sign bit is known zero. This can enable a setcc combine that
shrinks compares with zero_extend. This reduces the use count of
the zero_extend allowing other combines to turn it back into an
any_extend.
This restricts the combine to only cases where the result is used
by a CopyToReg. This works for my original motivating case. I
hope the CopyToReg use will prevent any converted extends from
turning back into an any_extend.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D106754
This patch adds support for lowering the saturating vector add/sub
intrinsics to RVV instructions, for both fixed-length and
scalable-vector forms alike.
Note that some of the DAG combines are still not triggering for the
scalable-vector tests. These require a bit more work in the DAGCombiner
itself.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D106651
I stumbled onto a case where our (sext_inreg (assertzexti32 (fptoui X)), i32)
isel pattern can cause an fcvt.wu and fcvt.lu to be emitted if
the assertzexti32 has an additional user. If we add a one use check
it would just cause a fcvt.lu followed by a sext.w when only need
a fcvt.wu to satisfy both users.
To mitigate this I've added custom isel and new ISD opcodes for
fcvt.wu. This allows us to keep know it started life as a conversion
to i32 without needing to match multiple nodes. ComputeNumSignBits
has been taught that this new nodes produces 33 sign bits. To
prevent regressions when we need to zero extend the result of an
(i32 (fptoui X)), I've added a DAG combine to convert it to an
(i64 (fptoui X)) before type legalization. In most cases this would
happen in InstCombine, but a zero_extend can be created for function
returns or arguments.
To keep everything consistent I've added new nodes for fptosi as well.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D106346
Lowering certain float vectors without legal vector types could cause a
crash due to a bad interaction between passing floats via GPRs and
argument splitting. Split vector floats appear just like scalar floats.
Under certain situations we choose to pass these float arguments via
GPRs and use an XLenVT location and set the 'BCvt' info to track how
they must be converted back to floating-point values. However, later
logic for handling split arguments may take over, in which case we lose
the previous information and set the 'Indirect' info, thus incorrectly
lowering to integer types.
I don't believe that we would have come across the notion of split
floating-point arguments before. This patch addresses the issue by
updating the lowering so that split arguments are only passed indirectly
when they are scalar integer types.
This has some change to how we lower some larger illegal float vectors,
as can be seen in 'fastcc-float.ll' where the vector is now passed
partly in registers and partly on the stack.
Reviewed By: luismarques
Differential Revision: https://reviews.llvm.org/D102852
This relands a6ca88e908 which was originally
reverted due to overflow bugs in e3fa2b1eab.
This patch teaches the compiler to identify a wider variety of
`BUILD_VECTOR`s which form integer arithmetic sequences, and to lower
them to `vid.v` with modifications for non-unit steps and non-zero
addends.
The sequences handled by this optimization must either be monotonically
increasing or decreasing. Consecutive elements holding the same value
indicate a fractional step which, while simple mathematically,
becomes more complex to handle both in the realm of lossy integer
division and in the presence of `undef`s.
For example, a common "interleaving" shuffle index will be lowered by
LLVM to both `<0,u,1,u,2,...>` and `<u,0,u,1,u,...>` `BUILD_VECTOR`
nodes. Either of these would ideally be lowered to `vid.v` shifted right
by 1. Detection of this sequence in presence of general `undef` values
is more complicated, however: `<0,u,u,1,>` could match either
`<0,0,0,1,>` or `<0,0,1,1,>` depending on later values in the sequence.
Both are possible, so backtracking or multiple passes is inevitable.
Sticking to monotonic sequences keeps the logic simpler as it can be
done in one pass. Fractional steps will likely be a separate
optimization in a future patch.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D104921
The existing rule about the operand type is strange. Instead, just say
the operand is a TargetConstant with the right width. (Legalization
ignores TargetConstants, so it doesn't matter if that width is legal.)
Highlights:
1. I had to substantially rewrite the AArch64 isel patterns to expect a
TargetConstant. Nothing too exotic, but maybe a little hairy. Maybe
worth considering a target-specific node with some dagcombines instead
of this complicated nest of isel patterns.
2. Our behavior on RV32 for vectors of i64 has changed slightly. In
particular, we correctly preserve the width of the arithmetic through
legalization. This changes the DAG a bit. Maybe room for
improvement here.
3. I explicitly defined the behavior around overflow. This is necessary
to make the DAGCombine transforms legal, and I don't think it causes any
practical issues.
Differential Revision: https://reviews.llvm.org/D105673
If we need to shift left anyway we might be able to take advantage
of LUI implicitly shifting its immediate left by 12 to cover part
of the shift. This allows us to use more bits of the LUI immediate
to avoid an ADDI.
isDesirableToCommuteWithShift now considers compressed instruction
opportunities when deciding if commuting should be allowed.
I believe this is the same or similar to one of the optimizations
from D79492.
Reviewed By: luismarques, arcbbb
Differential Revision: https://reviews.llvm.org/D105417
I don't think the semantics of the llvm masked gather intrinsic care
about the order the elements are loaded. For example, type legalization
by splitting will chain them in parallel. This is different than
scatter which we do chain in order.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D106025
RISCV would prefer a sign extended constant since that works better
with our constant materialization. We have an existing TLI hook we
use to control sign extension of setcc operands in type legalization.
That hook happens to do the right check we need here, but might be
straying from its original purpose. With only RISCV defining this
hook in tree, I wasn't sure if it was worth adding another hook
with identical behavior.
This is an alternative to D105785 where I tried to handle this in
the RISCV backend by not creating ANY_EXTENDs in some places.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D105918
Craig Topper