In D154687, we added a transform to narrow indexed load/store indices of the
form (shl (zext), C). We can move this into a generic transform over the
target independent nodes instead, and pick up the fixed vector cases with no
additional work required. This is an alternative to D158163.
Performing this transform points out that we weren't eliminating zero_extends
via the the generic DAG combine. Adjust the (existing) callbacks so that we
do.
This change *removes* the existing transform on the target specific intrinsic
nodes. If anyone has a use case this impacts, please speak up.
Note: Reviewed as part of a stack of changes in PR# 66405.
(shl (zext to iXLenVec), C) is a possible pattern in auto-vectorized code for
indexed loads/stores. But extending to iXLen might be too aggressive, RVV
indexed load/store instructions zero extend their indexed operand to XLEN.
The patch tries to narrow the type of the zero extension. It's benefit to
decrease register pressure.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D154687
Since we use match shl (v, splat 1) to vadd, we could also expand to widening add.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D153112
The MC layer instructions have the correct register classes, and
the pseudos don't have any additional operands. So there doesn't
seem to be any reason for them to exist.
The pseudos were incorrectly going through code in RISCVMCInstLower
that converted LMUL>1 register classes to LMUL1 register class.
This makes the MCInst technically malformed, and prevented the
vl2r.v, vl4r.v, and vl8r.v InstAliases from matching. This accounts
for all of the .ll test diffs.
Differential Revision: https://reviews.llvm.org/D139511
Cannonical frame address after RVV stack adjustment is sp + StackSize +
RVVStackSize * vlenb, and since vlenb is unknown at compile-time (but it
is a constant for particular HW implementation), emit
.cfi_def_cfa_expression so libunwind can read VLENB CSR register at
run-time and obtain correct frame address.
Fixes https://github.com/llvm/llvm-project/issues/58356 (but additional
run-time support for reading CSR may be required)
Differential Revision: https://reviews.llvm.org/D136263
Continuing the theme of adding branchless lowerings for simple selects, this time handle the 0 arm case. This is very common for various umin idioms, etc..
Differential Revision: https://reviews.llvm.org/D135600
This changes the default value used for mask policy from mask undisturbed to mask agnostic. In hardware, there may be a minor preference for ta/ma, but since this is only going to apply to instructions which don't use the mask policy bit, this is functionally mostly a nop. The main value is to make future changes to using MA when legal for masked instructions easier to review by reducing test churn.
The prior code was motivated by a desire to minimize state transitions between masked and unmasked code. This patch achieves the same effect using the demanded field logic (landed in afb45ff), and there are no regressions I spotted in the test diffs. (Given the size, I have only been able to skim.) I do want to call out that regressions are possible here; the demanded analysis only works on a block local scope right now, so e.g. a tight loop mixing masked and unmasked computation might see an extra vsetvli or two.
Differential Revision: https://reviews.llvm.org/D133803
RISCV doesn't actually support a scaled form of indexed load and store. We previously handled this by forming the scaled SDNode, and then doing custom legalization during lowering. This patch instead adds a callback via TLI to prevent formation entirely.
This has two effects:
* First, the GEP gets expanded (and used). Instead of the shift being created with an SDLoc of the memory operation, it has the SDLoc of the GEP instruction. This avoids the scheduler perturbing IR order when there's no reason to.
* Second, we fix what appears to be a bug in index calculation with RV32. The rules for GEPs require index calculation be done in particular bitwidth, and it appears the custom legalization code got this wrong for the case where index type exceeds pointer width. (Or at least, I trust the generic GEP lowering to be correct a lot more.)
The DAGCombiner change to handle VPScatter/VPGather is technically separate, but is required to prevent a regression on those intrinsics.
Differential Revision: https://reviews.llvm.org/D134382
I have a couple data points that some microarchitectures prefer
the immediate 0 over x0. Does anyone know of microarchitectures
where the opposite is true?
Unfortunately, this is different than the vncvt.x.x.w alias
from the spec. Perhaps the alias was poorly chosen if x0 isn't
as optimal as immediate 0 on all microarchitectures.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D132041
The mask being NoRegister prevented the existing aliases from matching
since NoRegister isn't in the VMV0 register class.
To workaround this I've added new aliases that look for zero_reg.
I had to motify tablegen to generate matching code for zero_reg.
And as a consequence, I had to change the EmitPriority for an ARM
alias that used zero_reg that started printing.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D121496
Currently we allow half types in vectors if the scalar Zfh extension
is enabled. This behavior is not inline with the vector spec. For f32
and f64 types, the Zve32f, Zve64f, Zve64d, and V explicitly control
the availablity of floating point types in vectors.
In order to make our compiler compliant, we either need to remove all support
for half in vectors or we need an extension to control it.
Draft spec here https://github.com/riscv/riscv-v-spec/pull/780
Reviewed By: kito-cheng
Differential Revision: https://reviews.llvm.org/D121345
Inspired by a recent Discourse post on undef vs. poison usage, this
series of patches should reduce the number of undefs in LLVM tests by
around 10%.
Only undef vector operands to insertelement/shufflevector have been
handled, which are by far the most common we've got.
The switchover is split into 3 fairly arbitrary clusters to make it
slightly more manageable: vector predication, fixed-length vectors,
scalable vectors.
We were creating a truncate with the default for the type, but for
VP intrinsics we have a VL that we should use.
Reviewed By: frasercrmck
Differential Revision: https://reviews.llvm.org/D118406
This matches what the spec uses for the vncvt.x.x.w assembly
pseudoinstruction.
Reviewed By: kito-cheng
Differential Revision: https://reviews.llvm.org/D118295
Split these nodes in a similar way as their masked versions.
Reviewed By: frasercrmck, craig.topper
Differential Revision: https://reviews.llvm.org/D117760
GPR uses argument registers as the first group of registers to allocate.
This patch uses vector argument registers, v8 to v23, as the first group
to allocate.
Differential Revision: https://reviews.llvm.org/D111304
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
