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
A new pass MachineLateInstrsCleanup is added to be run after PEI.
This is a simple pass that removes redundant and identical instructions
whenever found by scanning the MF once while keeping track of register
definitions in a map. These instructions are typically immediate loads
resulting from rematerialization, and address loads emitted by target in
eliminateFrameInde().
This is enabled by default, but a target could easily disable it by means of
'disablePass(&MachineLateInstrsCleanupID);'.
This late cleanup is naturally not "optimal" in removing instructions as it
is done by looking at phys-regs, but still quite effective. It would be
desirable to improve other parts of CodeGen and avoid these redundant
instructions in the first place, but there are no ideas for this yet.
Differential Revision: https://reviews.llvm.org/D123394
Reviewed By: RKSimon, foad, craig.topper, arsenm, asb
We can reuse constants if we use SRL followed by AND and AND followed by SHL.
Similar was done to bitreverse previously.
Differential Revision: https://reviews.llvm.org/D138045
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
RVV doesn't have immediate field for memory addressing. Currently
we build MachineInstructions in PEI to computing stack offset for
RVV load store instructions. These instructions were added too late to
can be optimized by CSE, LICM... passes.
This patch makes FrameIndex SDNodes can't be matched in RVV Load Store
instruction selection patterns. So that the FrameIndex SDNodes would be
selected as `ADDI GPR, targetframeindex`.
There are 2 advantages for such change:
1. Stack objects address computing can be optimized by machine function
passes.
2. Since the ADDI instruction's destination register can be used as a
temp register, we can save an emergency spill slot.
Differential Revision: https://reviews.llvm.org/D128187
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 an alias of `addi [x], zero, imm` to generate pseudo
instruction li, which makes assembly mush more readable.
For existed tests, users can update them by running script
`llvm/utils/update_llc_test_checks.py`.
Reviewed By: asb
Differential Revision: https://reviews.llvm.org/D112692
