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Support mod (modify) operands, for better efficiency with regalloc.rs/Cranelift shim.

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This commit is contained in:
Chris Fallin
2021-05-07 19:48:34 -07:00
parent d2cc4f1ac2
commit a6e3128821
4 changed files with 87 additions and 56 deletions
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6
src/checker.rs
View File

@@ -297,10 +297,8 @@ impl CheckerState {
// the requirements of the OperandPolicy.
for (op, alloc) in operands.iter().zip(allocs.iter()) {
let is_here = match (op.pos(), pos) {
(OperandPos::Before, InstPosition::Before)
| (OperandPos::Both, InstPosition::Before) => true,
(OperandPos::After, InstPosition::After)
| (OperandPos::Both, InstPosition::After) => true,
(OperandPos::Before, InstPosition::Before) => true,
(OperandPos::After, InstPosition::After) => true,
_ => false,
};
if !is_here {

62
src/ion/mod.rs
View File

@@ -326,19 +326,16 @@ struct PRegData {
/*
* Environment setup:
*
* We have seven fundamental objects: LiveRange, LiveBundle, SpillSet, Use, Def, VReg, PReg.
* We have seven fundamental objects: LiveRange, LiveBundle, SpillSet, Use, VReg, PReg.
*
* The relationship is as follows:
*
* LiveRange --(vreg)--> shared(VReg)
* LiveRange --(bundle)--> shared(LiveBundle)
* LiveRange --(def)--> owns(Def)
* LiveRange --(use) --> list(Use)
*
* Use --(vreg)--> shared(VReg)
*
* Def --(vreg) --> owns(VReg)
*
* LiveBundle --(range)--> list(LiveRange)
* LiveBundle --(spillset)--> shared(SpillSet)
* LiveBundle --(parent)--> parent(LiveBundle)
@@ -565,6 +562,7 @@ enum Requirement {
Any(RegClass),
}
impl Requirement {
#[inline(always)]
fn class(self) -> RegClass {
match self {
Requirement::Fixed(preg) => preg.class(),
@@ -573,7 +571,7 @@ impl Requirement {
}
}
}
#[inline(always)]
fn merge(self, other: Requirement) -> Option<Requirement> {
if self.class() != other.class() {
return None;
@@ -590,6 +588,7 @@ impl Requirement {
_ => None,
}
}
#[inline(always)]
fn from_operand(op: Operand) -> Requirement {
match op.policy() {
OperandPolicy::FixedReg(preg) => Requirement::Fixed(preg),
@@ -1034,7 +1033,7 @@ impl<'a, F: Function> Env<'a, F> {
);
lrdata.uses_spill_weight_and_flags -= spill_weight_from_policy(usedata.operand.policy());
if usedata.operand.kind() == OperandKind::Def {
if usedata.operand.kind() != OperandKind::Use {
lrdata.uses_spill_weight_and_flags -= 2000;
}
}
@@ -1083,7 +1082,7 @@ impl<'a, F: Function> Env<'a, F> {
spill_weight_from_policy(policy)
);
self.ranges[into.index()].uses_spill_weight_and_flags += spill_weight_from_policy(policy);
if self.uses[u.index()].operand.kind() == OperandKind::Def {
if self.uses[u.index()].operand.kind() != OperandKind::Use {
self.ranges[into.index()].uses_spill_weight_and_flags += 2000;
}
log::debug!(" -> now {}", self.ranges[into.index()].uses_spill_weight());
@@ -1149,11 +1148,11 @@ impl<'a, F: Function> Env<'a, F> {
live.set(dst.vreg(), false);
live.set(src.vreg(), true);
}
for pos in &[OperandPos::After, OperandPos::Both, OperandPos::Before] {
for pos in &[OperandPos::After, OperandPos::Before] {
for op in self.func.inst_operands(inst) {
if op.pos() == *pos {
match op.kind() {
OperandKind::Use => {
OperandKind::Use | OperandKind::Mod => {
live.set(op.vreg().vreg(), true);
}
OperandKind::Def => {
@@ -1355,11 +1354,12 @@ impl<'a, F: Function> Env<'a, F> {
// don't borrow `self`
let operand = self.func.inst_operands(inst)[i];
match operand.kind() {
OperandKind::Def => {
OperandKind::Def | OperandKind::Mod => {
// Create the Def object.
let pos = match operand.pos() {
OperandPos::Before | OperandPos::Both => ProgPoint::before(inst),
OperandPos::After => ProgPoint::after(inst),
let pos = match (operand.kind(), operand.pos()) {
(OperandKind::Mod, _) => ProgPoint::before(inst),
(_, OperandPos::Before) => ProgPoint::before(inst),
(_, OperandPos::After) => ProgPoint::after(inst),
};
let u = UseIndex(self.uses.len() as u32);
self.uses
@@ -1370,11 +1370,6 @@ impl<'a, F: Function> Env<'a, F> {
// Fill in vreg's actual data.
self.vreg_regs[operand.vreg().vreg()] = operand.vreg();
// Trim the range for this vreg to start
// at `pos` if it previously ended at the
// start of this block (i.e. was not
// merged into some larger LiveRange due
// to out-of-order blocks).
let mut lr = vreg_ranges[operand.vreg().vreg()];
log::debug!(" -> has existing LR {:?}", lr);
// If there was no liverange (dead def), create a trivial one.
@@ -1389,22 +1384,34 @@ impl<'a, F: Function> Env<'a, F> {
);
log::debug!(" -> invalid; created {:?}", lr);
}
self.insert_use_into_liverange_and_update_stats(lr, u);
if operand.kind() == OperandKind::Def {
// Trim the range for this vreg to start
// at `pos` if it previously ended at the
// start of this block (i.e. was not
// merged into some larger LiveRange due
// to out-of-order blocks).
if self.ranges[lr.index()].range.from
== self.cfginfo.block_entry[block.index()]
{
log::debug!(" -> started at block start; trimming to {:?}", pos);
log::debug!(
" -> started at block start; trimming to {:?}",
pos
);
self.ranges[lr.index()].range.from = pos;
}
self.insert_use_into_liverange_and_update_stats(lr, u);
// Remove from live-set.
live.set(operand.vreg().vreg(), false);
vreg_ranges[operand.vreg().vreg()] = LiveRangeIndex::invalid();
}
}
OperandKind::Use => {
// Establish where the use occurs.
let mut pos = match operand.pos() {
OperandPos::Before => ProgPoint::before(inst),
OperandPos::Both | OperandPos::After => ProgPoint::after(inst),
OperandPos::After => ProgPoint::after(inst),
};
// If there are any reused inputs in this
// instruction, and this is *not* the
@@ -2612,8 +2619,9 @@ impl<'a, F: Function> Env<'a, F> {
// the def so we don't need to insert a move.
use_data.pos
} else {
// For an use, split before the instruction --
// this allows us to insert a move if necessary.
// For an use or mod, split before the instruction
// -- this allows us to insert a move if
// necessary.
ProgPoint::before(use_data.pos.inst())
};
let after_use_inst = ProgPoint::before(use_data.pos.inst().next());
@@ -4118,9 +4126,11 @@ impl<'a, F: Function> Env<'a, F> {
);
}
// Ensure edits are in sorted ProgPoint order.
self.edits
.sort_unstable_by_key(|&(pos, prio, _)| (pos, prio));
// Ensure edits are in sorted ProgPoint order. N.B.: this must
// be a stable sort! We have to keep the order produced by the
// parallel-move resolver for all moves within a single sort
// key.
self.edits.sort_by_key(|&(pos, prio, _)| (pos, prio));
self.stats.edits_count = self.edits.len();
// Add debug annotations.

55
src/lib.rs
View File

@@ -209,7 +209,7 @@ pub struct Operand {
/// so that clients, if they wish, can track just one `u32` per
/// register slot and edit it in-place after allocation.
///
/// policy:3 kind:1 pos:2 class:1 preg:5 vreg:20
/// policy:3 kind:2 pos:1 class:1 preg:5 vreg:20
bits: u32,
}
@@ -237,7 +237,7 @@ impl Operand {
| (preg_field << 20)
| (class_field << 25)
| (pos_field << 26)
| (kind_field << 28)
| (kind_field << 27)
| (policy_field << 29),
}
}
@@ -253,7 +253,12 @@ impl Operand {
}
#[inline(always)]
pub fn reg_use_at_end(vreg: VReg) -> Self {
Operand::new(vreg, OperandPolicy::Reg, OperandKind::Use, OperandPos::Both)
Operand::new(
vreg,
OperandPolicy::Reg,
OperandKind::Use,
OperandPos::After,
)
}
#[inline(always)]
pub fn reg_def(vreg: VReg) -> Self {
@@ -266,11 +271,21 @@ impl Operand {
}
#[inline(always)]
pub fn reg_def_at_start(vreg: VReg) -> Self {
Operand::new(vreg, OperandPolicy::Reg, OperandKind::Def, OperandPos::Both)
Operand::new(
vreg,
OperandPolicy::Reg,
OperandKind::Def,
OperandPos::Before,
)
}
#[inline(always)]
pub fn reg_temp(vreg: VReg) -> Self {
Operand::new(vreg, OperandPolicy::Reg, OperandKind::Def, OperandPos::Both)
Operand::new(
vreg,
OperandPolicy::Reg,
OperandKind::Def,
OperandPos::Before,
)
}
#[inline(always)]
pub fn reg_reuse_def(vreg: VReg, idx: usize) -> Self {
@@ -278,7 +293,7 @@ impl Operand {
vreg,
OperandPolicy::Reuse(idx),
OperandKind::Def,
OperandPos::Both,
OperandPos::After,
)
}
#[inline(always)]
@@ -318,21 +333,21 @@ impl Operand {
#[inline(always)]
pub fn kind(self) -> OperandKind {
let kind_field = (self.bits >> 28) & 1;
let kind_field = (self.bits >> 27) & 3;
match kind_field {
0 => OperandKind::Def,
1 => OperandKind::Use,
1 => OperandKind::Mod,
2 => OperandKind::Use,
_ => unreachable!(),
}
}
#[inline(always)]
pub fn pos(self) -> OperandPos {
let pos_field = (self.bits >> 26) & 3;
let pos_field = (self.bits >> 26) & 1;
match pos_field {
0 => OperandPos::Before,
1 => OperandPos::After,
2 => OperandPos::Both,
_ => unreachable!(),
}
}
@@ -415,14 +430,14 @@ impl std::fmt::Display for OperandPolicy {
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum OperandKind {
Def = 0,
Use = 1,
Mod = 1,
Use = 2,
}
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum OperandPos {
Before = 0,
After = 1,
Both = 2,
}
/// An Allocation represents the end result of regalloc for an
@@ -585,7 +600,8 @@ impl OperandOrAllocation {
let bits = alloc.bits()
| match kind {
OperandKind::Def => 0,
OperandKind::Use => 1 << 28,
OperandKind::Mod => 1 << 27,
OperandKind::Use => 2 << 27,
};
Self { bits }
}
@@ -604,11 +620,11 @@ impl OperandOrAllocation {
}
pub fn as_allocation(&self) -> Option<Allocation> {
if self.is_allocation() {
// Remove the def/use bit -- the canonical `Allocation`
// does not have this, and we want allocs to continue to
// be comparable whether they are used for reads or
// writes.
Some(Allocation::from_bits(self.bits & !(1 << 28)))
// Remove the kind (def/use/mod) bits -- the canonical
// `Allocation` does not have this, and we want allocs to
// continue to be comparable whether they are used for
// reads or writes.
Some(Allocation::from_bits(self.bits & !(3 << 27)))
} else {
None
}
@@ -618,7 +634,8 @@ impl OperandOrAllocation {
let kind_field = (self.bits >> 28) & 1;
match kind_field {
0 => OperandKind::Def,
1 => OperandKind::Use,
1 => OperandKind::Mod,
2 => OperandKind::Use,
_ => unreachable!(),
}
}

6
src/ssa.rs
View File

@@ -47,6 +47,12 @@ pub fn validate_ssa<F: Function>(f: &F, cfginfo: &CFGInfo) -> Result<(), RegAllo
}
defined[operand.vreg().vreg()] = true;
}
OperandKind::Mod => {
// Mod (modify) operands are not used in SSA,
// but can be used by non-SSA code (e.g. with
// the regalloc.rs compatibility shim).
return Err(RegAllocError::SSA(operand.vreg(), iix));
}
}
}
}