Skip to content

Commit

Permalink
Split reverse analysis into header / body phases.
Browse files Browse the repository at this point in the history 
This is the precursor to us passing register information to the body
phase: there is no meaningful functional change here.
  • Loading branch information
@ltratt
ltratt committed Dec 29, 2024
1 parent 242f484 commit 5258b15
Show file tree
Hide file tree
Showing 2 changed files with 96 additions and 55 deletions.
4 changes: 3 additions & 1 deletion ykrt/src/compile/jitc_yk/codegen/x64/lsregalloc.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -154,7 +154,7 @@ impl<'a> LSRegAlloc<'a> {
stack.grow(interp_stack_len);

let mut rev_an = RevAnalyse::new(m);
rev_an.analyse();
rev_an.analyse_header();
LSRegAlloc {
m,
rev_an,
Expand Down Expand Up @@ -185,6 +185,8 @@ impl<'a> LSRegAlloc<'a> {
self.fp_reg_states[usize::from(reg.code())] = RegState::Reserved;
}
self.fp_regset = RegSet::with_fp_reserved();

self.rev_an.analyse_body();
}

/// Before generating code for the instruction at `iidx`, see which registers are no longer
Expand Down
147 changes: 93 additions & 54 deletions ykrt/src/compile/jitc_yk/codegen/x64/rev_analyse.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
use super::reg_alloc::{Register, VarLocation};
use crate::compile::jitc_yk::jit_ir::{
BinOp, BinOpInst, DynPtrAddInst, ICmpInst, Inst, InstIdx, LoadInst, Module, Operand,
PtrAddInst, SExtInst, SelectInst, StoreInst, TruncInst, ZExtInst,
PtrAddInst, SExtInst, SelectInst, StoreInst, TraceKind, TruncInst, ZExtInst,
};
use dynasmrt::x64::Rq;
use vob::Vob;
Expand Down Expand Up @@ -38,56 +38,95 @@ impl<'a> RevAnalyse<'a> {
}
}

pub(crate) fn analyse(&mut self) {
/// Analyse a trace header. If the trace is [TraceKind::HeaderAndBody], you must call
/// [Self::analyse_body] as soon as you have processed the trace header.
pub fn analyse_header(&mut self) {
let mut iter = self.m.iter_skipping_insts().rev();
match self.m.tracekind() {
TraceKind::HeaderOnly | TraceKind::Sidetrace => {
for (iidx, inst) in self.m.iter_skipping_insts().rev() {
self.analyse(iidx, inst);
}
}
TraceKind::HeaderAndBody => {
// OPT: We could pass the index for `TraceHeaderEnd` around, perhaps in the
// `TraceKind` to avoid having to find it this way.
let mut next = iter.next();
while let Some((_, inst)) = next {
if let Inst::TraceHeaderEnd = inst {
break;
}
next = iter.next();
}

while let Some((iidx, inst)) = next {
self.analyse(iidx, inst);
next = iter.next();
}
}
}
}

/// Analyse a trace body. This must be called iff both of the following are true:
/// 1. the trace is [TraceKind::HeaderAndBody]
/// 2. [Self::analyse_header] has already been called.
pub fn analyse_body(&mut self) {
for (iidx, inst) in self.m.iter_skipping_insts().rev() {
if self.used_insts.get(usize::from(iidx)).unwrap()
|| inst.has_store_effect(self.m)
|| inst.is_barrier(self.m)
{
self.used_insts.set(usize::from(iidx), true);
if let Inst::TraceHeaderEnd = inst {
break;
}
self.analyse(iidx, inst);
}
}

match inst {
Inst::BinOp(x) => self.an_binop(iidx, x),
Inst::ICmp(x) => self.an_icmp(iidx, x),
Inst::PtrAdd(x) => self.an_ptradd(iidx, x),
Inst::DynPtrAdd(x) => self.an_dynptradd(iidx, x),
// "Inline" `PtrAdd`s into loads/stores, and don't mark the `PtrAdd` as used. This
// means that some (though not all) `PtrAdd`s will not lead to actual code being
// generated.
Inst::Load(x) => {
if self.an_load(iidx, x) {
continue;
}
}
Inst::Store(x) => {
if self.an_store(iidx, x) {
continue;
}
}
Inst::TraceHeaderEnd => {
self.an_header_end();
}
Inst::TraceBodyEnd => {
self.an_body_end();
}
Inst::SidetraceEnd => {
self.an_sidetrace_end();
fn analyse(&mut self, iidx: InstIdx, inst: Inst) {
if self.used_insts.get(usize::from(iidx)).unwrap()
|| inst.has_store_effect(self.m)
|| inst.is_barrier(self.m)
{
self.used_insts.set(usize::from(iidx), true);

match inst {
Inst::BinOp(x) => self.an_binop(iidx, x),
Inst::ICmp(x) => self.an_icmp(iidx, x),
Inst::PtrAdd(x) => self.an_ptradd(iidx, x),
Inst::DynPtrAdd(x) => self.an_dynptradd(iidx, x),
// "Inline" `PtrAdd`s into loads/stores, and don't mark the `PtrAdd` as used. This
// means that some (though not all) `PtrAdd`s will not lead to actual code being
// generated.
Inst::Load(x) => {
if self.an_load(iidx, x) {
return;
}
Inst::SExt(x) => self.an_sext(iidx, x),
Inst::ZExt(x) => self.an_zext(iidx, x),
Inst::Select(x) => self.an_select(iidx, x),
Inst::Trunc(x) => self.an_trunc(iidx, x),
_ => (),
}

// Calculate inst_vals_alive_until
inst.map_operand_vars(self.m, &mut |x| {
self.used_insts.set(usize::from(x), true);
if self.inst_vals_alive_until[usize::from(x)] < iidx {
self.inst_vals_alive_until[usize::from(x)] = iidx;
Inst::Store(x) => {
if self.an_store(iidx, x) {
return;
}
});
}
Inst::TraceHeaderEnd => {
self.an_header_end();
}
Inst::TraceBodyEnd => {
self.an_body_end();
}
Inst::SidetraceEnd => {
self.an_sidetrace_end();
}
Inst::SExt(x) => self.an_sext(iidx, x),
Inst::ZExt(x) => self.an_zext(iidx, x),
Inst::Select(x) => self.an_select(iidx, x),
Inst::Trunc(x) => self.an_trunc(iidx, x),
_ => (),
}

// Calculate inst_vals_alive_until
inst.map_operand_vars(self.m, &mut |x| {
self.used_insts.set(usize::from(x), true);
if self.inst_vals_alive_until[usize::from(x)] < iidx {
self.inst_vals_alive_until[usize::from(x)] = iidx;
}
});
}
}

Expand Down Expand Up @@ -262,9 +301,9 @@ mod test {
use std::assert_matches::assert_matches;
use vob::vob;

fn rev_analyse<'a>(m: &'a Module) -> RevAnalyse<'a> {
fn rev_analyse_header<'a>(m: &'a Module) -> RevAnalyse<'a> {
let mut rev_an = RevAnalyse::new(m);
rev_an.analyse();
rev_an.analyse_header();
rev_an
}

Expand All @@ -274,12 +313,12 @@ mod test {
"
entry:
%0: i8 = param 0
body_start [%0]
header_start [%0]
%2: i8 = %0
body_end [%2]
header_end [%2]
",
);
let rev_an = rev_analyse(&m);
let rev_an = rev_analyse_header(&m);
assert_eq!(
rev_an.inst_vals_alive_until,
vec![3, 0, 0, 0]
Expand All @@ -292,14 +331,14 @@ mod test {
"
entry:
%0: i8 = param 0
body_start [%0]
header_start [%0]
%2: i8 = add %0, %0
%3: i8 = add %0, %0
%4: i8 = %2
body_end [%4]
header_end [%4]
",
);
let rev_an = rev_analyse(&m);
let rev_an = rev_analyse_header(&m);
assert_eq!(
rev_an.inst_vals_alive_until,
vec![2, 0, 5, 0, 0, 0]
Expand All @@ -323,7 +362,7 @@ mod test {
black_box %3
",
);
let rev_an = rev_analyse(&m);
let rev_an = rev_analyse_header(&m);
assert_eq!(
rev_an.used_insts,
vob![true, false, true, true, true, true, true]
Expand Down

0 comments on commit 5258b15

Please sign in to comment.