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Merge pull request #1729 from cfallin/machinst-branch-opt

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Fix MachBuffer branch optimization.
This commit is contained in:
Chris Fallin
2020-05-20 14:43:57 -07:00
committed by GitHub
parent e229fbc79c 13e12908a6
commit c9e3b71c39
3 changed files with 447 additions and 81 deletions
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29
cranelift/codegen/src/isa/aarch64/inst/emit.rs
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@@ -1163,17 +1163,13 @@ impl MachInstEmit for Inst {
}
&Inst::Jump { ref dest } => {
let off = sink.cur_offset();
// Emit the jump itself.
sink.put4(enc_jump26(0b000101, dest.as_offset26_or_zero()));
// After the jump has been emitted, indicate that it uses a
// label, if so, so that a fixup can occur later. This happens
// after we emit the bytes because the fixup might occur right
// away (so the bytes must actually exist now).
// Indicate that the jump uses a label, if so, so that a fixup can occur later.
if let Some(l) = dest.as_label() {
sink.use_label_at_offset(off, l, LabelUse::Branch26);
let cur_off = sink.cur_offset();
sink.add_uncond_branch(off, cur_off, l);
sink.add_uncond_branch(off, off + 4, l);
}
// Emit the jump itself.
sink.put4(enc_jump26(0b000101, dest.as_offset26_or_zero()));
}
&Inst::Ret => {
sink.put4(0xd65f03c0);
@@ -1208,28 +1204,27 @@ impl MachInstEmit for Inst {
} => {
// Conditional part first.
let cond_off = sink.cur_offset();
sink.put4(enc_conditional_br(taken, kind));
if let Some(l) = taken.as_label() {
sink.use_label_at_offset(cond_off, l, LabelUse::Branch19);
let cur_off = sink.cur_offset();
let inverted = enc_conditional_br(taken, kind.invert()).to_le_bytes();
sink.add_cond_branch(cond_off, cur_off, l, &inverted[..]);
sink.add_cond_branch(cond_off, cond_off + 4, l, &inverted[..]);
}
// Unconditional part.
sink.put4(enc_conditional_br(taken, kind));
// Unconditional part next.
let uncond_off = sink.cur_offset();
sink.put4(enc_jump26(0b000101, not_taken.as_offset26_or_zero()));
if let Some(l) = not_taken.as_label() {
sink.use_label_at_offset(uncond_off, l, LabelUse::Branch26);
let cur_off = sink.cur_offset();
sink.add_uncond_branch(uncond_off, cur_off, l);
sink.add_uncond_branch(uncond_off, uncond_off + 4, l);
}
sink.put4(enc_jump26(0b000101, not_taken.as_offset26_or_zero()));
}
&Inst::OneWayCondBr { target, kind } => {
let off = sink.cur_offset();
sink.put4(enc_conditional_br(target, kind));
if let Some(l) = target.as_label() {
sink.use_label_at_offset(off, l, LabelUse::Branch19);
}
sink.put4(enc_conditional_br(target, kind));
}
&Inst::IndirectBr { rn, .. } => {
sink.put4(enc_br(rn));
@@ -1307,12 +1302,12 @@ impl MachInstEmit for Inst {
for &target in targets.iter() {
let word_off = sink.cur_offset();
let off_into_table = word_off - jt_off;
sink.put4(off_into_table);
sink.use_label_at_offset(
word_off,
target.as_label().unwrap(),
LabelUse::PCRel32,
);
sink.put4(off_into_table);
}
// Lowering produces an EmitIsland before using a JTSequence, so we can safely