Struct cranelift_codegen::ir::ValueLabel

source ·

pub struct ValueLabel(_);

Expand description

Marked with a label value.

Implementations§

source §

impl ValueLabel

source

pub fn from_u32(x: u32) -> Self

Create a new instance from a u32.

Examples found in repository ?

src/machinst/vcode.rs (line 1112)

    fn compute_value_labels_ranges(
        &self,
        regalloc: &regalloc2::Output,
        inst_offsets: &[CodeOffset],
        func_body_len: u32,
    ) -> ValueLabelsRanges {
        if self.debug_value_labels.is_empty() {
            return ValueLabelsRanges::default();
        }

        let mut value_labels_ranges: ValueLabelsRanges = HashMap::new();
        for &(label, from, to, alloc) in &regalloc.debug_locations {
            let ranges = value_labels_ranges
                .entry(ValueLabel::from_u32(label))
                .or_insert_with(|| vec![]);
            let from_offset = inst_offsets[from.inst().index()];
            let to_offset = if to.inst().index() == inst_offsets.len() {
                func_body_len
            } else {
                inst_offsets[to.inst().index()]
            };

            // Empty range or to-offset of zero can happen because of
            // cold blocks (see above).
            if to_offset == 0 || from_offset == to_offset {
                continue;
            }

            let loc = if let Some(preg) = alloc.as_reg() {
                LabelValueLoc::Reg(Reg::from(preg))
            } else {
                // We can't translate spillslot locations at the
                // moment because ValueLabelLoc requires an
                // instantaneous SP offset, and this can *change*
                // within the range we have here because of callsites
                // adjusting SP temporarily. To avoid the complexity
                // of accurately plumbing through nominal-SP
                // adjustment sites, we just omit debug info for
                // values that are spilled. Not ideal, but debug info
                // is best-effort.
                continue;
            };

            ranges.push(ValueLocRange {
                loc,
                // ValueLocRanges are recorded by *instruction-end
                // offset*. `from_offset` is the *start* of the
                // instruction; that is the same as the end of another
                // instruction, so we only want to begin coverage once
                // we are past the previous instruction's end.
                start: from_offset + 1,
                // Likewise, `end` is exclusive, but we want to
                // *include* the end of the last
                // instruction. `to_offset` is the start of the
                // `to`-instruction, which is the exclusive end, i.e.,
                // the first instruction not covered. That
                // instruction's start is the same as the end of the
                // last instruction that is included, so we go one
                // byte further to be sure to include it.
                end: to_offset + 1,
            });
        }

        value_labels_ranges
    }

source

pub fn as_u32(self) -> u32

Return the underlying index value as a u32.

Examples found in repository ?

src/machinst/vcode.rs (line 533)

    fn reverse_and_finalize(&mut self) {
        let n_insts = self.vcode.insts.len();
        if n_insts == 0 {
            return;
        }

        // Reverse the per-block and per-inst sequences.
        self.vcode.block_ranges.reverse();
        // block_params_range is indexed by block (and blocks were
        // traversed in reverse) so we reverse it; but block-param
        // sequences in the concatenated vec can remain in reverse
        // order (it is effectively an arena of arbitrarily-placed
        // referenced sequences).
        self.vcode.block_params_range.reverse();
        // Likewise, we reverse block_succ_range, but the block_succ
        // concatenated array can remain as-is.
        self.vcode.block_succ_range.reverse();
        self.vcode.insts.reverse();
        self.vcode.srclocs.reverse();
        // Likewise, branch_block_arg_succ_range is indexed by block
        // so must be reversed.
        self.vcode.branch_block_arg_succ_range.reverse();

        // To translate an instruction index *endpoint* in reversed
        // order to forward order, compute `n_insts - i`.
        //
        // Why not `n_insts - 1 - i`? That would be correct to
        // translate an individual instruction index (for ten insts 0
        // to 9 inclusive, inst 0 becomes 9, and inst 9 becomes
        // 0). But for the usual inclusive-start, exclusive-end range
        // idiom, inclusive starts become exclusive ends and
        // vice-versa, so e.g. an (inclusive) start of 0 becomes an
        // (exclusive) end of 10.
        let translate = |inst: InsnIndex| InsnIndex::new(n_insts - inst.index());

        // Edit the block-range instruction indices.
        for tuple in &mut self.vcode.block_ranges {
            let (start, end) = *tuple;
            *tuple = (translate(end), translate(start)); // Note reversed order.
        }

        // Generate debug-value labels based on per-label maps.
        for (label, tuples) in &self.debug_info {
            for &(start, end, vreg) in tuples {
                let vreg = self.resolve_vreg_alias(vreg);
                let fwd_start = translate(end);
                let fwd_end = translate(start);
                self.vcode
                    .debug_value_labels
                    .push((vreg, fwd_start, fwd_end, label.as_u32()));
            }
        }

        // Now sort debug value labels by VReg, as required
        // by regalloc2.
        self.vcode
            .debug_value_labels
            .sort_unstable_by_key(|(vreg, _, _, _)| *vreg);
    }