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Return a Result from constant_hash::probe.

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When a hash table probe fails, return the index of the failed entry.
This can be used to store default values in the sentinel entries.
This commit is contained in:
Jakob Stoklund Olesen
2017-07-21 21:10:32 -07:00
parent 35cbe68a70
commit 4142a9ca9c
4 changed files with 38 additions and 22 deletions
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40
lib/cretonne/src/isa/enc_tables.rs
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@@ -5,6 +5,7 @@
use ir::{Type, Opcode, InstructionData};
use isa::{Encoding, Legalize};
use constant_hash::{Table, probe};
use std::ops::Range;
/// Level 1 hash table entry.
///
@@ -27,6 +28,14 @@ pub struct Level1Entry<OffT: Into<u32> + Copy> {
pub offset: OffT,
}
impl<OffT: Into<u32> + Copy> Level1Entry<OffT> {
/// Get the level 2 table range indicated by this entry.
fn range(&self) -> Range<usize> {
let b = self.offset.into() as usize;
b..b + (1 << self.log2len)
}
}
impl<OffT: Into<u32> + Copy> Table<Type> for [Level1Entry<OffT>] {
fn len(&self) -> usize {
self.len()
@@ -83,20 +92,23 @@ pub fn lookup_enclist<OffT1, OffT2>(ctrl_typevar: Type,
OffT2: Into<u32> + Copy
{
// TODO: The choice of legalization actions here is naive. This needs to be configurable.
probe(level1_table, ctrl_typevar, ctrl_typevar.index())
.ok_or_else(|| if ctrl_typevar.lane_type().bits() > 32 {
Legalize::Narrow
} else {
Legalize::Expand
})
.and_then(|l1idx| {
let l1ent = &level1_table[l1idx];
let l2off = l1ent.offset.into() as usize;
let l2tab = &level2_table[l2off..l2off + (1 << l1ent.log2len)];
probe(l2tab, opcode, opcode as usize)
.map(|l2idx| l2tab[l2idx].offset.into() as usize)
.ok_or(Legalize::Expand)
})
match probe(level1_table, ctrl_typevar, ctrl_typevar.index()) {
Err(_) => {
// No level 1 entry for the type.
Err(if ctrl_typevar.lane_type().bits() > 32 {
Legalize::Narrow
} else {
Legalize::Expand
})
}
Ok(l1idx) => {
let l1ent = &level1_table[l1idx];
let l2tab = &level2_table[l1ent.range()];
probe(l2tab, opcode, opcode as usize)
.map(|l2idx| l2tab[l2idx].offset.into() as usize)
.map_err(|_| Legalize::Expand)
}
}
}
/// Encoding list entry.