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Auto merge of #85195 - Mark-Simulacrum:variant-by-idx, r=petrochenkov

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Store VariantIdx to distinguish enum variants

This saves ~24% of the instructions on the match-stress-enum benchmark, but I'm not 100% sure that this is OK - if we ever compare two constructors across enums (e.g., a Result and an Option), then this is obviously insufficient; I can experiment with continuing to store the DefId for comparison purposes in that case.
This commit is contained in:
bors 2021-05-14 00:59:01 +00:00
commit 754d17121d
1 changed files with 7 additions and 10 deletions
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17
compiler/rustc_mir_build/src/thir/pattern/deconstruct_pat.rs
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@ -52,7 +52,6 @@ use super::{FieldPat, Pat, PatKind, PatRange};
use rustc_data_structures::captures::Captures;
use rustc_index::vec::Idx;
use rustc_hir::def_id::DefId;
use rustc_hir::{HirId, RangeEnd};
use rustc_middle::mir::interpret::ConstValue;
use rustc_middle::mir::Field;
@ -590,7 +589,7 @@ pub(super) enum Constructor<'tcx> {
/// and fixed-length arrays.
Single,
/// Enum variants.
Variant(DefId),
Variant(VariantIdx),
/// Ranges of integer literal values (`2`, `2..=5` or `2..5`).
IntRange(IntRange),
/// Ranges of floating-point literal values (`2.0..=5.2`).
@ -634,7 +633,7 @@ impl<'tcx> Constructor<'tcx> {
fn variant_index_for_adt(&self, adt: &'tcx ty::AdtDef) -> VariantIdx {
match *self {
Variant(id) => adt.variant_index_with_id(id),
Variant(idx) => idx,
Single => {
assert!(!adt.is_enum());
VariantIdx::new(0)
@ -649,9 +648,7 @@ impl<'tcx> Constructor<'tcx> {
PatKind::AscribeUserType { .. } => bug!(), // Handled by `expand_pattern`
PatKind::Binding { .. } | PatKind::Wild => Wildcard,
PatKind::Leaf { .. } | PatKind::Deref { .. } => Single,
&PatKind::Variant { adt_def, variant_index, .. } => {
Variant(adt_def.variants[variant_index].def_id)
}
&PatKind::Variant { variant_index, .. } => Variant(variant_index),
PatKind::Constant { value } => {
if let Some(int_range) = IntRange::from_const(cx.tcx, cx.param_env, value) {
IntRange(int_range)
@ -928,15 +925,15 @@ impl<'tcx> SplitWildcard<'tcx> {
// If `exhaustive_patterns` is enabled, we exclude variants known to be
// uninhabited.
def.variants
.iter()
.filter(|v| {
.iter_enumerated()
.filter(|(_, v)| {
!v.uninhabited_from(cx.tcx, substs, def.adt_kind(), cx.param_env)
.contains(cx.tcx, cx.module)
})
.map(|v| Variant(v.def_id))
.map(|(idx, _)| Variant(idx))
.collect()
} else {
def.variants.iter().map(|v| Variant(v.def_id)).collect()
def.variants.indices().map(|idx| Variant(idx)).collect()
}
}
ty::Char => {