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Use PackedOption<Value> instead of NO_VALUE.

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- Remove NO_VALUE and ExpandedValue::None.
- Remove the Default implelmentation for Value.
- InstructionData::second_result() returns an Option<Value>.
- InstructionData::second_result() returns a reference to the packed
  option.
This commit is contained in:
Jakob Stoklund Olesen
2017-01-19 15:52:29 -08:00
parent 1389a51c7a
commit 0d77b19708
7 changed files with 97 additions and 104 deletions
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136
lib/cretonne/src/ir/dfg.rs
View File

@@ -1,14 +1,14 @@
//! Data flow graph tracking Instructions, Values, and EBBs.
use ir::{Ebb, Inst, Value, Type, SigRef, Signature, FuncRef};
use ir::entities::{NO_VALUE, ExpandedValue};
use ir::entities::ExpandedValue;
use ir::instructions::{Opcode, InstructionData, CallInfo};
use ir::extfunc::ExtFuncData;
use entity_map::{EntityMap, PrimaryEntityData};
use ir::builder::{InsertBuilder, ReplaceBuilder};
use ir::layout::Cursor;
use packed_option::PackedOption;
use std::mem;
use std::ops::{Index, IndexMut};
use std::u16;
@@ -103,7 +103,6 @@ impl DataFlowGraph {
ValueData::Alias { ty, .. } => ty,
}
}
None => panic!("NO_VALUE has no type"),
}
}
@@ -126,7 +125,6 @@ impl DataFlowGraph {
}
}
}
None => panic!("NO_VALUE has no def"),
}
}
@@ -237,7 +235,7 @@ enum ValueData {
ty: Type,
num: u16, // Result number starting from 0.
inst: Inst,
next: Value, // Next result defined by `def`.
next: PackedOption<Value>, // Next result defined by `def`.
},
// Value is an EBB argument.
@@ -245,7 +243,7 @@ enum ValueData {
ty: Type,
num: u16, // Argument number, starting from 0.
ebb: Ebb,
next: Value, // Next argument to `ebb`.
next: PackedOption<Value>, // Next argument to `ebb`.
},
// Value is an alias of another value.
@@ -262,31 +260,30 @@ enum ValueData {
/// A value iterator borrows a `DataFlowGraph` reference.
pub struct Values<'a> {
dfg: &'a DataFlowGraph,
cur: Value,
cur: Option<Value>,
}
impl<'a> Iterator for Values<'a> {
type Item = Value;
fn next(&mut self) -> Option<Self::Item> {
let prev = self.cur;
// Advance self.cur to the next value, or NO_VALUE.
self.cur = match prev.expand() {
ExpandedValue::Direct(inst) => self.dfg.insts[inst].second_result().unwrap_or_default(),
ExpandedValue::Table(index) => {
match self.dfg.extended_values[index] {
ValueData::Inst { next, .. } => next,
ValueData::Arg { next, .. } => next,
ValueData::Alias { .. } => {
panic!("Alias value {} appeared in value list", prev)
let rval = self.cur;
if let Some(prev) = rval {
// Advance self.cur to the next value, or `None`.
self.cur = match prev.expand() {
ExpandedValue::Direct(inst) => self.dfg.insts[inst].second_result(),
ExpandedValue::Table(index) => {
match self.dfg.extended_values[index] {
ValueData::Inst { next, .. } => next.into(),
ValueData::Arg { next, .. } => next.into(),
ValueData::Alias { .. } => {
panic!("Alias value {} appeared in value list", prev)
}
}
}
}
ExpandedValue::None => return None,
};
Some(prev)
};
}
rval
}
}
@@ -334,7 +331,7 @@ impl DataFlowGraph {
// causes additional result values to be numbered backwards which is not the aestetic
// choice, but since it is only visible in extremely rare instructions with 3+ results,
// we don't care).
let mut head = NO_VALUE;
let mut head = None;
let mut first_type = None;
let mut rev_num = 1;
@@ -346,37 +343,37 @@ impl DataFlowGraph {
for res_idx in (0..var_results).rev() {
if let Some(ty) = first_type {
head = self.make_value(ValueData::Inst {
head = Some(self.make_value(ValueData::Inst {
ty: ty,
num: (total_results - rev_num) as u16,
inst: inst,
next: head,
});
next: head.into(),
}));
rev_num += 1;
}
first_type = Some(self.signatures[sig].return_types[res_idx].value_type);
}
}
// Then the fixed results whic will appear at the front of the list.
// Then the fixed results which will appear at the front of the list.
for res_idx in (0..fixed_results).rev() {
if let Some(ty) = first_type {
head = self.make_value(ValueData::Inst {
head = Some(self.make_value(ValueData::Inst {
ty: ty,
num: (total_results - rev_num) as u16,
inst: inst,
next: head,
});
next: head.into(),
}));
rev_num += 1;
}
first_type = Some(constraints.result_type(res_idx, ctrl_typevar));
}
// Update the second_result pointer in `inst`.
if head != NO_VALUE {
if head.is_some() {
*self.insts[inst]
.second_result_mut()
.expect("instruction format doesn't allow multiple results") = head;
.expect("instruction format doesn't allow multiple results") = head.into();
}
*self.insts[inst].first_type_mut() = first_type.unwrap_or_default();
@@ -403,8 +400,7 @@ impl DataFlowGraph {
/// Use this method to detach secondary values before using `replace(inst)` to provide an
/// alternate instruction for computing the primary result value.
pub fn detach_secondary_results(&mut self, inst: Inst) -> Values {
let second_result =
self[inst].second_result_mut().map(|r| mem::replace(r, NO_VALUE)).unwrap_or_default();
let second_result = self[inst].second_result_mut().and_then(|r| r.take());
Values {
dfg: self,
cur: second_result,
@@ -423,9 +419,9 @@ impl DataFlowGraph {
Values {
dfg: self,
cur: if self.insts[inst].first_type().is_void() {
NO_VALUE
None
} else {
Value::new_direct(inst)
Some(Value::new_direct(inst))
},
}
}
@@ -494,17 +490,16 @@ impl DataFlowGraph {
/// Get the number of arguments on `ebb`.
pub fn num_ebb_args(&self, ebb: Ebb) -> usize {
let last_arg = self.ebbs[ebb].last_arg;
match last_arg.expand() {
ExpandedValue::None => 0,
ExpandedValue::Table(idx) => {
if let ValueData::Arg { num, .. } = self.extended_values[idx] {
num as usize + 1
} else {
panic!("inconsistent value table entry for EBB arg");
match self.ebbs[ebb].last_arg.expand() {
None => 0,
Some(last_arg) => {
if let ExpandedValue::Table(idx) = last_arg.expand() {
if let ValueData::Arg { num, .. } = self.extended_values[idx] {
return num as usize + 1;
}
}
panic!("inconsistent value table entry for EBB arg");
}
ExpandedValue::Direct(_) => panic!("inconsistent value table entry for EBB arg"),
}
}
@@ -516,25 +511,30 @@ impl DataFlowGraph {
ty: ty,
ebb: ebb,
num: num_args as u16,
next: NO_VALUE,
next: None.into(),
});
let last_arg = self.ebbs[ebb].last_arg;
match last_arg.expand() {
// If last_arg is NO_VALUE, we're adding the first EBB argument.
ExpandedValue::None => {
self.ebbs[ebb].first_arg = val;
match self.ebbs[ebb].last_arg.expand() {
// If last_arg is `None`, we're adding the first EBB argument.
None => {
self.ebbs[ebb].first_arg = val.into();
}
// Append to linked list of arguments.
ExpandedValue::Table(idx) => {
if let ValueData::Arg { ref mut next, .. } = self.extended_values[idx] {
*next = val;
} else {
panic!("inconsistent value table entry for EBB arg");
Some(last_arg) => {
match last_arg.expand() {
// Append to linked list of arguments.
ExpandedValue::Table(idx) => {
if let ValueData::Arg { ref mut next, .. } = self.extended_values[idx] {
*next = val.into();
} else {
panic!("inconsistent value table entry for EBB arg");
}
}
ExpandedValue::Direct(_) => {
panic!("inconsistent value table entry for EBB arg")
}
}
}
ExpandedValue::Direct(_) => panic!("inconsistent value table entry for EBB arg"),
};
self.ebbs[ebb].last_arg = val;
}
self.ebbs[ebb].last_arg = val.into();
val
}
@@ -542,7 +542,7 @@ impl DataFlowGraph {
pub fn ebb_args(&self, ebb: Ebb) -> Values {
Values {
dfg: self,
cur: self.ebbs[ebb].first_arg,
cur: self.ebbs[ebb].first_arg.into(),
}
}
}
@@ -554,21 +554,21 @@ impl DataFlowGraph {
// match the function arguments.
#[derive(Clone)]
struct EbbData {
// First argument to this EBB, or `NO_VALUE` if the block has no arguments.
// First argument to this EBB, or `None` if the block has no arguments.
//
// The arguments are all ValueData::Argument entries that form a linked list from `first_arg`
// to `last_arg`.
first_arg: Value,
first_arg: PackedOption<Value>,
// Last argument to this EBB, or `NO_VALUE` if the block has no arguments.
last_arg: Value,
// Last argument to this EBB, or `None` if the block has no arguments.
last_arg: PackedOption<Value>,
}
impl EbbData {
fn new() -> EbbData {
EbbData {
first_arg: NO_VALUE,
last_arg: NO_VALUE,
first_arg: None.into(),
last_arg: None.into(),
}
}
}