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Make DataFlowGraph::insts public, but restricted (#5450)

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We have some operations defined on DataFlowGraph purely to work around borrow-checker issues with InstructionData and other data on DataFlowGraph. Part of the problem is that indexing the DFG directly hides the fact that we're only indexing the insts field of the DFG.

This PR makes the insts field of the DFG public, but wraps it in a newtype that only allows indexing. This means that the borrow checker is better able to tell when operations on memory held by the DFG won't conflict, which comes up frequently when mutating ValueLists held by InstructionData.
This commit is contained in:
Trevor Elliott
2022-12-16 10:46:09 -08:00
committed by GitHub
parent 6323b0f9f4
commit 25bf8e0e67
31 changed files with 182 additions and 178 deletions
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49
cranelift/codegen/meta/src/gen_inst.rs
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@@ -158,8 +158,8 @@ fn gen_arguments_method(formats: &[&InstructionFormat], fmt: &mut Formatter, is_
/// - `pub fn opcode(&self) -> Opcode`
/// - `pub fn arguments(&self, &pool) -> &[Value]`
/// - `pub fn arguments_mut(&mut self, &pool) -> &mut [Value]`
/// - `pub fn take_value_list(&mut self) -> Option<ir::ValueList>`
/// - `pub fn put_value_list(&mut self, args: ir::ValueList>`
/// - `pub fn value_list(&self) -> Option<ir::ValueList>`
/// - `pub fn value_list_mut(&mut self) -> Option<&mut ir::ValueList>`
/// - `pub fn eq(&self, &other: Self, &pool) -> bool`
/// - `pub fn hash<H: Hasher>(&self, state: &mut H, &pool)`
fn gen_instruction_data_impl(formats: &[&InstructionFormat], fmt: &mut Formatter) {
@@ -214,21 +214,17 @@ fn gen_instruction_data_impl(formats: &[&InstructionFormat], fmt: &mut Formatter
fmt.empty_line();
fmt.doc_comment(r#"
Take out the value list with all the value arguments and return
it.
This leaves the value list in the instruction empty. Use
`put_value_list` to put the value list back.
The ValueList for the instruction.
"#);
fmt.line("pub fn take_value_list(&mut self) -> Option<ir::ValueList> {");
fmt.line("pub fn value_list(&self) -> Option<ir::ValueList> {");
fmt.indent(|fmt| {
let mut m = Match::new("*self");
for format in formats {
if format.has_value_list {
m.arm(format!("Self::{}", format.name),
vec!["ref mut args", ".."],
"Some(args.take())".to_string());
vec!["args", ".."],
"Some(args)".to_string());
}
}
@@ -240,27 +236,24 @@ fn gen_instruction_data_impl(formats: &[&InstructionFormat], fmt: &mut Formatter
fmt.empty_line();
fmt.doc_comment(r#"
Put back a value list.
After removing a value list with `take_value_list()`, use this
method to put it back. It is required that this instruction has
a format that accepts a value list, and that the existing value
list is empty. This avoids leaking list pool memory.
A mutable reference to the ValueList for this instruction, if it
has one.
"#);
fmt.line("pub fn put_value_list(&mut self, vlist: ir::ValueList) {");
fmt.line("pub fn value_list_mut(&mut self) -> Option<&mut ir::ValueList> {");
fmt.indent(|fmt| {
fmt.line("let args = match *self {");
fmt.indent(|fmt| {
for format in formats {
if format.has_value_list {
fmtln!(fmt, "Self::{} {{ ref mut args, .. }} => args,", format.name);
}
let mut m = Match::new("*self");
for format in formats {
if format.has_value_list {
m.arm(format!("Self::{}", format.name),
vec!["ref mut args", ".."],
"Some(args)".to_string());
}
fmt.line("_ => panic!(\"No value list: {:?}\", self),");
});
fmt.line("};");
fmt.line("debug_assert!(args.is_empty(), \"Value list already in use\");");
fmt.line("*args = vlist;");
}
m.arm_no_fields("_", "None");
fmt.add_match(m);
});
fmt.line("}");
fmt.empty_line();