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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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10
cranelift/codegen/src/ir/function.rs
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@@ -282,7 +282,7 @@ impl FunctionStencil {
///
/// Note that this method ignores multi-destination branches like `br_table`.
pub fn change_branch_destination(&mut self, inst: Inst, new_dest: Block) {
match self.dfg[inst].branch_destination_mut() {
match self.dfg.insts[inst].branch_destination_mut() {
None => (),
Some(inst_dest) => *inst_dest = new_dest,
}
@@ -309,7 +309,7 @@ impl FunctionStencil {
});
if default_dest == Some(old_dest) {
match &mut self.dfg[inst] {
match &mut self.dfg.insts[inst] {
InstructionData::BranchTable { destination, .. } => {
*destination = new_dest;
}
@@ -333,13 +333,13 @@ impl FunctionStencil {
let inst_iter = self.layout.block_insts(block);
// Ignore all instructions prior to the first branch.
let mut inst_iter = inst_iter.skip_while(|&inst| !dfg[inst].opcode().is_branch());
let mut inst_iter = inst_iter.skip_while(|&inst| !dfg.insts[inst].opcode().is_branch());
// A conditional branch is permitted in a basic block only when followed
// by a terminal jump instruction.
if let Some(_branch) = inst_iter.next() {
if let Some(next) = inst_iter.next() {
match dfg[next].opcode() {
match dfg.insts[next].opcode() {
Opcode::Jump => (),
_ => return Err((next, "post-branch instruction not jump")),
}
@@ -377,7 +377,7 @@ impl FunctionStencil {
.zip(self.dfg.inst_results(src))
.all(|(a, b)| self.dfg.value_type(*a) == self.dfg.value_type(*b)));
self.dfg[dst] = self.dfg[src];
self.dfg.insts[dst] = self.dfg.insts[src];
self.layout.remove_inst(src);
}