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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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18
cranelift/codegen/src/inst_predicates.rs
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@@ -40,7 +40,7 @@ fn is_load_with_defined_trapping(opcode: Opcode, data: &InstructionData) -> bool
/// its value is unused?
#[inline(always)]
pub fn has_side_effect(func: &Function, inst: Inst) -> bool {
let data = &func.dfg[inst];
let data = &func.dfg.insts[inst];
let opcode = data.opcode();
trivially_has_side_effects(opcode) || is_load_with_defined_trapping(opcode, data)
}
@@ -51,7 +51,7 @@ pub fn has_side_effect(func: &Function, inst: Inst) -> bool {
/// - Actual pure nodes (arithmetic, etc)
/// - Loads with the `readonly` flag set
pub fn is_pure_for_egraph(func: &Function, inst: Inst) -> bool {
let is_readonly_load = match func.dfg[inst] {
let is_readonly_load = match func.dfg.insts[inst] {
InstructionData::Load {
opcode: Opcode::Load,
flags,
@@ -69,7 +69,7 @@ pub fn is_pure_for_egraph(func: &Function, inst: Inst) -> bool {
// are, we can always trivially eliminate them with no effect.)
let has_one_result = func.dfg.inst_results(inst).len() == 1;
let op = func.dfg[inst].opcode();
let op = func.dfg.insts[inst].opcode();
has_one_result && (is_readonly_load || (!op.can_load() && !trivially_has_side_effects(op)))
}
@@ -77,14 +77,14 @@ pub fn is_pure_for_egraph(func: &Function, inst: Inst) -> bool {
/// Does the given instruction have any side-effect as per [has_side_effect], or else is a load,
/// but not the get_pinned_reg opcode?
pub fn has_lowering_side_effect(func: &Function, inst: Inst) -> bool {
let op = func.dfg[inst].opcode();
let op = func.dfg.insts[inst].opcode();
op != Opcode::GetPinnedReg && (has_side_effect(func, inst) || op.can_load())
}
/// Is the given instruction a constant value (`iconst`, `fconst`) that can be
/// represented in 64 bits?
pub fn is_constant_64bit(func: &Function, inst: Inst) -> Option<u64> {
let data = &func.dfg[inst];
let data = &func.dfg.insts[inst];
if data.opcode() == Opcode::Null {
return Some(0);
}
@@ -98,7 +98,7 @@ pub fn is_constant_64bit(func: &Function, inst: Inst) -> Option<u64> {
/// Get the address, offset, and access type from the given instruction, if any.
pub fn inst_addr_offset_type(func: &Function, inst: Inst) -> Option<(Value, Offset32, Type)> {
let data = &func.dfg[inst];
let data = &func.dfg.insts[inst];
match data {
InstructionData::Load { arg, offset, .. } => {
let ty = func.dfg.value_type(func.dfg.inst_results(inst)[0]);
@@ -122,7 +122,7 @@ pub fn inst_addr_offset_type(func: &Function, inst: Inst) -> Option<(Value, Offs
/// Get the store data, if any, from an instruction.
pub fn inst_store_data(func: &Function, inst: Inst) -> Option<Value> {
let data = &func.dfg[inst];
let data = &func.dfg.insts[inst];
match data {
InstructionData::Store { args, .. } | InstructionData::StoreNoOffset { args, .. } => {
Some(args[0])
@@ -157,14 +157,14 @@ pub(crate) fn visit_block_succs<F: FnMut(Inst, Block, bool)>(
mut visit: F,
) {
for inst in f.layout.block_likely_branches(block) {
if f.dfg[inst].opcode().is_branch() {
if f.dfg.insts[inst].opcode().is_branch() {
visit_branch_targets(f, inst, &mut visit);
}
}
}
fn visit_branch_targets<F: FnMut(Inst, Block, bool)>(f: &Function, inst: Inst, visit: &mut F) {
match f.dfg[inst].analyze_branch(&f.dfg.value_lists) {
match f.dfg.insts[inst].analyze_branch(&f.dfg.value_lists) {
BranchInfo::NotABranch => {}
BranchInfo::SingleDest(dest, _) => {
visit(inst, dest, false);