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Minor code refactoring.

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This commit is contained in:
Dan Gohman
2018-04-20 21:42:09 -07:00
parent 3b1d805758
commit beddcc50f2
1 changed files with 49 additions and 44 deletions
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87
lib/codegen/src/legalizer/mod.rs
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@@ -32,6 +32,49 @@ use self::heap::expand_heap_addr;
use self::call::expand_call;
use self::libcall::expand_as_libcall;
/// Legalize `inst` for `isa`. Return true if any changes to the code were
/// made; return false if the instruction was successfully encoded as is.
fn legalize_inst(
inst: ir::Inst,
pos: &mut FuncCursor,
cfg: &mut ControlFlowGraph,
isa: &TargetIsa,
) -> bool {
let opcode = pos.func.dfg[inst].opcode();
// Check for ABI boundaries that need to be converted to the legalized signature.
if opcode.is_call() {
if boundary::handle_call_abi(inst, pos.func, cfg) {
return true;
}
} else if opcode.is_return() {
if boundary::handle_return_abi(inst, pos.func, cfg) {
return true;
}
} else if opcode.is_branch() {
split::simplify_branch_arguments(&mut pos.func.dfg, inst);
}
match pos.func.update_encoding(inst, isa) {
Ok(()) => false,
Err(action) => {
// We should transform the instruction into legal equivalents.
// If the current instruction was replaced, we need to double back and revisit
// the expanded sequence. This is both to assign encodings and possible to
// expand further.
// There's a risk of infinite looping here if the legalization patterns are
// unsound. Should we attempt to detect that?
if action(inst, pos.func, cfg, isa) {
return true;
}
// We don't have any pattern expansion for this instruction either.
// Try converting it to a library call as a last resort.
expand_as_libcall(inst, pos.func, isa)
}
}
}
/// Legalize `func` for `isa`.
///
/// - Transform any instructions that don't have a legal representation in `isa`.
@@ -55,54 +98,16 @@ pub fn legalize_function(func: &mut ir::Function, cfg: &mut ControlFlowGraph, is
let mut prev_pos = pos.position();
while let Some(inst) = pos.next_inst() {
let opcode = pos.func.dfg[inst].opcode();
// Check for ABI boundaries that need to be converted to the legalized signature.
if opcode.is_call() {
if boundary::handle_call_abi(inst, pos.func, cfg) {
// Go back and legalize the inserted argument conversion instructions.
pos.set_position(prev_pos);
continue;
}
} else if opcode.is_return() {
if boundary::handle_return_abi(inst, pos.func, cfg) {
if legalize_inst(inst, &mut pos, cfg, isa) {
// Go back and legalize the inserted return value conversion instructions.
pos.set_position(prev_pos);
continue;
}
} else if opcode.is_branch() {
split::simplify_branch_arguments(&mut pos.func.dfg, inst);
}
match pos.func.update_encoding(inst, isa) {
Ok(()) => {}
Err(action) => {
// We should transform the instruction into legal equivalents.
let changed = action(inst, pos.func, cfg, isa);
// If the current instruction was replaced, we need to double back and revisit
// the expanded sequence. This is both to assign encodings and possible to
// expand further.
// There's a risk of infinite looping here if the legalization patterns are
// unsound. Should we attempt to detect that?
if changed {
pos.set_position(prev_pos);
continue;
}
// We don't have any pattern expansion for this instruction either.
// Try converting it to a library call as a last resort.
if expand_as_libcall(inst, pos.func, isa) {
pos.set_position(prev_pos);
continue;
}
}
}
} else {
// Remember this position in case we need to double back.
prev_pos = pos.position();
}
}
}
}
// Include legalization patterns that were generated by `gen_legalizer.py` from the `XForms` in
// `lib/codegen/meta/base/legalize.py`.