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implement shortcircuiting and/or

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This commit is contained in:
Devyn Cairns 2024-07-09 04:00:23 -07:00
parent abbab2ef90
commit de3137f72b
1 changed files with 67 additions and 17 deletions
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84
crates/nu-engine/src/compile/operator.rs
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@ -1,5 +1,5 @@
use nu_protocol::{
ast::{Assignment, CellPath, Expr, Expression, Math, Operator, PathMember},
ast::{Assignment, Boolean, CellPath, Expr, Expression, Math, Operator, PathMember},
engine::StateWorkingSet,
ir::{Instruction, Literal},
IntoSpanned, RegId, Span, Spanned, ENV_VARIABLE_ID,
@ -56,25 +56,75 @@ pub(crate) fn compile_binary_op(
lhs_reg,
)?;
let rhs_reg = builder.next_register()?;
match op.item {
// `and` / `or` are short-circuiting, and we can get by with one register and a branch
Operator::Boolean(Boolean::And) => {
builder.branch_if(lhs_reg, builder.next_instruction_index() + 2, op.span)?;
compile_expression(
working_set,
builder,
rhs,
RedirectModes::capture_out(rhs.span),
None,
rhs_reg,
)?;
// If the branch was not taken it's false, so short circuit to load false
let jump_false = builder.jump_placeholder(op.span)?;
builder.push(
Instruction::BinaryOp {
lhs_dst: lhs_reg,
op: op.item,
rhs: rhs_reg,
compile_expression(
working_set,
builder,
rhs,
RedirectModes::capture_out(rhs.span),
None,
lhs_reg,
)?;
let jump_end = builder.jump_placeholder(op.span)?;
// Consumed by `branch-if`, so we have to set it false again
builder.set_branch_target(jump_false, builder.next_instruction_index())?;
builder.load_literal(lhs_reg, Literal::Bool(false).into_spanned(lhs.span))?;
builder.set_branch_target(jump_end, builder.next_instruction_index())?;
}
.into_spanned(op.span),
)?;
Operator::Boolean(Boolean::Or) => {
let branch_true = builder.branch_if_placeholder(lhs_reg, op.span)?;
// If the branch was not taken it's false, so do the right-side expression
compile_expression(
working_set,
builder,
rhs,
RedirectModes::capture_out(rhs.span),
None,
lhs_reg,
)?;
let jump_end = builder.jump_placeholder(op.span)?;
// Consumed by `branch-if`, so we have to set it true again
builder.set_branch_target(branch_true, builder.next_instruction_index())?;
builder.load_literal(lhs_reg, Literal::Bool(true).into_spanned(lhs.span))?;
builder.set_branch_target(jump_end, builder.next_instruction_index())?;
}
_ => {
// Any other operator, via `binary-op`
let rhs_reg = builder.next_register()?;
compile_expression(
working_set,
builder,
rhs,
RedirectModes::capture_out(rhs.span),
None,
rhs_reg,
)?;
builder.push(
Instruction::BinaryOp {
lhs_dst: lhs_reg,
op: op.item,
rhs: rhs_reg,
}
.into_spanned(op.span),
)?;
}
}
if lhs_reg != out_reg {
builder.push(