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try to reduce drops a bit

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This commit is contained in:
Devyn Cairns 2024-06-27 00:24:29 -07:00
parent 13e348ab57
commit 9e19f15cb5
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1 changed files with 14 additions and 4 deletions
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18
crates/nu-engine/src/compile/mod.rs
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@ -97,7 +97,9 @@ fn compile_block(
if index != last_index {
// Explicitly drain the out reg after each non-final pipeline, because that's how
// the semicolon functions.
builder.push(Instruction::Drain { src: out_reg }.into_spanned(span))?;
if builder.is_allocated(out_reg) {
builder.push(Instruction::Drain { src: out_reg }.into_spanned(span))?;
}
}
}
Ok(())
@ -1397,6 +1399,13 @@ impl BlockBuilder {
}
}
/// Check if a register is initialized with a value.
fn is_allocated(&self, reg_id: RegId) -> bool {
self.register_allocation_state
.get(reg_id.0 as usize)
.is_some_and(|state| *state)
}
/// Mark a register as initialized.
fn mark_register(&mut self, reg_id: RegId) -> Result<(), CompileError> {
if let Some(is_allocated) = self.register_allocation_state.get_mut(reg_id.0 as usize) {
@ -1558,15 +1567,16 @@ impl BlockBuilder {
Ok(reg_id)
}
/// Deallocate a register and set it to `Empty`
/// Deallocate a register and set it to `Empty`, if it is allocated
fn drop_reg(&mut self, reg_id: RegId) -> Result<(), CompileError> {
self.push(Instruction::Drop { src: reg_id }.into_spanned(Span::unknown()))?;
if self.is_allocated(reg_id) {
self.push(Instruction::Drop { src: reg_id }.into_spanned(Span::unknown()))?;
}
Ok(())
}
/// Set a register to `Empty`, but mark it as in-use, e.g. for input
fn load_empty(&mut self, reg_id: RegId) -> Result<(), CompileError> {
self.mark_register(reg_id)?;
self.drop_reg(reg_id)?;
self.mark_register(reg_id)
}