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simplify the writing of bytecode programs
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Instead of always having the caller specify all instructions, this
work introduces convenience functions into the program builder,
making the code a lot cleaner.
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@glommer
glommer committed Jan 31, 2025
1 parent b37317f commit 7aa3cc2
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Showing 2 changed files with 103 additions and 131 deletions.
170 changes: 39 additions & 131 deletions core/translate/mod.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -206,23 +206,9 @@ fn emit_schema_entry(
prev_largest_reg: 0,
});

let type_reg = program.alloc_register();
program.emit_insn(Insn::String8 {
value: entry_type.as_str().to_string(),
dest: type_reg,
});

let name_reg = program.alloc_register();
program.emit_insn(Insn::String8 {
value: name.to_string(),
dest: name_reg,
});

let tbl_name_reg = program.alloc_register();
program.emit_insn(Insn::String8 {
value: tbl_name.to_string(),
dest: tbl_name_reg,
});
let type_reg = program.emit_string8_new_reg(entry_type.as_str().to_string());
program.emit_string8_new_reg(name.to_string());
program.emit_string8_new_reg(tbl_name.to_string());

let rootpage_reg = program.alloc_register();
program.emit_insn(Insn::Copy {
Expand All @@ -233,15 +219,9 @@ fn emit_schema_entry(

let sql_reg = program.alloc_register();
if let Some(sql) = sql {
program.emit_insn(Insn::String8 {
value: sql,
dest: sql_reg,
});
program.emit_string8(sql, sql_reg);
} else {
program.emit_insn(Insn::Null {
dest: sql_reg,
dest_end: None,
});
program.emit_null(sql_reg);
}

let record_reg = program.alloc_register();
Expand Down Expand Up @@ -407,21 +387,13 @@ fn translate_create_table(
) -> Result<()> {
if schema.get_table(tbl_name.name.0.as_str()).is_some() {
if if_not_exists {
let init_label = program.allocate_label();
program.emit_insn(Insn::Init {
target_pc: init_label,
});
let init_label = program.emit_init();
let start_offset = program.offset();
program.emit_insn(Insn::Halt {
err_code: 0,
description: String::new(),
});
program.emit_halt();
program.resolve_label(init_label, program.offset());
program.emit_insn(Insn::Transaction { write: true });
program.emit_transaction(true);
program.emit_constant_insns();
program.emit_insn(Insn::Goto {
target_pc: start_offset,
});
program.emit_goto(start_offset);

return Ok(());
}
Expand All @@ -431,10 +403,7 @@ fn translate_create_table(
let sql = create_table_body_to_str(&tbl_name, &body);

let parse_schema_label = program.allocate_label();
let init_label = program.allocate_label();
program.emit_insn(Insn::Init {
target_pc: init_label,
});
let init_label = program.emit_init();
let start_offset = program.offset();
// TODO: ReadCookie
// TODO: If
Expand Down Expand Up @@ -533,16 +502,11 @@ fn translate_create_table(
});

// TODO: SqlExec
program.emit_insn(Insn::Halt {
err_code: 0,
description: String::new(),
});
program.emit_halt();
program.resolve_label(init_label, program.offset());
program.emit_insn(Insn::Transaction { write: true });
program.emit_transaction(true);
program.emit_constant_insns();
program.emit_insn(Insn::Goto {
target_pc: start_offset,
});
program.emit_goto(start_offset);

Ok(())
}
Expand All @@ -561,25 +525,14 @@ fn list_pragmas(
start_offset: BranchOffset,
) {
for x in PragmaName::iter() {
let register = program.alloc_register();
program.emit_insn(Insn::String8 {
value: x.to_string(),
dest: register,
});
program.emit_insn(Insn::ResultRow {
start_reg: register,
count: 1,
});
let register = program.emit_string8_new_reg(x.to_string());
program.emit_result_row(register, 1);
}
program.emit_insn(Insn::Halt {
err_code: 0,
description: String::new(),
});

program.emit_halt();
program.resolve_label(init_label, program.offset());
program.emit_constant_insns();
program.emit_insn(Insn::Goto {
target_pc: start_offset,
});
program.emit_goto(start_offset);
}

fn translate_pragma(
Expand All @@ -590,10 +543,7 @@ fn translate_pragma(
database_header: Rc<RefCell<DatabaseHeader>>,
pager: Rc<Pager>,
) -> Result<()> {
let init_label = program.allocate_label();
program.emit_insn(Insn::Init {
target_pc: init_label,
});
let init_label = program.emit_init();
let start_offset = program.offset();
let mut write = false;

Expand Down Expand Up @@ -648,16 +598,11 @@ fn translate_pragma(
}
},
};
program.emit_insn(Insn::Halt {
err_code: 0,
description: String::new(),
});
program.emit_halt();
program.resolve_label(init_label, program.offset());
program.emit_insn(Insn::Transaction { write });
program.emit_transaction(write);
program.emit_constant_insns();
program.emit_insn(Insn::Goto {
target_pc: start_offset,
});
program.emit_goto(start_offset);

Ok(())
}
Expand Down Expand Up @@ -714,24 +659,15 @@ fn query_pragma(
let register = program.alloc_register();
match pragma {
PragmaName::CacheSize => {
program.emit_insn(Insn::Integer {
value: database_header.borrow().default_page_cache_size.into(),
dest: register,
});
program.emit_insn(Insn::ResultRow {
start_reg: register,
count: 1,
});
program.emit_int(
database_header.borrow().default_page_cache_size.into(),
register,
);
program.emit_result_row(register, 1);
}
PragmaName::JournalMode => {
program.emit_insn(Insn::String8 {
value: "wal".into(),
dest: register,
});
program.emit_insn(Insn::ResultRow {
start_reg: register,
count: 1,
});
program.emit_string8("wal".into(), register);
program.emit_result_row(register, 1);
}
PragmaName::WalCheckpoint => {
// Checkpoint uses 3 registers: P1, P2, P3. Ref Insn::Checkpoint for more info.
Expand All @@ -743,10 +679,7 @@ fn query_pragma(
checkpoint_mode: CheckpointMode::Passive,
dest: register,
});
program.emit_insn(Insn::ResultRow {
start_reg: register,
count: 3,
});
program.emit_result_row(register, 3);
}
PragmaName::TableInfo => {
let table = match value {
Expand All @@ -766,55 +699,30 @@ fn query_pragma(
if let Some(table) = table {
for (i, column) in table.columns.iter().enumerate() {
// cid
program.emit_insn(Insn::Integer {
value: i as i64,
dest: base_reg,
});

program.emit_int(i as i64, base_reg);
// name
program.emit_insn(Insn::String8 {
value: column.name.clone(),
dest: base_reg + 1,
});
program.emit_string8(column.name.clone(), base_reg + 1);

// type
program.emit_insn(Insn::String8 {
value: column.ty_str.clone(),
dest: base_reg + 2,
});
program.emit_string8(column.ty_str.clone(), base_reg + 2);

// notnull
program.emit_insn(Insn::Integer {
value: if column.notnull { 1 } else { 0 },
dest: base_reg + 3,
});
program.emit_bool(column.notnull, base_reg + 3);

// dflt_value
match &column.default {
None => {
program.emit_insn(Insn::Null {
dest: base_reg + 4,
dest_end: Some(base_reg + 5),
});
program.emit_null(base_reg + 4);
}
Some(expr) => {
program.emit_insn(Insn::String8 {
value: expr.to_string(),
dest: base_reg + 4,
});
program.emit_string8(expr.to_string(), base_reg + 4);
}
}

// pk
program.emit_insn(Insn::Integer {
value: if column.primary_key { 1 } else { 0 },
dest: base_reg + 5,
});

program.emit_insn(Insn::ResultRow {
start_reg: base_reg,
count: 6,
});
program.emit_bool(column.primary_key, base_reg + 5);

program.emit_result_row(base_reg, 6);
}
}
}
Expand Down
64 changes: 64 additions & 0 deletions core/vdbe/builder.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -98,6 +98,70 @@ impl ProgramBuilder {
self.insns.push(insn);
}

pub fn emit_string8(&mut self, value: String, dest: usize) {
self.emit_insn(Insn::String8 { value, dest });
}

pub fn emit_string8_new_reg(&mut self, value: String) -> usize {
let dest = self.alloc_register();
self.emit_insn(Insn::String8 { value, dest });
dest
}

pub fn emit_int(&mut self, value: i64, dest: usize) {
self.emit_insn(Insn::Integer { value, dest });
}

pub fn emit_bool(&mut self, value: bool, dest: usize) {
self.emit_insn(Insn::Integer {
value: if value { 1 } else { 0 },
dest,
});
}

pub fn emit_null(&mut self, dest: usize) {
self.emit_insn(Insn::Null {
dest,
dest_end: None,
});
}

pub fn emit_result_row(&mut self, start_reg: usize, count: usize) {
self.emit_insn(Insn::ResultRow { start_reg, count });
}

pub fn emit_halt(&mut self) {
self.emit_insn(Insn::Halt {
err_code: 0,
description: String::new(),
});
}

// no users yet, but I want to avoid someone else in the future
// just adding parameters to emit_halt! If you use this, remove the
// clippy warning please.
#[allow(dead_code)]
pub fn emit_halt_err(&mut self, err_code: usize, description: String) {
self.emit_insn(Insn::Halt {
err_code,
description,
});
}

pub fn emit_init(&mut self) -> BranchOffset {
let target_pc = self.allocate_label();
self.emit_insn(Insn::Init { target_pc });
target_pc
}

pub fn emit_transaction(&mut self, write: bool) {
self.emit_insn(Insn::Transaction { write });
}

pub fn emit_goto(&mut self, target_pc: BranchOffset) {
self.emit_insn(Insn::Goto { target_pc });
}

pub fn add_comment(&mut self, insn_index: BranchOffset, comment: &'static str) {
self.comments.insert(insn_index.to_offset_int(), comment);
}
Expand Down

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