Merge 'Fix DELETE not emitting constant WhereTerms' from Pedro Muniz

Fixes DELETE not emitting conditional jumps at all if the associated
WhereTerm is a constant, e.g.
```sql
limbo> create table t(x);
limbo> explain DELETE FROM t WHERE 5-5;
addr  opcode             p1    p2    p3    p4             p5  comment
----  -----------------  ----  ----  ----  -------------  --  -------
0     Init               0     7     0                    0   Start at 7
1     OpenWrite          0     2     0                    0   root=2; t
2     Rewind             0     6     0                    0   Rewind table t
3       RowId            0     1     0                    0   r[1]=t.rowid
4       Delete           0     0     0                    0
5     Next               0     3     0                    0
6     Halt               0     0     0                    0
7     Transaction        0     1     0                    0   write=true
8     Goto               0     1     0                    0
```
I was adding more stuff to the simulator in a Branch of mine, and I
caught this error with delete. Upstreaming the fix here. As we do with
Update, I added the translation step for the `WhereTerms` of the query.
Edit: Closes #1732. Closes #1733. Closes #1734. Closes #1735. Closes
#1736. Closes #1738. Closes #1739. Closes #1740.
Edit: Also pushes constant where term translation to `init_loop` for
Update and Select as well.

Reviewed-by: Jussi Saurio <jussi.saurio@gmail.com>

Closes #1746

core/translate/emitter.rs

@@ -7,7 +7,7 @@ use limbo_sqlite3_parser::ast::{self, Expr};
 use tracing::{instrument, Level};
 
 use super::aggregation::emit_ungrouped_aggregation;
-use super::expr::{translate_condition_expr, translate_expr, ConditionMetadata};
+use super::expr::translate_expr;
 use super::group_by::{
     group_by_agg_phase, group_by_emit_row_phase, init_group_by, GroupByMetadata, GroupByRowSource,
 };
@@ -333,6 +333,7 @@ pub fn emit_query<'a>(
         &mut plan.aggregates,
         plan.group_by.as_ref(),
         OperationMode::SELECT,
+        &plan.where_clause,
     )?;
 
     if plan.is_simple_count() {
@@ -340,27 +341,6 @@ pub fn emit_query<'a>(
         return Ok(t_ctx.reg_result_cols_start.unwrap());
     }
 
-    for where_term in plan
-        .where_clause
-        .iter()
-        .filter(|wt| wt.should_eval_before_loop(&plan.join_order))
-    {
-        let jump_target_when_true = program.allocate_label();
-        let condition_metadata = ConditionMetadata {
-            jump_if_condition_is_true: false,
-            jump_target_when_false: after_main_loop_label,
-            jump_target_when_true,
-        };
-        translate_condition_expr(
-            program,
-            &plan.table_references,
-            &where_term.expr,
-            condition_metadata,
-            &t_ctx.resolver,
-        )?;
-        program.preassign_label_to_next_insn(jump_target_when_true);
-    }
-
     // Set up main query execution loop
     open_loop(
         program,
@@ -449,6 +429,7 @@ fn emit_program_for_delete(
         &mut [],
         None,
         OperationMode::DELETE,
+        &plan.where_clause,
     )?;
 
     // Set up main query execution loop
@@ -629,6 +610,7 @@ fn emit_program_for_update(
         &mut [],
         None,
         OperationMode::UPDATE,
+        &plan.where_clause,
     )?;
     // Open indexes for update.
     let mut index_cursors = Vec::with_capacity(plan.indexes_to_update.len());
@@ -723,26 +705,6 @@ fn emit_update_insns(
         },
     };
 
-    for cond in plan
-        .where_clause
-        .iter()
-        .filter(|c| c.should_eval_before_loop(&[JoinOrderMember::default()]))
-    {
-        let jump_target = program.allocate_label();
-        let meta = ConditionMetadata {
-            jump_if_condition_is_true: false,
-            jump_target_when_true: jump_target,
-            jump_target_when_false: t_ctx.label_main_loop_end.unwrap(),
-        };
-        translate_condition_expr(
-            program,
-            &plan.table_references,
-            &cond.expr,
-            meta,
-            &t_ctx.resolver,
-        )?;
-        program.preassign_label_to_next_insn(jump_target);
-    }
     let beg = program.alloc_registers(
         table_ref.table.columns().len()
             + if is_virtual {
@@ -809,27 +771,6 @@ fn emit_update_insns(
         });
     }
 
-    for cond in plan
-        .where_clause
-        .iter()
-        .filter(|c| c.should_eval_before_loop(&[JoinOrderMember::default()]))
-    {
-        let jump_target = program.allocate_label();
-        let meta = ConditionMetadata {
-            jump_if_condition_is_true: false,
-            jump_target_when_true: jump_target,
-            jump_target_when_false: loop_labels.next,
-        };
-        translate_condition_expr(
-            program,
-            &plan.table_references,
-            &cond.expr,
-            meta,
-            &t_ctx.resolver,
-        )?;
-        program.preassign_label_to_next_insn(jump_target);
-    }
-
     // we scan a column at a time, loading either the column's values, or the new value
     // from the Set expression, into registers so we can emit a MakeRecord and update the row.
     let start = if is_virtual { beg + 2 } else { beg + 1 };

core/translate/main_loop.rs

@@ -111,6 +111,7 @@ pub fn init_loop(
     aggregates: &mut [Aggregate],
     group_by: Option<&GroupBy>,
     mode: OperationMode,
+    where_clause: &[WhereTerm],
 ) -> Result<()> {
     assert!(
         t_ctx.meta_left_joins.len() == tables.joined_tables().len(),
@@ -330,6 +331,20 @@ pub fn init_loop(
         }
     }
 
+    for cond in where_clause
+        .iter()
+        .filter(|c| c.should_eval_before_loop(&[JoinOrderMember::default()]))
+    {
+        let jump_target = program.allocate_label();
+        let meta = ConditionMetadata {
+            jump_if_condition_is_true: false,
+            jump_target_when_true: jump_target,
+            jump_target_when_false: t_ctx.label_main_loop_end.unwrap(),
+        };
+        translate_condition_expr(program, &tables, &cond.expr, meta, &t_ctx.resolver)?;
+        program.preassign_label_to_next_insn(jump_target);
+    }
+
     Ok(())
 }
 

testing/delete.test

@@ -62,3 +62,19 @@ if {[info exists ::env(SQLITE_EXEC)] && $::env(SQLITE_EXEC) eq "scripts/limbo-sq
         SELECT * FROM t;
     } {}
 }
+
+do_execsql_test_on_specific_db {:memory:} delete_where_falsy {
+    CREATE TABLE resourceful_schurz (diplomatic_kaplan BLOB);
+    INSERT INTO resourceful_schurz VALUES (X'696E646570656E64656E745F6A6165636B6C65'), (X'67656E65726F75735F62617262616E65677261'), (X'73757065725F74616E6E656E6261756D'), (X'6D6F76696E675F6E616F756D6F76'), (X'7374756E6E696E675F6B62');
+    INSERT INTO resourceful_schurz VALUES (X'70617373696F6E6174655F726F62696E'), (X'666169746866756C5F74686F6D6173'), (X'76696272616E745F6D69726F736C6176'), (X'737061726B6C696E675F67726179');
+    DELETE FROM resourceful_schurz WHERE - x'666169746866756c5f74686f6d6173';
+    SELECT * FROM resourceful_schurz;
+} {independent_jaeckle
+generous_barbanegra
+super_tannenbaum
+moving_naoumov
+stunning_kb
+passionate_robin
+faithful_thomas
+vibrant_miroslav
+sparkling_gray}