internal/core/adt: reuse reqSets slices via OpContext

Benchmarking the reduction at https://cuelang.org/issue/3334
via benchcmd -n 12 CueVetIssue3334 cue vet -c f.cue:

                    │     old     │                 new                 │
                    │   sec/op    │   sec/op     vs base                │
    CueVetIssue3334   175.3m ± 1%   154.9m ± 1%  -11.67% (p=0.000 n=12)

                    │     old     │                 new                 │
                    │ user-sec/op │ user-sec/op  vs base                │
    CueVetIssue3334   332.1m ± 4%   270.8m ± 5%  -18.46% (p=0.000 n=12)

                    │     old      │              new               │
                    │  sys-sec/op  │  sys-sec/op   vs base          │
    CueVetIssue3334   27.61m ± 16%   21.92m ± 30%  ~ (p=0.089 n=12)

                    │      old       │                  new                  │
                    │ peak-RSS-bytes │ peak-RSS-bytes  vs base               │
    CueVetIssue3334     182.2Mi ± 4%     177.4Mi ± 1%  -2.61% (p=0.000 n=12)

Updates #3334.

Signed-off-by: Daniel Martí <[email protected]>
Change-Id: I1f066de341e8fd2e9d508304e3de1b86234f60a6
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1213055
Unity-Result: CUE porcuepine <[email protected]>
TryBot-Result: CUEcueckoo <[email protected]>
Reviewed-by: Marcel van Lohuizen <[email protected]>

Author: mvdan

internal/core/adt/context.go

@@ -188,6 +188,8 @@ type OpContext struct {
 	currentDisjunctionID int // sequence number for call to processDisjunctions
 
 	disjunctStack []disjunctInfo // stack of disjunct IDs
+
+	reqSetsBuf reqSets // reuse a reqSets slice
 }
 
 func (c *OpContext) CloseInfo() CloseInfo         { return c.ci }

internal/core/adt/typocheck.go

@@ -487,7 +487,7 @@ func (n *nodeContext) checkTypos() {
 		replacements := na.getReplacements(nil) // TODO(perf): use buffer
 		required := slices.Clone(required)      // TODO(perf): use buffer
 		// do the right thing in appendRequired either way.
-		required.replaceIDs(replacements...)
+		required.replaceIDs(n.ctx, replacements...)
 
 		a = a.DerefDisjunct()
 		// TODO(perf): somehow prevent error generation of recursive structures,
@@ -617,10 +617,10 @@ func (a reqSets) assert() {
 // - If in active definition, replace old definition
 // - If in embed, replace embed in respective sets. definition starts new group
 // - child definition replaces parent definition
-func (a *reqSets) replaceIDs(b ...replaceID) {
+func (a *reqSets) replaceIDs(ctx *OpContext, b ...replaceID) {
 	temp := *a
 	temp = temp[:0]
-	var buf reqSets
+	buf := ctx.reqSetsBuf[:0]
 outer:
 	for i := 0; i < len(*a); {
 		e := (*a)[i]
@@ -641,7 +641,7 @@ outer:
 				} else {
 					temp = append(temp, buf...)
 				}
-				buf = buf[:0] // TODO(perf): use OpContext buffer.
+				buf = buf[:0]
 			}
 		}
 
@@ -653,6 +653,7 @@ outer:
 		buf[0].size = uint32(len(buf))
 		temp = append(temp, buf...)
 	}
+	ctx.reqSetsBuf = buf[:0] // to be reused later on
 	*a = temp
 }
 
@@ -772,7 +773,7 @@ outer:
 		})
 	}
 
-	a.replaceIDs(n.replaceIDs...)
+	a.replaceIDs(n.ctx, n.replaceIDs...)
 
 	// If 'v' is a hidden field, then all reqSets in 'a' for which there is no
 	// corresponding entry in conjunctInfo should be removed from 'a'.

internal/core/adt/typocheck_test.go

@@ -477,7 +477,7 @@ func TestReplaceIDs(t *testing.T) {
 			tt.reqSets.assert()
 			tt.expected.assert()
 
-			tt.reqSets.replaceIDs(tt.replace...)
+			tt.reqSets.replaceIDs(&OpContext{}, tt.replace...)
 			if !slices.Equal(tt.reqSets, tt.expected) {
 				t.Errorf("got: \n%v, want:\n%v", tt.reqSets, tt.expected)
 			}