[tools] gopls/internal/golang: pre-filter identifiers by name in localReferences

[Robert Findley (Gerrit)]

Robert Findley has uploaded the change for review

Commit message

gopls/internal/golang: pre-filter identifiers by name in localReferences

Build a set of target object names and skip identifiers whose name is
not in the set before consulting TypesInfo.Uses. Also add a fast path
to containsOrigin: check for an exact match first, and return false
immediately when origin(obj) == obj (the non-generic case) since the
exact-match check is then exhaustive.

Benchstat on x/tools, incremental over the parent CL (Xeon 8488C):

                    │   parent    │              this CL                │
                    │   sec/op    │   sec/op     vs base                │
References/tools-64  3.765m ± 2%   2.221m ± 3%  -41.02% (p=0.000 n=10)

                    │ cpu_seconds/op │ cpu_seconds/op  vs base          │
References/tools-64    4.023m ± 7%     1.550m ± 35%  -61.46% (p=0.000 n=10)

Updates golang/go#69523

Change-Id: I58d32eebeb3fce5072af666d99999c9fc978aaa6

Change diff

diff --git a/gopls/internal/golang/origin.go b/gopls/internal/golang/origin.go
index aa77a9b..cdaec01 100644
--- a/gopls/internal/golang/origin.go
+++ b/gopls/internal/golang/origin.go
@@ -10,7 +10,13 @@
 // with the same origin as the provided obj (which may be a synthetic object
 // created during instantiation).
 func containsOrigin(objSet map[types.Object]bool, obj types.Object) bool {
+	if objSet[obj] {
+		return true // fast path: exact match (common for non-generic code)
+	}
 	objOrigin := origin(obj)
+	if objOrigin == obj {
+		return false // non-generic: origin is identity, so no match
+	}
 	for target := range objSet {
 		if origin(target) == objOrigin {
 			return true
diff --git a/gopls/internal/golang/references.go b/gopls/internal/golang/references.go
index ed89c33..91e992a 100644
--- a/gopls/internal/golang/references.go
+++ b/gopls/internal/golang/references.go
@@ -599,10 +599,20 @@
 		return false
 	}
 
+	// Collect target names for fast pre-filtering:
+	// skip identifiers whose name can't match any target.
+	targetNames := make(map[string]struct{}, len(targets))
+	for obj := range targets {
+		targetNames[obj.Name()] = struct{}{}
+	}
+
 	// Scan through syntax looking for uses of one of the target objects.
 	for _, pgf := range pkg.CompiledGoFiles() {
 		for curId := range pgf.Cursor().Preorder((*ast.Ident)(nil)) {
 			id := curId.Node().(*ast.Ident)
+			if _, ok := targetNames[id.Name]; !ok {
+				continue
+			}
 			if obj, ok := pkg.TypesInfo().Uses[id]; ok && matches(obj) {
 				report(mustLocation(pgf, id), false)
 			}

Change information

Files:

• M gopls/internal/golang/origin.go
• M gopls/internal/golang/references.go

Change size: S

Delta: 2 files changed, 16 insertions(+), 0 deletions(-)

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Gerrit

Gerrit-MessageType: newchange

Gerrit-Project: tools

Gerrit-Branch: master

Gerrit-Change-Id: I58d32eebeb3fce5072af666d99999c9fc978aaa6

Gerrit-Change-Number: 763742

Gerrit-PatchSet: 1

Gerrit-Owner: Robert Findley <rfin...@golang.org>