Use paged indexes for type-node and signature caches

Resolved type nodes and signatures still kept AST pointers as map keys
despite already having stable node identities. Those maps add redundant
pointer storage, GC scanning, hashing, and growth allocations.

Reuse the existing node-link store's pointer-free paged indexes for
these two high-volume caches. Ordinary IDs and IDs outside the dense
reserved range retain the existing fallback, and caches stay
checker-local.

Six fresh-process interleaved VS Code comparisons against the parent
commit, using normal GC, reduce retained heap 1.20%, scan bytes 2.12%,
allocated bytes 2.11%, and allocation events 0.20%. Instructions are
inconclusive. This saves another roughly 43 MiB of heap and 66 MiB of
scanning.

Production diagnostics and semantic counts match exactly. Tests cover
cache identity, ordinary/reserved IDs, clone isolation, growth,
GC reachability, and independent checkers.

goos: linux
goarch: amd64
pkg: github.com/microsoft/TypeScript/tsc/internal/checker
cpu: Intel(R) Core(TM) i9-10900K CPU @ 3.70GHz
                   │ vscode-paged-before-6.txt │         vscode-paged-6.txt         │
                   │        retained-B         │  retained-B   vs base              │
ExternalProgram-20                3.497Gi ± 0%   3.455Gi ± 0%  -1.20% (p=0.002 n=6)

                   │ vscode-paged-before-6.txt │         vscode-paged-6.txt         │
                   │          scan-B           │    scan-B     vs base              │
ExternalProgram-20                3.061Gi ± 0%   2.997Gi ± 0%  -2.12% (p=0.002 n=6)

                   │ vscode-paged-before-6.txt │         vscode-paged-6.txt         │
                   │           B/op            │     B/op      vs base              │
ExternalProgram-20                5.129Gi ± 0%   5.021Gi ± 0%  -2.11% (p=0.002 n=6)

                   │ vscode-paged-before-6.txt │        vscode-paged-6.txt         │
                   │         allocs/op         │  allocs/op   vs base              │
ExternalProgram-20                 31.16M ± 0%   31.09M ± 0%  -0.20% (p=0.002 n=6)

                        │ paged-before-instructions.txt │      paged-instructions.txt      │
                        │        instructions/op        │ instructions/op  vs base         │
ExternalInstructions-20                     279.8G ± 5%       270.5G ± 2%  ~ (p=0.589 n=6)

Author: jakebailey

tsc/internal/checker/checker.go

@@ -695,9 +695,9 @@ type Checker struct {
 	mergedExportsChecked                        collections.Set[*ast.Symbol]
 	factory                                     ast.NodeFactory
 	nodeLinks                                   core.LinkStore[*ast.Node, NodeLinks]
-	signatureLinks                              core.LinkStore[*ast.Node, SignatureLinks]
+	signatureLinks                              nodeLinkStore[SignatureLinks]
 	symbolNodeLinks                             nodeLinkStore[SymbolNodeLinks]
-	typeNodeLinks                               core.LinkStore[*ast.Node, TypeNodeLinks]
+	typeNodeLinks                               nodeLinkStore[TypeNodeLinks]
 	enumMemberLinks                             core.LinkStore[*ast.Node, EnumMemberLinks]
 	assertionLinks                              core.LinkStore[*ast.Node, AssertionLinks]
 	arrayLiteralLinks                           core.LinkStore[*ast.Node, ArrayLiteralLinks]

tsc/internal/checker/types_test.go

@@ -15,6 +15,38 @@ import (
 	"gotest.tools/v3/assert"
 )
 
+func TestCheckerNodeLinkStores(t *testing.T) {
+	t.Parallel()
+	f := ast.NewNodeFactory(ast.NodeFactoryHooks{})
+	first := &Checker{}
+	second := &Checker{}
+	nodes := make([]*ast.Node, 4096)
+	for i := range nodes {
+		node := f.NewIdentifier(strconv.Itoa(i))
+		if i%2 == 0 {
+			ast.GetNodeId(node)
+		}
+		nodes[i] = node
+		assert.Assert(t, !first.typeNodeLinks.Has(node))
+		assert.Assert(t, !first.signatureLinks.Has(node))
+		first.typeNodeLinks.Get(node).resolvedType = &Type{id: TypeId(i + 1)}
+		first.signatureLinks.Get(node).resolvedSignature = &Signature{id: SignatureId(i + 1)}
+		second.typeNodeLinks.Get(node).resolvedType = &Type{id: TypeId(i + 2)}
+		second.signatureLinks.Get(node).resolvedSignature = &Signature{id: SignatureId(i + 2)}
+	}
+	f.ReleaseArenas()
+	runtime.GC()
+	for i, node := range nodes {
+		assert.Equal(t, first.typeNodeLinks.Get(node).resolvedType.id, TypeId(i+1))
+		assert.Equal(t, first.signatureLinks.Get(node).resolvedSignature.id, SignatureId(i+1))
+		assert.Equal(t, second.typeNodeLinks.Get(node).resolvedType.id, TypeId(i+2))
+		assert.Equal(t, second.signatureLinks.Get(node).resolvedSignature.id, SignatureId(i+2))
+	}
+	clone := nodes[0].Clone(f)
+	assert.Assert(t, !first.typeNodeLinks.Has(clone))
+	assert.Assert(t, !first.signatureLinks.Has(clone))
+}
+
 func TestTypeCasts(t *testing.T) {
 	t.Parallel()
 	type bases interface {