Initialize module and dependencies

vendor/golang.org/x/tools/go/ssa/instantiate.go

@@ -0,0 +1,127 @@
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package ssa
+
+import (
+	"fmt"
+	"go/types"
+	"slices"
+	"sync"
+)
+
+// A generic records information about a generic origin function,
+// including a cache of existing instantiations.
+type generic struct {
+	instancesMu sync.Mutex
+	instances   map[*typeList]*Function // canonical type arguments to an instance.
+}
+
+// instance returns a Function that is the instantiation of generic
+// origin function fn with the type arguments targs.
+//
+// Any created instance is added to cr.
+//
+// Acquires fn.generic.instancesMu.
+func (fn *Function) instance(targs []types.Type, b *builder) *Function {
+	key := fn.Prog.canon.List(targs)
+
+	gen := fn.generic
+
+	gen.instancesMu.Lock()
+	defer gen.instancesMu.Unlock()
+	inst, ok := gen.instances[key]
+	if !ok {
+		inst = createInstance(fn, targs)
+		inst.buildshared = b.shared()
+		b.enqueue(inst)
+
+		if gen.instances == nil {
+			gen.instances = make(map[*typeList]*Function)
+		}
+		gen.instances[key] = inst
+	} else {
+		b.waitForSharedFunction(inst)
+	}
+	return inst
+}
+
+// createInstance returns the instantiation of generic function fn using targs.
+//
+// Requires fn.generic.instancesMu.
+func createInstance(fn *Function, targs []types.Type) *Function {
+	prog := fn.Prog
+
+	// Compute signature.
+	var sig *types.Signature
+	var obj *types.Func
+	if recv := fn.Signature.Recv(); recv != nil {
+		// method
+		obj = prog.canon.instantiateMethod(fn.object, targs, prog.ctxt)
+		sig = obj.Type().(*types.Signature)
+	} else {
+		// function
+		instSig, err := types.Instantiate(prog.ctxt, fn.Signature, targs, false)
+		if err != nil {
+			panic(err)
+		}
+		instance, ok := instSig.(*types.Signature)
+		if !ok {
+			panic("Instantiate of a Signature returned a non-signature")
+		}
+		obj = fn.object // instantiation does not exist yet
+		sig = prog.canon.Type(instance).(*types.Signature)
+	}
+
+	// Choose strategy (instance or wrapper).
+	var (
+		synthetic string
+		subst     *subster
+		build     buildFunc
+	)
+	if prog.mode&InstantiateGenerics != 0 && !prog.isParameterized(targs...) {
+		synthetic = fmt.Sprintf("instance of %s", fn.Name())
+		if fn.syntax != nil {
+			subst = makeSubster(prog.ctxt, obj, fn.typeparams, targs)
+			build = (*builder).buildFromSyntax
+		} else {
+			build = (*builder).buildParamsOnly
+		}
+	} else {
+		synthetic = fmt.Sprintf("instantiation wrapper of %s", fn.Name())
+		build = (*builder).buildInstantiationWrapper
+	}
+
+	/* generic instance or instantiation wrapper */
+	return &Function{
+		name:           fmt.Sprintf("%s%s", fn.Name(), targs), // may not be unique
+		object:         obj,
+		Signature:      sig,
+		Synthetic:      synthetic,
+		syntax:         fn.syntax,    // \
+		info:           fn.info,      //  } empty for non-created packages
+		goversion:      fn.goversion, // /
+		build:          build,
+		topLevelOrigin: fn,
+		pos:            obj.Pos(),
+		Pkg:            nil,
+		Prog:           fn.Prog,
+		typeparams:     fn.typeparams, // share with origin
+		typeargs:       targs,
+		subst:          subst,
+	}
+}
+
+// isParameterized reports whether any of the specified types contains
+// a free type parameter. It is safe to call concurrently.
+func (prog *Program) isParameterized(ts ...types.Type) bool {
+	prog.hasParamsMu.Lock()
+	defer prog.hasParamsMu.Unlock()
+
+	// TODO(adonovan): profile. If this operation is expensive,
+	// handle the most common but shallow cases such as T, pkg.T,
+	// *T without consulting the cache under the lock.
+
+	return slices.ContainsFunc(ts, prog.hasParams.Has)
+}