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go/ssa/testdata/objlookup.go

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go.tools/ssa: add debug information for all ast.Idents. This CL adds three new functions to determine the SSA Value for a given syntactic var, func or const object: Program.{Const,Func,Var}Value. Since constants and functions are immutable, the first two only need a types.Object; but each distinct reference to a var may return a distinct Value, so the third requires an ast.Ident parameter too. Debug information for local vars is encoded in the instruction stream in the form of DebugRef instructions, which are a no-op but relate their operand to a particular ident in the AST. The beauty of this approach is that it naturally stays consistent during optimisation passes (e.g. lifting) without additional bookkeeping. DebugRef instructions are only generated if the DebugMode builder flag is set; I plan to make the policy more fine- grained (per function). DebugRef instructions are inserted for: - expr(Ident) for rvalue idents - address.store() for idents that update an lvalue - address.address() for idents that take address of lvalue (this new method replaces all uses of lval.(address).addr) - expr() for all constant expressions - local ValueSpecs with implicit zero initialization (no RHS) (this case doesn't call store() or address()) To ensure we don't forget to emit debug info for uses of Idents, we must use the lvalue mechanism consistently. (Previously, many simple cases had effectively inlined these functions.) Similarly setCallFunc no longer inlines expr(Ident). Also: - Program.Value() has been inlined & specialized. - Program.Package() has moved nearer the new lookup functions. - refactoring: funcSyntax has lost paramFields, resultFields; gained funcType, which provides access to both. - add package-level constants to Package.values map. - opt: don't call localValueSpec for constants. (The resulting code is always optimised away.) There are a number of comments asking whether Literals should have positions. Will address in a follow-up. Added tests of all interesting cases. R=gri CC=golang-dev https://golang.org/cl/11259044
2013-07-15 11:56:46 -06:00
//+build ignore
package main
// This file is the input to TestObjValueLookup in source_test.go,
// which ensures that each occurrence of an ident defining or
// referring to a func, var or const object can be mapped to its
// corresponding SSA Value.
//
// For every reference to a var object, we use annotations in comments
// to denote both the expected SSA Value kind, and whether to expect
// its value (x) or its address (&x).
//
// For const and func objects, the results don't vary by reference and
// are always values not addresses, so no annotations are needed.
import "fmt"
type J int
func (*J) method() {}
const globalConst = 0
var globalVar int // &globalVar::Global
func globalFunc() {}
type I interface {
interfaceMethod() // TODO(adonovan): unimplemented (blacklisted in source_test)
}
type S struct {
x int
}
func main() {
var v0 int = 1 // v0::Literal (simple local value spec)
if v0 > 0 { // v0::Literal
v0 = 2 // v0::Literal
}
print(v0) // v0::Phi
// v1 is captured and thus implicitly address-taken.
var v1 int = 1 // v1::Literal
v1 = 2 // v1::Literal
fmt.Println(v1) // v1::UnOp (load)
f := func(param int) { // f::MakeClosure param::Parameter
if y := 1; y > 0 { // y::Literal
print(v1, param) // v1::UnOp (load) param::Parameter
}
param = 2 // param::Literal
println(param) // param::Literal
}
f(0) // f::MakeClosure
var v2 int // v2::Literal (implicitly zero-initialized local value spec)
print(v2) // v2::Literal
m := make(map[string]int) // m::MakeMap
// Local value spec with multi-valued RHS:
var v3, v4 = m[""] // v3::Extract v4::Extract m::MakeMap
print(v3) // v3::Extract
print(v4) // v4::Extract
v3++ // v3::BinOp (assign with op)
v3 += 2 // v3::BinOp (assign with op)
v5, v6 := false, "" // v5::Literal v6::Literal (defining assignment)
print(v5) // v5::Literal
print(v6) // v6::Literal
var v7 S // v7::UnOp (load from Alloc)
v7.x = 1 // &v7::Alloc
var v8 [1]int // v8::UnOp (load from Alloc)
v8[0] = 0 // &v8::Alloc
print(v8[:]) // &v8::Alloc
_ = v8[0] // v8::UnOp (load from Alloc)
_ = v8[:][0] // &v8::Alloc
v8ptr := &v8 // v8ptr::Alloc &v8::Alloc
_ = v8ptr[0] // v8ptr::Alloc
_ = *v8ptr // v8ptr::Alloc
v9 := S{} // &v9::Alloc
v10 := &v9 // v10::Alloc &v9::Alloc
var v11 *J = nil // v11::Literal
v11.method() // v11::Literal
var v12 J // v12::UnOp (load from Alloc)
v12.method() // &v12::Alloc (implicitly address-taken)
// These vars are optimised away.
if false {
v13 := 0 // v13::nil
println(v13) // v13::nil
}
switch x := 1; x { // x::Literal
case v0: // v0::Phi
}
for k, v := range m { // k::Extract v::Extract m::MakeMap
v++ // v::BinOp
}
if y := 0; y > 1 { // y::Literal y::Literal
}
var i interface{} // i::Literal (nil interface)
i = 1 // i::MakeInterface
switch i := i.(type) { // i::MakeInterface i::MakeInterface
case int:
println(i) // i::Extract
}
ch := make(chan int) // ch::MakeChan
select {
case x := <-ch: // x::UnOp (receive) ch::MakeChan
}
}