From 5736eb0013cb8c9b67432c98b08f68e9f370810c Mon Sep 17 00:00:00 2001 From: Matthew Dempsky Date: Thu, 29 Oct 2020 01:13:16 -0700 Subject: [PATCH] cmd/compile: support inlining of type switches This CL adds support for inlining type switches, including exporting and importing them. Type switches are represented mostly the same as expression switches. However, if the type switch guard includes a short variable declaration, then there are two differences: (1) there's an ONONAME (in the OTYPESW's Left) to represent the overall pseudo declaration; and (2) there's an ONAME (in each OCASE's Rlist) to represent the per-case variables. For simplicity, this CL simply writes out each variable separately using iimport/iiexport's normal Vargen mechanism for disambiguating identically named variables within a function. This could be improved somewhat, but inlinable type switches are probably too uncommon to merit the complexity. While here, remove "case OCASE" from typecheck1. We only type check "case" clauses as part of a "select" or "switch" statement, never as standalone statements. Fixes #37837 Change-Id: I8f42f6c9afdd821d6202af4a6bf1dbcbba0ef424 Reviewed-on: https://go-review.googlesource.com/c/go/+/266203 Run-TryBot: Matthew Dempsky TryBot-Result: Go Bot Reviewed-by: Keith Randall Trust: Matthew Dempsky --- src/cmd/compile/internal/gc/iexport.go | 40 +++++++++++++++++++---- src/cmd/compile/internal/gc/iimport.go | 41 +++++++++++++++++++----- src/cmd/compile/internal/gc/inl.go | 4 --- src/cmd/compile/internal/gc/typecheck.go | 5 --- test/fixedbugs/issue37837.dir/a.go | 33 +++++++++++++++++++ test/fixedbugs/issue37837.dir/b.go | 32 ++++++++++++++++++ test/fixedbugs/issue37837.go | 7 ++++ test/inline.go | 3 +- 8 files changed, 140 insertions(+), 25 deletions(-) create mode 100644 test/fixedbugs/issue37837.dir/a.go create mode 100644 test/fixedbugs/issue37837.dir/b.go create mode 100644 test/fixedbugs/issue37837.go diff --git a/src/cmd/compile/internal/gc/iexport.go b/src/cmd/compile/internal/gc/iexport.go index 9bc1f64600..1f53d8ca7d 100644 --- a/src/cmd/compile/internal/gc/iexport.go +++ b/src/cmd/compile/internal/gc/iexport.go @@ -1138,13 +1138,10 @@ func (w *exportWriter) stmt(n *Node) { w.pos(n.Pos) w.stmtList(n.Ninit) w.exprsOrNil(n.Left, nil) - w.stmtList(n.List) + w.caseList(n) - case OCASE: - w.op(OCASE) - w.pos(n.Pos) - w.stmtList(n.List) - w.stmtList(n.Nbody) + // case OCASE: + // handled by caseList case OFALL: w.op(OFALL) @@ -1168,6 +1165,24 @@ func (w *exportWriter) stmt(n *Node) { } } +func (w *exportWriter) caseList(sw *Node) { + namedTypeSwitch := sw.Op == OSWITCH && sw.Left != nil && sw.Left.Op == OTYPESW && sw.Left.Left != nil + + cases := sw.List.Slice() + w.uint64(uint64(len(cases))) + for _, cas := range cases { + if cas.Op != OCASE { + Fatalf("expected OCASE, got %v", cas) + } + w.pos(cas.Pos) + w.stmtList(cas.List) + if namedTypeSwitch { + w.localName(cas.Rlist.First()) + } + w.stmtList(cas.Nbody) + } +} + func (w *exportWriter) exprList(list Nodes) { for _, n := range list.Slice() { w.expr(n) @@ -1232,6 +1247,19 @@ func (w *exportWriter) expr(n *Node) { w.op(OTYPE) w.typ(n.Type) + case OTYPESW: + w.op(OTYPESW) + w.pos(n.Pos) + var s *types.Sym + if n.Left != nil { + if n.Left.Op != ONONAME { + Fatalf("expected ONONAME, got %v", n.Left) + } + s = n.Left.Sym + } + w.localIdent(s, 0) // declared pseudo-variable, if any + w.exprsOrNil(n.Right, nil) + // case OTARRAY, OTMAP, OTCHAN, OTSTRUCT, OTINTER, OTFUNC: // should have been resolved by typechecking - handled by default case diff --git a/src/cmd/compile/internal/gc/iimport.go b/src/cmd/compile/internal/gc/iimport.go index 7f2b05f288..c0114d0e53 100644 --- a/src/cmd/compile/internal/gc/iimport.go +++ b/src/cmd/compile/internal/gc/iimport.go @@ -784,6 +784,28 @@ func (r *importReader) stmtList() []*Node { return list } +func (r *importReader) caseList(sw *Node) []*Node { + namedTypeSwitch := sw.Op == OSWITCH && sw.Left != nil && sw.Left.Op == OTYPESW && sw.Left.Left != nil + + cases := make([]*Node, r.uint64()) + for i := range cases { + cas := nodl(r.pos(), OCASE, nil, nil) + cas.List.Set(r.stmtList()) + if namedTypeSwitch { + // Note: per-case variables will have distinct, dotted + // names after import. That's okay: swt.go only needs + // Sym for diagnostics anyway. + caseVar := newnamel(cas.Pos, r.ident()) + declare(caseVar, dclcontext) + cas.Rlist.Set1(caseVar) + caseVar.Name.Defn = sw.Left + } + cas.Nbody.Set(r.stmtList()) + cases[i] = cas + } + return cases +} + func (r *importReader) exprList() []*Node { var list []*Node for { @@ -831,6 +853,14 @@ func (r *importReader) node() *Node { case OTYPE: return typenod(r.typ()) + case OTYPESW: + n := nodl(r.pos(), OTYPESW, nil, nil) + if s := r.ident(); s != nil { + n.Left = npos(n.Pos, newnoname(s)) + } + n.Right, _ = r.exprsOrNil() + return n + // case OTARRAY, OTMAP, OTCHAN, OTSTRUCT, OTINTER, OTFUNC: // unreachable - should have been resolved by typechecking @@ -1025,16 +1055,11 @@ func (r *importReader) node() *Node { n := nodl(r.pos(), op, nil, nil) n.Ninit.Set(r.stmtList()) n.Left, _ = r.exprsOrNil() - n.List.Set(r.stmtList()) + n.List.Set(r.caseList(n)) return n - case OCASE: - n := nodl(r.pos(), OCASE, nil, nil) - n.List.Set(r.exprList()) - // TODO(gri) eventually we must declare variables for type switch - // statements (type switch statements are not yet exported) - n.Nbody.Set(r.stmtList()) - return n + // case OCASE: + // handled by caseList case OFALL: n := nodl(r.pos(), OFALL, nil, nil) diff --git a/src/cmd/compile/internal/gc/inl.go b/src/cmd/compile/internal/gc/inl.go index 253036fea6..139572f652 100644 --- a/src/cmd/compile/internal/gc/inl.go +++ b/src/cmd/compile/internal/gc/inl.go @@ -392,13 +392,9 @@ func (v *hairyVisitor) visit(n *Node) bool { v.reason = "call to recover" return true - case OCALLPART: - // OCALLPART is inlineable, but no extra cost to the budget - case OCLOSURE, ORANGE, OSELECT, - OTYPESW, OGO, ODEFER, ODCLTYPE, // can't print yet diff --git a/src/cmd/compile/internal/gc/typecheck.go b/src/cmd/compile/internal/gc/typecheck.go index 8ebeaf1330..cbba5ff79c 100644 --- a/src/cmd/compile/internal/gc/typecheck.go +++ b/src/cmd/compile/internal/gc/typecheck.go @@ -2065,11 +2065,6 @@ func typecheck1(n *Node, top int) (res *Node) { n.Type = nil return n - case OCASE: - ok |= ctxStmt - typecheckslice(n.List.Slice(), ctxExpr) - typecheckslice(n.Nbody.Slice(), ctxStmt) - case ODCLFUNC: ok |= ctxStmt typecheckfunc(n) diff --git a/test/fixedbugs/issue37837.dir/a.go b/test/fixedbugs/issue37837.dir/a.go new file mode 100644 index 0000000000..49d830ffbc --- /dev/null +++ b/test/fixedbugs/issue37837.dir/a.go @@ -0,0 +1,33 @@ +// Copyright 2020 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 a + +func F(i interface{}) int { // ERROR "can inline F" "i does not escape" + switch i.(type) { + case nil: + return 0 + case int: + return 1 + case float64: + return 2 + default: + return 3 + } +} + +func G(i interface{}) interface{} { // ERROR "can inline G" "leaking param: i" + switch i := i.(type) { + case nil: // ERROR "moved to heap: i" + return &i + case int: // ERROR "moved to heap: i" + return &i + case float64: // ERROR "moved to heap: i" + return &i + case string, []byte: // ERROR "moved to heap: i" + return &i + default: // ERROR "moved to heap: i" + return &i + } +} diff --git a/test/fixedbugs/issue37837.dir/b.go b/test/fixedbugs/issue37837.dir/b.go new file mode 100644 index 0000000000..461f5c7a55 --- /dev/null +++ b/test/fixedbugs/issue37837.dir/b.go @@ -0,0 +1,32 @@ +// Copyright 2020 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 main + +import "./a" + +func main() { + // Test that inlined type switches without short variable + // declarations work correctly. + check(0, a.F(nil)) // ERROR "inlining call to a.F" + check(1, a.F(0)) // ERROR "inlining call to a.F" "does not escape" + check(2, a.F(0.0)) // ERROR "inlining call to a.F" "does not escape" + check(3, a.F("")) // ERROR "inlining call to a.F" "does not escape" + + // Test that inlined type switches with short variable + // declarations work correctly. + _ = a.G(nil).(*interface{}) // ERROR "inlining call to a.G" + _ = a.G(1).(*int) // ERROR "inlining call to a.G" "does not escape" + _ = a.G(2.0).(*float64) // ERROR "inlining call to a.G" "does not escape" + _ = (*a.G("").(*interface{})).(string) // ERROR "inlining call to a.G" "does not escape" + _ = (*a.G(([]byte)(nil)).(*interface{})).([]byte) // ERROR "inlining call to a.G" "does not escape" + _ = (*a.G(true).(*interface{})).(bool) // ERROR "inlining call to a.G" "does not escape" +} + +//go:noinline +func check(want, got int) { + if want != got { + println("want", want, "but got", got) + } +} diff --git a/test/fixedbugs/issue37837.go b/test/fixedbugs/issue37837.go new file mode 100644 index 0000000000..2e8abc5f05 --- /dev/null +++ b/test/fixedbugs/issue37837.go @@ -0,0 +1,7 @@ +// errorcheckandrundir -0 -m + +// Copyright 2020 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 ignored diff --git a/test/inline.go b/test/inline.go index 470414f883..d754f06e03 100644 --- a/test/inline.go +++ b/test/inline.go @@ -152,8 +152,7 @@ func switchBreak(x, y int) int { return n } -// can't currently inline functions with a type switch -func switchType(x interface{}) int { // ERROR "x does not escape" +func switchType(x interface{}) int { // ERROR "can inline switchType" "x does not escape" switch x.(type) { case int: return x.(int) -- 2.50.0