From 61ae2b734cdbc0db342036a2a026fe1fccdccde3 Mon Sep 17 00:00:00 2001 From: Matthew Dempsky Date: Tue, 21 Jun 2022 02:30:21 -0700 Subject: [PATCH] [dev.unified] cmd/compile: plumb rtype through OSWITCH/OCASE clauses For (value) switch statements, we may generate OEQ comparisons between values of interface and concrete type, which in turn may require access to the concrete type's RType. To plumb this through, this CL adds CaseClause.RTypes to hold the rtype values, updates the GOEXPERIMENT=unified frontend to set it, and updates walk to plumb rtypes through into generated OEQ nodes. Change-Id: I6f1de2a1167ce54f5770147498a0a591efb3f012 Reviewed-on: https://go-review.googlesource.com/c/go/+/413361 Reviewed-by: Keith Randall Reviewed-by: David Chase Run-TryBot: Matthew Dempsky TryBot-Result: Gopher Robot --- src/cmd/compile/internal/ir/stmt.go | 11 +++++++++ src/cmd/compile/internal/noder/reader.go | 23 ++++++++++++++++++- .../compile/internal/reflectdata/helpers.go | 4 +--- src/cmd/compile/internal/walk/switch.go | 19 ++++++++++----- 4 files changed, 47 insertions(+), 10 deletions(-) diff --git a/src/cmd/compile/internal/ir/stmt.go b/src/cmd/compile/internal/ir/stmt.go index 6a82df58f8..10f8b5e394 100644 --- a/src/cmd/compile/internal/ir/stmt.go +++ b/src/cmd/compile/internal/ir/stmt.go @@ -170,6 +170,17 @@ type CaseClause struct { miniStmt Var *Name // declared variable for this case in type switch List Nodes // list of expressions for switch, early select + + // RTypes is a list of RType expressions, which are copied to the + // corresponding OEQ nodes that are emitted when switch statements + // are desugared. RTypes[i] must be non-nil if the emitted + // comparison for List[i] will be a mixed interface/concrete + // comparison; see reflectdata.CompareRType for details. + // + // Because mixed interface/concrete switch cases are rare, we allow + // len(RTypes) < len(List). Missing entries are implicitly nil. + RTypes Nodes + Body Nodes } diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go index 32276e7553..aa2cccf86b 100644 --- a/src/cmd/compile/internal/noder/reader.go +++ b/src/cmd/compile/internal/noder/reader.go @@ -1487,7 +1487,7 @@ func (r *reader) switchStmt(label *types.Sym) ir.Node { r.openScope() pos := r.pos() - var cases []ir.Node + var cases, rtypes []ir.Node if iface != nil { cases = make([]ir.Node, r.Len()) if len(cases) == 0 { @@ -1498,9 +1498,30 @@ func (r *reader) switchStmt(label *types.Sym) ir.Node { } } else { cases = r.exprList() + + tagType := types.Types[types.TBOOL] + if tag != nil { + tagType = tag.Type() + } + for i, cas := range cases { + if cas.Op() == ir.ONIL { + continue // never needs rtype + } + if tagType.IsInterface() != cas.Type().IsInterface() { + typ := tagType + if typ.IsInterface() { + typ = cas.Type() + } + for len(rtypes) < i { + rtypes = append(rtypes, nil) + } + rtypes = append(rtypes, reflectdata.TypePtr(typ)) + } + } } clause := ir.NewCaseStmt(pos, cases, nil) + clause.RTypes = rtypes if ident != nil { pos := r.pos() diff --git a/src/cmd/compile/internal/reflectdata/helpers.go b/src/cmd/compile/internal/reflectdata/helpers.go index 66f1864474..5edb495a81 100644 --- a/src/cmd/compile/internal/reflectdata/helpers.go +++ b/src/cmd/compile/internal/reflectdata/helpers.go @@ -84,9 +84,7 @@ func AppendElemRType(pos src.XPos, n *ir.CallExpr) ir.Node { func CompareRType(pos src.XPos, n *ir.BinaryExpr) ir.Node { assertOp2(n, ir.OEQ, ir.ONE) base.AssertfAt(n.X.Type().IsInterface() != n.Y.Type().IsInterface(), n.Pos(), "expect mixed interface and non-interface, have %L and %L", n.X, n.Y) - // TODO(mdempsky): Need to propagate RType from OSWITCH/OCASE - // clauses to emitted OEQ nodes. - if haveRType(n, n.RType, "RType", false) { + if haveRType(n, n.RType, "RType", true) { return n.RType } typ := n.X.Type() diff --git a/src/cmd/compile/internal/walk/switch.go b/src/cmd/compile/internal/walk/switch.go index 6cac8f2937..257903c0b3 100644 --- a/src/cmd/compile/internal/walk/switch.go +++ b/src/cmd/compile/internal/walk/switch.go @@ -85,8 +85,12 @@ func walkSwitchExpr(sw *ir.SwitchStmt) { defaultGoto = jmp } - for _, n1 := range ncase.List { - s.Add(ncase.Pos(), n1, jmp) + for i, n1 := range ncase.List { + var rtype ir.Node + if i < len(ncase.RTypes) { + rtype = ncase.RTypes[i] + } + s.Add(ncase.Pos(), n1, rtype, jmp) } // Process body. @@ -124,11 +128,12 @@ type exprSwitch struct { type exprClause struct { pos src.XPos lo, hi ir.Node + rtype ir.Node // *runtime._type for OEQ node jmp ir.Node } -func (s *exprSwitch) Add(pos src.XPos, expr, jmp ir.Node) { - c := exprClause{pos: pos, lo: expr, hi: expr, jmp: jmp} +func (s *exprSwitch) Add(pos src.XPos, expr, rtype, jmp ir.Node) { + c := exprClause{pos: pos, lo: expr, hi: expr, rtype: rtype, jmp: jmp} if types.IsOrdered[s.exprname.Type().Kind()] && expr.Op() == ir.OLITERAL { s.clauses = append(s.clauses, c) return @@ -233,7 +238,7 @@ func (s *exprSwitch) flush() { // Add length case to outer switch. cas := ir.NewBasicLit(pos, constant.MakeInt64(runLen(run))) jmp := ir.NewBranchStmt(pos, ir.OGOTO, label) - outer.Add(pos, cas, jmp) + outer.Add(pos, cas, nil, jmp) } s.done.Append(ir.NewLabelStmt(s.pos, outerLabel)) outer.Emit(&s.done) @@ -342,7 +347,9 @@ func (c *exprClause) test(exprname ir.Node) ir.Node { } } - return ir.NewBinaryExpr(c.pos, ir.OEQ, exprname, c.lo) + n := ir.NewBinaryExpr(c.pos, ir.OEQ, exprname, c.lo) + n.RType = c.rtype + return n } func allCaseExprsAreSideEffectFree(sw *ir.SwitchStmt) bool { -- 2.50.0