1// Copyright 2015 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5package ssa 6 7import ( 8 "cmd/compile/internal/types" 9 "fmt" 10) 11 12// A place that an ssa variable can reside. 13type Location interface { 14 String() string // name to use in assembly templates: AX, 16(SP), ... 15} 16 17// A Register is a machine register, like AX. 18// They are numbered densely from 0 (for each architecture). 19type Register struct { 20 num int32 // dense numbering 21 objNum int16 // register number from cmd/internal/obj/$ARCH 22 gcNum int16 // GC register map number (dense numbering of registers that can contain pointers) 23 name string 24} 25 26func (r *Register) String() string { 27 return r.name 28} 29 30// ObjNum returns the register number from cmd/internal/obj/$ARCH that 31// corresponds to this register. 32func (r *Register) ObjNum() int16 { 33 return r.objNum 34} 35 36// GCNum returns the runtime GC register index of r, or -1 if this 37// register can't contain pointers. 38func (r *Register) GCNum() int16 { 39 return r.gcNum 40} 41 42// A LocalSlot is a location in the stack frame, which identifies and stores 43// part or all of a PPARAM, PPARAMOUT, or PAUTO ONAME node. 44// It can represent a whole variable, part of a larger stack slot, or part of a 45// variable that has been decomposed into multiple stack slots. 46// As an example, a string could have the following configurations: 47// 48// stack layout LocalSlots 49// 50// Optimizations are disabled. s is on the stack and represented in its entirety. 51// [ ------- s string ---- ] { N: s, Type: string, Off: 0 } 52// 53// s was not decomposed, but the SSA operates on its parts individually, so 54// there is a LocalSlot for each of its fields that points into the single stack slot. 55// [ ------- s string ---- ] { N: s, Type: *uint8, Off: 0 }, {N: s, Type: int, Off: 8} 56// 57// s was decomposed. Each of its fields is in its own stack slot and has its own LocalSLot. 58// [ ptr *uint8 ] [ len int] { N: ptr, Type: *uint8, Off: 0, SplitOf: parent, SplitOffset: 0}, 59// { N: len, Type: int, Off: 0, SplitOf: parent, SplitOffset: 8} 60// parent = &{N: s, Type: string} 61type LocalSlot struct { 62 N GCNode // an ONAME *gc.Node representing a stack location. 63 Type *types.Type // type of slot 64 Off int64 // offset of slot in N 65 66 SplitOf *LocalSlot // slot is a decomposition of SplitOf 67 SplitOffset int64 // .. at this offset. 68} 69 70func (s LocalSlot) String() string { 71 if s.Off == 0 { 72 return fmt.Sprintf("%v[%v]", s.N, s.Type) 73 } 74 return fmt.Sprintf("%v+%d[%v]", s.N, s.Off, s.Type) 75} 76 77type LocPair [2]Location 78 79func (t LocPair) String() string { 80 n0, n1 := "nil", "nil" 81 if t[0] != nil { 82 n0 = t[0].String() 83 } 84 if t[1] != nil { 85 n1 = t[1].String() 86 } 87 return fmt.Sprintf("<%s,%s>", n0, n1) 88} 89