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 5 package ssa 6 7 import ( 8 "cmd/compile/internal/ir" 9 "cmd/compile/internal/types" 10 "fmt" 11 ) 12 13 // A place that an ssa variable can reside. 14 type Location interface { 15 String() string // name to use in assembly templates: AX, 16(SP), ... 16 } 17 18 // A Register is a machine register, like AX. 19 // They are numbered densely from 0 (for each architecture). 20 type Register struct { 21 num int32 // dense numbering 22 objNum int16 // register number from cmd/internal/obj/$ARCH 23 gcNum int16 // GC register map number (dense numbering of registers that can contain pointers) 24 name string 25 } 26 27 func (r *Register) String() string { 28 return r.name 29 } 30 31 // ObjNum returns the register number from cmd/internal/obj/$ARCH that 32 // corresponds to this register. 33 func (r *Register) ObjNum() int16 { 34 return r.objNum 35 } 36 37 // GCNum returns the runtime GC register index of r, or -1 if this 38 // register can't contain pointers. 39 func (r *Register) GCNum() int16 { 40 return r.gcNum 41 } 42 43 // A LocalSlot is a location in the stack frame, which identifies and stores 44 // part or all of a PPARAM, PPARAMOUT, or PAUTO ONAME node. 45 // It can represent a whole variable, part of a larger stack slot, or part of a 46 // variable that has been decomposed into multiple stack slots. 47 // As an example, a string could have the following configurations: 48 // 49 // stack layout LocalSlots 50 // 51 // Optimizations are disabled. s is on the stack and represented in its entirety. 52 // [ ------- s string ---- ] { N: s, Type: string, Off: 0 } 53 // 54 // s was not decomposed, but the SSA operates on its parts individually, so 55 // there is a LocalSlot for each of its fields that points into the single stack slot. 56 // [ ------- s string ---- ] { N: s, Type: *uint8, Off: 0 }, {N: s, Type: int, Off: 8} 57 // 58 // s was decomposed. Each of its fields is in its own stack slot and has its own LocalSLot. 59 // [ ptr *uint8 ] [ len int] { N: ptr, Type: *uint8, Off: 0, SplitOf: parent, SplitOffset: 0}, 60 // { N: len, Type: int, Off: 0, SplitOf: parent, SplitOffset: 8} 61 // parent = &{N: s, Type: string} 62 type LocalSlot struct { 63 N *ir.Name // an ONAME *ir.Name representing a stack location. 64 Type *types.Type // type of slot 65 Off int64 // offset of slot in N 66 67 SplitOf *LocalSlot // slot is a decomposition of SplitOf 68 SplitOffset int64 // .. at this offset. 69 } 70 71 func (s LocalSlot) String() string { 72 if s.Off == 0 { 73 return fmt.Sprintf("%v[%v]", s.N, s.Type) 74 } 75 return fmt.Sprintf("%v+%d[%v]", s.N, s.Off, s.Type) 76 } 77 78 type LocPair [2]Location 79 80 func (t LocPair) String() string { 81 n0, n1 := "nil", "nil" 82 if t[0] != nil { 83 n0 = t[0].String() 84 } 85 if t[1] != nil { 86 n1 = t[1].String() 87 } 88 return fmt.Sprintf("<%s,%s>", n0, n1) 89 } 90 91 type LocResults []Location 92 93 func (t LocResults) String() string { 94 s := "" 95 a := "<" 96 for _, r := range t { 97 a += s 98 s = "," 99 a += r.String() 100 } 101 a += ">" 102 return a 103 } 104 105 type Spill struct { 106 Type *types.Type 107 Offset int64 108 Reg int16 109 } 110