| // Copyright 2015 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 ssa |
| |
| import ( |
| "cmd/compile/internal/abi" |
| "cmd/compile/internal/ir" |
| "cmd/compile/internal/types" |
| "cmd/internal/obj" |
| "fmt" |
| "strings" |
| ) |
| |
| // An Op encodes the specific operation that a Value performs. |
| // Opcodes' semantics can be modified by the type and aux fields of the Value. |
| // For instance, OpAdd can be 32 or 64 bit, signed or unsigned, float or complex, depending on Value.Type. |
| // Semantics of each op are described in the opcode files in _gen/*Ops.go. |
| // There is one file for generic (architecture-independent) ops and one file |
| // for each architecture. |
| type Op int32 |
| |
| type opInfo struct { |
| name string |
| reg regInfo |
| auxType auxType |
| argLen int32 // the number of arguments, -1 if variable length |
| asm obj.As |
| generic bool // this is a generic (arch-independent) opcode |
| rematerializeable bool // this op is rematerializeable |
| commutative bool // this operation is commutative (e.g. addition) |
| resultInArg0 bool // (first, if a tuple) output of v and v.Args[0] must be allocated to the same register |
| resultNotInArgs bool // outputs must not be allocated to the same registers as inputs |
| clobberFlags bool // this op clobbers flags register |
| needIntTemp bool // need a temporary free integer register |
| call bool // is a function call |
| tailCall bool // is a tail call |
| nilCheck bool // this op is a nil check on arg0 |
| faultOnNilArg0 bool // this op will fault if arg0 is nil (and aux encodes a small offset) |
| faultOnNilArg1 bool // this op will fault if arg1 is nil (and aux encodes a small offset) |
| usesScratch bool // this op requires scratch memory space |
| hasSideEffects bool // for "reasons", not to be eliminated. E.g., atomic store, #19182. |
| zeroWidth bool // op never translates into any machine code. example: copy, which may sometimes translate to machine code, is not zero-width. |
| unsafePoint bool // this op is an unsafe point, i.e. not safe for async preemption |
| symEffect SymEffect // effect this op has on symbol in aux |
| scale uint8 // amd64/386 indexed load scale |
| } |
| |
| type inputInfo struct { |
| idx int // index in Args array |
| regs regMask // allowed input registers |
| } |
| |
| type outputInfo struct { |
| idx int // index in output tuple |
| regs regMask // allowed output registers |
| } |
| |
| type regInfo struct { |
| // inputs encodes the register restrictions for an instruction's inputs. |
| // Each entry specifies an allowed register set for a particular input. |
| // They are listed in the order in which regalloc should pick a register |
| // from the register set (most constrained first). |
| // Inputs which do not need registers are not listed. |
| inputs []inputInfo |
| // clobbers encodes the set of registers that are overwritten by |
| // the instruction (other than the output registers). |
| clobbers regMask |
| // outputs is the same as inputs, but for the outputs of the instruction. |
| outputs []outputInfo |
| } |
| |
| func (r *regInfo) String() string { |
| s := "" |
| s += "INS:\n" |
| for _, i := range r.inputs { |
| mask := fmt.Sprintf("%64b", i.regs) |
| mask = strings.Replace(mask, "0", ".", -1) |
| s += fmt.Sprintf("%2d |%s|\n", i.idx, mask) |
| } |
| s += "OUTS:\n" |
| for _, i := range r.outputs { |
| mask := fmt.Sprintf("%64b", i.regs) |
| mask = strings.Replace(mask, "0", ".", -1) |
| s += fmt.Sprintf("%2d |%s|\n", i.idx, mask) |
| } |
| s += "CLOBBERS:\n" |
| mask := fmt.Sprintf("%64b", r.clobbers) |
| mask = strings.Replace(mask, "0", ".", -1) |
| s += fmt.Sprintf(" |%s|\n", mask) |
| return s |
| } |
| |
| type auxType int8 |
| |
| type AuxNameOffset struct { |
| Name *ir.Name |
| Offset int64 |
| } |
| |
| func (a *AuxNameOffset) CanBeAnSSAAux() {} |
| func (a *AuxNameOffset) String() string { |
| return fmt.Sprintf("%s+%d", a.Name.Sym().Name, a.Offset) |
| } |
| |
| func (a *AuxNameOffset) FrameOffset() int64 { |
| return a.Name.FrameOffset() + a.Offset |
| } |
| |
| type AuxCall struct { |
| Fn *obj.LSym |
| reg *regInfo // regInfo for this call |
| abiInfo *abi.ABIParamResultInfo |
| } |
| |
| // Reg returns the regInfo for a given call, combining the derived in/out register masks |
| // with the machine-specific register information in the input i. (The machine-specific |
| // regInfo is much handier at the call site than it is when the AuxCall is being constructed, |
| // therefore do this lazily). |
| // |
| // TODO: there is a Clever Hack that allows pre-generation of a small-ish number of the slices |
| // of inputInfo and outputInfo used here, provided that we are willing to reorder the inputs |
| // and outputs from calls, so that all integer registers come first, then all floating registers. |
| // At this point (active development of register ABI) that is very premature, |
| // but if this turns out to be a cost, we could do it. |
| func (a *AuxCall) Reg(i *regInfo, c *Config) *regInfo { |
| if a.reg.clobbers != 0 { |
| // Already updated |
| return a.reg |
| } |
| if a.abiInfo.InRegistersUsed()+a.abiInfo.OutRegistersUsed() == 0 { |
| // Shortcut for zero case, also handles old ABI. |
| a.reg = i |
| return a.reg |
| } |
| |
| k := len(i.inputs) |
| for _, p := range a.abiInfo.InParams() { |
| for _, r := range p.Registers { |
| m := archRegForAbiReg(r, c) |
| a.reg.inputs = append(a.reg.inputs, inputInfo{idx: k, regs: (1 << m)}) |
| k++ |
| } |
| } |
| a.reg.inputs = append(a.reg.inputs, i.inputs...) // These are less constrained, thus should come last |
| k = len(i.outputs) |
| for _, p := range a.abiInfo.OutParams() { |
| for _, r := range p.Registers { |
| m := archRegForAbiReg(r, c) |
| a.reg.outputs = append(a.reg.outputs, outputInfo{idx: k, regs: (1 << m)}) |
| k++ |
| } |
| } |
| a.reg.outputs = append(a.reg.outputs, i.outputs...) |
| a.reg.clobbers = i.clobbers |
| return a.reg |
| } |
| func (a *AuxCall) ABI() *abi.ABIConfig { |
| return a.abiInfo.Config() |
| } |
| func (a *AuxCall) ABIInfo() *abi.ABIParamResultInfo { |
| return a.abiInfo |
| } |
| func (a *AuxCall) ResultReg(c *Config) *regInfo { |
| if a.abiInfo.OutRegistersUsed() == 0 { |
| return a.reg |
| } |
| if len(a.reg.inputs) > 0 { |
| return a.reg |
| } |
| k := 0 |
| for _, p := range a.abiInfo.OutParams() { |
| for _, r := range p.Registers { |
| m := archRegForAbiReg(r, c) |
| a.reg.inputs = append(a.reg.inputs, inputInfo{idx: k, regs: (1 << m)}) |
| k++ |
| } |
| } |
| return a.reg |
| } |
| |
| // For ABI register index r, returns the (dense) register number used in |
| // SSA backend. |
| func archRegForAbiReg(r abi.RegIndex, c *Config) uint8 { |
| var m int8 |
| if int(r) < len(c.intParamRegs) { |
| m = c.intParamRegs[r] |
| } else { |
| m = c.floatParamRegs[int(r)-len(c.intParamRegs)] |
| } |
| return uint8(m) |
| } |
| |
| // For ABI register index r, returns the register number used in the obj |
| // package (assembler). |
| func ObjRegForAbiReg(r abi.RegIndex, c *Config) int16 { |
| m := archRegForAbiReg(r, c) |
| return c.registers[m].objNum |
| } |
| |
| // ArgWidth returns the amount of stack needed for all the inputs |
| // and outputs of a function or method, including ABI-defined parameter |
| // slots and ABI-defined spill slots for register-resident parameters. |
| // |
| // The name is taken from the types package's ArgWidth(<function type>), |
| // which predated changes to the ABI; this version handles those changes. |
| func (a *AuxCall) ArgWidth() int64 { |
| return a.abiInfo.ArgWidth() |
| } |
| |
| // ParamAssignmentForResult returns the ABI Parameter assignment for result which (indexed 0, 1, etc). |
| func (a *AuxCall) ParamAssignmentForResult(which int64) *abi.ABIParamAssignment { |
| return a.abiInfo.OutParam(int(which)) |
| } |
| |
| // OffsetOfResult returns the SP offset of result which (indexed 0, 1, etc). |
| func (a *AuxCall) OffsetOfResult(which int64) int64 { |
| n := int64(a.abiInfo.OutParam(int(which)).Offset()) |
| return n |
| } |
| |
| // OffsetOfArg returns the SP offset of argument which (indexed 0, 1, etc). |
| // If the call is to a method, the receiver is the first argument (i.e., index 0) |
| func (a *AuxCall) OffsetOfArg(which int64) int64 { |
| n := int64(a.abiInfo.InParam(int(which)).Offset()) |
| return n |
| } |
| |
| // RegsOfResult returns the register(s) used for result which (indexed 0, 1, etc). |
| func (a *AuxCall) RegsOfResult(which int64) []abi.RegIndex { |
| return a.abiInfo.OutParam(int(which)).Registers |
| } |
| |
| // RegsOfArg returns the register(s) used for argument which (indexed 0, 1, etc). |
| // If the call is to a method, the receiver is the first argument (i.e., index 0) |
| func (a *AuxCall) RegsOfArg(which int64) []abi.RegIndex { |
| return a.abiInfo.InParam(int(which)).Registers |
| } |
| |
| // NameOfResult returns the ir.Name of result which (indexed 0, 1, etc). |
| func (a *AuxCall) NameOfResult(which int64) *ir.Name { |
| return a.abiInfo.OutParam(int(which)).Name |
| } |
| |
| // TypeOfResult returns the type of result which (indexed 0, 1, etc). |
| func (a *AuxCall) TypeOfResult(which int64) *types.Type { |
| return a.abiInfo.OutParam(int(which)).Type |
| } |
| |
| // TypeOfArg returns the type of argument which (indexed 0, 1, etc). |
| // If the call is to a method, the receiver is the first argument (i.e., index 0) |
| func (a *AuxCall) TypeOfArg(which int64) *types.Type { |
| return a.abiInfo.InParam(int(which)).Type |
| } |
| |
| // SizeOfResult returns the size of result which (indexed 0, 1, etc). |
| func (a *AuxCall) SizeOfResult(which int64) int64 { |
| return a.TypeOfResult(which).Size() |
| } |
| |
| // SizeOfArg returns the size of argument which (indexed 0, 1, etc). |
| // If the call is to a method, the receiver is the first argument (i.e., index 0) |
| func (a *AuxCall) SizeOfArg(which int64) int64 { |
| return a.TypeOfArg(which).Size() |
| } |
| |
| // NResults returns the number of results. |
| func (a *AuxCall) NResults() int64 { |
| return int64(len(a.abiInfo.OutParams())) |
| } |
| |
| // LateExpansionResultType returns the result type (including trailing mem) |
| // for a call that will be expanded later in the SSA phase. |
| func (a *AuxCall) LateExpansionResultType() *types.Type { |
| var tys []*types.Type |
| for i := int64(0); i < a.NResults(); i++ { |
| tys = append(tys, a.TypeOfResult(i)) |
| } |
| tys = append(tys, types.TypeMem) |
| return types.NewResults(tys) |
| } |
| |
| // NArgs returns the number of arguments (including receiver, if there is one). |
| func (a *AuxCall) NArgs() int64 { |
| return int64(len(a.abiInfo.InParams())) |
| } |
| |
| // String returns "AuxCall{<fn>}" |
| func (a *AuxCall) String() string { |
| var fn string |
| if a.Fn == nil { |
| fn = "AuxCall{nil" // could be interface/closure etc. |
| } else { |
| fn = fmt.Sprintf("AuxCall{%v", a.Fn) |
| } |
| // TODO how much of the ABI should be printed? |
| |
| return fn + "}" |
| } |
| |
| // StaticAuxCall returns an AuxCall for a static call. |
| func StaticAuxCall(sym *obj.LSym, paramResultInfo *abi.ABIParamResultInfo) *AuxCall { |
| if paramResultInfo == nil { |
| panic(fmt.Errorf("Nil paramResultInfo, sym=%v", sym)) |
| } |
| var reg *regInfo |
| if paramResultInfo.InRegistersUsed()+paramResultInfo.OutRegistersUsed() > 0 { |
| reg = ®Info{} |
| } |
| return &AuxCall{Fn: sym, abiInfo: paramResultInfo, reg: reg} |
| } |
| |
| // InterfaceAuxCall returns an AuxCall for an interface call. |
| func InterfaceAuxCall(paramResultInfo *abi.ABIParamResultInfo) *AuxCall { |
| var reg *regInfo |
| if paramResultInfo.InRegistersUsed()+paramResultInfo.OutRegistersUsed() > 0 { |
| reg = ®Info{} |
| } |
| return &AuxCall{Fn: nil, abiInfo: paramResultInfo, reg: reg} |
| } |
| |
| // ClosureAuxCall returns an AuxCall for a closure call. |
| func ClosureAuxCall(paramResultInfo *abi.ABIParamResultInfo) *AuxCall { |
| var reg *regInfo |
| if paramResultInfo.InRegistersUsed()+paramResultInfo.OutRegistersUsed() > 0 { |
| reg = ®Info{} |
| } |
| return &AuxCall{Fn: nil, abiInfo: paramResultInfo, reg: reg} |
| } |
| |
| func (*AuxCall) CanBeAnSSAAux() {} |
| |
| // OwnAuxCall returns a function's own AuxCall. |
| func OwnAuxCall(fn *obj.LSym, paramResultInfo *abi.ABIParamResultInfo) *AuxCall { |
| // TODO if this remains identical to ClosureAuxCall above after new ABI is done, should deduplicate. |
| var reg *regInfo |
| if paramResultInfo.InRegistersUsed()+paramResultInfo.OutRegistersUsed() > 0 { |
| reg = ®Info{} |
| } |
| return &AuxCall{Fn: fn, abiInfo: paramResultInfo, reg: reg} |
| } |
| |
| const ( |
| auxNone auxType = iota |
| auxBool // auxInt is 0/1 for false/true |
| auxInt8 // auxInt is an 8-bit integer |
| auxInt16 // auxInt is a 16-bit integer |
| auxInt32 // auxInt is a 32-bit integer |
| auxInt64 // auxInt is a 64-bit integer |
| auxInt128 // auxInt represents a 128-bit integer. Always 0. |
| auxUInt8 // auxInt is an 8-bit unsigned integer |
| auxFloat32 // auxInt is a float32 (encoded with math.Float64bits) |
| auxFloat64 // auxInt is a float64 (encoded with math.Float64bits) |
| auxFlagConstant // auxInt is a flagConstant |
| auxCCop // auxInt is a ssa.Op that represents a flags-to-bool conversion (e.g. LessThan) |
| auxNameOffsetInt8 // aux is a &struct{Name ir.Name, Offset int64}; auxInt is index in parameter registers array |
| auxString // aux is a string |
| auxSym // aux is a symbol (a *gc.Node for locals, an *obj.LSym for globals, or nil for none) |
| auxSymOff // aux is a symbol, auxInt is an offset |
| auxSymValAndOff // aux is a symbol, auxInt is a ValAndOff |
| auxTyp // aux is a type |
| auxTypSize // aux is a type, auxInt is a size, must have Aux.(Type).Size() == AuxInt |
| auxCall // aux is a *ssa.AuxCall |
| auxCallOff // aux is a *ssa.AuxCall, AuxInt is int64 param (in+out) size |
| |
| // architecture specific aux types |
| auxARM64BitField // aux is an arm64 bitfield lsb and width packed into auxInt |
| auxS390XRotateParams // aux is a s390x rotate parameters object encoding start bit, end bit and rotate amount |
| auxS390XCCMask // aux is a s390x 4-bit condition code mask |
| auxS390XCCMaskInt8 // aux is a s390x 4-bit condition code mask, auxInt is an int8 immediate |
| auxS390XCCMaskUint8 // aux is a s390x 4-bit condition code mask, auxInt is a uint8 immediate |
| ) |
| |
| // A SymEffect describes the effect that an SSA Value has on the variable |
| // identified by the symbol in its Aux field. |
| type SymEffect int8 |
| |
| const ( |
| SymRead SymEffect = 1 << iota |
| SymWrite |
| SymAddr |
| |
| SymRdWr = SymRead | SymWrite |
| |
| SymNone SymEffect = 0 |
| ) |
| |
| // A Sym represents a symbolic offset from a base register. |
| // Currently a Sym can be one of 3 things: |
| // - a *gc.Node, for an offset from SP (the stack pointer) |
| // - a *obj.LSym, for an offset from SB (the global pointer) |
| // - nil, for no offset |
| type Sym interface { |
| CanBeAnSSASym() |
| CanBeAnSSAAux() |
| } |
| |
| // A ValAndOff is used by the several opcodes. It holds |
| // both a value and a pointer offset. |
| // A ValAndOff is intended to be encoded into an AuxInt field. |
| // The zero ValAndOff encodes a value of 0 and an offset of 0. |
| // The high 32 bits hold a value. |
| // The low 32 bits hold a pointer offset. |
| type ValAndOff int64 |
| |
| func (x ValAndOff) Val() int32 { return int32(int64(x) >> 32) } |
| func (x ValAndOff) Val64() int64 { return int64(x) >> 32 } |
| func (x ValAndOff) Val16() int16 { return int16(int64(x) >> 32) } |
| func (x ValAndOff) Val8() int8 { return int8(int64(x) >> 32) } |
| |
| func (x ValAndOff) Off64() int64 { return int64(int32(x)) } |
| func (x ValAndOff) Off() int32 { return int32(x) } |
| |
| func (x ValAndOff) String() string { |
| return fmt.Sprintf("val=%d,off=%d", x.Val(), x.Off()) |
| } |
| |
| // validVal reports whether the value can be used |
| // as an argument to makeValAndOff. |
| func validVal(val int64) bool { |
| return val == int64(int32(val)) |
| } |
| |
| func makeValAndOff(val, off int32) ValAndOff { |
| return ValAndOff(int64(val)<<32 + int64(uint32(off))) |
| } |
| |
| func (x ValAndOff) canAdd32(off int32) bool { |
| newoff := x.Off64() + int64(off) |
| return newoff == int64(int32(newoff)) |
| } |
| func (x ValAndOff) canAdd64(off int64) bool { |
| newoff := x.Off64() + off |
| return newoff == int64(int32(newoff)) |
| } |
| |
| func (x ValAndOff) addOffset32(off int32) ValAndOff { |
| if !x.canAdd32(off) { |
| panic("invalid ValAndOff.addOffset32") |
| } |
| return makeValAndOff(x.Val(), x.Off()+off) |
| } |
| func (x ValAndOff) addOffset64(off int64) ValAndOff { |
| if !x.canAdd64(off) { |
| panic("invalid ValAndOff.addOffset64") |
| } |
| return makeValAndOff(x.Val(), x.Off()+int32(off)) |
| } |
| |
| // int128 is a type that stores a 128-bit constant. |
| // The only allowed constant right now is 0, so we can cheat quite a bit. |
| type int128 int64 |
| |
| type BoundsKind uint8 |
| |
| const ( |
| BoundsIndex BoundsKind = iota // indexing operation, 0 <= idx < len failed |
| BoundsIndexU // ... with unsigned idx |
| BoundsSliceAlen // 2-arg slicing operation, 0 <= high <= len failed |
| BoundsSliceAlenU // ... with unsigned high |
| BoundsSliceAcap // 2-arg slicing operation, 0 <= high <= cap failed |
| BoundsSliceAcapU // ... with unsigned high |
| BoundsSliceB // 2-arg slicing operation, 0 <= low <= high failed |
| BoundsSliceBU // ... with unsigned low |
| BoundsSlice3Alen // 3-arg slicing operation, 0 <= max <= len failed |
| BoundsSlice3AlenU // ... with unsigned max |
| BoundsSlice3Acap // 3-arg slicing operation, 0 <= max <= cap failed |
| BoundsSlice3AcapU // ... with unsigned max |
| BoundsSlice3B // 3-arg slicing operation, 0 <= high <= max failed |
| BoundsSlice3BU // ... with unsigned high |
| BoundsSlice3C // 3-arg slicing operation, 0 <= low <= high failed |
| BoundsSlice3CU // ... with unsigned low |
| BoundsConvert // conversion to array pointer failed |
| BoundsKindCount |
| ) |
| |
| // boundsABI determines which register arguments a bounds check call should use. For an [a:b:c] slice, we do: |
| // |
| // CMPQ c, cap |
| // JA fail1 |
| // CMPQ b, c |
| // JA fail2 |
| // CMPQ a, b |
| // JA fail3 |
| // |
| // fail1: CALL panicSlice3Acap (c, cap) |
| // fail2: CALL panicSlice3B (b, c) |
| // fail3: CALL panicSlice3C (a, b) |
| // |
| // When we register allocate that code, we want the same register to be used for |
| // the first arg of panicSlice3Acap and the second arg to panicSlice3B. That way, |
| // initializing that register once will satisfy both calls. |
| // That desire ends up dividing the set of bounds check calls into 3 sets. This function |
| // determines which set to use for a given panic call. |
| // The first arg for set 0 should be the second arg for set 1. |
| // The first arg for set 1 should be the second arg for set 2. |
| func boundsABI(b int64) int { |
| switch BoundsKind(b) { |
| case BoundsSlice3Alen, |
| BoundsSlice3AlenU, |
| BoundsSlice3Acap, |
| BoundsSlice3AcapU, |
| BoundsConvert: |
| return 0 |
| case BoundsSliceAlen, |
| BoundsSliceAlenU, |
| BoundsSliceAcap, |
| BoundsSliceAcapU, |
| BoundsSlice3B, |
| BoundsSlice3BU: |
| return 1 |
| case BoundsIndex, |
| BoundsIndexU, |
| BoundsSliceB, |
| BoundsSliceBU, |
| BoundsSlice3C, |
| BoundsSlice3CU: |
| return 2 |
| default: |
| panic("bad BoundsKind") |
| } |
| } |
| |
| // arm64BitField is the GO type of ARM64BitField auxInt. |
| // if x is an ARM64BitField, then width=x&0xff, lsb=(x>>8)&0xff, and |
| // width+lsb<64 for 64-bit variant, width+lsb<32 for 32-bit variant. |
| // the meaning of width and lsb are instruction-dependent. |
| type arm64BitField int16 |