go expand_calls 源码
golang expand_calls 代码
文件路径：/src/cmd/compile/internal/ssa/expand_calls.go
// 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 ssa
import (
"cmd/compile/internal/abi"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/types"
"cmd/internal/src"
"fmt"
"sort"
)
type selKey struct {
from *Value // what is selected from
offsetOrIndex int64 // whatever is appropriate for the selector
size int64
typ *types.Type
}
type Abi1RO uint8 // An offset within a parameter's slice of register indices, for abi1.
func isBlockMultiValueExit(b *Block) bool {
return (b.Kind == BlockRet || b.Kind == BlockRetJmp) && b.Controls[0] != nil && b.Controls[0].Op == OpMakeResult
}
func badVal(s string, v *Value) error {
return fmt.Errorf("%s %s", s, v.LongString())
}
// removeTrivialWrapperTypes unwraps layers of
// struct { singleField SomeType } and [1]SomeType
// until a non-wrapper type is reached. This is useful
// for working with assignments to/from interface data
// fields (either second operand to OpIMake or OpIData)
// where the wrapping or type conversion can be elided
// because of type conversions/assertions in source code
// that do not appear in SSA.
func removeTrivialWrapperTypes(t *types.Type) *types.Type {
for {
if t.IsStruct() && t.NumFields() == 1 {
t = t.Field(0).Type
continue
}
if t.IsArray() && t.NumElem() == 1 {
t = t.Elem()
continue
}
break
}
return t
}
// A registerCursor tracks which register is used for an Arg or regValues, or a piece of such.
type registerCursor struct {
// TODO(register args) convert this to a generalized target cursor.
storeDest *Value // if there are no register targets, then this is the base of the store.
regsLen int // the number of registers available for this Arg/result (which is all in registers or not at all)
nextSlice Abi1RO // the next register/register-slice offset
config *abi.ABIConfig
regValues *[]*Value // values assigned to registers accumulate here
}
func (rc *registerCursor) String() string {
dest := "<none>"
if rc.storeDest != nil {
dest = rc.storeDest.String()
}
regs := "<none>"
if rc.regValues != nil {
regs = ""
for i, x := range *rc.regValues {
if i > 0 {
regs = regs + "; "
}
regs = regs + x.LongString()
}
}
// not printing the config because that has not been useful
return fmt.Sprintf("RCSR{storeDest=%v, regsLen=%d, nextSlice=%d, regValues=[%s]}", dest, rc.regsLen, rc.nextSlice, regs)
}
// next effectively post-increments the register cursor; the receiver is advanced,
// the old value is returned.
func (c *registerCursor) next(t *types.Type) registerCursor {
rc := *c
if int(c.nextSlice) < c.regsLen {
w := c.config.NumParamRegs(t)
c.nextSlice += Abi1RO(w)
}
return rc
}
// plus returns a register cursor offset from the original, without modifying the original.
func (c *registerCursor) plus(regWidth Abi1RO) registerCursor {
rc := *c
rc.nextSlice += regWidth
return rc
}
const (
// Register offsets for fields of built-in aggregate types; the ones not listed are zero.
RO_complex_imag = 1
RO_string_len = 1
RO_slice_len = 1
RO_slice_cap = 2
RO_iface_data = 1
)
func (x *expandState) regWidth(t *types.Type) Abi1RO {
return Abi1RO(x.abi1.NumParamRegs(t))
}
// regOffset returns the register offset of the i'th element of type t
func (x *expandState) regOffset(t *types.Type, i int) Abi1RO {
// TODO maybe cache this in a map if profiling recommends.
if i == 0 {
return 0
}
if t.IsArray() {
return Abi1RO(i) * x.regWidth(t.Elem())
}
if t.IsStruct() {
k := Abi1RO(0)
for j := 0; j < i; j++ {
k += x.regWidth(t.FieldType(j))
}
return k
}
panic("Haven't implemented this case yet, do I need to?")
}
// at returns the register cursor for component i of t, where the first
// component is numbered 0.
func (c *registerCursor) at(t *types.Type, i int) registerCursor {
rc := *c
if i == 0 || c.regsLen == 0 {
return rc
}
if t.IsArray() {
w := c.config.NumParamRegs(t.Elem())
rc.nextSlice += Abi1RO(i * w)
return rc
}
if t.IsStruct() {
for j := 0; j < i; j++ {
rc.next(t.FieldType(j))
}
return rc
}
panic("Haven't implemented this case yet, do I need to?")
}
func (c *registerCursor) init(regs []abi.RegIndex, info *abi.ABIParamResultInfo, result *[]*Value, storeDest *Value) {
c.regsLen = len(regs)
c.nextSlice = 0
if len(regs) == 0 {
c.storeDest = storeDest // only save this if there are no registers, will explode if misused.
return
}
c.config = info.Config()
c.regValues = result
}
func (c *registerCursor) addArg(v *Value) {
*c.regValues = append(*c.regValues, v)
}
func (c *registerCursor) hasRegs() bool {
return c.regsLen > 0
}
type expandState struct {
f *Func
abi1 *abi.ABIConfig
debug int // odd values log lost statement markers, so likely settings are 1 (stmts), 2 (expansion), and 3 (both)
canSSAType func(*types.Type) bool
regSize int64
sp *Value
typs *Types
ptrSize int64
hiOffset int64
lowOffset int64
hiRo Abi1RO
loRo Abi1RO
namedSelects map[*Value][]namedVal
sdom SparseTree
commonSelectors map[selKey]*Value // used to de-dupe selectors
commonArgs map[selKey]*Value // used to de-dupe OpArg/OpArgIntReg/OpArgFloatReg
memForCall map[ID]*Value // For a call, need to know the unique selector that gets the mem.
transformedSelects map[ID]bool // OpSelectN after rewriting, either created or renumbered.
indentLevel int // Indentation for debugging recursion
}
// intPairTypes returns the pair of 32-bit int types needed to encode a 64-bit integer type on a target
// that has no 64-bit integer registers.
func (x *expandState) intPairTypes(et types.Kind) (tHi, tLo *types.Type) {
tHi = x.typs.UInt32
if et == types.TINT64 {
tHi = x.typs.Int32
}
tLo = x.typs.UInt32
return
}
// isAlreadyExpandedAggregateType returns whether a type is an SSA-able "aggregate" (multiple register) type
// that was expanded in an earlier phase (currently, expand_calls is intended to run after decomposeBuiltin,
// so this is all aggregate types -- small struct and array, complex, interface, string, slice, and 64-bit
// integer on 32-bit).
func (x *expandState) isAlreadyExpandedAggregateType(t *types.Type) bool {
if !x.canSSAType(t) {
return false
}
return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice() ||
(t.Size() > x.regSize && (t.IsInteger() || (x.f.Config.SoftFloat && t.IsFloat())))
}
// offsetFrom creates an offset from a pointer, simplifying chained offsets and offsets from SP
// TODO should also optimize offsets from SB?
func (x *expandState) offsetFrom(b *Block, from *Value, offset int64, pt *types.Type) *Value {
ft := from.Type
if offset == 0 {
if ft == pt {
return from
}
// This captures common, (apparently) safe cases. The unsafe cases involve ft == uintptr
if (ft.IsPtr() || ft.IsUnsafePtr()) && pt.IsPtr() {
return from
}
}
// Simplify, canonicalize
for from.Op == OpOffPtr {
offset += from.AuxInt
from = from.Args[0]
}
if from == x.sp {
return x.f.ConstOffPtrSP(pt, offset, x.sp)
}
return b.NewValue1I(from.Pos.WithNotStmt(), OpOffPtr, pt, offset, from)
}
// splitSlots splits one "field" (specified by sfx, offset, and ty) out of the LocalSlots in ls and returns the new LocalSlots this generates.
func (x *expandState) splitSlots(ls []*LocalSlot, sfx string, offset int64, ty *types.Type) []*LocalSlot {
var locs []*LocalSlot
for i := range ls {
locs = append(locs, x.f.SplitSlot(ls[i], sfx, offset, ty))
}
return locs
}
// prAssignForArg returns the ABIParamAssignment for v, assumed to be an OpArg.
func (x *expandState) prAssignForArg(v *Value) *abi.ABIParamAssignment {
if v.Op != OpArg {
panic(badVal("Wanted OpArg, instead saw", v))
}
return ParamAssignmentForArgName(x.f, v.Aux.(*ir.Name))
}
// ParamAssignmentForArgName returns the ABIParamAssignment for f's arg with matching name.
func ParamAssignmentForArgName(f *Func, name *ir.Name) *abi.ABIParamAssignment {
abiInfo := f.OwnAux.abiInfo
ip := abiInfo.InParams()
for i, a := range ip {
if a.Name == name {
return &ip[i]
}
}
panic(fmt.Errorf("Did not match param %v in prInfo %+v", name, abiInfo.InParams()))
}
// indent increments (or decrements) the indentation.
func (x *expandState) indent(n int) {
x.indentLevel += n
}
// Printf does an indented fmt.Printf on te format and args.
func (x *expandState) Printf(format string, a ...interface{}) (n int, err error) {
if x.indentLevel > 0 {
fmt.Printf("%[1]*s", x.indentLevel, "")
}
return fmt.Printf(format, a...)
}
// Calls that need lowering have some number of inputs, including a memory input,
// and produce a tuple of (value1, value2, ..., mem) where valueK may or may not be SSA-able.
// With the current ABI those inputs need to be converted into stores to memory,
// rethreading the call's memory input to the first, and the new call now receiving the last.
// With the current ABI, the outputs need to be converted to loads, which will all use the call's
// memory output as their input.
// rewriteSelect recursively walks from leaf selector to a root (OpSelectN, OpLoad, OpArg)
// through a chain of Struct/Array/builtin Select operations. If the chain of selectors does not
// end in an expected root, it does nothing (this can happen depending on compiler phase ordering).
// The "leaf" provides the type, the root supplies the container, and the leaf-to-root path
// accumulates the offset.
// It emits the code necessary to implement the leaf select operation that leads to the root.
//
// TODO when registers really arrive, must also decompose anything split across two registers or registers and memory.
func (x *expandState) rewriteSelect(leaf *Value, selector *Value, offset int64, regOffset Abi1RO) []*LocalSlot {
if x.debug > 1 {
x.indent(3)
defer x.indent(-3)
x.Printf("rewriteSelect(%s; %s; memOff=%d; regOff=%d)\n", leaf.LongString(), selector.LongString(), offset, regOffset)
}
var locs []*LocalSlot
leafType := leaf.Type
if len(selector.Args) > 0 {
w := selector.Args[0]
if w.Op == OpCopy {
for w.Op == OpCopy {
w = w.Args[0]
}
selector.SetArg(0, w)
}
}
switch selector.Op {
case OpArgIntReg, OpArgFloatReg:
if leafType == selector.Type { // OpIData leads us here, sometimes.
leaf.copyOf(selector)
} else {
x.f.Fatalf("Unexpected %s type, selector=%s, leaf=%s\n", selector.Op.String(), selector.LongString(), leaf.LongString())
}
if x.debug > 1 {
x.Printf("---%s, break\n", selector.Op.String())
}
case OpArg:
if !x.isAlreadyExpandedAggregateType(selector.Type) {
if leafType == selector.Type { // OpIData leads us here, sometimes.
x.newArgToMemOrRegs(selector, leaf, offset, regOffset, leafType, leaf.Pos)
} else {
x.f.Fatalf("Unexpected OpArg type, selector=%s, leaf=%s\n", selector.LongString(), leaf.LongString())
}
if x.debug > 1 {
x.Printf("---OpArg, break\n")
}
break
}
switch leaf.Op {
case OpIData, OpStructSelect, OpArraySelect:
leafType = removeTrivialWrapperTypes(leaf.Type)
}
x.newArgToMemOrRegs(selector, leaf, offset, regOffset, leafType, leaf.Pos)
for _, s := range x.namedSelects[selector] {
locs = append(locs, x.f.Names[s.locIndex])
}
case OpLoad: // We end up here because of IData of immediate structures.
// Failure case:
// (note the failure case is very rare; w/o this case, make.bash and run.bash both pass, as well as
// the hard cases of building {syscall,math,math/cmplx,math/bits,go/constant} on ppc64le and mips-softfloat).
//
// GOSSAFUNC='(*dumper).dump' go build -gcflags=-l -tags=math_big_pure_go cmd/compile/internal/gc
// cmd/compile/internal/gc/dump.go:136:14: internal compiler error: '(*dumper).dump': not lowered: v827, StructSelect PTR PTR
// b2: ← b1
// v20 (+142) = StaticLECall <interface {},mem> {AuxCall{reflect.Value.Interface([reflect.Value,0])[interface {},24]}} [40] v8 v1
// v21 (142) = SelectN <mem> [1] v20
// v22 (142) = SelectN <interface {}> [0] v20
// b15: ← b8
// v71 (+143) = IData <Nodes> v22 (v[Nodes])
// v73 (+146) = StaticLECall <[]*Node,mem> {AuxCall{"".Nodes.Slice([Nodes,0])[[]*Node,8]}} [32] v71 v21
//
// translates (w/o the "case OpLoad:" above) to:
//
// b2: ← b1
// v20 (+142) = StaticCall <mem> {AuxCall{reflect.Value.Interface([reflect.Value,0])[interface {},24]}} [40] v715
// v23 (142) = Load <*uintptr> v19 v20
// v823 (142) = IsNonNil <bool> v23
// v67 (+143) = Load <*[]*Node> v880 v20
// b15: ← b8
// v827 (146) = StructSelect <*[]*Node> [0] v67
// v846 (146) = Store <mem> {*[]*Node} v769 v827 v20
// v73 (+146) = StaticCall <mem> {AuxCall{"".Nodes.Slice([Nodes,0])[[]*Node,8]}} [32] v846
// i.e., the struct select is generated and remains in because it is not applied to an actual structure.
// The OpLoad was created to load the single field of the IData
// This case removes that StructSelect.
if leafType != selector.Type {
if x.f.Config.SoftFloat && selector.Type.IsFloat() {
if x.debug > 1 {
x.Printf("---OpLoad, break\n")
}
break // softfloat pass will take care of that
}
x.f.Fatalf("Unexpected Load as selector, leaf=%s, selector=%s\n", leaf.LongString(), selector.LongString())
}
leaf.copyOf(selector)
for _, s := range x.namedSelects[selector] {
locs = append(locs, x.f.Names[s.locIndex])
}
case OpSelectN:
// TODO(register args) result case
// if applied to Op-mumble-call, the Aux tells us which result, regOffset specifies offset within result. If a register, should rewrite to OpSelectN for new call.
// TODO these may be duplicated. Should memoize. Intermediate selectors will go dead, no worries there.
call := selector.Args[0]
call0 := call
aux := call.Aux.(*AuxCall)
which := selector.AuxInt
if x.transformedSelects[selector.ID] {
// This is a minor hack. Either this select has had its operand adjusted (mem) or
// it is some other intermediate node that was rewritten to reference a register (not a generic arg).
// This can occur with chains of selection/indexing from single field/element aggregates.
leaf.copyOf(selector)
break
}
if which == aux.NResults() { // mem is after the results.
// rewrite v as a Copy of call -- the replacement call will produce a mem.
if leaf != selector {
panic(fmt.Errorf("Unexpected selector of memory, selector=%s, call=%s, leaf=%s", selector.LongString(), call.LongString(), leaf.LongString()))
}
if aux.abiInfo == nil {
panic(badVal("aux.abiInfo nil for call", call))
}
if existing := x.memForCall[call.ID]; existing == nil {
selector.AuxInt = int64(aux.abiInfo.OutRegistersUsed())
x.memForCall[call.ID] = selector
x.transformedSelects[selector.ID] = true // operand adjusted
} else {
selector.copyOf(existing)
}
} else {
leafType := removeTrivialWrapperTypes(leaf.Type)
if x.canSSAType(leafType) {
pt := types.NewPtr(leafType)
// Any selection right out of the arg area/registers has to be same Block as call, use call as mem input.
// Create a "mem" for any loads that need to occur.
if mem := x.memForCall[call.ID]; mem != nil {
if mem.Block != call.Block {
panic(fmt.Errorf("selector and call need to be in same block, selector=%s; call=%s", selector.LongString(), call.LongString()))
}
call = mem
} else {
mem = call.Block.NewValue1I(call.Pos.WithNotStmt(), OpSelectN, types.TypeMem, int64(aux.abiInfo.OutRegistersUsed()), call)
x.transformedSelects[mem.ID] = true // select uses post-expansion indexing
x.memForCall[call.ID] = mem
call = mem
}
outParam := aux.abiInfo.OutParam(int(which))
if len(outParam.Registers) > 0 {
firstReg := uint32(0)
for i := 0; i < int(which); i++ {
firstReg += uint32(len(aux.abiInfo.OutParam(i).Registers))
}
reg := int64(regOffset + Abi1RO(firstReg))
if leaf.Block == call.Block {
leaf.reset(OpSelectN)
leaf.SetArgs1(call0)
leaf.Type = leafType
leaf.AuxInt = reg
x.transformedSelects[leaf.ID] = true // leaf, rewritten to use post-expansion indexing.
} else {
w := call.Block.NewValue1I(leaf.Pos, OpSelectN, leafType, reg, call0)
x.transformedSelects[w.ID] = true // select, using post-expansion indexing.
leaf.copyOf(w)
}
} else {
off := x.offsetFrom(x.f.Entry, x.sp, offset+aux.OffsetOfResult(which), pt)
if leaf.Block == call.Block {
leaf.reset(OpLoad)
leaf.SetArgs2(off, call)
leaf.Type = leafType
} else {
w := call.Block.NewValue2(leaf.Pos, OpLoad, leafType, off, call)
leaf.copyOf(w)
if x.debug > 1 {
x.Printf("---new %s\n", w.LongString())
}
}
}
for _, s := range x.namedSelects[selector] {
locs = append(locs, x.f.Names[s.locIndex])
}
} else {
x.f.Fatalf("Should not have non-SSA-able OpSelectN, selector=%s", selector.LongString())
}
}
case OpStructSelect:
w := selector.Args[0]
var ls []*LocalSlot
if w.Type.Kind() != types.TSTRUCT { // IData artifact
ls = x.rewriteSelect(leaf, w, offset, regOffset)
} else {
fldi := int(selector.AuxInt)
ls = x.rewriteSelect(leaf, w, offset+w.Type.FieldOff(fldi), regOffset+x.regOffset(w.Type, fldi))
if w.Op != OpIData {
for _, l := range ls {
locs = append(locs, x.f.SplitStruct(l, int(selector.AuxInt)))
}
}
}
case OpArraySelect:
w := selector.Args[0]
index := selector.AuxInt
x.rewriteSelect(leaf, w, offset+selector.Type.Size()*index, regOffset+x.regOffset(w.Type, int(index)))
case OpInt64Hi:
w := selector.Args[0]
ls := x.rewriteSelect(leaf, w, offset+x.hiOffset, regOffset+x.hiRo)
locs = x.splitSlots(ls, ".hi", x.hiOffset, leafType)
case OpInt64Lo:
w := selector.Args[0]
ls := x.rewriteSelect(leaf, w, offset+x.lowOffset, regOffset+x.loRo)
locs = x.splitSlots(ls, ".lo", x.lowOffset, leafType)
case OpStringPtr:
ls := x.rewriteSelect(leaf, selector.Args[0], offset, regOffset)
locs = x.splitSlots(ls, ".ptr", 0, x.typs.BytePtr)
case OpSlicePtr, OpSlicePtrUnchecked:
w := selector.Args[0]
ls := x.rewriteSelect(leaf, w, offset, regOffset)
locs = x.splitSlots(ls, ".ptr", 0, types.NewPtr(w.Type.Elem()))
case OpITab:
w := selector.Args[0]
ls := x.rewriteSelect(leaf, w, offset, regOffset)
sfx := ".itab"
if w.Type.IsEmptyInterface() {
sfx = ".type"
}
locs = x.splitSlots(ls, sfx, 0, x.typs.Uintptr)
case OpComplexReal:
ls := x.rewriteSelect(leaf, selector.Args[0], offset, regOffset)
locs = x.splitSlots(ls, ".real", 0, selector.Type)
case OpComplexImag:
ls := x.rewriteSelect(leaf, selector.Args[0], offset+selector.Type.Size(), regOffset+RO_complex_imag) // result is FloatNN, width of result is offset of imaginary part.
locs = x.splitSlots(ls, ".imag", selector.Type.Size(), selector.Type)
case OpStringLen, OpSliceLen:
ls := x.rewriteSelect(leaf, selector.Args[0], offset+x.ptrSize, regOffset+RO_slice_len)
locs = x.splitSlots(ls, ".len", x.ptrSize, leafType)
case OpIData:
ls := x.rewriteSelect(leaf, selector.Args[0], offset+x.ptrSize, regOffset+RO_iface_data)
locs = x.splitSlots(ls, ".data", x.ptrSize, leafType)
case OpSliceCap:
ls := x.rewriteSelect(leaf, selector.Args[0], offset+2*x.ptrSize, regOffset+RO_slice_cap)
locs = x.splitSlots(ls, ".cap", 2*x.ptrSize, leafType)
case OpCopy: // If it's an intermediate result, recurse
locs = x.rewriteSelect(leaf, selector.Args[0], offset, regOffset)
for _, s := range x.namedSelects[selector] {
// this copy may have had its own name, preserve that, too.
locs = append(locs, x.f.Names[s.locIndex])
}
default:
// Ignore dead ends. These can occur if this phase is run before decompose builtin (which is not intended, but allowed).
}
return locs
}
func (x *expandState) rewriteDereference(b *Block, base, a, mem *Value, offset, size int64, typ *types.Type, pos src.XPos) *Value {
source := a.Args[0]
dst := x.offsetFrom(b, base, offset, source.Type)
if a.Uses == 1 && a.Block == b {
a.reset(OpMove)
a.Pos = pos
a.Type = types.TypeMem
a.Aux = typ
a.AuxInt = size
a.SetArgs3(dst, source, mem)
mem = a
} else {
mem = b.NewValue3A(pos, OpMove, types.TypeMem, typ, dst, source, mem)
mem.AuxInt = size
}
return mem
}
var indexNames [1]string = [1]string{"[0]"}
// pathTo returns the selection path to the leaf type at offset within container.
// e.g. len(thing.field[0]) => ".field[0].len"
// this is for purposes of generating names ultimately fed to a debugger.
func (x *expandState) pathTo(container, leaf *types.Type, offset int64) string {
if container == leaf || offset == 0 && container.Size() == leaf.Size() {
return ""
}
path := ""
outer:
for {
switch container.Kind() {
case types.TARRAY:
container = container.Elem()
if container.Size() == 0 {
return path
}
i := offset / container.Size()
offset = offset % container.Size()
// If a future compiler/ABI supports larger SSA/Arg-able arrays, expand indexNames.
path = path + indexNames[i]
continue
case types.TSTRUCT:
for i := 0; i < container.NumFields(); i++ {
fld := container.Field(i)
if fld.Offset+fld.Type.Size() > offset {
offset -= fld.Offset
path += "." + fld.Sym.Name
container = fld.Type
continue outer
}
}
return path
case types.TINT64, types.TUINT64:
if container.Size() == x.regSize {
return path
}
if offset == x.hiOffset {
return path + ".hi"
}
return path + ".lo"
case types.TINTER:
if offset != 0 {
return path + ".data"
}
if container.IsEmptyInterface() {
return path + ".type"
}
return path + ".itab"
case types.TSLICE:
if offset == 2*x.regSize {
return path + ".cap"
}
fallthrough
case types.TSTRING:
if offset == 0 {
return path + ".ptr"
}
return path + ".len"
case types.TCOMPLEX64, types.TCOMPLEX128:
if offset == 0 {
return path + ".real"
}
return path + ".imag"
}
return path
}
}
// decomposeArg is a helper for storeArgOrLoad.
// It decomposes a Load or an Arg into smaller parts and returns the new mem.
// If the type does not match one of the expected aggregate types, it returns nil instead.
// Parameters:
//
// pos -- the location of any generated code.
// b -- the block into which any generated code should normally be placed
// source -- the value, possibly an aggregate, to be stored.
// mem -- the mem flowing into this decomposition (loads depend on it, stores updated it)
// t -- the type of the value to be stored
// storeOffset -- if the value is stored in memory, it is stored at base (see storeRc) + storeOffset
// loadRegOffset -- regarding source as a value in registers, the register offset in ABI1. Meaningful only if source is OpArg.
// storeRc -- storeRC; if the value is stored in registers, this specifies the registers.
// StoreRc also identifies whether the target is registers or memory, and has the base for the store operation.
func (x *expandState) decomposeArg(pos src.XPos, b *Block, source, mem *Value, t *types.Type, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
pa := x.prAssignForArg(source)
var locs []*LocalSlot
for _, s := range x.namedSelects[source] {
locs = append(locs, x.f.Names[s.locIndex])
}
if len(pa.Registers) > 0 {
// Handle the in-registers case directly
rts, offs := pa.RegisterTypesAndOffsets()
last := loadRegOffset + x.regWidth(t)
if offs[loadRegOffset] != 0 {
// Document the problem before panicking.
for i := 0; i < len(rts); i++ {
rt := rts[i]
off := offs[i]
fmt.Printf("rt=%s, off=%d, rt.Width=%d, rt.Align=%d\n", rt.String(), off, rt.Size(), uint8(rt.Alignment()))
}
panic(fmt.Errorf("offset %d of requested register %d should be zero, source=%s", offs[loadRegOffset], loadRegOffset, source.LongString()))
}
if x.debug > 1 {
x.Printf("decompose arg %s has %d locs\n", source.LongString(), len(locs))
}
for i := loadRegOffset; i < last; i++ {
rt := rts[i]
off := offs[i]
w := x.commonArgs[selKey{source, off, rt.Size(), rt}]
if w == nil {
w = x.newArgToMemOrRegs(source, w, off, i, rt, pos)
suffix := x.pathTo(source.Type, rt, off)
if suffix != "" {
x.splitSlotsIntoNames(locs, suffix, off, rt, w)
}
}
if t.IsPtrShaped() {
// Preserve the original store type. This ensures pointer type
// properties aren't discarded (e.g, notinheap).
if rt.Size() != t.Size() || len(pa.Registers) != 1 || i != loadRegOffset {
b.Func.Fatalf("incompatible store type %v and %v, i=%d", t, rt, i)
}
rt = t
}
mem = x.storeArgOrLoad(pos, b, w, mem, rt, storeOffset+off, i, storeRc.next(rt))
}
return mem
}
u := source.Type
switch u.Kind() {
case types.TARRAY:
elem := u.Elem()
elemRO := x.regWidth(elem)
for i := int64(0); i < u.NumElem(); i++ {
elemOff := i * elem.Size()
mem = storeOneArg(x, pos, b, locs, indexNames[i], source, mem, elem, elemOff, storeOffset+elemOff, loadRegOffset, storeRc.next(elem))
loadRegOffset += elemRO
pos = pos.WithNotStmt()
}
return mem
case types.TSTRUCT:
for i := 0; i < u.NumFields(); i++ {
fld := u.Field(i)
mem = storeOneArg(x, pos, b, locs, "."+fld.Sym.Name, source, mem, fld.Type, fld.Offset, storeOffset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
loadRegOffset += x.regWidth(fld.Type)
pos = pos.WithNotStmt()
}
return mem
case types.TINT64, types.TUINT64:
if t.Size() == x.regSize {
break
}
tHi, tLo := x.intPairTypes(t.Kind())
mem = storeOneArg(x, pos, b, locs, ".hi", source, mem, tHi, x.hiOffset, storeOffset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
pos = pos.WithNotStmt()
return storeOneArg(x, pos, b, locs, ".lo", source, mem, tLo, x.lowOffset, storeOffset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.loRo))
case types.TINTER:
sfx := ".itab"
if u.IsEmptyInterface() {
sfx = ".type"
}
return storeTwoArg(x, pos, b, locs, sfx, ".idata", source, mem, x.typs.Uintptr, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc)
case types.TSTRING:
return storeTwoArg(x, pos, b, locs, ".ptr", ".len", source, mem, x.typs.BytePtr, x.typs.Int, 0, storeOffset, loadRegOffset, storeRc)
case types.TCOMPLEX64:
return storeTwoArg(x, pos, b, locs, ".real", ".imag", source, mem, x.typs.Float32, x.typs.Float32, 0, storeOffset, loadRegOffset, storeRc)
case types.TCOMPLEX128:
return storeTwoArg(x, pos, b, locs, ".real", ".imag", source, mem, x.typs.Float64, x.typs.Float64, 0, storeOffset, loadRegOffset, storeRc)
case types.TSLICE:
mem = storeOneArg(x, pos, b, locs, ".ptr", source, mem, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
return storeTwoArg(x, pos, b, locs, ".len", ".cap", source, mem, x.typs.Int, x.typs.Int, x.ptrSize, storeOffset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc)
}
return nil
}
func (x *expandState) splitSlotsIntoNames(locs []*LocalSlot, suffix string, off int64, rt *types.Type, w *Value) {
wlocs := x.splitSlots(locs, suffix, off, rt)
for _, l := range wlocs {
old, ok := x.f.NamedValues[*l]
x.f.NamedValues[*l] = append(old, w)
if !ok {
x.f.Names = append(x.f.Names, l)
}
}
}
// decomposeLoad is a helper for storeArgOrLoad.
// It decomposes a Load into smaller parts and returns the new mem.
// If the type does not match one of the expected aggregate types, it returns nil instead.
// Parameters:
//
// pos -- the location of any generated code.
// b -- the block into which any generated code should normally be placed
// source -- the value, possibly an aggregate, to be stored.
// mem -- the mem flowing into this decomposition (loads depend on it, stores updated it)
// t -- the type of the value to be stored
// storeOffset -- if the value is stored in memory, it is stored at base (see storeRc) + offset
// loadRegOffset -- regarding source as a value in registers, the register offset in ABI1. Meaningful only if source is OpArg.
// storeRc -- storeRC; if the value is stored in registers, this specifies the registers.
// StoreRc also identifies whether the target is registers or memory, and has the base for the store operation.
//
// TODO -- this needs cleanup; it just works for SSA-able aggregates, and won't fully generalize to register-args aggregates.
func (x *expandState) decomposeLoad(pos src.XPos, b *Block, source, mem *Value, t *types.Type, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
u := source.Type
switch u.Kind() {
case types.TARRAY:
elem := u.Elem()
elemRO := x.regWidth(elem)
for i := int64(0); i < u.NumElem(); i++ {
elemOff := i * elem.Size()
mem = storeOneLoad(x, pos, b, source, mem, elem, elemOff, storeOffset+elemOff, loadRegOffset, storeRc.next(elem))
loadRegOffset += elemRO
pos = pos.WithNotStmt()
}
return mem
case types.TSTRUCT:
for i := 0; i < u.NumFields(); i++ {
fld := u.Field(i)
mem = storeOneLoad(x, pos, b, source, mem, fld.Type, fld.Offset, storeOffset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
loadRegOffset += x.regWidth(fld.Type)
pos = pos.WithNotStmt()
}
return mem
case types.TINT64, types.TUINT64:
if t.Size() == x.regSize {
break
}
tHi, tLo := x.intPairTypes(t.Kind())
mem = storeOneLoad(x, pos, b, source, mem, tHi, x.hiOffset, storeOffset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
pos = pos.WithNotStmt()
return storeOneLoad(x, pos, b, source, mem, tLo, x.lowOffset, storeOffset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.loRo))
case types.TINTER:
return storeTwoLoad(x, pos, b, source, mem, x.typs.Uintptr, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc)
case types.TSTRING:
return storeTwoLoad(x, pos, b, source, mem, x.typs.BytePtr, x.typs.Int, 0, storeOffset, loadRegOffset, storeRc)
case types.TCOMPLEX64:
return storeTwoLoad(x, pos, b, source, mem, x.typs.Float32, x.typs.Float32, 0, storeOffset, loadRegOffset, storeRc)
case types.TCOMPLEX128:
return storeTwoLoad(x, pos, b, source, mem, x.typs.Float64, x.typs.Float64, 0, storeOffset, loadRegOffset, storeRc)
case types.TSLICE:
mem = storeOneLoad(x, pos, b, source, mem, x.typs.BytePtr, 0, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
return storeTwoLoad(x, pos, b, source, mem, x.typs.Int, x.typs.Int, x.ptrSize, storeOffset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc)
}
return nil
}
// storeOneArg creates a decomposed (one step) arg that is then stored.
// pos and b locate the store instruction, source is the "base" of the value input,
// mem is the input mem, t is the type in question, and offArg and offStore are the offsets from the respective bases.
func storeOneArg(x *expandState, pos src.XPos, b *Block, locs []*LocalSlot, suffix string, source, mem *Value, t *types.Type, argOffset, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
if x.debug > 1 {
x.indent(3)
defer x.indent(-3)
x.Printf("storeOneArg(%s; %s; %s; aO=%d; sO=%d; lrO=%d; %s)\n", source.LongString(), mem.String(), t.String(), argOffset, storeOffset, loadRegOffset, storeRc.String())
}
w := x.commonArgs[selKey{source, argOffset, t.Size(), t}]
if w == nil {
w = x.newArgToMemOrRegs(source, w, argOffset, loadRegOffset, t, pos)
x.splitSlotsIntoNames(locs, suffix, argOffset, t, w)
}
return x.storeArgOrLoad(pos, b, w, mem, t, storeOffset, loadRegOffset, storeRc)
}
// storeOneLoad creates a decomposed (one step) load that is then stored.
func storeOneLoad(x *expandState, pos src.XPos, b *Block, source, mem *Value, t *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
from := x.offsetFrom(source.Block, source.Args[0], offArg, types.NewPtr(t))
w := source.Block.NewValue2(source.Pos, OpLoad, t, from, mem)
return x.storeArgOrLoad(pos, b, w, mem, t, offStore, loadRegOffset, storeRc)
}
func storeTwoArg(x *expandState, pos src.XPos, b *Block, locs []*LocalSlot, suffix1 string, suffix2 string, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
mem = storeOneArg(x, pos, b, locs, suffix1, source, mem, t1, offArg, offStore, loadRegOffset, storeRc.next(t1))
pos = pos.WithNotStmt()
t1Size := t1.Size()
return storeOneArg(x, pos, b, locs, suffix2, source, mem, t2, offArg+t1Size, offStore+t1Size, loadRegOffset+1, storeRc)
}
// storeTwoLoad creates a pair of decomposed (one step) loads that are then stored.
// the elements of the pair must not require any additional alignment.
func storeTwoLoad(x *expandState, pos src.XPos, b *Block, source, mem *Value, t1, t2 *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
mem = storeOneLoad(x, pos, b, source, mem, t1, offArg, offStore, loadRegOffset, storeRc.next(t1))
pos = pos.WithNotStmt()
t1Size := t1.Size()
return storeOneLoad(x, pos, b, source, mem, t2, offArg+t1Size, offStore+t1Size, loadRegOffset+1, storeRc)
}
// storeArgOrLoad converts stores of SSA-able potentially aggregatable arguments (passed to a call) into a series of primitive-typed
// stores of non-aggregate types. It recursively walks up a chain of selectors until it reaches a Load or an Arg.
// If it does not reach a Load or an Arg, nothing happens; this allows a little freedom in phase ordering.
func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value, t *types.Type, storeOffset int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
if x.debug > 1 {
x.indent(3)
defer x.indent(-3)
x.Printf("storeArgOrLoad(%s; %s; %s; %d; %s)\n", source.LongString(), mem.String(), t.String(), storeOffset, storeRc.String())
}
// Start with Opcodes that can be disassembled
switch source.Op {
case OpCopy:
return x.storeArgOrLoad(pos, b, source.Args[0], mem, t, storeOffset, loadRegOffset, storeRc)
case OpLoad, OpDereference:
ret := x.decomposeLoad(pos, b, source, mem, t, storeOffset, loadRegOffset, storeRc)
if ret != nil {
return ret
}
case OpArg:
ret := x.decomposeArg(pos, b, source, mem, t, storeOffset, loadRegOffset, storeRc)
if ret != nil {
return ret
}
case OpArrayMake0, OpStructMake0:
// TODO(register args) is this correct for registers?
return mem
case OpStructMake1, OpStructMake2, OpStructMake3, OpStructMake4:
for i := 0; i < t.NumFields(); i++ {
fld := t.Field(i)
mem = x.storeArgOrLoad(pos, b, source.Args[i], mem, fld.Type, storeOffset+fld.Offset, 0, storeRc.next(fld.Type))
pos = pos.WithNotStmt()
}
return mem
case OpArrayMake1:
return x.storeArgOrLoad(pos, b, source.Args[0], mem, t.Elem(), storeOffset, 0, storeRc.at(t, 0))
case OpInt64Make:
tHi, tLo := x.intPairTypes(t.Kind())
mem = x.storeArgOrLoad(pos, b, source.Args[0], mem, tHi, storeOffset+x.hiOffset, 0, storeRc.next(tHi))
pos = pos.WithNotStmt()
return x.storeArgOrLoad(pos, b, source.Args[1], mem, tLo, storeOffset+x.lowOffset, 0, storeRc)
case OpComplexMake:
tPart := x.typs.Float32
wPart := t.Size() / 2
if wPart == 8 {
tPart = x.typs.Float64
}
mem = x.storeArgOrLoad(pos, b, source.Args[0], mem, tPart, storeOffset, 0, storeRc.next(tPart))
pos = pos.WithNotStmt()
return x.storeArgOrLoad(pos, b, source.Args[1], mem, tPart, storeOffset+wPart, 0, storeRc)
case OpIMake:
mem = x.storeArgOrLoad(pos, b, source.Args[0], mem, x.typs.Uintptr, storeOffset, 0, storeRc.next(x.typs.Uintptr))
pos = pos.WithNotStmt()
return x.storeArgOrLoad(pos, b, source.Args[1], mem, x.typs.BytePtr, storeOffset+x.ptrSize, 0, storeRc)
case OpStringMake:
mem = x.storeArgOrLoad(pos, b, source.Args[0], mem, x.typs.BytePtr, storeOffset, 0, storeRc.next(x.typs.BytePtr))
pos = pos.WithNotStmt()
return x.storeArgOrLoad(pos, b, source.Args[1], mem, x.typs.Int, storeOffset+x.ptrSize, 0, storeRc)
case OpSliceMake:
mem = x.storeArgOrLoad(pos, b, source.Args[0], mem, x.typs.BytePtr, storeOffset, 0, storeRc.next(x.typs.BytePtr))
pos = pos.WithNotStmt()
mem = x.storeArgOrLoad(pos, b, source.Args[1], mem, x.typs.Int, storeOffset+x.ptrSize, 0, storeRc.next(x.typs.Int))
return x.storeArgOrLoad(pos, b, source.Args[2], mem, x.typs.Int, storeOffset+2*x.ptrSize, 0, storeRc)
}
// For nodes that cannot be taken apart -- OpSelectN, other structure selectors.
switch t.Kind() {
case types.TARRAY:
elt := t.Elem()
if source.Type != t && t.NumElem() == 1 && elt.Size() == t.Size() && t.Size() == x.regSize {
t = removeTrivialWrapperTypes(t)
// it could be a leaf type, but the "leaf" could be complex64 (for example)
return x.storeArgOrLoad(pos, b, source, mem, t, storeOffset, loadRegOffset, storeRc)
}
eltRO := x.regWidth(elt)
source.Type = t
for i := int64(0); i < t.NumElem(); i++ {
sel := source.Block.NewValue1I(pos, OpArraySelect, elt, i, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, elt, storeOffset+i*elt.Size(), loadRegOffset, storeRc.at(t, 0))
loadRegOffset += eltRO
pos = pos.WithNotStmt()
}
return mem
case types.TSTRUCT:
if source.Type != t && t.NumFields() == 1 && t.Field(0).Type.Size() == t.Size() && t.Size() == x.regSize {
// This peculiar test deals with accesses to immediate interface data.
// It works okay because everything is the same size.
// Example code that triggers this can be found in go/constant/value.go, function ToComplex
// v119 (+881) = IData <intVal> v6
// v121 (+882) = StaticLECall <floatVal,mem> {AuxCall{"".itof([intVal,0])[floatVal,8]}} [16] v119 v1
// This corresponds to the generic rewrite rule "(StructSelect [0] (IData x)) => (IData x)"
// Guard against "struct{struct{*foo}}"
// Other rewriting phases create minor glitches when they transform IData, for instance the
// interface-typed Arg "x" of ToFloat in go/constant/value.go
// v6 (858) = Arg <Value> {x} (x[Value], x[Value])
// is rewritten by decomposeArgs into
// v141 (858) = Arg <uintptr> {x}
// v139 (858) = Arg <*uint8> {x} [8]
// because of a type case clause on line 862 of go/constant/value.go
// case intVal:
// return itof(x)
// v139 is later stored as an intVal == struct{val *big.Int} which naively requires the fields of
// of a *uint8, which does not succeed.
t = removeTrivialWrapperTypes(t)
// it could be a leaf type, but the "leaf" could be complex64 (for example)
return x.storeArgOrLoad(pos, b, source, mem, t, storeOffset, loadRegOffset, storeRc)
}
source.Type = t
for i := 0; i < t.NumFields(); i++ {
fld := t.Field(i)
sel := source.Block.NewValue1I(pos, OpStructSelect, fld.Type, int64(i), source)
mem = x.storeArgOrLoad(pos, b, sel, mem, fld.Type, storeOffset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
loadRegOffset += x.regWidth(fld.Type)
pos = pos.WithNotStmt()
}
return mem
case types.TINT64, types.TUINT64:
if t.Size() == x.regSize {
break
}
tHi, tLo := x.intPairTypes(t.Kind())
sel := source.Block.NewValue1(pos, OpInt64Hi, tHi, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, tHi, storeOffset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
pos = pos.WithNotStmt()
sel = source.Block.NewValue1(pos, OpInt64Lo, tLo, source)
return x.storeArgOrLoad(pos, b, sel, mem, tLo, storeOffset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.hiRo))
case types.TINTER:
sel := source.Block.NewValue1(pos, OpITab, x.typs.BytePtr, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.BytePtr, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
pos = pos.WithNotStmt()
sel = source.Block.NewValue1(pos, OpIData, x.typs.BytePtr, source)
return x.storeArgOrLoad(pos, b, sel, mem, x.typs.BytePtr, storeOffset+x.ptrSize, loadRegOffset+RO_iface_data, storeRc)
case types.TSTRING:
sel := source.Block.NewValue1(pos, OpStringPtr, x.typs.BytePtr, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.BytePtr, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
pos = pos.WithNotStmt()
sel = source.Block.NewValue1(pos, OpStringLen, x.typs.Int, source)
return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Int, storeOffset+x.ptrSize, loadRegOffset+RO_string_len, storeRc)
case types.TSLICE:
et := types.NewPtr(t.Elem())
sel := source.Block.NewValue1(pos, OpSlicePtr, et, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, et, storeOffset, loadRegOffset, storeRc.next(et))
pos = pos.WithNotStmt()
sel = source.Block.NewValue1(pos, OpSliceLen, x.typs.Int, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.Int, storeOffset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc.next(x.typs.Int))
sel = source.Block.NewValue1(pos, OpSliceCap, x.typs.Int, source)
return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Int, storeOffset+2*x.ptrSize, loadRegOffset+RO_slice_cap, storeRc)
case types.TCOMPLEX64:
sel := source.Block.NewValue1(pos, OpComplexReal, x.typs.Float32, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float32, storeOffset, loadRegOffset, storeRc.next(x.typs.Float32))
pos = pos.WithNotStmt()
sel = source.Block.NewValue1(pos, OpComplexImag, x.typs.Float32, source)
return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float32, storeOffset+4, loadRegOffset+RO_complex_imag, storeRc)
case types.TCOMPLEX128:
sel := source.Block.NewValue1(pos, OpComplexReal, x.typs.Float64, source)
mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float64, storeOffset, loadRegOffset, storeRc.next(x.typs.Float64))
pos = pos.WithNotStmt()
sel = source.Block.NewValue1(pos, OpComplexImag, x.typs.Float64, source)
return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float64, storeOffset+8, loadRegOffset+RO_complex_imag, storeRc)
}
s := mem
if source.Op == OpDereference {
source.Op = OpLoad // For purposes of parameter passing expansion, a Dereference is a Load.
}
if storeRc.hasRegs() {
storeRc.addArg(source)
} else {
dst := x.offsetFrom(b, storeRc.storeDest, storeOffset, types.NewPtr(t))
s = b.NewValue3A(pos, OpStore, types.TypeMem, t, dst, source, mem)
}
if x.debug > 1 {
x.Printf("-->storeArg returns %s, storeRc=%s\n", s.LongString(), storeRc.String())
}
return s
}
// rewriteArgs replaces all the call-parameter Args to a call with their register translation (if any).
// Preceding parameters (code pointers, closure pointer) are preserved, and the memory input is modified
// to account for any parameter stores required.
// Any of the old Args that have their use count fall to zero are marked OpInvalid.
func (x *expandState) rewriteArgs(v *Value, firstArg int) {
if x.debug > 1 {
x.indent(3)
defer x.indent(-3)
x.Printf("rewriteArgs(%s; %d)\n", v.LongString(), firstArg)
}
// Thread the stores on the memory arg
aux := v.Aux.(*AuxCall)
m0 := v.MemoryArg()
mem := m0
newArgs := []*Value{}
oldArgs := []*Value{}
sp := x.sp
if v.Op == OpTailLECall {
// For tail call, we unwind the frame before the call so we'll use the caller's
// SP.
sp = x.f.Entry.NewValue0(src.NoXPos, OpGetCallerSP, x.typs.Uintptr)
}
for i, a := range v.Args[firstArg : len(v.Args)-1] { // skip leading non-parameter SSA Args and trailing mem SSA Arg.
oldArgs = append(oldArgs, a)
auxI := int64(i)
aRegs := aux.RegsOfArg(auxI)
aType := aux.TypeOfArg(auxI)
if len(aRegs) == 0 && a.Op == OpDereference {
aOffset := aux.OffsetOfArg(auxI)
if a.MemoryArg() != m0 {
x.f.Fatalf("Op...LECall and OpDereference have mismatched mem, %s and %s", v.LongString(), a.LongString())
}
if v.Op == OpTailLECall {
// It's common for a tail call passing the same arguments (e.g. method wrapper),
// so this would be a self copy. Detect this and optimize it out.
a0 := a.Args[0]
if a0.Op == OpLocalAddr {
n := a0.Aux.(*ir.Name)
if n.Class == ir.PPARAM && n.FrameOffset()+x.f.Config.ctxt.Arch.FixedFrameSize == aOffset {
continue
}
}
}
// "Dereference" of addressed (probably not-SSA-eligible) value becomes Move
// TODO(register args) this will be more complicated with registers in the picture.
mem = x.rewriteDereference(v.Block, sp, a, mem, aOffset, aux.SizeOfArg(auxI), aType, a.Pos)
} else {
var rc registerCursor
var result *[]*Value
var aOffset int64
if len(aRegs) > 0 {
result = &newArgs
} else {
aOffset = aux.OffsetOfArg(auxI)
}
if v.Op == OpTailLECall && a.Op == OpArg && a.AuxInt == 0 {
// It's common for a tail call passing the same arguments (e.g. method wrapper),
// so this would be a self copy. Detect this and optimize it out.
n := a.Aux.(*ir.Name)
if n.Class == ir.PPARAM && n.FrameOffset()+x.f.Config.ctxt.Arch.FixedFrameSize == aOffset {
continue
}
}
if x.debug > 1 {
x.Printf("...storeArg %s, %v, %d\n", a.LongString(), aType, aOffset)
}
rc.init(aRegs, aux.abiInfo, result, sp)
mem = x.storeArgOrLoad(a.Pos, v.Block, a, mem, aType, aOffset, 0, rc)
}
}
var preArgStore [2]*Value
preArgs := append(preArgStore[:0], v.Args[0:firstArg]...)
v.resetArgs()
v.AddArgs(preArgs...)
v.AddArgs(newArgs...)
v.AddArg(mem)
for _, a := range oldArgs {
if a.Uses == 0 {
x.invalidateRecursively(a)
}
}
return
}
func (x *expandState) invalidateRecursively(a *Value) {
var s string
if x.debug > 0 {
plus := " "
if a.Pos.IsStmt() == src.PosIsStmt {
plus = " +"
}
s = a.String() + plus + a.Pos.LineNumber() + " " + a.LongString()
if x.debug > 1 {
x.Printf("...marking %v unused\n", s)
}
}
lost := a.invalidateRecursively()
if x.debug&1 != 0 && lost { // For odd values of x.debug, do this.
x.Printf("Lost statement marker in %s on former %s\n", base.Ctxt.Pkgpath+"."+x.f.Name, s)
}
}
// expandCalls converts LE (Late Expansion) calls that act like they receive value args into a lower-level form
// that is more oriented to a platform's ABI. The SelectN operations that extract results are rewritten into
// more appropriate forms, and any StructMake or ArrayMake inputs are decomposed until non-struct values are
// reached. On the callee side, OpArg nodes are not decomposed until this phase is run.
// TODO results should not be lowered until this phase.
func expandCalls(f *Func) {
// Calls that need lowering have some number of inputs, including a memory input,
// and produce a tuple of (value1, value2, ..., mem) where valueK may or may not be SSA-able.
// With the current ABI those inputs need to be converted into stores to memory,
// rethreading the call's memory input to the first, and the new call now receiving the last.
// With the current ABI, the outputs need to be converted to loads, which will all use the call's
// memory output as their input.
sp, _ := f.spSb()
x := &expandState{
f: f,
abi1: f.ABI1,
debug: f.pass.debug,
canSSAType: f.fe.CanSSA,
regSize: f.Config.RegSize,
sp: sp,
typs: &f.Config.Types,
ptrSize: f.Config.PtrSize,
namedSelects: make(map[*Value][]namedVal),
sdom: f.Sdom(),
commonArgs: make(map[selKey]*Value),
memForCall: make(map[ID]*Value),
transformedSelects: make(map[ID]bool),
}
// For 32-bit, need to deal with decomposition of 64-bit integers, which depends on endianness.
if f.Config.BigEndian {
x.lowOffset, x.hiOffset = 4, 0
x.loRo, x.hiRo = 1, 0
} else {
x.lowOffset, x.hiOffset = 0, 4
x.loRo, x.hiRo = 0, 1
}
if x.debug > 1 {
x.Printf("\nexpandsCalls(%s)\n", f.Name)
}
for i, name := range f.Names {
t := name.Type
if x.isAlreadyExpandedAggregateType(t) {
for j, v := range f.NamedValues[*name] {
if v.Op == OpSelectN || v.Op == OpArg && x.isAlreadyExpandedAggregateType(v.Type) {
ns := x.namedSelects[v]
x.namedSelects[v] = append(ns, namedVal{locIndex: i, valIndex: j})
}
}
}
}
// TODO if too slow, whole program iteration can be replaced w/ slices of appropriate values, accumulated in first loop here.
// Step 0: rewrite the calls to convert args to calls into stores/register movement.
for _, b := range f.Blocks {
for _, v := range b.Values {
firstArg := 0
switch v.Op {
case OpStaticLECall, OpTailLECall:
case OpInterLECall:
firstArg = 1
case OpClosureLECall:
firstArg = 2
default:
continue
}
x.rewriteArgs(v, firstArg)
}
if isBlockMultiValueExit(b) {
x.indent(3)
// Very similar to code in rewriteArgs, but results instead of args.
v := b.Controls[0]
m0 := v.MemoryArg()
mem := m0
aux := f.OwnAux
allResults := []*Value{}
if x.debug > 1 {
x.Printf("multiValueExit rewriting %s\n", v.LongString())
}
var oldArgs []*Value
for j, a := range v.Args[:len(v.Args)-1] {
oldArgs = append(oldArgs, a)
i := int64(j)
auxType := aux.TypeOfResult(i)
auxBase := b.NewValue2A(v.Pos, OpLocalAddr, types.NewPtr(auxType), aux.NameOfResult(i), x.sp, mem)
auxOffset := int64(0)
auxSize := aux.SizeOfResult(i)
aRegs := aux.RegsOfResult(int64(j))
if len(aRegs) == 0 && a.Op == OpDereference {
// Avoid a self-move, and if one is detected try to remove the already-inserted VarDef for the assignment that won't happen.
if dAddr, dMem := a.Args[0], a.Args[1]; dAddr.Op == OpLocalAddr && dAddr.Args[0].Op == OpSP &&
dAddr.Args[1] == dMem && dAddr.Aux == aux.NameOfResult(i) {
if dMem.Op == OpVarDef && dMem.Aux == dAddr.Aux {
dMem.copyOf(dMem.MemoryArg()) // elide the VarDef
}
continue
}
mem = x.rewriteDereference(v.Block, auxBase, a, mem, auxOffset, auxSize, auxType, a.Pos)
} else {
if a.Op == OpLoad && a.Args[0].Op == OpLocalAddr {
addr := a.Args[0] // This is a self-move. // TODO(register args) do what here for registers?
if addr.MemoryArg() == a.MemoryArg() && addr.Aux == aux.NameOfResult(i) {
continue
}
}
var rc registerCursor
var result *[]*Value
if len(aRegs) > 0 {
result = &allResults
}
rc.init(aRegs, aux.abiInfo, result, auxBase)
mem = x.storeArgOrLoad(v.Pos, b, a, mem, aux.TypeOfResult(i), auxOffset, 0, rc)
}
}
v.resetArgs()
v.AddArgs(allResults...)
v.AddArg(mem)
v.Type = types.NewResults(append(abi.RegisterTypes(aux.abiInfo.OutParams()), types.TypeMem))
b.SetControl(v)
for _, a := range oldArgs {
if a.Uses == 0 {
if x.debug > 1 {
x.Printf("...marking %v unused\n", a.LongString())
}
x.invalidateRecursively(a)
}
}
if x.debug > 1 {
x.Printf("...multiValueExit new result %s\n", v.LongString())
}
x.indent(-3)
}
}
// Step 1: any stores of aggregates remaining are believed to be sourced from call results or args.
// Decompose those stores into a series of smaller stores, adding selection ops as necessary.
for _, b := range f.Blocks {
for _, v := range b.Values {
if v.Op == OpStore {
t := v.Aux.(*types.Type)
source := v.Args[1]
tSrc := source.Type
iAEATt := x.isAlreadyExpandedAggregateType(t)
if !iAEATt {
// guarding against store immediate struct into interface data field -- store type is *uint8
// TODO can this happen recursively?
iAEATt = x.isAlreadyExpandedAggregateType(tSrc)
if iAEATt {
t = tSrc
}
}
dst, mem := v.Args[0], v.Args[2]
mem = x.storeArgOrLoad(v.Pos, b, source, mem, t, 0, 0, registerCursor{storeDest: dst})
v.copyOf(mem)
}
}
}
val2Preds := make(map[*Value]int32) // Used to accumulate dependency graph of selection operations for topological ordering.
// Step 2: transform or accumulate selection operations for rewrite in topological order.
//
// Aggregate types that have already (in earlier phases) been transformed must be lowered comprehensively to finish
// the transformation (user-defined structs and arrays, slices, strings, interfaces, complex, 64-bit on 32-bit architectures),
//
// Any select-for-addressing applied to call results can be transformed directly.
for _, b := range f.Blocks {
for _, v := range b.Values {
// Accumulate chains of selectors for processing in topological order
switch v.Op {
case OpStructSelect, OpArraySelect,
OpIData, OpITab,
OpStringPtr, OpStringLen,
OpSlicePtr, OpSliceLen, OpSliceCap, OpSlicePtrUnchecked,
OpComplexReal, OpComplexImag,
OpInt64Hi, OpInt64Lo:
w := v.Args[0]
switch w.Op {
case OpStructSelect, OpArraySelect, OpSelectN, OpArg:
val2Preds[w] += 1
if x.debug > 1 {
x.Printf("v2p[%s] = %d\n", w.LongString(), val2Preds[w])
}
}
fallthrough
case OpSelectN:
if _, ok := val2Preds[v]; !ok {
val2Preds[v] = 0
if x.debug > 1 {
x.Printf("v2p[%s] = %d\n", v.LongString(), val2Preds[v])
}
}
case OpArg:
if !x.isAlreadyExpandedAggregateType(v.Type) {
continue
}
if _, ok := val2Preds[v]; !ok {
val2Preds[v] = 0
if x.debug > 1 {
x.Printf("v2p[%s] = %d\n", v.LongString(), val2Preds[v])
}
}
case OpSelectNAddr:
// Do these directly, there are no chains of selectors.
call := v.Args[0]
which := v.AuxInt
aux := call.Aux.(*AuxCall)
pt := v.Type
off := x.offsetFrom(x.f.Entry, x.sp, aux.OffsetOfResult(which), pt)
v.copyOf(off)
}
}
}
// Step 3: Compute topological order of selectors,
// then process it in reverse to eliminate duplicates,
// then forwards to rewrite selectors.
//
// All chains of selectors end up in same block as the call.
// Compilation must be deterministic, so sort after extracting first zeroes from map.
// Sorting allows dominators-last order within each batch,
// so that the backwards scan for duplicates will most often find copies from dominating blocks (it is best-effort).
var toProcess []*Value
less := func(i, j int) bool {
vi, vj := toProcess[i], toProcess[j]
bi, bj := vi.Block, vj.Block
if bi == bj {
return vi.ID < vj.ID
}
return x.sdom.domorder(bi) > x.sdom.domorder(bj) // reverse the order to put dominators last.
}
// Accumulate order in allOrdered
var allOrdered []*Value
for v, n := range val2Preds {
if n == 0 {
allOrdered = append(allOrdered, v)
}
}
last := 0 // allOrdered[0:last] has been top-sorted and processed
for len(val2Preds) > 0 {
toProcess = allOrdered[last:]
last = len(allOrdered)
sort.SliceStable(toProcess, less)
for _, v := range toProcess {
delete(val2Preds, v)
if v.Op == OpArg {
continue // no Args[0], hence done.
}
w := v.Args[0]
n, ok := val2Preds[w]
if !ok {
continue
}
if n == 1 {
allOrdered = append(allOrdered, w)
delete(val2Preds, w)
continue
}
val2Preds[w] = n - 1
}
}
x.commonSelectors = make(map[selKey]*Value)
// Rewrite duplicate selectors as copies where possible.
for i := len(allOrdered) - 1; i >= 0; i-- {
v := allOrdered[i]
if v.Op == OpArg {
continue
}
w := v.Args[0]
if w.Op == OpCopy {
for w.Op == OpCopy {
w = w.Args[0]
}
v.SetArg(0, w)
}
typ := v.Type
if typ.IsMemory() {
continue // handled elsewhere, not an indexable result
}
size := typ.Size()
offset := int64(0)
switch v.Op {
case OpStructSelect:
if w.Type.Kind() == types.TSTRUCT {
offset = w.Type.FieldOff(int(v.AuxInt))
} else { // Immediate interface data artifact, offset is zero.
f.Fatalf("Expand calls interface data problem, func %s, v=%s, w=%s\n", f.Name, v.LongString(), w.LongString())
}
case OpArraySelect:
offset = size * v.AuxInt
case OpSelectN:
offset = v.AuxInt // offset is just a key, really.
case OpInt64Hi:
offset = x.hiOffset
case OpInt64Lo:
offset = x.lowOffset
case OpStringLen, OpSliceLen, OpIData:
offset = x.ptrSize
case OpSliceCap:
offset = 2 * x.ptrSize
case OpComplexImag:
offset = size
}
sk := selKey{from: w, size: size, offsetOrIndex: offset, typ: typ}
dupe := x.commonSelectors[sk]
if dupe == nil {
x.commonSelectors[sk] = v
} else if x.sdom.IsAncestorEq(dupe.Block, v.Block) {
if x.debug > 1 {
x.Printf("Duplicate, make %s copy of %s\n", v, dupe)
}
v.copyOf(dupe)
} else {
// Because values are processed in dominator order, the old common[s] will never dominate after a miss is seen.
// Installing the new value might match some future values.
x.commonSelectors[sk] = v
}
}
// Indices of entries in f.Names that need to be deleted.
var toDelete []namedVal
// Rewrite selectors.
for i, v := range allOrdered {
if x.debug > 1 {
b := v.Block
x.Printf("allOrdered[%d] = b%d, %s, uses=%d\n", i, b.ID, v.LongString(), v.Uses)
}
if v.Uses == 0 {
x.invalidateRecursively(v)
continue
}
if v.Op == OpCopy {
continue
}
locs := x.rewriteSelect(v, v, 0, 0)
// Install new names.
if v.Type.IsMemory() {
continue
}
// Leaf types may have debug locations
if !x.isAlreadyExpandedAggregateType(v.Type) {
for _, l := range locs {
if _, ok := f.NamedValues[*l]; !ok {
f.Names = append(f.Names, l)
}
f.NamedValues[*l] = append(f.NamedValues[*l], v)
}
continue
}
if ns, ok := x.namedSelects[v]; ok {
// Not-leaf types that had debug locations need to lose them.
toDelete = append(toDelete, ns...)
}
}
deleteNamedVals(f, toDelete)
// Step 4: rewrite the calls themselves, correcting the type.
for _, b := range f.Blocks {
for _, v := range b.Values {
switch v.Op {
case OpArg:
x.rewriteArgToMemOrRegs(v)
case OpStaticLECall:
v.Op = OpStaticCall
rts := abi.RegisterTypes(v.Aux.(*AuxCall).abiInfo.OutParams())
v.Type = types.NewResults(append(rts, types.TypeMem))
case OpTailLECall:
v.Op = OpTailCall
rts := abi.RegisterTypes(v.Aux.(*AuxCall).abiInfo.OutParams())
v.Type = types.NewResults(append(rts, types.TypeMem))
case OpClosureLECall:
v.Op = OpClosureCall
rts := abi.RegisterTypes(v.Aux.(*AuxCall).abiInfo.OutParams())
v.Type = types.NewResults(append(rts, types.TypeMem))
case OpInterLECall:
v.Op = OpInterCall
rts := abi.RegisterTypes(v.Aux.(*AuxCall).abiInfo.OutParams())
v.Type = types.NewResults(append(rts, types.TypeMem))
}
}
}
// Step 5: dedup OpArgXXXReg values. Mostly it is already dedup'd by commonArgs,
// but there are cases that we have same OpArgXXXReg values with different types.
// E.g. string is sometimes decomposed as { *int8, int }, sometimes as { unsafe.Pointer, uintptr }.
// (Can we avoid that?)
var IArg, FArg [32]*Value
for _, v := range f.Entry.Values {
switch v.Op {
case OpArgIntReg:
i := v.AuxInt
if w := IArg[i]; w != nil {
if w.Type.Size() != v.Type.Size() {
f.Fatalf("incompatible OpArgIntReg [%d]: %s and %s", i, v.LongString(), w.LongString())
}
if w.Type.IsUnsafePtr() && !v.Type.IsUnsafePtr() {
// Update unsafe.Pointer type if we know the actual pointer type.
w.Type = v.Type
}
// TODO: don't dedup pointer and scalar? Rewrite to OpConvert? Can it happen?
v.copyOf(w)
} else {
IArg[i] = v
}
case OpArgFloatReg:
i := v.AuxInt
if w := FArg[i]; w != nil {
if w.Type.Size() != v.Type.Size() {
f.Fatalf("incompatible OpArgFloatReg [%d]: %v and %v", i, v, w)
}
v.copyOf(w)
} else {
FArg[i] = v
}
}
}
// Step 6: elide any copies introduced.
// Update named values.
for _, name := range f.Names {
values := f.NamedValues[*name]
for i, v := range values {
if v.Op == OpCopy {
a := v.Args[0]
for a.Op == OpCopy {
a = a.Args[0]
}
values[i] = a
}
}
}
for _, b := range f.Blocks {
for _, v := range b.Values {
for i, a := range v.Args {
if a.Op != OpCopy {
continue
}
aa := copySource(a)
v.SetArg(i, aa)
for a.Uses == 0 {
b := a.Args[0]
x.invalidateRecursively(a)
a = b
}
}
}
}
// Rewriting can attach lines to values that are unlikely to survive code generation, so move them to a use.
for _, b := range f.Blocks {
for _, v := range b.Values {
for _, a := range v.Args {
if a.Pos.IsStmt() != src.PosIsStmt {
continue
}
if a.Type.IsMemory() {
continue
}
if a.Pos.Line() != v.Pos.Line() {
continue
}
if !a.Pos.SameFile(v.Pos) {
continue
}
switch a.Op {
case OpArgIntReg, OpArgFloatReg, OpSelectN:
v.Pos = v.Pos.WithIsStmt()
a.Pos = a.Pos.WithDefaultStmt()
}
}
}
}
}
// rewriteArgToMemOrRegs converts OpArg v in-place into the register version of v,
// if that is appropriate.
func (x *expandState) rewriteArgToMemOrRegs(v *Value) *Value {
if x.debug > 1 {
x.indent(3)
defer x.indent(-3)
x.Printf("rewriteArgToMemOrRegs(%s)\n", v.LongString())
}
pa := x.prAssignForArg(v)
switch len(pa.Registers) {
case 0:
frameOff := v.Aux.(*ir.Name).FrameOffset()
if pa.Offset() != int32(frameOff+x.f.ABISelf.LocalsOffset()) {
panic(fmt.Errorf("Parameter assignment %d and OpArg.Aux frameOffset %d disagree, op=%s",
pa.Offset(), frameOff, v.LongString()))
}
case 1:
t := v.Type
key := selKey{v, 0, t.Size(), t}
w := x.commonArgs[key]
if w != nil && w.Uses != 0 { // do not reuse dead value
v.copyOf(w)
break
}
r := pa.Registers[0]
var i int64
v.Op, i = ArgOpAndRegisterFor(r, x.f.ABISelf)
v.Aux = &AuxNameOffset{v.Aux.(*ir.Name), 0}
v.AuxInt = i
x.commonArgs[key] = v
default:
panic(badVal("Saw unexpanded OpArg", v))
}
if x.debug > 1 {
x.Printf("-->%s\n", v.LongString())
}
return v
}
// newArgToMemOrRegs either rewrites toReplace into an OpArg referencing memory or into an OpArgXXXReg to a register,
// or rewrites it into a copy of the appropriate OpArgXXX. The actual OpArgXXX is determined by combining baseArg (an OpArg)
// with offset, regOffset, and t to determine which portion of it to reference (either all or a part, in memory or in registers).
func (x *expandState) newArgToMemOrRegs(baseArg, toReplace *Value, offset int64, regOffset Abi1RO, t *types.Type, pos src.XPos) *Value {
if x.debug > 1 {
x.indent(3)
defer x.indent(-3)
x.Printf("newArgToMemOrRegs(base=%s; toReplace=%s; t=%s; memOff=%d; regOff=%d)\n", baseArg.String(), toReplace.LongString(), t.String(), offset, regOffset)
}
key := selKey{baseArg, offset, t.Size(), t}
w := x.commonArgs[key]
if w != nil && w.Uses != 0 { // do not reuse dead value
if toReplace != nil {
toReplace.copyOf(w)
if x.debug > 1 {
x.Printf("...replace %s\n", toReplace.LongString())
}
}
if x.debug > 1 {
x.Printf("-->%s\n", w.LongString())
}
return w
}
pa := x.prAssignForArg(baseArg)
if len(pa.Registers) == 0 { // Arg is on stack
frameOff := baseArg.Aux.(*ir.Name).FrameOffset()
if pa.Offset() != int32(frameOff+x.f.ABISelf.LocalsOffset()) {
panic(fmt.Errorf("Parameter assignment %d and OpArg.Aux frameOffset %d disagree, op=%s",
pa.Offset(), frameOff, baseArg.LongString()))
}
aux := baseArg.Aux
auxInt := baseArg.AuxInt + offset
if toReplace != nil && toReplace.Block == baseArg.Block {
toReplace.reset(OpArg)
toReplace.Aux = aux
toReplace.AuxInt = auxInt
toReplace.Type = t
w = toReplace
} else {
w = baseArg.Block.NewValue0IA(pos, OpArg, t, auxInt, aux)
}
x.commonArgs[key] = w
if toReplace != nil {
toReplace.copyOf(w)
}
if x.debug > 1 {
x.Printf("-->%s\n", w.LongString())
}
return w
}
// Arg is in registers
r := pa.Registers[regOffset]
op, auxInt := ArgOpAndRegisterFor(r, x.f.ABISelf)
if op == OpArgIntReg && t.IsFloat() || op == OpArgFloatReg && t.IsInteger() {
fmt.Printf("pa=%v\nx.f.OwnAux.abiInfo=%s\n",
pa.ToString(x.f.ABISelf, true),
x.f.OwnAux.abiInfo.String())
panic(fmt.Errorf("Op/Type mismatch, op=%s, type=%s", op.String(), t.String()))
}
if baseArg.AuxInt != 0 {
base.Fatalf("BaseArg %s bound to registers has non-zero AuxInt", baseArg.LongString())
}
aux := &AuxNameOffset{baseArg.Aux.(*ir.Name), offset}
if toReplace != nil && toReplace.Block == baseArg.Block {
toReplace.reset(op)
toReplace.Aux = aux
toReplace.AuxInt = auxInt
toReplace.Type = t
w = toReplace
} else {
w = baseArg.Block.NewValue0IA(pos, op, t, auxInt, aux)
}
x.commonArgs[key] = w
if toReplace != nil {
toReplace.copyOf(w)
}
if x.debug > 1 {
x.Printf("-->%s\n", w.LongString())
}
return w
}
// argOpAndRegisterFor converts an abi register index into an ssa Op and corresponding
// arg register index.
func ArgOpAndRegisterFor(r abi.RegIndex, abiConfig *abi.ABIConfig) (Op, int64) {
i := abiConfig.FloatIndexFor(r)
if i >= 0 { // float PR
return OpArgFloatReg, i
}
return OpArgIntReg, int64(r)
}
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