func.go

     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/abi"
     9  	"cmd/compile/internal/base"
    10  	"cmd/compile/internal/ir"
    11  	"cmd/compile/internal/typecheck"
    12  	"cmd/compile/internal/types"
    13  	"cmd/internal/obj"
    14  	"cmd/internal/src"
    15  	"fmt"
    16  	"math"
    17  	"strings"
    18  )
    19  
    20  // A Func represents a Go func declaration (or function literal) and its body.
    21  // This package compiles each Func independently.
    22  // Funcs are single-use; a new Func must be created for every compiled function.
    23  type Func struct {
    24  	Config *Config     // architecture information
    25  	Cache  *Cache      // re-usable cache
    26  	fe     Frontend    // frontend state associated with this Func, callbacks into compiler frontend
    27  	pass   *pass       // current pass information (name, options, etc.)
    28  	Name   string      // e.g. NewFunc or (*Func).NumBlocks (no package prefix)
    29  	Type   *types.Type // type signature of the function.
    30  	Blocks []*Block    // unordered set of all basic blocks (note: not indexable by ID)
    31  	Entry  *Block      // the entry basic block
    32  
    33  	bid idAlloc // block ID allocator
    34  	vid idAlloc // value ID allocator
    35  
    36  	HTMLWriter     *HTMLWriter    // html writer, for debugging
    37  	PrintOrHtmlSSA bool           // true if GOSSAFUNC matches, true even if fe.Log() (spew phase results to stdout) is false.  There's an odd dependence on this in debug.go for method logf.
    38  	ruleMatches    map[string]int // number of times countRule was called during compilation for any given string
    39  	ABI0           *abi.ABIConfig // A copy, for no-sync access
    40  	ABI1           *abi.ABIConfig // A copy, for no-sync access
    41  	ABISelf        *abi.ABIConfig // ABI for function being compiled
    42  	ABIDefault     *abi.ABIConfig // ABI for rtcall and other no-parsed-signature/pragma functions.
    43  
    44  	scheduled         bool  // Values in Blocks are in final order
    45  	laidout           bool  // Blocks are ordered
    46  	NoSplit           bool  // true if function is marked as nosplit.  Used by schedule check pass.
    47  	dumpFileSeq       uint8 // the sequence numbers of dump file. (%s_%02d__%s.dump", funcname, dumpFileSeq, phaseName)
    48  	IsPgoHot          bool
    49  	HasDeferRangeFunc bool // if true, needs a deferreturn so deferrangefunc can use it for recover() return PC
    50  
    51  	// when register allocation is done, maps value ids to locations
    52  	RegAlloc []Location
    53  
    54  	// temporary registers allocated to rare instructions
    55  	tempRegs map[ID]*Register
    56  
    57  	// map from LocalSlot to set of Values that we want to store in that slot.
    58  	NamedValues map[LocalSlot][]*Value
    59  	// Names is a copy of NamedValues.Keys. We keep a separate list
    60  	// of keys to make iteration order deterministic.
    61  	Names []*LocalSlot
    62  	// Canonicalize root/top-level local slots, and canonicalize their pieces.
    63  	// Because LocalSlot pieces refer to their parents with a pointer, this ensures that equivalent slots really are equal.
    64  	CanonicalLocalSlots  map[LocalSlot]*LocalSlot
    65  	CanonicalLocalSplits map[LocalSlotSplitKey]*LocalSlot
    66  
    67  	// RegArgs is a slice of register-memory pairs that must be spilled and unspilled in the uncommon path of function entry.
    68  	RegArgs []Spill
    69  	// OwnAux describes parameters and results for this function.
    70  	OwnAux *AuxCall
    71  	// CloSlot holds the compiler-synthesized name (".closureptr")
    72  	// where we spill the closure pointer for range func bodies.
    73  	CloSlot *ir.Name
    74  
    75  	freeValues *Value // free Values linked by argstorage[0].  All other fields except ID are 0/nil.
    76  	freeBlocks *Block // free Blocks linked by succstorage[0].b.  All other fields except ID are 0/nil.
    77  
    78  	cachedPostorder  []*Block   // cached postorder traversal
    79  	cachedIdom       []*Block   // cached immediate dominators
    80  	cachedSdom       SparseTree // cached dominator tree
    81  	cachedLoopnest   *loopnest  // cached loop nest information
    82  	cachedLineStarts *xposmap   // cached map/set of xpos to integers
    83  
    84  	auxmap    auxmap             // map from aux values to opaque ids used by CSE
    85  	constants map[int64][]*Value // constants cache, keyed by constant value; users must check value's Op and Type
    86  }
    87  
    88  type LocalSlotSplitKey struct {
    89  	parent *LocalSlot
    90  	Off    int64       // offset of slot in N
    91  	Type   *types.Type // type of slot
    92  }
    93  
    94  // NewFunc returns a new, empty function object.
    95  // Caller must reset cache before calling NewFunc.
    96  func (c *Config) NewFunc(fe Frontend, cache *Cache) *Func {
    97  	return &Func{
    98  		fe:     fe,
    99  		Config: c,
   100  		Cache:  cache,
   101  
   102  		NamedValues:          make(map[LocalSlot][]*Value),
   103  		CanonicalLocalSlots:  make(map[LocalSlot]*LocalSlot),
   104  		CanonicalLocalSplits: make(map[LocalSlotSplitKey]*LocalSlot),
   105  	}
   106  }
   107  
   108  // NumBlocks returns an integer larger than the id of any Block in the Func.
   109  func (f *Func) NumBlocks() int {
   110  	return f.bid.num()
   111  }
   112  
   113  // NumValues returns an integer larger than the id of any Value in the Func.
   114  func (f *Func) NumValues() int {
   115  	return f.vid.num()
   116  }
   117  
   118  // NameABI returns the function name followed by comma and the ABI number.
   119  // This is intended for use with GOSSAFUNC and HTML dumps, and differs from
   120  // the linker's "<1>" convention because "<" and ">" require shell quoting
   121  // and are not legal file names (for use with GOSSADIR) on Windows.
   122  func (f *Func) NameABI() string {
   123  	return FuncNameABI(f.Name, f.ABISelf.Which())
   124  }
   125  
   126  // FuncNameABI returns n followed by a comma and the value of a.
   127  // This is a separate function to allow a single point encoding
   128  // of the format, which is used in places where there's not a Func yet.
   129  func FuncNameABI(n string, a obj.ABI) string {
   130  	return fmt.Sprintf("%s,%d", n, a)
   131  }
   132  
   133  // newSparseSet returns a sparse set that can store at least up to n integers.
   134  func (f *Func) newSparseSet(n int) *sparseSet {
   135  	return f.Cache.allocSparseSet(n)
   136  }
   137  
   138  // retSparseSet returns a sparse set to the config's cache of sparse
   139  // sets to be reused by f.newSparseSet.
   140  func (f *Func) retSparseSet(ss *sparseSet) {
   141  	f.Cache.freeSparseSet(ss)
   142  }
   143  
   144  // newSparseMap returns a sparse map that can store at least up to n integers.
   145  func (f *Func) newSparseMap(n int) *sparseMap {
   146  	return f.Cache.allocSparseMap(n)
   147  }
   148  
   149  // retSparseMap returns a sparse map to the config's cache of sparse
   150  // sets to be reused by f.newSparseMap.
   151  func (f *Func) retSparseMap(ss *sparseMap) {
   152  	f.Cache.freeSparseMap(ss)
   153  }
   154  
   155  // newSparseMapPos returns a sparse map that can store at least up to n integers.
   156  func (f *Func) newSparseMapPos(n int) *sparseMapPos {
   157  	return f.Cache.allocSparseMapPos(n)
   158  }
   159  
   160  // retSparseMapPos returns a sparse map to the config's cache of sparse
   161  // sets to be reused by f.newSparseMapPos.
   162  func (f *Func) retSparseMapPos(ss *sparseMapPos) {
   163  	f.Cache.freeSparseMapPos(ss)
   164  }
   165  
   166  // newPoset returns a new poset from the internal cache
   167  func (f *Func) newPoset() *poset {
   168  	if len(f.Cache.scrPoset) > 0 {
   169  		po := f.Cache.scrPoset[len(f.Cache.scrPoset)-1]
   170  		f.Cache.scrPoset = f.Cache.scrPoset[:len(f.Cache.scrPoset)-1]
   171  		return po
   172  	}
   173  	return newPoset()
   174  }
   175  
   176  // retPoset returns a poset to the internal cache
   177  func (f *Func) retPoset(po *poset) {
   178  	f.Cache.scrPoset = append(f.Cache.scrPoset, po)
   179  }
   180  
   181  func (f *Func) localSlotAddr(slot LocalSlot) *LocalSlot {
   182  	a, ok := f.CanonicalLocalSlots[slot]
   183  	if !ok {
   184  		a = new(LocalSlot)
   185  		*a = slot // don't escape slot
   186  		f.CanonicalLocalSlots[slot] = a
   187  	}
   188  	return a
   189  }
   190  
   191  func (f *Func) SplitString(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   192  	ptrType := types.NewPtr(types.Types[types.TUINT8])
   193  	lenType := types.Types[types.TINT]
   194  	// Split this string up into two separate variables.
   195  	p := f.SplitSlot(name, ".ptr", 0, ptrType)
   196  	l := f.SplitSlot(name, ".len", ptrType.Size(), lenType)
   197  	return p, l
   198  }
   199  
   200  func (f *Func) SplitInterface(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   201  	n := name.N
   202  	u := types.Types[types.TUINTPTR]
   203  	t := types.NewPtr(types.Types[types.TUINT8])
   204  	// Split this interface up into two separate variables.
   205  	sfx := ".itab"
   206  	if n.Type().IsEmptyInterface() {
   207  		sfx = ".type"
   208  	}
   209  	c := f.SplitSlot(name, sfx, 0, u) // see comment in typebits.Set
   210  	d := f.SplitSlot(name, ".data", u.Size(), t)
   211  	return c, d
   212  }
   213  
   214  func (f *Func) SplitSlice(name *LocalSlot) (*LocalSlot, *LocalSlot, *LocalSlot) {
   215  	ptrType := types.NewPtr(name.Type.Elem())
   216  	lenType := types.Types[types.TINT]
   217  	p := f.SplitSlot(name, ".ptr", 0, ptrType)
   218  	l := f.SplitSlot(name, ".len", ptrType.Size(), lenType)
   219  	c := f.SplitSlot(name, ".cap", ptrType.Size()+lenType.Size(), lenType)
   220  	return p, l, c
   221  }
   222  
   223  func (f *Func) SplitComplex(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   224  	s := name.Type.Size() / 2
   225  	var t *types.Type
   226  	if s == 8 {
   227  		t = types.Types[types.TFLOAT64]
   228  	} else {
   229  		t = types.Types[types.TFLOAT32]
   230  	}
   231  	r := f.SplitSlot(name, ".real", 0, t)
   232  	i := f.SplitSlot(name, ".imag", t.Size(), t)
   233  	return r, i
   234  }
   235  
   236  func (f *Func) SplitInt64(name *LocalSlot) (*LocalSlot, *LocalSlot) {
   237  	var t *types.Type
   238  	if name.Type.IsSigned() {
   239  		t = types.Types[types.TINT32]
   240  	} else {
   241  		t = types.Types[types.TUINT32]
   242  	}
   243  	if f.Config.BigEndian {
   244  		return f.SplitSlot(name, ".hi", 0, t), f.SplitSlot(name, ".lo", t.Size(), types.Types[types.TUINT32])
   245  	}
   246  	return f.SplitSlot(name, ".hi", t.Size(), t), f.SplitSlot(name, ".lo", 0, types.Types[types.TUINT32])
   247  }
   248  
   249  func (f *Func) SplitStruct(name *LocalSlot, i int) *LocalSlot {
   250  	st := name.Type
   251  	return f.SplitSlot(name, st.FieldName(i), st.FieldOff(i), st.FieldType(i))
   252  }
   253  func (f *Func) SplitArray(name *LocalSlot) *LocalSlot {
   254  	n := name.N
   255  	at := name.Type
   256  	if at.NumElem() != 1 {
   257  		base.FatalfAt(n.Pos(), "bad array size")
   258  	}
   259  	et := at.Elem()
   260  	return f.SplitSlot(name, "[0]", 0, et)
   261  }
   262  
   263  func (f *Func) SplitSlot(name *LocalSlot, sfx string, offset int64, t *types.Type) *LocalSlot {
   264  	lssk := LocalSlotSplitKey{name, offset, t}
   265  	if als, ok := f.CanonicalLocalSplits[lssk]; ok {
   266  		return als
   267  	}
   268  	// Note: the _ field may appear several times.  But
   269  	// have no fear, identically-named but distinct Autos are
   270  	// ok, albeit maybe confusing for a debugger.
   271  	ls := f.fe.SplitSlot(name, sfx, offset, t)
   272  	f.CanonicalLocalSplits[lssk] = &ls
   273  	return &ls
   274  }
   275  
   276  // newValue allocates a new Value with the given fields and places it at the end of b.Values.
   277  func (f *Func) newValue(op Op, t *types.Type, b *Block, pos src.XPos) *Value {
   278  	var v *Value
   279  	if f.freeValues != nil {
   280  		v = f.freeValues
   281  		f.freeValues = v.argstorage[0]
   282  		v.argstorage[0] = nil
   283  	} else {
   284  		ID := f.vid.get()
   285  		if int(ID) < len(f.Cache.values) {
   286  			v = &f.Cache.values[ID]
   287  			v.ID = ID
   288  		} else {
   289  			v = &Value{ID: ID}
   290  		}
   291  	}
   292  	v.Op = op
   293  	v.Type = t
   294  	v.Block = b
   295  	if notStmtBoundary(op) {
   296  		pos = pos.WithNotStmt()
   297  	}
   298  	v.Pos = pos
   299  	b.Values = append(b.Values, v)
   300  	return v
   301  }
   302  
   303  // newValueNoBlock allocates a new Value with the given fields.
   304  // The returned value is not placed in any block.  Once the caller
   305  // decides on a block b, it must set b.Block and append
   306  // the returned value to b.Values.
   307  func (f *Func) newValueNoBlock(op Op, t *types.Type, pos src.XPos) *Value {
   308  	var v *Value
   309  	if f.freeValues != nil {
   310  		v = f.freeValues
   311  		f.freeValues = v.argstorage[0]
   312  		v.argstorage[0] = nil
   313  	} else {
   314  		ID := f.vid.get()
   315  		if int(ID) < len(f.Cache.values) {
   316  			v = &f.Cache.values[ID]
   317  			v.ID = ID
   318  		} else {
   319  			v = &Value{ID: ID}
   320  		}
   321  	}
   322  	v.Op = op
   323  	v.Type = t
   324  	v.Block = nil // caller must fix this.
   325  	if notStmtBoundary(op) {
   326  		pos = pos.WithNotStmt()
   327  	}
   328  	v.Pos = pos
   329  	return v
   330  }
   331  
   332  // LogStat writes a string key and int value as a warning in a
   333  // tab-separated format easily handled by spreadsheets or awk.
   334  // file names, lines, and function names are included to provide enough (?)
   335  // context to allow item-by-item comparisons across runs.
   336  // For example:
   337  // awk 'BEGIN {FS="\t"} $3~/TIME/{sum+=$4} END{print "t(ns)=",sum}' t.log
   338  func (f *Func) LogStat(key string, args ...interface{}) {
   339  	value := ""
   340  	for _, a := range args {
   341  		value += fmt.Sprintf("\t%v", a)
   342  	}
   343  	n := "missing_pass"
   344  	if f.pass != nil {
   345  		n = strings.Replace(f.pass.name, " ", "_", -1)
   346  	}
   347  	f.Warnl(f.Entry.Pos, "\t%s\t%s%s\t%s", n, key, value, f.Name)
   348  }
   349  
   350  // unCacheLine removes v from f's constant cache "line" for aux,
   351  // resets v.InCache when it is found (and removed),
   352  // and returns whether v was found in that line.
   353  func (f *Func) unCacheLine(v *Value, aux int64) bool {
   354  	vv := f.constants[aux]
   355  	for i, cv := range vv {
   356  		if v == cv {
   357  			vv[i] = vv[len(vv)-1]
   358  			vv[len(vv)-1] = nil
   359  			f.constants[aux] = vv[0 : len(vv)-1]
   360  			v.InCache = false
   361  			return true
   362  		}
   363  	}
   364  	return false
   365  }
   366  
   367  // unCache removes v from f's constant cache.
   368  func (f *Func) unCache(v *Value) {
   369  	if v.InCache {
   370  		aux := v.AuxInt
   371  		if f.unCacheLine(v, aux) {
   372  			return
   373  		}
   374  		if aux == 0 {
   375  			switch v.Op {
   376  			case OpConstNil:
   377  				aux = constNilMagic
   378  			case OpConstSlice:
   379  				aux = constSliceMagic
   380  			case OpConstString:
   381  				aux = constEmptyStringMagic
   382  			case OpConstInterface:
   383  				aux = constInterfaceMagic
   384  			}
   385  			if aux != 0 && f.unCacheLine(v, aux) {
   386  				return
   387  			}
   388  		}
   389  		f.Fatalf("unCached value %s not found in cache, auxInt=0x%x, adjusted aux=0x%x", v.LongString(), v.AuxInt, aux)
   390  	}
   391  }
   392  
   393  // freeValue frees a value. It must no longer be referenced or have any args.
   394  func (f *Func) freeValue(v *Value) {
   395  	if v.Block == nil {
   396  		f.Fatalf("trying to free an already freed value")
   397  	}
   398  	if v.Uses != 0 {
   399  		f.Fatalf("value %s still has %d uses", v, v.Uses)
   400  	}
   401  	if len(v.Args) != 0 {
   402  		f.Fatalf("value %s still has %d args", v, len(v.Args))
   403  	}
   404  	// Clear everything but ID (which we reuse).
   405  	id := v.ID
   406  	if v.InCache {
   407  		f.unCache(v)
   408  	}
   409  	*v = Value{}
   410  	v.ID = id
   411  	v.argstorage[0] = f.freeValues
   412  	f.freeValues = v
   413  }
   414  
   415  // NewBlock allocates a new Block of the given kind and places it at the end of f.Blocks.
   416  func (f *Func) NewBlock(kind BlockKind) *Block {
   417  	var b *Block
   418  	if f.freeBlocks != nil {
   419  		b = f.freeBlocks
   420  		f.freeBlocks = b.succstorage[0].b
   421  		b.succstorage[0].b = nil
   422  	} else {
   423  		ID := f.bid.get()
   424  		if int(ID) < len(f.Cache.blocks) {
   425  			b = &f.Cache.blocks[ID]
   426  			b.ID = ID
   427  		} else {
   428  			b = &Block{ID: ID}
   429  		}
   430  	}
   431  	b.Kind = kind
   432  	b.Func = f
   433  	b.Preds = b.predstorage[:0]
   434  	b.Succs = b.succstorage[:0]
   435  	b.Values = b.valstorage[:0]
   436  	f.Blocks = append(f.Blocks, b)
   437  	f.invalidateCFG()
   438  	return b
   439  }
   440  
   441  func (f *Func) freeBlock(b *Block) {
   442  	if b.Func == nil {
   443  		f.Fatalf("trying to free an already freed block")
   444  	}
   445  	// Clear everything but ID (which we reuse).
   446  	id := b.ID
   447  	*b = Block{}
   448  	b.ID = id
   449  	b.succstorage[0].b = f.freeBlocks
   450  	f.freeBlocks = b
   451  }
   452  
   453  // NewValue0 returns a new value in the block with no arguments and zero aux values.
   454  func (b *Block) NewValue0(pos src.XPos, op Op, t *types.Type) *Value {
   455  	v := b.Func.newValue(op, t, b, pos)
   456  	v.AuxInt = 0
   457  	v.Args = v.argstorage[:0]
   458  	return v
   459  }
   460  
   461  // NewValue0I returns a new value in the block with no arguments and an auxint value.
   462  func (b *Block) NewValue0I(pos src.XPos, op Op, t *types.Type, auxint int64) *Value {
   463  	v := b.Func.newValue(op, t, b, pos)
   464  	v.AuxInt = auxint
   465  	v.Args = v.argstorage[:0]
   466  	return v
   467  }
   468  
   469  // NewValue0A returns a new value in the block with no arguments and an aux value.
   470  func (b *Block) NewValue0A(pos src.XPos, op Op, t *types.Type, aux Aux) *Value {
   471  	v := b.Func.newValue(op, t, b, pos)
   472  	v.AuxInt = 0
   473  	v.Aux = aux
   474  	v.Args = v.argstorage[:0]
   475  	return v
   476  }
   477  
   478  // NewValue0IA returns a new value in the block with no arguments and both an auxint and aux values.
   479  func (b *Block) NewValue0IA(pos src.XPos, op Op, t *types.Type, auxint int64, aux Aux) *Value {
   480  	v := b.Func.newValue(op, t, b, pos)
   481  	v.AuxInt = auxint
   482  	v.Aux = aux
   483  	v.Args = v.argstorage[:0]
   484  	return v
   485  }
   486  
   487  // NewValue1 returns a new value in the block with one argument and zero aux values.
   488  func (b *Block) NewValue1(pos src.XPos, op Op, t *types.Type, arg *Value) *Value {
   489  	v := b.Func.newValue(op, t, b, pos)
   490  	v.AuxInt = 0
   491  	v.Args = v.argstorage[:1]
   492  	v.argstorage[0] = arg
   493  	arg.Uses++
   494  	return v
   495  }
   496  
   497  // NewValue1I returns a new value in the block with one argument and an auxint value.
   498  func (b *Block) NewValue1I(pos src.XPos, op Op, t *types.Type, auxint int64, arg *Value) *Value {
   499  	v := b.Func.newValue(op, t, b, pos)
   500  	v.AuxInt = auxint
   501  	v.Args = v.argstorage[:1]
   502  	v.argstorage[0] = arg
   503  	arg.Uses++
   504  	return v
   505  }
   506  
   507  // NewValue1A returns a new value in the block with one argument and an aux value.
   508  func (b *Block) NewValue1A(pos src.XPos, op Op, t *types.Type, aux Aux, arg *Value) *Value {
   509  	v := b.Func.newValue(op, t, b, pos)
   510  	v.AuxInt = 0
   511  	v.Aux = aux
   512  	v.Args = v.argstorage[:1]
   513  	v.argstorage[0] = arg
   514  	arg.Uses++
   515  	return v
   516  }
   517  
   518  // NewValue1IA returns a new value in the block with one argument and both an auxint and aux values.
   519  func (b *Block) NewValue1IA(pos src.XPos, op Op, t *types.Type, auxint int64, aux Aux, arg *Value) *Value {
   520  	v := b.Func.newValue(op, t, b, pos)
   521  	v.AuxInt = auxint
   522  	v.Aux = aux
   523  	v.Args = v.argstorage[:1]
   524  	v.argstorage[0] = arg
   525  	arg.Uses++
   526  	return v
   527  }
   528  
   529  // NewValue2 returns a new value in the block with two arguments and zero aux values.
   530  func (b *Block) NewValue2(pos src.XPos, op Op, t *types.Type, arg0, arg1 *Value) *Value {
   531  	v := b.Func.newValue(op, t, b, pos)
   532  	v.AuxInt = 0
   533  	v.Args = v.argstorage[:2]
   534  	v.argstorage[0] = arg0
   535  	v.argstorage[1] = arg1
   536  	arg0.Uses++
   537  	arg1.Uses++
   538  	return v
   539  }
   540  
   541  // NewValue2A returns a new value in the block with two arguments and one aux values.
   542  func (b *Block) NewValue2A(pos src.XPos, op Op, t *types.Type, aux Aux, arg0, arg1 *Value) *Value {
   543  	v := b.Func.newValue(op, t, b, pos)
   544  	v.AuxInt = 0
   545  	v.Aux = aux
   546  	v.Args = v.argstorage[:2]
   547  	v.argstorage[0] = arg0
   548  	v.argstorage[1] = arg1
   549  	arg0.Uses++
   550  	arg1.Uses++
   551  	return v
   552  }
   553  
   554  // NewValue2I returns a new value in the block with two arguments and an auxint value.
   555  func (b *Block) NewValue2I(pos src.XPos, op Op, t *types.Type, auxint int64, arg0, arg1 *Value) *Value {
   556  	v := b.Func.newValue(op, t, b, pos)
   557  	v.AuxInt = auxint
   558  	v.Args = v.argstorage[:2]
   559  	v.argstorage[0] = arg0
   560  	v.argstorage[1] = arg1
   561  	arg0.Uses++
   562  	arg1.Uses++
   563  	return v
   564  }
   565  
   566  // NewValue2IA returns a new value in the block with two arguments and both an auxint and aux values.
   567  func (b *Block) NewValue2IA(pos src.XPos, op Op, t *types.Type, auxint int64, aux Aux, arg0, arg1 *Value) *Value {
   568  	v := b.Func.newValue(op, t, b, pos)
   569  	v.AuxInt = auxint
   570  	v.Aux = aux
   571  	v.Args = v.argstorage[:2]
   572  	v.argstorage[0] = arg0
   573  	v.argstorage[1] = arg1
   574  	arg0.Uses++
   575  	arg1.Uses++
   576  	return v
   577  }
   578  
   579  // NewValue3 returns a new value in the block with three arguments and zero aux values.
   580  func (b *Block) NewValue3(pos src.XPos, op Op, t *types.Type, arg0, arg1, arg2 *Value) *Value {
   581  	v := b.Func.newValue(op, t, b, pos)
   582  	v.AuxInt = 0
   583  	v.Args = v.argstorage[:3]
   584  	v.argstorage[0] = arg0
   585  	v.argstorage[1] = arg1
   586  	v.argstorage[2] = arg2
   587  	arg0.Uses++
   588  	arg1.Uses++
   589  	arg2.Uses++
   590  	return v
   591  }
   592  
   593  // NewValue3I returns a new value in the block with three arguments and an auxint value.
   594  func (b *Block) NewValue3I(pos src.XPos, op Op, t *types.Type, auxint int64, arg0, arg1, arg2 *Value) *Value {
   595  	v := b.Func.newValue(op, t, b, pos)
   596  	v.AuxInt = auxint
   597  	v.Args = v.argstorage[:3]
   598  	v.argstorage[0] = arg0
   599  	v.argstorage[1] = arg1
   600  	v.argstorage[2] = arg2
   601  	arg0.Uses++
   602  	arg1.Uses++
   603  	arg2.Uses++
   604  	return v
   605  }
   606  
   607  // NewValue3A returns a new value in the block with three argument and an aux value.
   608  func (b *Block) NewValue3A(pos src.XPos, op Op, t *types.Type, aux Aux, arg0, arg1, arg2 *Value) *Value {
   609  	v := b.Func.newValue(op, t, b, pos)
   610  	v.AuxInt = 0
   611  	v.Aux = aux
   612  	v.Args = v.argstorage[:3]
   613  	v.argstorage[0] = arg0
   614  	v.argstorage[1] = arg1
   615  	v.argstorage[2] = arg2
   616  	arg0.Uses++
   617  	arg1.Uses++
   618  	arg2.Uses++
   619  	return v
   620  }
   621  
   622  // NewValue4 returns a new value in the block with four arguments and zero aux values.
   623  func (b *Block) NewValue4(pos src.XPos, op Op, t *types.Type, arg0, arg1, arg2, arg3 *Value) *Value {
   624  	v := b.Func.newValue(op, t, b, pos)
   625  	v.AuxInt = 0
   626  	v.Args = []*Value{arg0, arg1, arg2, arg3}
   627  	arg0.Uses++
   628  	arg1.Uses++
   629  	arg2.Uses++
   630  	arg3.Uses++
   631  	return v
   632  }
   633  
   634  // NewValue4I returns a new value in the block with four arguments and auxint value.
   635  func (b *Block) NewValue4I(pos src.XPos, op Op, t *types.Type, auxint int64, arg0, arg1, arg2, arg3 *Value) *Value {
   636  	v := b.Func.newValue(op, t, b, pos)
   637  	v.AuxInt = auxint
   638  	v.Args = []*Value{arg0, arg1, arg2, arg3}
   639  	arg0.Uses++
   640  	arg1.Uses++
   641  	arg2.Uses++
   642  	arg3.Uses++
   643  	return v
   644  }
   645  
   646  // constVal returns a constant value for c.
   647  func (f *Func) constVal(op Op, t *types.Type, c int64, setAuxInt bool) *Value {
   648  	if f.constants == nil {
   649  		f.constants = make(map[int64][]*Value)
   650  	}
   651  	vv := f.constants[c]
   652  	for _, v := range vv {
   653  		if v.Op == op && v.Type.Compare(t) == types.CMPeq {
   654  			if setAuxInt && v.AuxInt != c {
   655  				panic(fmt.Sprintf("cached const %s should have AuxInt of %d", v.LongString(), c))
   656  			}
   657  			return v
   658  		}
   659  	}
   660  	var v *Value
   661  	if setAuxInt {
   662  		v = f.Entry.NewValue0I(src.NoXPos, op, t, c)
   663  	} else {
   664  		v = f.Entry.NewValue0(src.NoXPos, op, t)
   665  	}
   666  	f.constants[c] = append(vv, v)
   667  	v.InCache = true
   668  	return v
   669  }
   670  
   671  // These magic auxint values let us easily cache non-numeric constants
   672  // using the same constants map while making collisions unlikely.
   673  // These values are unlikely to occur in regular code and
   674  // are easy to grep for in case of bugs.
   675  const (
   676  	constSliceMagic       = 1122334455
   677  	constInterfaceMagic   = 2233445566
   678  	constNilMagic         = 3344556677
   679  	constEmptyStringMagic = 4455667788
   680  )
   681  
   682  // ConstBool returns an int constant representing its argument.
   683  func (f *Func) ConstBool(t *types.Type, c bool) *Value {
   684  	i := int64(0)
   685  	if c {
   686  		i = 1
   687  	}
   688  	return f.constVal(OpConstBool, t, i, true)
   689  }
   690  func (f *Func) ConstInt8(t *types.Type, c int8) *Value {
   691  	return f.constVal(OpConst8, t, int64(c), true)
   692  }
   693  func (f *Func) ConstInt16(t *types.Type, c int16) *Value {
   694  	return f.constVal(OpConst16, t, int64(c), true)
   695  }
   696  func (f *Func) ConstInt32(t *types.Type, c int32) *Value {
   697  	return f.constVal(OpConst32, t, int64(c), true)
   698  }
   699  func (f *Func) ConstInt64(t *types.Type, c int64) *Value {
   700  	return f.constVal(OpConst64, t, c, true)
   701  }
   702  func (f *Func) ConstFloat32(t *types.Type, c float64) *Value {
   703  	return f.constVal(OpConst32F, t, int64(math.Float64bits(float64(float32(c)))), true)
   704  }
   705  func (f *Func) ConstFloat64(t *types.Type, c float64) *Value {
   706  	return f.constVal(OpConst64F, t, int64(math.Float64bits(c)), true)
   707  }
   708  
   709  func (f *Func) ConstSlice(t *types.Type) *Value {
   710  	return f.constVal(OpConstSlice, t, constSliceMagic, false)
   711  }
   712  func (f *Func) ConstInterface(t *types.Type) *Value {
   713  	return f.constVal(OpConstInterface, t, constInterfaceMagic, false)
   714  }
   715  func (f *Func) ConstNil(t *types.Type) *Value {
   716  	return f.constVal(OpConstNil, t, constNilMagic, false)
   717  }
   718  func (f *Func) ConstEmptyString(t *types.Type) *Value {
   719  	v := f.constVal(OpConstString, t, constEmptyStringMagic, false)
   720  	v.Aux = StringToAux("")
   721  	return v
   722  }
   723  func (f *Func) ConstOffPtrSP(t *types.Type, c int64, sp *Value) *Value {
   724  	v := f.constVal(OpOffPtr, t, c, true)
   725  	if len(v.Args) == 0 {
   726  		v.AddArg(sp)
   727  	}
   728  	return v
   729  }
   730  
   731  func (f *Func) Frontend() Frontend                                  { return f.fe }
   732  func (f *Func) Warnl(pos src.XPos, msg string, args ...interface{}) { f.fe.Warnl(pos, msg, args...) }
   733  func (f *Func) Logf(msg string, args ...interface{})                { f.fe.Logf(msg, args...) }
   734  func (f *Func) Log() bool                                           { return f.fe.Log() }
   735  
   736  func (f *Func) Fatalf(msg string, args ...interface{}) {
   737  	stats := "crashed"
   738  	if f.Log() {
   739  		f.Logf("  pass %s end %s\n", f.pass.name, stats)
   740  		printFunc(f)
   741  	}
   742  	if f.HTMLWriter != nil {
   743  		f.HTMLWriter.WritePhase(f.pass.name, fmt.Sprintf("%s <span class=\"stats\">%s</span>", f.pass.name, stats))
   744  		f.HTMLWriter.flushPhases()
   745  	}
   746  	f.fe.Fatalf(f.Entry.Pos, msg, args...)
   747  }
   748  
   749  // postorder returns the reachable blocks in f in a postorder traversal.
   750  func (f *Func) postorder() []*Block {
   751  	if f.cachedPostorder == nil {
   752  		f.cachedPostorder = postorder(f)
   753  	}
   754  	return f.cachedPostorder
   755  }
   756  
   757  func (f *Func) Postorder() []*Block {
   758  	return f.postorder()
   759  }
   760  
   761  // Idom returns a map from block ID to the immediate dominator of that block.
   762  // f.Entry.ID maps to nil. Unreachable blocks map to nil as well.
   763  func (f *Func) Idom() []*Block {
   764  	if f.cachedIdom == nil {
   765  		f.cachedIdom = dominators(f)
   766  	}
   767  	return f.cachedIdom
   768  }
   769  
   770  // Sdom returns a sparse tree representing the dominator relationships
   771  // among the blocks of f.
   772  func (f *Func) Sdom() SparseTree {
   773  	if f.cachedSdom == nil {
   774  		f.cachedSdom = newSparseTree(f, f.Idom())
   775  	}
   776  	return f.cachedSdom
   777  }
   778  
   779  // loopnest returns the loop nest information for f.
   780  func (f *Func) loopnest() *loopnest {
   781  	if f.cachedLoopnest == nil {
   782  		f.cachedLoopnest = loopnestfor(f)
   783  	}
   784  	return f.cachedLoopnest
   785  }
   786  
   787  // invalidateCFG tells f that its CFG has changed.
   788  func (f *Func) invalidateCFG() {
   789  	f.cachedPostorder = nil
   790  	f.cachedIdom = nil
   791  	f.cachedSdom = nil
   792  	f.cachedLoopnest = nil
   793  }
   794  
   795  // DebugHashMatch returns
   796  //
   797  //	base.DebugHashMatch(this function's package.name)
   798  //
   799  // for use in bug isolation.  The return value is true unless
   800  // environment variable GOCOMPILEDEBUG=gossahash=X is set, in which case "it depends on X".
   801  // See [base.DebugHashMatch] for more information.
   802  func (f *Func) DebugHashMatch() bool {
   803  	if !base.HasDebugHash() {
   804  		return true
   805  	}
   806  	sym := f.fe.Func().Sym()
   807  	return base.DebugHashMatchPkgFunc(sym.Pkg.Path, sym.Name)
   808  }
   809  
   810  func (f *Func) spSb() (sp, sb *Value) {
   811  	initpos := src.NoXPos // These are originally created with no position in ssa.go; if they are optimized out then recreated, should be the same.
   812  	for _, v := range f.Entry.Values {
   813  		if v.Op == OpSB {
   814  			sb = v
   815  		}
   816  		if v.Op == OpSP {
   817  			sp = v
   818  		}
   819  		if sb != nil && sp != nil {
   820  			return
   821  		}
   822  	}
   823  	if sb == nil {
   824  		sb = f.Entry.NewValue0(initpos.WithNotStmt(), OpSB, f.Config.Types.Uintptr)
   825  	}
   826  	if sp == nil {
   827  		sp = f.Entry.NewValue0(initpos.WithNotStmt(), OpSP, f.Config.Types.Uintptr)
   828  	}
   829  	return
   830  }
   831  
   832  // useFMA allows targeted debugging w/ GOFMAHASH
   833  // If you have an architecture-dependent FP glitch, this will help you find it.
   834  func (f *Func) useFMA(v *Value) bool {
   835  	if !f.Config.UseFMA {
   836  		return false
   837  	}
   838  	if base.FmaHash == nil {
   839  		return true
   840  	}
   841  	return base.FmaHash.MatchPos(v.Pos, nil)
   842  }
   843  
   844  // NewLocal returns a new anonymous local variable of the given type.
   845  func (f *Func) NewLocal(pos src.XPos, typ *types.Type) *ir.Name {
   846  	nn := typecheck.TempAt(pos, f.fe.Func(), typ) // Note: adds new auto to fn.Dcl list
   847  	nn.SetNonMergeable(true)
   848  	return nn
   849  }
   850  
   851  // IsMergeCandidate returns true if variable n could participate in
   852  // stack slot merging. For now we're restricting the set to things to
   853  // items larger than what CanSSA would allow (approximateky, we disallow things
   854  // marked as open defer slots so as to avoid complicating liveness
   855  // analysis.
   856  func IsMergeCandidate(n *ir.Name) bool {
   857  	if base.Debug.MergeLocals == 0 ||
   858  		base.Flag.N != 0 ||
   859  		n.Class != ir.PAUTO ||
   860  		n.Type().Size() <= int64(3*types.PtrSize) ||
   861  		n.Addrtaken() ||
   862  		n.NonMergeable() ||
   863  		n.OpenDeferSlot() {
   864  		return false
   865  	}
   866  	return true
   867  }
   868
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