Source file src/cmd/compile/internal/ssa/func.go

Documentation: cmd/compile/internal/ssa

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

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