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// Copyright 2011 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 gc
import (
"internal/race"
"math/rand"
"sort"
"sync"
"cmd/compile/internal/base"
"cmd/compile/internal/ir"
"cmd/compile/internal/liveness"
"cmd/compile/internal/ssagen"
"cmd/compile/internal/typecheck"
"cmd/compile/internal/types"
"cmd/compile/internal/walk"
)
// "Portable" code generation.
var (
compilequeue []*ir.Func // functions waiting to be compiled
)
func enqueueFunc(fn *ir.Func) {
if ir.CurFunc != nil {
base.FatalfAt(fn.Pos(), "enqueueFunc %v inside %v", fn, ir.CurFunc)
}
if ir.FuncName(fn) == "_" {
// Skip compiling blank functions.
// Frontend already reported any spec-mandated errors (#29870).
return
}
if clo := fn.OClosure; clo != nil && !ir.IsTrivialClosure(clo) {
return // we'll get this as part of its enclosing function
}
if len(fn.Body) == 0 {
// Initialize ABI wrappers if necessary.
ssagen.InitLSym(fn, false)
types.CalcSize(fn.Type()) // TODO register args; remove this once all is done by abiutils
a := ssagen.AbiForFunc(fn)
a.ABIAnalyze(fn.Type(), true) // will set parameter spill/home locations correctly
liveness.WriteFuncMap(fn)
return
}
errorsBefore := base.Errors()
todo := []*ir.Func{fn}
for len(todo) > 0 {
next := todo[len(todo)-1]
todo = todo[:len(todo)-1]
prepareFunc(next)
todo = append(todo, next.Closures...)
}
if base.Errors() > errorsBefore {
return
}
// Enqueue just fn itself. compileFunctions will handle
// scheduling compilation of its closures after it's done.
compilequeue = append(compilequeue, fn)
}
// prepareFunc handles any remaining frontend compilation tasks that
// aren't yet safe to perform concurrently.
func prepareFunc(fn *ir.Func) {
// Set up the function's LSym early to avoid data races with the assemblers.
// Do this before walk, as walk needs the LSym to set attributes/relocations
// (e.g. in MarkTypeUsedInInterface).
ssagen.InitLSym(fn, true)
// Calculate parameter offsets.
types.CalcSize(fn.Type())
typecheck.DeclContext = ir.PAUTO
ir.CurFunc = fn
walk.Walk(fn)
ir.CurFunc = nil // enforce no further uses of CurFunc
typecheck.DeclContext = ir.PEXTERN
}
// compileFunctions compiles all functions in compilequeue.
// It fans out nBackendWorkers to do the work
// and waits for them to complete.
func compileFunctions() {
if len(compilequeue) == 0 {
return
}
if race.Enabled {
// Randomize compilation order to try to shake out races.
tmp := make([]*ir.Func, len(compilequeue))
perm := rand.Perm(len(compilequeue))
for i, v := range perm {
tmp[v] = compilequeue[i]
}
copy(compilequeue, tmp)
} else {
// Compile the longest functions first,
// since they're most likely to be the slowest.
// This helps avoid stragglers.
sort.Slice(compilequeue, func(i, j int) bool {
return len(compilequeue[i].Body) > len(compilequeue[j].Body)
})
}
// We queue up a goroutine per function that needs to be
// compiled, but require them to grab an available worker ID
// before doing any substantial work to limit parallelism.
workerIDs := make(chan int, base.Flag.LowerC)
for i := 0; i < base.Flag.LowerC; i++ {
workerIDs <- i
}
var wg sync.WaitGroup
var asyncCompile func(*ir.Func)
asyncCompile = func(fn *ir.Func) {
wg.Add(1)
go func() {
worker := <-workerIDs
ssagen.Compile(fn, worker)
workerIDs <- worker
// Done compiling fn. Schedule it's closures for compilation.
for _, closure := range fn.Closures {
asyncCompile(closure)
}
wg.Done()
}()
}
types.CalcSizeDisabled = true // not safe to calculate sizes concurrently
base.Ctxt.InParallel = true
for _, fn := range compilequeue {
asyncCompile(fn)
}
compilequeue = nil
wg.Wait()
base.Ctxt.InParallel = false
types.CalcSizeDisabled = false
}
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