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Commit 5a0881a1 authored by David Crawshaw's avatar David Crawshaw
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cmd/link: calculate section alignment concurrently 

Reduces link time for cmd/go by 1%.

Change-Id: Iad4a16db0aedc56f81ddf73ba9b632e418dc1b19
Reviewed-on: https://go-review.googlesource.com/22242Reviewed-by: default avatarMichael Hudson-Doyle <michael.hudson@canonical.com>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
parent 45522a6a
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Showing with 70 additions and 75 deletions
src/cmd/link/internal/ld/data.go
View file @ 5a0881a1
......@@ -1131,19 +1131,6 @@ func aligndatsize(datsize int64, s *LSym) int64 {
return Rnd(datsize, int64(symalign(s)))
}
// maxalign returns the maximum required alignment for
// the slice of symbols syms
func maxalign(syms []*LSym) int32 {
var max int32
for _, sym := range syms {
align := symalign(sym)
if max < align {
max = align
}
}
return max
}
const debugGCProg = false
type GCProg struct {
......@@ -1225,18 +1212,12 @@ func (d bySizeAndName) Less(i, j int) bool {
return s1.name < s2.name
}
func growdatsize(datsizep *int64, s *LSym) {
datsize := *datsizep
const cutoff int64 = 2e9 // 2 GB (or so; looks better in errors than 2^31)
switch {
case s.Size < 0:
Diag("%s: negative size (%d bytes)", s.Name, s.Size)
case s.Size > cutoff:
Diag("%s: symbol too large (%d bytes)", s.Name, s.Size)
case datsize <= cutoff && datsize+s.Size > cutoff:
Diag("%s: too much data (over %d bytes)", s.Name, cutoff)
}
*datsizep = datsize + s.Size
const cutoff int64 = 2e9 // 2 GB (or so; looks better in errors than 2^31)
func checkdatsize(datsize int64, symn int) {
if datsize > cutoff {
Diag("too much data in section %v (over %d bytes)", symn, cutoff)
}
}
func list2slice(s *LSym) []*LSym {
......@@ -1327,12 +1308,13 @@ func dodata() {
}
// Sort symbols.
var dataMaxAlign [obj.SXREF]int32
var wg sync.WaitGroup
for symn := range data {
symn := symn
wg.Add(1)
go func() {
data[symn] = dodataSect(symn, data[symn])
data[symn], dataMaxAlign[symn] = dodataSect(symn, data[symn])
wg.Done()
}()
}
......@@ -1360,15 +1342,16 @@ func dodata() {
s.Sect = sect
s.Type = obj.SDATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
sect.Length = uint64(datsize) - sect.Vaddr
}
checkdatsize(datsize, symn)
}
// .got (and .toc on ppc64)
if len(data[obj.SELFGOT]) > 0 {
sect := addsection(&Segdata, ".got", 06)
sect.Align = maxalign(data[obj.SELFGOT])
sect.Align = dataMaxAlign[obj.SELFGOT]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
var toc *LSym
......@@ -1389,15 +1372,15 @@ func dodata() {
toc.Value = 0x8000
}
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SELFGOT)
sect.Length = uint64(datsize) - sect.Vaddr
}
/* pointer-free data */
sect := addsection(&Segdata, ".noptrdata", 06)
sect.Align = maxalign(data[obj.SNOPTRDATA])
sect.Align = dataMaxAlign[obj.SNOPTRDATA]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.noptrdata", 0).Sect = sect
......@@ -1407,8 +1390,9 @@ func dodata() {
s.Sect = sect
s.Type = obj.SDATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SNOPTRDATA)
sect.Length = uint64(datsize) - sect.Vaddr
hasinitarr := Linkshared
......@@ -1420,21 +1404,22 @@ func dodata() {
}
if hasinitarr {
sect := addsection(&Segdata, ".init_array", 06)
sect.Align = maxalign(data[obj.SINITARR])
sect.Align = dataMaxAlign[obj.SINITARR]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
for _, s := range data[obj.SINITARR] {
datsize = aligndatsize(datsize, s)
s.Sect = sect
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
sect.Length = uint64(datsize) - sect.Vaddr
checkdatsize(datsize, obj.SINITARR)
}
/* data */
sect = addsection(&Segdata, ".data", 06)
sect.Align = maxalign(data[obj.SDATA])
sect.Align = dataMaxAlign[obj.SDATA]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.data", 0).Sect = sect
......@@ -1447,14 +1432,15 @@ func dodata() {
datsize = aligndatsize(datsize, s)
s.Value = int64(uint64(datsize) - sect.Vaddr)
gc.AddSym(s)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SDATA)
sect.Length = uint64(datsize) - sect.Vaddr
gc.End(int64(sect.Length))
/* bss */
sect = addsection(&Segdata, ".bss", 06)
sect.Align = maxalign(data[obj.SBSS])
sect.Align = dataMaxAlign[obj.SBSS]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.bss", 0).Sect = sect
......@@ -1466,15 +1452,15 @@ func dodata() {
datsize = aligndatsize(datsize, s)
s.Value = int64(uint64(datsize) - sect.Vaddr)
gc.AddSym(s)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SBSS)
sect.Length = uint64(datsize) - sect.Vaddr
gc.End(int64(sect.Length))
/* pointer-free bss */
sect = addsection(&Segdata, ".noptrbss", 06)
sect.Align = maxalign(data[obj.SNOPTRBSS])
sect.Align = dataMaxAlign[obj.SNOPTRBSS]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.noptrbss", 0).Sect = sect
......@@ -1483,16 +1469,12 @@ func dodata() {
datsize = aligndatsize(datsize, s)
s.Sect = sect
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
sect.Length = uint64(datsize) - sect.Vaddr
Linklookup(Ctxt, "runtime.end", 0).Sect = sect
// The compiler uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
if datsize != int64(uint32(datsize)) {
Diag("data or bss segment too large")
}
checkdatsize(datsize, obj.SNOPTRBSS)
if len(data[obj.STLSBSS]) > 0 {
var sect *Section
......@@ -1507,8 +1489,9 @@ func dodata() {
datsize = aligndatsize(datsize, s)
s.Sect = sect
s.Value = datsize
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.STLSBSS)
if sect != nil {
sect.Length = uint64(datsize)
......@@ -1546,8 +1529,9 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
sect.Length = uint64(datsize) - sect.Vaddr
checkdatsize(datsize, obj.SELFRXSECT)
}
/* read-only data */
......@@ -1571,7 +1555,7 @@ func dodata() {
obj.SFUNCTAB,
}
for _, symn := range roSects {
align := maxalign(data[symn])
align := dataMaxAlign[symn]
if sect.Align < align {
sect.Align = align
}
......@@ -1583,8 +1567,9 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, symn)
}
sect.Length = uint64(datsize) - sect.Vaddr
......@@ -1621,7 +1606,7 @@ func dodata() {
obj.SFUNCTABRELRO,
}
for _, symn := range relroSects {
align := maxalign(data[symn])
align := dataMaxAlign[symn]
if sect.Align < align {
sect.Align = align
}
......@@ -1636,8 +1621,9 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, symn)
}
sect.Length = uint64(datsize) - sect.Vaddr
......@@ -1646,7 +1632,7 @@ func dodata() {
/* typelink */
sect = addsection(segro, relro_prefix+".typelink", relro_perms)
sect.Align = maxalign(data[obj.STYPELINK])
sect.Align = dataMaxAlign[obj.STYPELINK]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.typelink", 0).Sect = sect
......@@ -1656,14 +1642,14 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.STYPELINK)
sect.Length = uint64(datsize) - sect.Vaddr
/* itablink */
sect = addsection(segro, relro_prefix+".itablink", relro_perms)
sect.Align = maxalign(data[obj.SITABLINK])
sect.Align = dataMaxAlign[obj.SITABLINK]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.itablink", 0).Sect = sect
......@@ -1673,14 +1659,14 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SITABLINK)
sect.Length = uint64(datsize) - sect.Vaddr
/* gosymtab */
sect = addsection(segro, relro_prefix+".gosymtab", relro_perms)
sect.Align = maxalign(data[obj.SSYMTAB])
sect.Align = dataMaxAlign[obj.SSYMTAB]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.symtab", 0).Sect = sect
......@@ -1690,14 +1676,14 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SSYMTAB)
sect.Length = uint64(datsize) - sect.Vaddr
/* gopclntab */
sect = addsection(segro, relro_prefix+".gopclntab", relro_perms)
sect.Align = maxalign(data[obj.SPCLNTAB])
sect.Align = dataMaxAlign[obj.SPCLNTAB]
datsize = Rnd(datsize, int64(sect.Align))
sect.Vaddr = uint64(datsize)
Linklookup(Ctxt, "runtime.pclntab", 0).Sect = sect
......@@ -1707,8 +1693,9 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
}
checkdatsize(datsize, obj.SRODATA)
sect.Length = uint64(datsize) - sect.Vaddr
/* read-only ELF, Mach-O sections */
......@@ -1720,9 +1707,10 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
sect.Length = uint64(datsize) - sect.Vaddr
}
checkdatsize(datsize, obj.SELFROSECT)
for _, s := range data[obj.SMACHOPLT] {
sect = addsection(segro, s.Name, 04)
......@@ -1732,9 +1720,10 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
sect.Length = uint64(datsize) - sect.Vaddr
}
checkdatsize(datsize, obj.SMACHOPLT)
// 6g uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
if datsize != int64(uint32(datsize)) {
......@@ -1756,9 +1745,10 @@ func dodata() {
s.Sect = sect
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
growdatsize(&datsize, s)
datsize += s.Size
sect.Length = uint64(datsize) - sect.Vaddr
}
checkdatsize(datsize, obj.SDWARFSECT)
if s != nil {
sect = addsection(&Segdwarf, ".debug_info", 04)
......@@ -1770,14 +1760,10 @@ func dodata() {
s.Type = obj.SRODATA
s.Value = int64(uint64(datsize) - sect.Vaddr)
s.Attr |= AttrLocal
growdatsize(&datsize, s)
datsize += s.Size
}
sect.Length = uint64(datsize) - sect.Vaddr
}
// The compiler uses 4-byte relocation offsets, so the entire segment must fit in 32 bits.
if datsize != int64(uint32(datsize)) {
Diag("dwarf segment too large")
checkdatsize(datsize, obj.SDWARFINFO)
}
/* number the sections */
......@@ -1801,7 +1787,7 @@ func dodata() {
}
}
func dodataSect(symn int, syms []*LSym) []*LSym {
func dodataSect(symn int, syms []*LSym) (result []*LSym, maxAlign int32) {
if HEADTYPE == obj.Hdarwin {
// Some symbols may no longer belong in syms
// due to movement in machosymorder.
......@@ -1820,8 +1806,13 @@ func dodataSect(symn int, syms []*LSym) []*LSym {
log.Fatalf("symbol %s listed multiple times", s.Name)
}
s.Attr |= AttrOnList
if int64(len(s.P)) > s.Size {
switch {
case s.Size < int64(len(s.P)):
Diag("%s: initialize bounds (%d < %d)", s.Name, s.Size, len(s.P))
case s.Size < 0:
Diag("%s: negative size (%d bytes)", s.Name, s.Size)
case s.Size > cutoff:
Diag("%s: symbol too large (%d bytes)", s.Name, s.Size)
}
symsSort[i] = dataSortKey{
......@@ -1848,6 +1839,10 @@ func dodataSect(symn int, syms []*LSym) []*LSym {
for i, symSort := range symsSort {
syms[i] = symSort.lsym
align := symalign(symSort.lsym)
if maxAlign < align {
maxAlign = align
}
}
if Iself && symn == obj.SELFROSECT {
......@@ -1876,7 +1871,7 @@ func dodataSect(symn int, syms []*LSym) []*LSym {
}
}
return syms
return syms, maxAlign
}
// Add buildid to beginning of text segment, on non-ELF systems.
......
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