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[dev.link] cmd/link: write data sections to heap in Asmb on Wasm

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Make Wasm more like other architectures, writing data sections to
heap in Asmb instead of Asmb2. Then we can remove the
copy-on-write logic in applying relocations.

Change-Id: I26d5315ea9fba032fe4bdb9b5c7fe483611c4373
Reviewed-on: https://go-review.googlesource.com/c/go/+/230465
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
This commit is contained in:
Cherry Zhang 2020-04-28 09:53:29 -04:00
parent 3e8975172f
commit dd34841de7
13 changed files with 39 additions and 35 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/link/internal/amd64/asm.go
View File

@ -684,7 +684,7 @@ func addgotsym2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s load
}
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

2
src/cmd/link/internal/arm/asm.go
View File

@ -682,7 +682,7 @@ func addgotsym2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s load
}
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

2
src/cmd/link/internal/arm64/asm.go
View File

@ -830,7 +830,7 @@ func addgotsym2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s load
}
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

9
src/cmd/link/internal/ld/data2.go
View File

@ -58,15 +58,6 @@ func relocsym2(target *Target, ldr *loader.Loader, err *ErrorReporter, syms *Arc
if len(s.R) == 0 {
return
}
if target.IsWasm() && s.Attr.ReadOnly() {
// The symbol's content is backed by read-only memory.
// Copy it to writable memory to apply relocations.
// Only need to do this on Wasm. On other platforms we
// apply relocations to the output buffer, which is
// always writeable.
s.P = append([]byte(nil), s.P...)
// No need to unset AttrReadOnly because it will not be used.
}
for ri := int32(0); ri < int32(len(s.R)); ri++ {
r := &s.R[ri]
if r.Done {

2
src/cmd/link/internal/ld/lib.go
View File

@ -265,7 +265,7 @@ type Arch struct {
// file. Typically, Asmb writes most of the content (sections and
// segments), for which we have computed the size and offset. Asmb2
// writes the rest.
Asmb func(*Link)
Asmb func(*Link, *loader.Loader)
Asmb2 func(*Link)
Elfreloc1 func(*Link, *sym.Reloc, int64) bool

2
src/cmd/link/internal/ld/main.go
View File

@ -325,7 +325,7 @@ func Main(arch *sys.Arch, theArch Arch) {
// Asmb will redirect symbols to the output file mmap, and relocations
// will be applied directly there.
bench.Start("Asmb")
thearch.Asmb(ctxt)
thearch.Asmb(ctxt, ctxt.loader)
bench.Start("reloc")
ctxt.reloc()
bench.Start("Asmb2")

2
src/cmd/link/internal/mips/asm.go
View File

@ -164,7 +164,7 @@ func archrelocvariant(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym
return -1
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

2
src/cmd/link/internal/mips64/asm.go
View File

@ -170,7 +170,7 @@ func archrelocvariant(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym
return -1
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

2
src/cmd/link/internal/ppc64/asm.go
View File

@ -1082,7 +1082,7 @@ func ensureglinkresolver2(ctxt *ld.Link, ldr *loader.Loader) *loader.SymbolBuild
return glink
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

2
src/cmd/link/internal/riscv64/asm.go
View File

@ -98,7 +98,7 @@ func archrelocvariant(target *ld.Target, syms *ld.ArchSyms, r *sym.Reloc, s *sym
return -1
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

2
src/cmd/link/internal/s390x/asm.go
View File

@ -485,7 +485,7 @@ func addgotsym2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s load
}
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}

43
src/cmd/link/internal/wasm/asm.go
View File

@ -92,7 +92,30 @@ func assignAddress(ldr *loader.Loader, sect *sym.Section, n int, s loader.Sym, v
return sect, n, va
}
func asmb(ctxt *ld.Link) {} // dummy
type wasmDataSect struct {
sect *sym.Section
data []byte
}
var dataSects []wasmDataSect
func asmb(ctxt *ld.Link, ldr *loader.Loader) {
sections := []*sym.Section{
ldr.SymSect(ldr.Lookup("runtime.rodata", 0)),
ldr.SymSect(ldr.Lookup("runtime.typelink", 0)),
ldr.SymSect(ldr.Lookup("runtime.itablink", 0)),
ldr.SymSect(ldr.Lookup("runtime.symtab", 0)),
ldr.SymSect(ldr.Lookup("runtime.pclntab", 0)),
ldr.SymSect(ldr.Lookup("runtime.noptrdata", 0)),
ldr.SymSect(ldr.Lookup("runtime.data", 0)),
}
dataSects = make([]wasmDataSect, len(sections))
for i, sect := range sections {
data := ld.DatblkBytes(ctxt, int64(sect.Vaddr), int64(sect.Length))
dataSects[i] = wasmDataSect{sect, data}
}
}
// asmb writes the final WebAssembly module binary.
// Spec: https://webassembly.github.io/spec/core/binary/modules.html
@ -396,16 +419,6 @@ func writeCodeSec(ctxt *ld.Link, fns []*wasmFunc) {
func writeDataSec(ctxt *ld.Link) {
sizeOffset := writeSecHeader(ctxt, sectionData)
sections := []*sym.Section{
ctxt.Syms.Lookup("runtime.rodata", 0).Sect,
ctxt.Syms.Lookup("runtime.typelink", 0).Sect,
ctxt.Syms.Lookup("runtime.itablink", 0).Sect,
ctxt.Syms.Lookup("runtime.symtab", 0).Sect,
ctxt.Syms.Lookup("runtime.pclntab", 0).Sect,
ctxt.Syms.Lookup("runtime.noptrdata", 0).Sect,
ctxt.Syms.Lookup("runtime.data", 0).Sect,
}
type dataSegment struct {
offset int32
data []byte
@ -420,9 +433,9 @@ func writeDataSec(ctxt *ld.Link) {
const maxNumSegments = 100000
var segments []*dataSegment
for secIndex, sec := range sections {
data := ld.DatblkBytes(ctxt, int64(sec.Vaddr), int64(sec.Length))
offset := int32(sec.Vaddr)
for secIndex, ds := range dataSects {
data := ds.data
offset := int32(ds.sect.Vaddr)
// skip leading zeroes
for len(data) > 0 && data[0] == 0 {
@ -433,7 +446,7 @@ func writeDataSec(ctxt *ld.Link) {
for len(data) > 0 {
dataLen := int32(len(data))
var segmentEnd, zeroEnd int32
if len(segments)+(len(sections)-secIndex) == maxNumSegments {
if len(segments)+(len(dataSects)-secIndex) == maxNumSegments {
segmentEnd = dataLen
zeroEnd = dataLen
} else {

2
src/cmd/link/internal/x86/asm.go
View File

@ -564,7 +564,7 @@ func addgotsym2(target *ld.Target, ldr *loader.Loader, syms *ld.ArchSyms, s load
}
}
func asmb(ctxt *ld.Link) {
func asmb(ctxt *ld.Link, _ *loader.Loader) {
if ctxt.IsELF {
ld.Asmbelfsetup()
}