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Revert "cmd/asm: align an instruction or a function's address"

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This reverts CL 212767.

Reason for revert: new test is persistently failing on freebsd-arm64-dmgk builder.

Change-Id: Ifd1227628e0e747688ddb4dc580170b2a103a89e
Reviewed-on: https://go-review.googlesource.com/c/go/+/226597
Run-TryBot: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Bryan C. Mills 2020-03-31 15:35:28 +00:00
parent a3d8c210ad
commit 5970480c68
15 changed files with 25 additions and 168 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/cmd/internal/goobj/read.go
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@ -95,7 +95,6 @@ type Var struct {
type Func struct {
Args int64 // size in bytes of argument frame: inputs and outputs
Frame int64 // size in bytes of local variable frame
Align uint32 // alignment requirement in bytes for the address of the function
Leaf bool // function omits save of link register (ARM)
NoSplit bool // function omits stack split prologue
TopFrame bool // function is the top of the call stack
@ -591,7 +590,6 @@ func (r *objReader) parseObject(prefix []byte) error {
s.Func = f
f.Args = r.readInt()
f.Frame = r.readInt()
f.Align = uint32(r.readInt())
flags := r.readInt()
f.Leaf = flags&(1<<0) != 0
f.TopFrame = flags&(1<<4) != 0

1
src/cmd/internal/goobj/readnew.go
View File

@ -149,7 +149,6 @@ func (r *objReader) readNew() {
f := &Func{
Args: int64(info.Args),
Frame: int64(info.Locals),
Align: info.Align,
NoSplit: info.NoSplit != 0,
Leaf: osym.Leaf(),
TopFrame: osym.TopFrame(),

3
src/cmd/internal/goobj2/funcinfo.go
View File

@ -18,7 +18,6 @@ type FuncInfo struct {
Args uint32
Locals uint32
Align uint32
Pcsp uint32
Pcfile uint32
@ -43,7 +42,6 @@ func (a *FuncInfo) Write(w *bytes.Buffer) {
writeUint32(a.Args)
writeUint32(a.Locals)
writeUint32(a.Align)
writeUint32(a.Pcsp)
writeUint32(a.Pcfile)
@ -81,7 +79,6 @@ func (a *FuncInfo) Read(b []byte) {
a.Args = readUint32()
a.Locals = readUint32()
a.Align = readUint32()
a.Pcsp = readUint32()
a.Pcfile = readUint32()

33
src/cmd/internal/obj/arm64/asm7.go
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@ -886,10 +886,25 @@ const OP_NOOP = 0xd503201f
// align code to a certain length by padding bytes.
func pcAlignPadLength(pc int64, alignedValue int64, ctxt *obj.Link) int {
if !((alignedValue&(alignedValue-1) == 0) && 8 <= alignedValue && alignedValue <= 2048) {
ctxt.Diag("alignment value of an instruction must be a power of two and in the range [8, 2048], got %d\n", alignedValue)
switch alignedValue {
case 8:
if pc%8 == 4 {
return 4
}
case 16:
switch pc % 16 {
case 4:
return 12
case 8:
return 8
case 12:
return 4
}
default:
ctxt.Diag("Unexpected alignment: %d for PCALIGN directive\n", alignedValue)
}
return int(-pc & (alignedValue - 1))
return 0
}
func span7(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
@ -925,12 +940,8 @@ func span7(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
if m == 0 {
switch p.As {
case obj.APCALIGN:
alignedValue := p.From.Offset
m = pcAlignPadLength(pc, alignedValue, ctxt)
// Update the current text symbol ailgnment value.
if int32(alignedValue) > cursym.Func.Align {
cursym.Func.Align = int32(alignedValue)
}
a := p.From.Offset
m = pcAlignPadLength(pc, a, ctxt)
break
case obj.ANOP, obj.AFUNCDATA, obj.APCDATA:
continue
@ -1006,8 +1017,8 @@ func span7(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
if m == 0 {
switch p.As {
case obj.APCALIGN:
alignedValue := p.From.Offset
m = pcAlignPadLength(pc, alignedValue, ctxt)
a := p.From.Offset
m = pcAlignPadLength(pc, a, ctxt)
break
case obj.ANOP, obj.AFUNCDATA, obj.APCDATA:
continue

27
src/cmd/internal/obj/arm64/asm_test.go
View File

@ -18,9 +18,7 @@ import (
// TestLarge generates a very large file to verify that large
// program builds successfully, in particular, too-far
// conditional branches are fixed, and also verify that the
// instruction's pc can be correctly aligned even when branches
// need to be fixed.
// conditional branches are fixed.
func TestLarge(t *testing.T) {
if testing.Short() {
t.Skip("Skip in short mode")
@ -43,27 +41,10 @@ func TestLarge(t *testing.T) {
t.Fatalf("can't write output: %v\n", err)
}
pattern := `0x0080\s00128\s\(.*\)\tMOVD\t\$3,\sR3`
// assemble generated file
cmd := exec.Command(testenv.GoToolPath(t), "tool", "asm", "-S", "-o", filepath.Join(dir, "test.o"), tmpfile)
// build generated file
cmd := exec.Command(testenv.GoToolPath(t), "tool", "asm", "-o", filepath.Join(dir, "x.o"), tmpfile)
cmd.Env = append(os.Environ(), "GOARCH=arm64", "GOOS=linux")
out, err := cmd.CombinedOutput()
if err != nil {
t.Errorf("Assemble failed: %v, output: %s", err, out)
}
matched, err := regexp.MatchString(pattern, string(out))
if err != nil {
t.Fatal(err)
}
if !matched {
t.Errorf("The alignment is not correct: %t, output:%s\n", matched, out)
}
// build generated file
cmd = exec.Command(testenv.GoToolPath(t), "tool", "asm", "-o", filepath.Join(dir, "x.o"), tmpfile)
cmd.Env = append(os.Environ(), "GOARCH=arm64", "GOOS=linux")
out, err = cmd.CombinedOutput()
if err != nil {
t.Errorf("Build failed: %v, output: %s", err, out)
}
@ -75,8 +56,6 @@ func gen(buf *bytes.Buffer) {
fmt.Fprintln(buf, "TBZ $5, R0, label")
fmt.Fprintln(buf, "CBZ R0, label")
fmt.Fprintln(buf, "BEQ label")
fmt.Fprintln(buf, "PCALIGN $128")
fmt.Fprintln(buf, "MOVD $3, R3")
for i := 0; i < 1<<19; i++ {
fmt.Fprintln(buf, "MOVD R0, R1")
}

1
src/cmd/internal/obj/link.go
View File

@ -398,7 +398,6 @@ type LSym struct {
type FuncInfo struct {
Args int32
Locals int32
Align int32
Text *Prog
Autot map[*LSym]struct{}
Pcln Pcln

1
src/cmd/internal/obj/objfile.go
View File

@ -346,7 +346,6 @@ func (w *objWriter) writeSym(s *LSym) {
w.writeInt(int64(s.Func.Args))
w.writeInt(int64(s.Func.Locals))
w.writeInt(int64(s.Func.Align))
w.writeBool(s.NoSplit())
flags = int64(0)
if s.Leaf() {

1
src/cmd/internal/obj/objfile2.go
View File

@ -374,7 +374,6 @@ func genFuncInfoSyms(ctxt *Link) {
NoSplit: nosplit,
Args: uint32(s.Func.Args),
Locals: uint32(s.Func.Locals),
Align: uint32(s.Func.Align),
}
pc := &s.Func.Pcln
o.Pcsp = pcdataoff

7
src/cmd/internal/obj/plist.go
View File

@ -133,13 +133,6 @@ func (ctxt *Link) InitTextSym(s *LSym, flag int) {
s.Set(AttrNeedCtxt, flag&NEEDCTXT != 0)
s.Set(AttrNoFrame, flag&NOFRAME != 0)
s.Set(AttrTopFrame, flag&TOPFRAME != 0)
if flag&ALIGN2048 != 0 {
if objabi.GOARCH != "arm64" {
ctxt.Diag("ALIGN2048 flag only works on ARM64 at present.")
}
s.Func.Align = 2048
}
s.Type = objabi.STEXT
ctxt.Text = append(ctxt.Text, s)

5
src/cmd/internal/obj/textflag.go
View File

@ -51,9 +51,4 @@ const (
// Function is the top of the call stack. Call stack unwinders should stop
// at this function.
TOPFRAME = 2048
// ALIGN2048 means that the address of the function must be aligned to a
// 2048 bytes boundary.
// Only works on arm64 at present.
ALIGN2048 = 4096
)

4
src/cmd/link/internal/ld/data.go
View File

@ -2119,10 +2119,6 @@ func assignAddress(ctxt *Link, sect *sym.Section, n int, s *sym.Symbol, va uint6
funcsize = uint64(s.Size)
}
if sect.Align < s.Align {
sect.Align = s.Align
}
// On ppc64x a text section should not be larger than 2^26 bytes due to the size of
// call target offset field in the bl instruction. Splitting into smaller text
// sections smaller than this limit allows the GNU linker to modify the long calls

1
src/cmd/link/internal/loader/loader.go
View File

@ -1227,7 +1227,6 @@ func loadObjFull(l *Loader, r *oReader) {
info.Pcdata = append(info.Pcdata, info.PcdataEnd) // for the ease of knowing where it ends
pc.Args = int32(info.Args)
pc.Locals = int32(info.Locals)
s.Align = int32(info.Align)
npc := len(info.Pcdata) - 1 // -1 as we appended one above
pc.Pcdata = pcDataBatch[:npc:npc]

1
src/cmd/link/internal/objfile/objfile.go
View File

@ -312,7 +312,6 @@ overwrite:
pc.Args = r.readInt32()
pc.Locals = r.readInt32()
s.Align = r.readInt32()
if r.readUint8() != 0 {
s.Attr |= sym.AttrNoSplit
}

101
src/cmd/link/link_test.go
View File

@ -3,7 +3,6 @@ package main
import (
"bufio"
"bytes"
"cmd/internal/objabi"
"debug/macho"
"internal/testenv"
"io/ioutil"
@ -448,103 +447,3 @@ func TestStrictDup(t *testing.T) {
t.Errorf("unexpected output:\n%s", out)
}
}
const testFuncAlignSrc = `
package main
import (
"fmt"
"reflect"
)
func alignFunc()
func alignPc()
func main() {
addr1 := reflect.ValueOf(alignFunc).Pointer()
addr2 := reflect.ValueOf(alignPc).Pointer()
switch {
case (addr1 % 2048) != 0 && (addr2 % 512) != 0:
fmt.Printf("expected 2048 bytes alignment, got %v; expected 512 bytes alignment, got %v\n", addr1, addr2)
case (addr2 % 512) != 0:
fmt.Printf("expected 512 bytes alignment, got %v\n", addr2)
case (addr1 % 2048) != 0:
fmt.Printf("expected 2048 bytes alignment, got %v\n", addr1)
default:
fmt.Printf("PASS")
}
}
`
const testFuncAlignAsmSrc = `
#include "textflag.h"
TEXT ·alignFunc(SB),NOSPLIT|ALIGN2048, $0-0
MOVD $1, R0
MOVD $2, R1
RET
TEXT ·alignPc(SB),NOSPLIT, $0-0
MOVD $2, R0
PCALIGN $512
MOVD $3, R1
RET
`
// TestFuncAlign verifies that the address of a function can be aligned
// with a specfic value on arm64.
func TestFuncAlign(t *testing.T) {
if objabi.GOARCH != "arm64" {
t.Skipf("Skipping FuncAlign test on %s", objabi.GOARCH)
}
testenv.MustHaveGoBuild(t)
tmpdir, err := ioutil.TempDir("", "TestFuncAlign")
if err != nil {
t.Fatal(err)
}
defer os.RemoveAll(tmpdir)
src := filepath.Join(tmpdir, "falign.go")
err = ioutil.WriteFile(src, []byte(testFuncAlignSrc), 0666)
if err != nil {
t.Fatal(err)
}
src = filepath.Join(tmpdir, "falign.s")
err = ioutil.WriteFile(src, []byte(testFuncAlignAsmSrc), 0666)
if err != nil {
t.Fatal(err)
}
// Build and run with old object file format.
cmd := exec.Command(testenv.GoToolPath(t), "build", "-o", "falign")
cmd.Env = append(os.Environ(), "GOARCH=arm64", "GOOS=linux")
cmd.Dir = tmpdir
out, err := cmd.CombinedOutput()
if err != nil {
t.Errorf("build failed: %v", err)
}
cmd = exec.Command(tmpdir + "/falign")
out, err = cmd.CombinedOutput()
if err != nil {
t.Errorf("failed to run with err %v, output: %s", err, out)
}
if string(out) != "PASS" {
t.Errorf("unexpected output: %s\n", out)
}
// Build and run with new object file format.
cmd = exec.Command(testenv.GoToolPath(t), "build", "-o", "falign", "-gcflags=all=-newobj", "-asmflags=all=-newobj", "-ldflags=-newobj")
cmd.Env = append(os.Environ(), "GOARCH=arm64", "GOOS=linux")
cmd.Dir = tmpdir
out, err = cmd.CombinedOutput()
if err != nil {
t.Errorf("build with newobj failed: %v", err)
}
cmd = exec.Command(tmpdir + "/falign")
out, err = cmd.CombinedOutput()
if err != nil {
t.Errorf("failed to run with -newobj, err: %v, output: %s", err, out)
}
if string(out) != "PASS" {
t.Errorf("unexpected output with -newobj: %s\n", out)
}
}

5
src/runtime/textflag.h
View File

@ -35,8 +35,3 @@
// Function is the top of the call stack. Call stack unwinders should stop
// at this function.
#define TOPFRAME 2048
// ALIGN2048 means that the address of the function must be aligned to a
// 2048 bytes boundary.
// Only works on arm64 at present.
#define ALIGN2048 4096