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runtime: eliminate global state in mkpreempt.go

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We're going to start writing two files, so having a single global file
we're writing will be a problem.

This has no effect on the generated code.

This is a cherry-pick of CL 680897 from the dev.simd branch.

Change-Id: I49897ea0c6500a29eac89b597d75c0eb3e9b6706
Reviewed-on: https://go-review.googlesource.com/c/go/+/693395
Auto-Submit: Austin Clements <austin@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This commit is contained in:
Austin Clements 2025-06-12 18:37:01 -04:00 • committed by Gopher Robot
parent c0025d5e0b
commit cef381ba60
1 changed files with 96 additions and 74 deletions
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170
src/runtime/mkpreempt.go
View file

@ -73,16 +73,14 @@ var regNamesAMD64 = []string{
"X15",
}
var out io.Writer
var arches = map[string]func(){
var arches = map[string]func(g *gen){
"386": gen386,
"amd64": genAMD64,
"arm": genARM,
"arm64": genARM64,
"loong64": genLoong64,
"mips64x": func() { genMIPS(true) },
"mipsx": func() { genMIPS(false) },
"mips64x": func(g *gen) { genMIPS(g, true) },
"mipsx": func(g *gen) { genMIPS(g, false) },
"ppc64x": genPPC64,
"riscv64": genRISCV64,
"s390x": genS390X,
@ -93,53 +91,58 @@ var beLe = map[string]bool{"mips64x": true, "mipsx": true, "ppc64x": true}
func main() {
flag.Parse()
if flag.NArg() > 0 {
out = os.Stdout
for _, arch := range flag.Args() {
gen, ok := arches[arch]
genFn, ok := arches[arch]
if !ok {
log.Fatalf("unknown arch %s", arch)
}
header(arch)
gen()
g := gen{os.Stdout, arch}
g.asmHeader()
genFn(&g)
}
return
}
for arch, gen := range arches {
for arch, genFn := range arches {
f, err := os.Create(fmt.Sprintf("preempt_%s.s", arch))
if err != nil {
log.Fatal(err)
}
out = f
header(arch)
gen()
g := gen{f, arch}
g.asmHeader()
genFn(&g)
if err := f.Close(); err != nil {
log.Fatal(err)
}
}
}
func header(arch string) {
fmt.Fprintf(out, "// Code generated by mkpreempt.go; DO NOT EDIT.\n\n")
if beLe[arch] {
base := arch[:len(arch)-1]
fmt.Fprintf(out, "//go:build %s || %sle\n\n", base, base)
}
fmt.Fprintf(out, "#include \"go_asm.h\"\n")
if arch == "amd64" {
fmt.Fprintf(out, "#include \"asm_amd64.h\"\n")
}
fmt.Fprintf(out, "#include \"textflag.h\"\n\n")
fmt.Fprintf(out, "TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0\n")
type gen struct {
w io.Writer
goarch string
}
func p(f string, args ...any) {
func (g *gen) asmHeader() {
fmt.Fprintf(g.w, "// Code generated by mkpreempt.go; DO NOT EDIT.\n\n")
if beLe[g.goarch] {
base := g.goarch[:len(g.goarch)-1]
fmt.Fprintf(g.w, "//go:build %s || %sle\n\n", base, base)
}
fmt.Fprintf(g.w, "#include \"go_asm.h\"\n")
if g.goarch == "amd64" {
fmt.Fprintf(g.w, "#include \"asm_amd64.h\"\n")
}
fmt.Fprintf(g.w, "#include \"textflag.h\"\n\n")
fmt.Fprintf(g.w, "TEXT ·asyncPreempt(SB),NOSPLIT|NOFRAME,$0-0\n")
}
func (g *gen) p(f string, args ...any) {
fmted := fmt.Sprintf(f, args...)
fmt.Fprintf(out, "\t%s\n", strings.ReplaceAll(fmted, "\n", "\n\t"))
fmt.Fprintf(g.w, "\t%s\n", strings.ReplaceAll(fmted, "\n", "\n\t"))
}
func label(l string) {
fmt.Fprintf(out, "%s\n", l)
func (g *gen) label(l string) {
fmt.Fprintf(g.w, "%s\n", l)
}
type layout struct {
@ -176,28 +179,30 @@ func (l *layout) addSpecial(save, restore string, size int) {
l.stack += size
}
func (l *layout) save() {
func (l *layout) save(g *gen) {
for _, reg := range l.regs {
if reg.save != "" {
p(reg.save, reg.pos)
g.p(reg.save, reg.pos)
} else {
p("%s %s, %d(%s)", reg.saveOp, reg.reg, reg.pos, l.sp)
g.p("%s %s, %d(%s)", reg.saveOp, reg.reg, reg.pos, l.sp)
}
}
}
func (l *layout) restore() {
func (l *layout) restore(g *gen) {
for i := len(l.regs) - 1; i >= 0; i-- {
reg := l.regs[i]
if reg.restore != "" {
p(reg.restore, reg.pos)
g.p(reg.restore, reg.pos)
} else {
p("%s %d(%s), %s", reg.restoreOp, reg.pos, l.sp, reg.reg)
g.p("%s %d(%s), %s", reg.restoreOp, reg.pos, l.sp, reg.reg)
}
}
}
func gen386() {
func gen386(g *gen) {
p := g.p
p("PUSHFL")
// Save general purpose registers.
var l = layout{sp: "SP"}
@ -218,22 +223,24 @@ func gen386() {
p("ADJSP $%d", lSSE.stack)
p("NOP SP")
l.save()
l.save(g)
p("#ifndef %s", softfloat)
lSSE.save()
lSSE.save(g)
p("#endif")
p("CALL ·asyncPreempt2(SB)")
p("#ifndef %s", softfloat)
lSSE.restore()
lSSE.restore(g)
p("#endif")
l.restore()
l.restore(g)
p("ADJSP $%d", -lSSE.stack)
p("POPFL")
p("RET")
}
func genAMD64() {
func genAMD64(g *gen) {
p := g.p
// Assign stack offsets.
var l = layout{sp: "SP"}
for _, reg := range regNamesAMD64 {
@ -262,19 +269,21 @@ func genAMD64() {
p("// But vet doesn't know ADJSP, so suppress vet stack checking")
p("NOP SP")
l.save()
l.save(g)
lSSE.save()
lSSE.save(g)
p("CALL ·asyncPreempt2(SB)")
lSSE.restore()
l.restore()
lSSE.restore(g)
l.restore(g)
p("ADJSP $%d", -lSSE.stack)
p("POPFQ")
p("POPQ BP")
p("RET")
}
func genARM() {
func genARM(g *gen) {
p := g.p
// Add integer registers R0-R12.
// R13 (SP), R14 (LR), R15 (PC) are special and not saved here.
var l = layout{sp: "R13", stack: 4} // add LR slot
@ -303,22 +312,23 @@ func genARM() {
}
p("MOVW.W R14, -%d(R13)", lfp.stack) // allocate frame, save LR
l.save()
l.save(g)
p("MOVB ·goarmsoftfp(SB), R0\nCMP $0, R0\nBNE nofp") // test goarmsoftfp, and skip FP registers if goarmsoftfp!=0.
lfp.save()
label("nofp:")
lfp.save(g)
g.label("nofp:")
p("CALL ·asyncPreempt2(SB)")
p("MOVB ·goarmsoftfp(SB), R0\nCMP $0, R0\nBNE nofp2") // test goarmsoftfp, and skip FP registers if goarmsoftfp!=0.
lfp.restore()
label("nofp2:")
l.restore()
lfp.restore(g)
g.label("nofp2:")
l.restore(g)
p("MOVW %d(R13), R14", lfp.stack) // sigctxt.pushCall pushes LR on stack, restore it
p("MOVW.P %d(R13), R15", lfp.stack+4) // load PC, pop frame (including the space pushed by sigctxt.pushCall)
p("UNDEF") // shouldn't get here
}
func genARM64() {
func genARM64(g *gen) {
p := g.p
// Add integer registers R0-R26
// R27 (REGTMP), R28 (g), R29 (FP), R30 (LR), R31 (SP) are special
// and not saved here.
@ -362,9 +372,9 @@ func genARM64() {
p("MOVD R30, (RSP)")
p("#endif")
l.save()
l.save(g)
p("CALL ·asyncPreempt2(SB)")
l.restore()
l.restore(g)
p("MOVD %d(RSP), R30", l.stack) // sigctxt.pushCall has pushed LR (at interrupt) on stack, restore it
p("MOVD -8(RSP), R29") // restore frame pointer
@ -373,7 +383,9 @@ func genARM64() {
p("RET (R27)")
}
func genMIPS(_64bit bool) {
func genMIPS(g *gen, _64bit bool) {
p := g.p
mov := "MOVW"
movf := "MOVF"
add := "ADD"
@ -428,15 +440,15 @@ func genMIPS(_64bit bool) {
p(mov+" R31, -%d(R29)", lfp.stack)
p(sub+" $%d, R29", lfp.stack)
l.save()
l.save(g)
p("#ifndef %s", softfloat)
lfp.save()
lfp.save(g)
p("#endif")
p("CALL ·asyncPreempt2(SB)")
p("#ifndef %s", softfloat)
lfp.restore()
lfp.restore(g)
p("#endif")
l.restore()
l.restore(g)
p(mov+" %d(R29), R31", lfp.stack) // sigctxt.pushCall has pushed LR (at interrupt) on stack, restore it
p(mov + " (R29), R23") // load PC to REGTMP
@ -444,7 +456,9 @@ func genMIPS(_64bit bool) {
p("JMP (R23)")
}
func genLoong64() {
func genLoong64(g *gen) {
p := g.p
mov := "MOVV"
movf := "MOVD"
add := "ADDV"
@ -478,9 +492,9 @@ func genLoong64() {
p(mov+" R1, -%d(R3)", l.stack)
p(sub+" $%d, R3", l.stack)
l.save()
l.save(g)
p("CALL ·asyncPreempt2(SB)")
l.restore()
l.restore(g)
p(mov+" %d(R3), R1", l.stack) // sigctxt.pushCall has pushed LR (at interrupt) on stack, restore it
p(mov + " (R3), R30") // load PC to REGTMP
@ -488,7 +502,9 @@ func genLoong64() {
p("JMP (R30)")
}
func genPPC64() {
func genPPC64(g *gen) {
p := g.p
// Add integer registers R3-R29
// R0 (zero), R1 (SP), R30 (g) are special and not saved here.
// R2 (TOC pointer in PIC mode), R12 (function entry address in PIC mode) have been saved in sigctxt.pushCall.
@ -528,9 +544,9 @@ func genPPC64() {
p("MOVD LR, R31")
p("MOVDU R31, -%d(R1)", l.stack) // allocate frame, save PC of interrupted instruction (in LR)
l.save()
l.save(g)
p("CALL ·asyncPreempt2(SB)")
l.restore()
l.restore(g)
p("MOVD %d(R1), R31", l.stack) // sigctxt.pushCall has pushed LR, R2, R12 (at interrupt) on stack, restore them
p("MOVD R31, LR")
@ -543,7 +559,9 @@ func genPPC64() {
p("JMP (CTR)")
}
func genRISCV64() {
func genRISCV64(g *gen) {
p := g.p
// X0 (zero), X1 (LR), X2 (SP), X3 (GP), X4 (TP), X27 (g), X31 (TMP) are special.
var l = layout{sp: "X2", stack: 8}
@ -564,16 +582,18 @@ func genRISCV64() {
p("MOV X1, -%d(X2)", l.stack)
p("SUB $%d, X2", l.stack)
l.save()
l.save(g)
p("CALL ·asyncPreempt2(SB)")
l.restore()
l.restore(g)
p("MOV %d(X2), X1", l.stack)
p("MOV (X2), X31")
p("ADD $%d, X2", l.stack+8)
p("JMP (X31)")
}
func genS390X() {
func genS390X(g *gen) {
p := g.p
// Add integer registers R0-R12
// R13 (g), R14 (LR), R15 (SP) are special, and not saved here.
// Saving R10 (REGTMP) is not necessary, but it is saved anyway.
@ -594,9 +614,9 @@ func genS390X() {
p("ADD $-%d, R15", l.stack)
p("MOVW R10, 8(R15)") // save flags
l.save()
l.save(g)
p("CALL ·asyncPreempt2(SB)")
l.restore()
l.restore(g)
p("MOVD %d(R15), R14", l.stack) // sigctxt.pushCall has pushed LR (at interrupt) on stack, restore it
p("ADD $%d, R15", l.stack+8) // pop frame (including the space pushed by sigctxt.pushCall)
@ -606,12 +626,14 @@ func genS390X() {
p("JMP (R10)")
}
func genWasm() {
func genWasm(g *gen) {
p := g.p
p("// No async preemption on wasm")
p("UNDEF")
}
func notImplemented() {
func notImplemented(g *gen) {
p := g.p
p("// Not implemented yet")
p("JMP ·abort(SB)")
}