[pull] master from golang:master

src/cmd/compile/internal/abi/abiutils.go

@@ -278,13 +278,6 @@ func NewABIConfig(iRegsCount, fRegsCount int, offsetForLocals int64, which uint8
 	return &ABIConfig{offsetForLocals: offsetForLocals, regAmounts: RegAmounts{iRegsCount, fRegsCount}, which: obj.ABI(which)}
 }
 
-// Copy returns config.
-//
-// TODO(mdempsky): Remove.
-func (config *ABIConfig) Copy() *ABIConfig {
-	return config
-}
-
 // Which returns the ABI number
 func (config *ABIConfig) Which() obj.ABI {
 	return config.which

src/cmd/compile/internal/ssa/func.go

@@ -36,8 +36,8 @@ type Func struct {
 	HTMLWriter     *HTMLWriter    // html writer, for debugging
 	PrintOrHtmlSSA bool           // true if GOSSAFUNC matches, true even if fe.Log() (spew phase results to stdout) is false.  There's an odd dependence on this in debug.go for method logf.
 	ruleMatches    map[string]int // number of times countRule was called during compilation for any given string
-	ABI0           *abi.ABIConfig // A copy, for no-sync access
-	ABI1           *abi.ABIConfig // A copy, for no-sync access
+	ABI0           *abi.ABIConfig // ABI configuration for ABI0
+	ABI1           *abi.ABIConfig // ABI configuration for ABIInternal
 	ABISelf        *abi.ABIConfig // ABI for function being compiled
 	ABIDefault     *abi.ABIConfig // ABI for rtcall and other no-parsed-signature/pragma functions.
 

src/cmd/compile/internal/ssagen/ssa.go

@@ -223,12 +223,11 @@ func InitTables() {
 // any ABI wrapper that is present is nosplit, hence a precise
 // stack map is not needed there (the parameters survive only long
 // enough to call the wrapped assembly function).
-// This always returns a freshly copied ABI.
 func AbiForBodylessFuncStackMap(fn *ir.Func) *abi.ABIConfig {
-	return ssaConfig.ABI0.Copy() // No idea what races will result, be safe
+	return ssaConfig.ABI0
 }
 
-// abiForFunc implements ABI policy for a function, but does not return a copy of the ABI.
+// abiForFunc implements ABI policy for a function.
 // Passing a nil function returns the default ABI based on experiment configuration.
 func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
 	if buildcfg.Experiment.RegabiArgs {

src/html/template/template.go

@@ -25,7 +25,8 @@ type Template struct {
 	// we need to keep our version of the name space and the underlying
 	// template's in sync.
 	text *template.Template
-	// The underlying template's parse tree, updated to be HTML-safe.
+	// The underlying template's parse tree, updated to be HTML-safe
+	// after the first execution.
 	Tree       *parse.Tree
 	*nameSpace // common to all associated templates
 }
@@ -331,10 +332,12 @@ func (t *Template) Name() string {
 type FuncMap = template.FuncMap
 
 // Funcs adds the elements of the argument map to the template's function map.
-// It must be called before the template is parsed.
+// Any function used in the template must be added before the template is
+// parsed. Funcs may be called more than once, including after parsing (for
+// example, after [Template.Clone]), to replace a function of the same name;
+// the replacement is used when the template is executed.
 // It panics if a value in the map is not a function with appropriate return
-// type. However, it is legal to overwrite elements of the map. The return
-// value is the template, so calls can be chained.
+// type. The return value is the template, so calls can be chained.
 func (t *Template) Funcs(funcMap FuncMap) *Template {
 	t.text.Funcs(template.FuncMap(funcMap))
 	return t

src/internal/poll/fd_unix.go

@@ -148,7 +148,12 @@ func (fd *FD) Read(p []byte) (int, error) {
 		// without trying (but after acquiring the readLock).
 		// Otherwise syscall.Read returns 0, nil which looks like
 		// io.EOF.
-		// TODO(bradfitz): make it wait for readability? (Issue 15735)
+		//
+		// Waiting for readability instead was proposed in
+		// go.dev/cl/22031 and abandoned. Blocking would change
+		// the behavior of existing callers, and the netpoller's
+		// edge-triggered notifications alone cannot detect data
+		// that is already buffered. See go.dev/issue/15735.
 		return 0, nil
 	}
 	if err := fd.pd.prepareRead(fd.isFile); err != nil {

src/math/nextafter.go

@@ -8,7 +8,8 @@ package math
 //
 // Special cases are:
 //
-//	Nextafter32(x, x)   = x
+//	Nextafter32(x, y)   = x when x == y
+//	Nextafter32(0, y)   = ±SmallestNonzeroFloat32 towards y, for y ≠ 0
 //	Nextafter32(NaN, y) = NaN
 //	Nextafter32(x, NaN) = NaN
 func Nextafter32(x, y float32) (r float32) {
@@ -31,7 +32,8 @@ func Nextafter32(x, y float32) (r float32) {
 //
 // Special cases are:
 //
-//	Nextafter(x, x)   = x
+//	Nextafter(x, y)   = x when x == y
+//	Nextafter(0, y)   = ±SmallestNonzeroFloat64 towards y, for y ≠ 0
 //	Nextafter(NaN, y) = NaN
 //	Nextafter(x, NaN) = NaN
 func Nextafter(x, y float64) (r float64) {

src/os/exec.go

@@ -41,6 +41,7 @@ const (
 
 // Process stores the information about a process created by [StartProcess].
 type Process struct {
+	// Pid is the operating system process ID.
 	Pid int
 
 	// state contains the atomic process state.

src/os/file.go

@@ -867,6 +867,7 @@ func (dir dirFS) join(name string) (string, error) {
 // A successful call returns err == nil, not err == EOF.
 // Because ReadFile reads the whole file, it does not treat an EOF from Read
 // as an error to be reported.
+// If there is an error, it will be of type [*PathError].
 func ReadFile(name string) ([]byte, error) {
 	f, err := Open(name)
 	if err != nil {

src/runtime/mgcmark.go

@@ -1094,6 +1094,15 @@ func scanframeworker(frame *stkframe, state *stackScanState, gcw *gcWork) {
 		if frame.varp != 0 {
 			size := frame.varp - frame.sp
 			if size > 0 {
+				isSigPanic := frame.fn.valid() && frame.fn.funcID == abi.FuncID_sigpanic
+				if usesLR && (isSigPanic || isAsyncPreempt || isDebugCall) {
+					// Also include the small frame injected by
+					// (*sigctxt).pushCall. This is the same bump
+					// as the SP bump used in (*unwinder).next.
+					// We need this to ensure LR is scanned (for when
+					// it contains a pointer-y non-PC). See issue 80188.
+					size += alignUp(sys.MinFrameSize, sys.StackAlign)
+				}
 				scanConservative(frame.sp, size, nil, gcw, state)
 			}
 		}

src/runtime/traceback.go

@@ -501,6 +501,7 @@ func (u *unwinder) next() {
 	// before faking a call.
 	if usesLR && injectedCall {
 		x := *(*uintptr)(unsafe.Pointer(frame.sp))
+		// same as the size bump used in scanframeworker.
 		frame.sp += alignUp(sys.MinFrameSize, sys.StackAlign)
 		f = findfunc(frame.pc)
 		frame.fn = f

src/text/template/template.go

@@ -167,11 +167,13 @@ func (t *Template) Delims(left, right string) *Template {
 }
 
 // Funcs adds the elements of the argument map to the template's function map.
-// It must be called before the template is parsed.
+// Any function used in the template must be added before the template is
+// parsed. Funcs may be called more than once, including after parsing (for
+// example, after [Template.Clone]), to replace a function of the same name;
+// the replacement is used when the template is executed.
 // It panics if a value in the map is not a function with appropriate return
 // type or if the name cannot be used syntactically as a function in a template.
-// It is legal to overwrite elements of the map. The return value is the template,
-// so calls can be chained.
+// The return value is the template, so calls can be chained.
 func (t *Template) Funcs(funcMap FuncMap) *Template {
 	t.init()
 	t.muFuncs.Lock()

test/fixedbugs/issue80188.go

@@ -0,0 +1,238 @@
+// run
+
+// Copyright 2026 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 main
+
+import "runtime"
+
+type T struct {
+	a, b, c, d int
+}
+
+func (t *T) sum() int {
+	return t.a + t.b + t.c + t.d
+}
+
+//go:noinline
+func newT(x int) *T {
+	t := new(T)
+	t.a = x
+	t.b = x
+	t.c = x
+	t.d = x
+	return t
+}
+
+//go:noinline
+func intptr() *int {
+	return &g
+}
+
+var g int
+
+//go:noinline
+func f(x int) []*T {
+	const N = 40
+	var q [N]*T
+	for i := range N {
+		q[i] = newT(x)
+	}
+	var a [2]*int
+	for i := range a {
+		a[i] = intptr()
+	}
+
+	// reserve 2 registers we will later drop.
+	b := a[0]
+	c := a[1]
+
+	// Load pointers into registers (or spill slots)
+	p0 := q[0]
+	p1 := q[1]
+	p2 := q[2]
+	p3 := q[3]
+	p4 := q[4]
+	p5 := q[5]
+	p6 := q[6]
+	p7 := q[7]
+	p8 := q[8]
+	p9 := q[9]
+	p10 := q[10]
+	p11 := q[11]
+	p12 := q[12]
+	p13 := q[13]
+	p14 := q[14]
+	p15 := q[15]
+	p16 := q[16]
+	p17 := q[17]
+	p18 := q[18]
+	p19 := q[19]
+	p20 := q[20]
+	p21 := q[21]
+	p22 := q[22]
+	p23 := q[23]
+	p24 := q[24]
+	p25 := q[25]
+	p26 := q[26]
+	p27 := q[27]
+	p28 := q[28]
+	p29 := q[29]
+	p30 := q[30]
+	p31 := q[31]
+	p32 := q[32]
+	p33 := q[33]
+	p34 := q[34]
+	p35 := q[35]
+	p36 := q[36]
+	p37 := q[37]
+	p38 := q[38]
+	p39 := q[39]
+
+	// q is dead at this point. The only live reference to
+	// the objects allocated by newT are in the pXX variables.
+	// But if async preempted, we will scan the frame conservatively,
+	// which will find dead entries in q. Remove them.
+	q[0] = nil
+	q[1] = nil
+	q[2] = nil
+	q[3] = nil
+	q[4] = nil
+	q[5] = nil
+	q[6] = nil
+	q[7] = nil
+	q[8] = nil
+	q[9] = nil
+	q[10] = nil
+	q[11] = nil
+	q[12] = nil
+	q[13] = nil
+	q[14] = nil
+	q[15] = nil
+	q[16] = nil
+	q[17] = nil
+	q[18] = nil
+	q[19] = nil
+	q[20] = nil
+	q[21] = nil
+	q[22] = nil
+	q[23] = nil
+	q[24] = nil
+	q[25] = nil
+	q[26] = nil
+	q[27] = nil
+	q[28] = nil
+	q[29] = nil
+	q[30] = nil
+	q[31] = nil
+	q[32] = nil
+	q[33] = nil
+	q[34] = nil
+	q[35] = nil
+	q[36] = nil
+	q[37] = nil
+	q[38] = nil
+	q[39] = nil
+
+	// Some pXX is held in R30.
+	// If async preemption happens here, the pointer in R30
+	// will not get scanned and might cause the pointed-to
+	// object to be collected prematurely. It does not live
+	// anywhere else in this frame, and we will not scan
+	// this frame again later.
+	//
+	// Note that the write barrier has to be off for some of
+	// the newT calls for objects not to be allocated black.
+	// But it must be on here to get an async preempt.
+	// It must be off again by the final copy to not get put
+	// in a write barrier buffer somewhere.
+
+	// delay here to encourage async preemption
+	*b = 0
+	*c = 0
+	// The 2 registers holding b,c are now free. They
+	// can be used to implement this loop without spilling
+	// R30 to get a free register.
+	for range 10000 {
+	}
+
+	// Store registers back to stack memory (with no write barriers)
+	var z [N]*T
+	z[0] = p0
+	z[1] = p1
+	z[2] = p2
+	z[3] = p3
+	z[4] = p4
+	z[5] = p5
+	z[6] = p6
+	z[7] = p7
+	z[8] = p8
+	z[9] = p9
+	z[10] = p10
+	z[11] = p11
+	z[12] = p12
+	z[13] = p13
+	z[14] = p14
+	z[15] = p15
+	z[16] = p16
+	z[17] = p17
+	z[18] = p18
+	z[19] = p19
+	z[20] = p20
+	z[21] = p21
+	z[22] = p22
+	z[23] = p23
+	z[24] = p24
+	z[25] = p25
+	z[26] = p26
+	z[27] = p27
+	z[28] = p28
+	z[29] = p29
+	z[30] = p30
+	z[31] = p31
+	z[32] = p32
+	z[33] = p33
+	z[34] = p34
+	z[35] = p35
+	z[36] = p36
+	z[37] = p37
+	z[38] = p38
+	z[39] = p39
+
+	// Delay again, hoping GC finishes before we publish
+	// the unscanned pointer via the write barrier.
+	for range 10000 {
+	}
+
+	// Copy results to heap to return.
+	r := new([N]*T)
+	*r = z
+	return r[:]
+}
+
+func main() {
+	runtime.GOMAXPROCS(2)
+	c := make(chan bool)
+	for range 4 {
+		go goroutine(c)
+	}
+	for range 4 {
+		<-c
+	}
+}
+func goroutine(c chan bool) {
+	var all [][]*T
+	for x := range 10000 {
+		all = append(all, f(x))
+	}
+	for x, a := range all {
+		for _, t := range a {
+			if t.a != x || t.b != x || t.c != x || t.d != x {
+				panic("bad")
+			}
+		}
+	}
+	c <- true
+}