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internal/abi, runtime, cmd: merge StackSmall, StackBig consts into in…
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…ternal/abi

For #59670.

Change-Id: I04a17079b351b9b4999ca252825373c17afb8a88
Reviewed-on: https://go-review.googlesource.com/c/go/+/486379
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
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@aclements
aclements committed Apr 20, 2023
1 parent 22a840a commit f5f7755
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Showing 12 changed files with 66 additions and 53 deletions.
8 changes: 4 additions & 4 deletions src/cmd/internal/obj/arm/obj5.go
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Original file line number Diff line number Diff line change
Expand Up @@ -708,7 +708,7 @@ func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
// unnecessarily. See issue #35470.
p = c.ctxt.StartUnsafePoint(p, c.newprog)

if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP < stackguard
// CMP stackguard, SP
p = obj.Appendp(p, c.newprog)
Expand All @@ -717,7 +717,7 @@ func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.From.Type = obj.TYPE_REG
p.From.Reg = REG_R1
p.Reg = REGSP
} else if framesize <= objabi.StackBig {
} else if framesize <= abi.StackBig {
// large stack: SP-framesize < stackguard-StackSmall
// MOVW $-(framesize-StackSmall)(SP), R2
// CMP stackguard, R2
Expand All @@ -726,7 +726,7 @@ func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.As = AMOVW
p.From.Type = obj.TYPE_ADDR
p.From.Reg = REGSP
p.From.Offset = -(int64(framesize) - objabi.StackSmall)
p.From.Offset = -(int64(framesize) - abi.StackSmall)
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R2

Expand All @@ -753,7 +753,7 @@ func (c *ctxt5) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.As = ASUB
p.Scond = C_SBIT
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(framesize) - objabi.StackSmall
p.From.Offset = int64(framesize) - abi.StackSmall
p.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REG_R2
Expand Down
10 changes: 5 additions & 5 deletions src/cmd/internal/obj/arm64/obj7.go
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Original file line number Diff line number Diff line change
Expand Up @@ -169,7 +169,7 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p = c.ctxt.StartUnsafePoint(p, c.newprog)

q := (*obj.Prog)(nil)
if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP < stackguard
// CMP stackguard, SP

Expand All @@ -178,15 +178,15 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.From.Type = obj.TYPE_REG
p.From.Reg = REGRT1
p.Reg = REGSP
} else if framesize <= objabi.StackBig {
} else if framesize <= abi.StackBig {
// large stack: SP-framesize < stackguard-StackSmall
// SUB $(framesize-StackSmall), SP, RT2
// CMP stackguard, RT2
p = obj.Appendp(p, c.newprog)

p.As = ASUB
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(framesize) - objabi.StackSmall
p.From.Offset = int64(framesize) - abi.StackSmall
p.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGRT2
Expand All @@ -212,7 +212,7 @@ func (c *ctxt7) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p = obj.Appendp(p, c.newprog)
p.As = ASUBS
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(framesize) - objabi.StackSmall
p.From.Offset = int64(framesize) - abi.StackSmall
p.Reg = REGSP
p.To.Type = obj.TYPE_REG
p.To.Reg = REGRT2
Expand Down Expand Up @@ -582,7 +582,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
}
}

if p.Mark&LEAF != 0 && c.autosize < objabi.StackSmall {
if p.Mark&LEAF != 0 && c.autosize < abi.StackSmall {
// A leaf function with a small stack can be marked
// NOSPLIT, avoiding a stack check.
p.From.Sym.Set(obj.AttrNoSplit, true)
Expand Down
7 changes: 3 additions & 4 deletions src/cmd/internal/obj/loong64/obj.go
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@ package loong64

import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"log"
"math"
Expand Down Expand Up @@ -593,7 +592,7 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p = c.ctxt.StartUnsafePoint(p, c.newprog)

var q *obj.Prog
if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP < stackguard
// AGTU SP, stackguard, R19
p = obj.Appendp(p, c.newprog)
Expand All @@ -606,8 +605,8 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.To.Reg = REG_R19
} else {
// large stack: SP-framesize < stackguard-StackSmall
offset := int64(framesize) - objabi.StackSmall
if framesize > objabi.StackBig {
offset := int64(framesize) - abi.StackSmall
if framesize > abi.StackBig {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
Expand Down
7 changes: 3 additions & 4 deletions src/cmd/internal/obj/mips/obj0.go
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,6 @@ package mips

import (
"cmd/internal/obj"
"cmd/internal/objabi"
"cmd/internal/sys"
"encoding/binary"
"fmt"
Expand Down Expand Up @@ -774,7 +773,7 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p = c.ctxt.StartUnsafePoint(p, c.newprog)

var q *obj.Prog
if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP < stackguard
// AGTU SP, stackguard, R1
p = obj.Appendp(p, c.newprog)
Expand All @@ -787,8 +786,8 @@ func (c *ctxt0) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.To.Reg = REG_R1
} else {
// large stack: SP-framesize < stackguard-StackSmall
offset := int64(framesize) - objabi.StackSmall
if framesize > objabi.StackBig {
offset := int64(framesize) - abi.StackSmall
if framesize > abi.StackBig {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
Expand Down
8 changes: 4 additions & 4 deletions src/cmd/internal/obj/ppc64/obj9.go
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Original file line number Diff line number Diff line change
Expand Up @@ -632,7 +632,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
autosize += int32(c.ctxt.Arch.FixedFrameSize)
}

if p.Mark&LEAF != 0 && autosize < objabi.StackSmall {
if p.Mark&LEAF != 0 && autosize < abi.StackSmall {
// A leaf function with a small stack can be marked
// NOSPLIT, avoiding a stack check.
p.From.Sym.Set(obj.AttrNoSplit, true)
Expand Down Expand Up @@ -1177,7 +1177,7 @@ func (c *ctxt9) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p = c.ctxt.StartUnsafePoint(p, c.newprog)

var q *obj.Prog
if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP < stackguard
// CMP stackguard, SP
p = obj.Appendp(p, c.newprog)
Expand All @@ -1189,8 +1189,8 @@ func (c *ctxt9) stacksplit(p *obj.Prog, framesize int32) *obj.Prog {
p.To.Reg = REGSP
} else {
// large stack: SP-framesize < stackguard-StackSmall
offset := int64(framesize) - objabi.StackSmall
if framesize > objabi.StackBig {
offset := int64(framesize) - abi.StackSmall
if framesize > abi.StackBig {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
Expand Down
6 changes: 3 additions & 3 deletions src/cmd/internal/obj/riscv/obj.go
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Original file line number Diff line number Diff line change
Expand Up @@ -828,7 +828,7 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, cursym *obj.LSym, newprog obj.ProgA

var to_done, to_more *obj.Prog

if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack
// // if SP > stackguard { goto done }
// BLTU stackguard, SP, done
Expand All @@ -841,8 +841,8 @@ func stacksplit(ctxt *obj.Link, p *obj.Prog, cursym *obj.LSym, newprog obj.ProgA
to_done = p
} else {
// large stack: SP-framesize < stackguard-StackSmall
offset := int64(framesize) - objabi.StackSmall
if framesize > objabi.StackBig {
offset := int64(framesize) - abi.StackSmall
if framesize > abi.StackBig {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
Expand Down
8 changes: 4 additions & 4 deletions src/cmd/internal/obj/s390x/objz.go
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Original file line number Diff line number Diff line change
Expand Up @@ -313,7 +313,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
autosize += int32(c.ctxt.Arch.FixedFrameSize)
}

if p.Mark&LEAF != 0 && autosize < objabi.StackSmall {
if p.Mark&LEAF != 0 && autosize < abi.StackSmall {
// A leaf function with a small stack can be marked
// NOSPLIT, avoiding a stack check.
p.From.Sym.Set(obj.AttrNoSplit, true)
Expand Down Expand Up @@ -662,7 +662,7 @@ func (c *ctxtz) stacksplitPre(p *obj.Prog, framesize int32) (pPre, pPreempt, pCh
// unnecessarily. See issue #35470.
p = c.ctxt.StartUnsafePoint(p, c.newprog)

if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP < stackguard
// CMPUBGE stackguard, SP, label-of-call-to-morestack

Expand All @@ -678,8 +678,8 @@ func (c *ctxtz) stacksplitPre(p *obj.Prog, framesize int32) (pPre, pPreempt, pCh

// large stack: SP-framesize < stackguard-StackSmall

offset := int64(framesize) - objabi.StackSmall
if framesize > objabi.StackBig {
offset := int64(framesize) - abi.StackSmall
if framesize > abi.StackBig {
// Such a large stack we need to protect against underflow.
// The runtime guarantees SP > objabi.StackBig, but
// framesize is large enough that SP-framesize may
Expand Down
5 changes: 3 additions & 2 deletions src/cmd/internal/obj/wasm/wasmobj.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ import (
"cmd/internal/sys"
"encoding/binary"
"fmt"
"internal/abi"
"io"
"math"
)
Expand Down Expand Up @@ -472,7 +473,7 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
if needMoreStack {
p := pMorestack

if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP <= stackguard
// Get SP
// Get g
Expand Down Expand Up @@ -500,7 +501,7 @@ func preprocess(ctxt *obj.Link, s *obj.LSym, newprog obj.ProgAlloc) {
p = appendp(p, AGet, regAddr(REGG))
p = appendp(p, AI32WrapI64)
p = appendp(p, AI32Load, constAddr(2*int64(ctxt.Arch.PtrSize))) // G.stackguard0
p = appendp(p, AI32Const, constAddr(framesize-objabi.StackSmall))
p = appendp(p, AI32Const, constAddr(framesize-abi.StackSmall))
p = appendp(p, AI32Add)
p = appendp(p, AI32LeU)
}
Expand Down
12 changes: 6 additions & 6 deletions src/cmd/internal/obj/x86/obj6.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -641,7 +641,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
}

// TODO(rsc): Remove 'ctxt.Arch.Family == sys.AMD64 &&'.
if ctxt.Arch.Family == sys.AMD64 && autoffset < objabi.StackSmall && !p.From.Sym.NoSplit() {
if ctxt.Arch.Family == sys.AMD64 && autoffset < abi.StackSmall && !p.From.Sym.NoSplit() {
leaf := true
LeafSearch:
for q := p; q != nil; q = q.Link {
Expand All @@ -655,7 +655,7 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
}
fallthrough
case obj.ADUFFCOPY, obj.ADUFFZERO:
if autoffset >= objabi.StackSmall-8 {
if autoffset >= abi.StackSmall-8 {
leaf = false
break LeafSearch
}
Expand Down Expand Up @@ -1087,7 +1087,7 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
p, rg = loadG(ctxt, cursym, p, newprog)

var q1 *obj.Prog
if framesize <= objabi.StackSmall {
if framesize <= abi.StackSmall {
// small stack: SP <= stackguard
// CMPQ SP, stackguard
p = obj.Appendp(p, newprog)
Expand All @@ -1107,7 +1107,7 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
// cleared, but we'll still call morestack, which will double the stack
// unnecessarily. See issue #35470.
p = ctxt.StartUnsafePoint(p, newprog)
} else if framesize <= objabi.StackBig {
} else if framesize <= abi.StackBig {
// large stack: SP-framesize <= stackguard-StackSmall
// LEAQ -xxx(SP), tmp
// CMPQ tmp, stackguard
Expand All @@ -1116,7 +1116,7 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
p.As = lea
p.From.Type = obj.TYPE_MEM
p.From.Reg = REG_SP
p.From.Offset = -(int64(framesize) - objabi.StackSmall)
p.From.Offset = -(int64(framesize) - abi.StackSmall)
p.To.Type = obj.TYPE_REG
p.To.Reg = tmp

Expand Down Expand Up @@ -1159,7 +1159,7 @@ func stacksplit(ctxt *obj.Link, cursym *obj.LSym, p *obj.Prog, newprog obj.ProgA
p = obj.Appendp(p, newprog)
p.As = sub
p.From.Type = obj.TYPE_CONST
p.From.Offset = int64(framesize) - objabi.StackSmall
p.From.Offset = int64(framesize) - abi.StackSmall
p.To.Type = obj.TYPE_REG
p.To.Reg = tmp

Expand Down
9 changes: 5 additions & 4 deletions src/cmd/internal/objabi/stack.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4,21 +4,22 @@

package objabi

import "internal/buildcfg"
import (
"internal/abi"
"internal/buildcfg"
)

// For the linkers. Must match Go definitions.

const (
STACKSYSTEM = 0
StackSystem = STACKSYSTEM
StackBig = 4096
StackSmall = 128
)

func StackLimit(race bool) int {
// This arithmetic must match that in runtime/stack.go:{_StackGuard,_StackLimit}.
stackGuard := 928*stackGuardMultiplier(race) + StackSystem
stackLimit := stackGuard - StackSystem - StackSmall
stackLimit := stackGuard - StackSystem - abi.StackSmall
return stackLimit
}

Expand Down
25 changes: 25 additions & 0 deletions src/internal/abi/stack.go
View file
Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
// Copyright 2023 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 abi

const (
// We have three different sequences for stack bounds checks, depending on
// whether the stack frame of a function is small, big, or huge.

// After a stack split check the SP is allowed to be StackSmall bytes below
// the stack guard.
//
// Functions that need frames <= StackSmall can perform the stack check
// using a single comparison directly between the stack guard and the SP
// because we ensure that StackSmall bytes of stack space are available
// beyond the stack guard.
StackSmall = 128

// Functions that need frames <= StackBig can assume that neither
// SP-framesize nor stackGuard-StackSmall will underflow, and thus use a
// more efficient check. In order to ensure this, StackBig must be <= the
// size of the unmapped space at zero.
StackBig = 4096
)
14 changes: 1 addition & 13 deletions src/runtime/stack.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -85,13 +85,6 @@ const (
_FixedStack6 = _FixedStack5 | (_FixedStack5 >> 16)
_FixedStack = _FixedStack6 + 1

// Functions that need frames bigger than this use an extra
// instruction to do the stack split check, to avoid overflow
// in case SP - framesize wraps below zero.
// This value can be no bigger than the size of the unmapped
// space at zero.
_StackBig = 4096

// The stack guard is a pointer this many bytes above the
// bottom of the stack.
//
Expand All @@ -101,15 +94,10 @@ const (
// This arithmetic must match that in cmd/internal/objabi/stack.go:StackLimit.
_StackGuard = 928*sys.StackGuardMultiplier + _StackSystem

// After a stack split check the SP is allowed to be this
// many bytes below the stack guard. This saves an instruction
// in the checking sequence for tiny frames.
_StackSmall = 128

// The maximum number of bytes that a chain of NOSPLIT
// functions can use.
// This arithmetic must match that in cmd/internal/objabi/stack.go:StackLimit.
_StackLimit = _StackGuard - _StackSystem - _StackSmall
_StackLimit = _StackGuard - _StackSystem - abi.StackSmall
)

const (
Expand Down

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