21 files changed, 1500 insertions, 0 deletions
diff --git a/src/internal/abi/abi.go b/src/internal/abi/abi.go
new file mode 100644
index 0000000..e1c8adc
--- /dev/null
+++ b/src/internal/abi/abi.go
@@ -0,0 +1,102 @@
+// Copyright 2020 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
+
+import (
+	"internal/goarch"
+	"unsafe"
+)
+
+// RegArgs is a struct that has space for each argument
+// and return value register on the current architecture.
+//
+// Assembly code knows the layout of the first two fields
+// of RegArgs.
+//
+// RegArgs also contains additional space to hold pointers
+// when it may not be safe to keep them only in the integer
+// register space otherwise.
+type RegArgs struct {
+	// Values in these slots should be precisely the bit-by-bit
+	// representation of how they would appear in a register.
+	//
+	// This means that on big endian arches, integer values should
+	// be in the top bits of the slot. Floats are usually just
+	// directly represented, but some architectures treat narrow
+	// width floating point values specially (e.g. they're promoted
+	// first, or they need to be NaN-boxed).
+	Ints   [IntArgRegs]uintptr  // untyped integer registers
+	Floats [FloatArgRegs]uint64 // untyped float registers
+
+	// Fields above this point are known to assembly.
+
+	// Ptrs is a space that duplicates Ints but with pointer type,
+	// used to make pointers passed or returned  in registers
+	// visible to the GC by making the type unsafe.Pointer.
+	Ptrs [IntArgRegs]unsafe.Pointer
+
+	// ReturnIsPtr is a bitmap that indicates which registers
+	// contain or will contain pointers on the return path from
+	// a reflectcall. The i'th bit indicates whether the i'th
+	// register contains or will contain a valid Go pointer.
+	ReturnIsPtr IntArgRegBitmap
+}
+
+func (r *RegArgs) Dump() {
+	print("Ints:")
+	for _, x := range r.Ints {
+		print(" ", x)
+	}
+	println()
+	print("Floats:")
+	for _, x := range r.Floats {
+		print(" ", x)
+	}
+	println()
+	print("Ptrs:")
+	for _, x := range r.Ptrs {
+		print(" ", x)
+	}
+	println()
+}
+
+// IntRegArgAddr returns a pointer inside of r.Ints[reg] that is appropriately
+// offset for an argument of size argSize.
+//
+// argSize must be non-zero, fit in a register, and a power-of-two.
+//
+// This method is a helper for dealing with the endianness of different CPU
+// architectures, since sub-word-sized arguments in big endian architectures
+// need to be "aligned" to the upper edge of the register to be interpreted
+// by the CPU correctly.
+func (r *RegArgs) IntRegArgAddr(reg int, argSize uintptr) unsafe.Pointer {
+	if argSize > goarch.PtrSize || argSize == 0 || argSize&(argSize-1) != 0 {
+		panic("invalid argSize")
+	}
+	offset := uintptr(0)
+	if goarch.BigEndian {
+		offset = goarch.PtrSize - argSize
+	}
+	return unsafe.Pointer(uintptr(unsafe.Pointer(&r.Ints[reg])) + offset)
+}
+
+// IntArgRegBitmap is a bitmap large enough to hold one bit per
+// integer argument/return register.
+type IntArgRegBitmap [(IntArgRegs + 7) / 8]uint8
+
+// Set sets the i'th bit of the bitmap to 1.
+func (b *IntArgRegBitmap) Set(i int) {
+	b[i/8] |= uint8(1) << (i % 8)
+}
+
+// Get returns whether the i'th bit of the bitmap is set.
+//
+// nosplit because it's called in extremely sensitive contexts, like
+// on the reflectcall return path.
+//
+//go:nosplit
+func (b *IntArgRegBitmap) Get(i int) bool {
+	return b[i/8]&(uint8(1)<<(i%8)) != 0
+}
diff --git a/src/internal/abi/abi_amd64.go b/src/internal/abi/abi_amd64.go
new file mode 100644
index 0000000..d3c5678
--- /dev/null
+++ b/src/internal/abi/abi_amd64.go
@@ -0,0 +1,18 @@
+// Copyright 2020 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 (
+	// See abi_generic.go.
+
+	// RAX, RBX, RCX, RDI, RSI, R8, R9, R10, R11.
+	IntArgRegs = 9
+
+	// X0 -> X14.
+	FloatArgRegs = 15
+
+	// We use SSE2 registers which support 64-bit float operations.
+	EffectiveFloatRegSize = 8
+)
diff --git a/src/internal/abi/abi_arm64.go b/src/internal/abi/abi_arm64.go
new file mode 100644
index 0000000..4dc5143
--- /dev/null
+++ b/src/internal/abi/abi_arm64.go
@@ -0,0 +1,17 @@
+// Copyright 2021 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 (
+	// See abi_generic.go.
+
+	// R0 - R15.
+	IntArgRegs = 16
+
+	// F0 - F15.
+	FloatArgRegs = 16
+
+	EffectiveFloatRegSize = 8
+)
diff --git a/src/internal/abi/abi_generic.go b/src/internal/abi/abi_generic.go
new file mode 100644
index 0000000..76ef2e2
--- /dev/null
+++ b/src/internal/abi/abi_generic.go
@@ -0,0 +1,38 @@
+// Copyright 2020 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.
+
+//go:build !goexperiment.regabiargs && !amd64 && !arm64 && !ppc64 && !ppc64le && !riscv64
+
+package abi
+
+const (
+	// ABI-related constants.
+	//
+	// In the generic case, these are all zero
+	// which lets them gracefully degrade to ABI0.
+
+	// IntArgRegs is the number of registers dedicated
+	// to passing integer argument values. Result registers are identical
+	// to argument registers, so this number is used for those too.
+	IntArgRegs = 0
+
+	// FloatArgRegs is the number of registers dedicated
+	// to passing floating-point argument values. Result registers are
+	// identical to argument registers, so this number is used for
+	// those too.
+	FloatArgRegs = 0
+
+	// EffectiveFloatRegSize describes the width of floating point
+	// registers on the current platform from the ABI's perspective.
+	//
+	// Since Go only supports 32-bit and 64-bit floating point primitives,
+	// this number should be either 0, 4, or 8. 0 indicates no floating
+	// point registers for the ABI or that floating point values will be
+	// passed via the softfloat ABI.
+	//
+	// For platforms that support larger floating point register widths,
+	// such as x87's 80-bit "registers" (not that we support x87 currently),
+	// use 8.
+	EffectiveFloatRegSize = 0
+)
diff --git a/src/internal/abi/abi_ppc64x.go b/src/internal/abi/abi_ppc64x.go
new file mode 100644
index 0000000..73416d7
--- /dev/null
+++ b/src/internal/abi/abi_ppc64x.go
@@ -0,0 +1,19 @@
+// Copyright 2021 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.
+
+//go:build ppc64 || ppc64le
+
+package abi
+
+const (
+	// See abi_generic.go.
+
+	// R3 - R10, R14 - R17.
+	IntArgRegs = 12
+
+	// F1 - F12.
+	FloatArgRegs = 12
+
+	EffectiveFloatRegSize = 8
+)
diff --git a/src/internal/abi/abi_riscv64.go b/src/internal/abi/abi_riscv64.go
new file mode 100644
index 0000000..2bcd9d6
--- /dev/null
+++ b/src/internal/abi/abi_riscv64.go
@@ -0,0 +1,17 @@
+// Copyright 2022 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 (
+	// See abi_generic.go.
+
+	// X8 - X23
+	IntArgRegs = 16
+
+	// F8 - F23.
+	FloatArgRegs = 16
+
+	EffectiveFloatRegSize = 8
+)
diff --git a/src/internal/abi/abi_test.go b/src/internal/abi/abi_test.go
new file mode 100644
index 0000000..44b9e78
--- /dev/null
+++ b/src/internal/abi/abi_test.go
@@ -0,0 +1,79 @@
+// Copyright 2021 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_test
+
+import (
+	"internal/abi"
+	"internal/testenv"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestFuncPC(t *testing.T) {
+	// Test that FuncPC* can get correct function PC.
+	pcFromAsm := abi.FuncPCTestFnAddr
+
+	// Test FuncPC for locally defined function
+	pcFromGo := abi.FuncPCTest()
+	if pcFromGo != pcFromAsm {
+		t.Errorf("FuncPC returns wrong PC, want %x, got %x", pcFromAsm, pcFromGo)
+	}
+
+	// Test FuncPC for imported function
+	pcFromGo = abi.FuncPCABI0(abi.FuncPCTestFn)
+	if pcFromGo != pcFromAsm {
+		t.Errorf("FuncPC returns wrong PC, want %x, got %x", pcFromAsm, pcFromGo)
+	}
+}
+
+func TestFuncPCCompileError(t *testing.T) {
+	// Test that FuncPC* on a function of a mismatched ABI is rejected.
+	testenv.MustHaveGoBuild(t)
+
+	// We want to test internal package, which we cannot normally import.
+	// Run the assembler and compiler manually.
+	tmpdir := t.TempDir()
+	asmSrc := filepath.Join("testdata", "x.s")
+	goSrc := filepath.Join("testdata", "x.go")
+	symabi := filepath.Join(tmpdir, "symabi")
+	obj := filepath.Join(tmpdir, "x.o")
+
+	// Write an importcfg file for the dependencies of the package.
+	importcfgfile := filepath.Join(tmpdir, "hello.importcfg")
+	testenv.WriteImportcfg(t, importcfgfile, nil, "internal/abi")
+
+	// parse assembly code for symabi.
+	cmd := testenv.Command(t, testenv.GoToolPath(t), "tool", "asm", "-gensymabis", "-o", symabi, asmSrc)
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("go tool asm -gensymabis failed: %v\n%s", err, out)
+	}
+
+	// compile go code.
+	cmd = testenv.Command(t, testenv.GoToolPath(t), "tool", "compile", "-importcfg="+importcfgfile, "-p=p", "-symabis", symabi, "-o", obj, goSrc)
+	out, err = cmd.CombinedOutput()
+	if err == nil {
+		t.Fatalf("go tool compile did not fail")
+	}
+
+	// Expect errors in line 17, 18, 20, no errors on other lines.
+	want := []string{"x.go:17", "x.go:18", "x.go:20"}
+	got := strings.Split(string(out), "\n")
+	if got[len(got)-1] == "" {
+		got = got[:len(got)-1] // remove last empty line
+	}
+	for i, s := range got {
+		if !strings.Contains(s, want[i]) {
+			t.Errorf("did not error on line %s", want[i])
+		}
+	}
+	if len(got) != len(want) {
+		t.Errorf("unexpected number of errors, want %d, got %d", len(want), len(got))
+	}
+	if t.Failed() {
+		t.Logf("output:\n%s", string(out))
+	}
+}
diff --git a/src/internal/abi/abi_test.s b/src/internal/abi/abi_test.s
new file mode 100644
index 0000000..93ace3e
--- /dev/null
+++ b/src/internal/abi/abi_test.s
@@ -0,0 +1,27 @@
+// Copyright 2021 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.
+
+#include "textflag.h"
+
+#ifdef GOARCH_386
+#define PTRSIZE 4
+#endif
+#ifdef GOARCH_arm
+#define PTRSIZE 4
+#endif
+#ifdef GOARCH_mips
+#define PTRSIZE 4
+#endif
+#ifdef GOARCH_mipsle
+#define PTRSIZE 4
+#endif
+#ifndef PTRSIZE
+#define PTRSIZE 8
+#endif
+
+TEXT	internal∕abi·FuncPCTestFn(SB),NOSPLIT,$0-0
+	RET
+
+GLOBL	internal∕abi·FuncPCTestFnAddr(SB), NOPTR, $PTRSIZE
+DATA	internal∕abi·FuncPCTestFnAddr(SB)/PTRSIZE, $internal∕abi·FuncPCTestFn(SB)
diff --git a/src/internal/abi/compiletype.go b/src/internal/abi/compiletype.go
new file mode 100644
index 0000000..d92adde
--- /dev/null
+++ b/src/internal/abi/compiletype.go
@@ -0,0 +1,167 @@
+// 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
+
+// These functions are the build-time version of the Go type data structures.
+
+// Their contents must be kept in sync with their definitions.
+// Because the host and target type sizes can differ, the compiler and
+// linker cannot use the host information that they might get from
+// either unsafe.Sizeof and Alignof, nor runtime, reflect, or reflectlite.
+
+// CommonSize returns sizeof(Type) for a compilation target with a given ptrSize
+func CommonSize(ptrSize int) int { return 4*ptrSize + 8 + 8 }
+
+// StructFieldSize returns sizeof(StructField) for a compilation target with a given ptrSize
+func StructFieldSize(ptrSize int) int { return 3 * ptrSize }
+
+// UncommonSize returns sizeof(UncommonType).  This currently does not depend on ptrSize.
+// This exported function is in an internal package, so it may change to depend on ptrSize in the future.
+func UncommonSize() uint64 { return 4 + 2 + 2 + 4 + 4 }
+
+// IMethodSize returns sizeof(IMethod) for a compilation target with a given ptrSize
+func IMethodSize(ptrSize int) int { return 4 + 4 }
+
+// KindOff returns the offset of Type.Kind_ for a compilation target with a given ptrSize
+func KindOff(ptrSize int) int { return 2*ptrSize + 7 }
+
+// SizeOff returns the offset of Type.Size_ for a compilation target with a given ptrSize
+func SizeOff(ptrSize int) int { return 0 }
+
+// PtrBytes returns the offset of Type.PtrBytes for a compilation target with a given ptrSize
+func PtrBytesOff(ptrSize int) int { return ptrSize }
+
+// TFlagOff returns the offset of Type.TFlag for a compilation target with a given ptrSize
+func TFlagOff(ptrSize int) int { return 2*ptrSize + 4 }
+
+// Offset is for computing offsets of type data structures at compile/link time;
+// the target platform may not be the host platform.  Its state includes the
+// current offset, necessary alignment for the sequence of types, and the size
+// of pointers and alignment of slices, interfaces, and strings (this is for tearing-
+// resistant access to these types, if/when that is supported).
+type Offset struct {
+	off        uint64 // the current offset
+	align      uint8  // the required alignmentof the container
+	ptrSize    uint8  // the size of a pointer in bytes
+	sliceAlign uint8  // the alignment of slices (and interfaces and strings)
+}
+
+// NewOffset returns a new Offset with offset 0 and alignment 1.
+func NewOffset(ptrSize uint8, twoWordAlignSlices bool) Offset {
+	if twoWordAlignSlices {
+		return Offset{off: 0, align: 1, ptrSize: ptrSize, sliceAlign: 2 * ptrSize}
+	}
+	return Offset{off: 0, align: 1, ptrSize: ptrSize, sliceAlign: ptrSize}
+}
+
+func assertIsAPowerOfTwo(x uint8) {
+	if x == 0 {
+		panic("Zero is not a power of two")
+	}
+	if x&-x == x {
+		return
+	}
+	panic("Not a power of two")
+}
+
+// InitializedOffset returns a new Offset with specified offset, alignment, pointer size, and slice alignment.
+func InitializedOffset(off int, align uint8, ptrSize uint8, twoWordAlignSlices bool) Offset {
+	assertIsAPowerOfTwo(align)
+	o0 := NewOffset(ptrSize, twoWordAlignSlices)
+	o0.off = uint64(off)
+	o0.align = align
+	return o0
+}
+
+func (o Offset) align_(a uint8) Offset {
+	o.off = (o.off + uint64(a) - 1) & ^(uint64(a) - 1)
+	if o.align < a {
+		o.align = a
+	}
+	return o
+}
+
+// Align returns the offset obtained by aligning offset to a multiple of a.
+// a must be a power of two.
+func (o Offset) Align(a uint8) Offset {
+	assertIsAPowerOfTwo(a)
+	return o.align_(a)
+}
+
+// plus returns the offset obtained by appending a power-of-2-sized-and-aligned object to o.
+func (o Offset) plus(x uint64) Offset {
+	o = o.align_(uint8(x))
+	o.off += x
+	return o
+}
+
+// D8 returns the offset obtained by appending an 8-bit field to o.
+func (o Offset) D8() Offset {
+	return o.plus(1)
+}
+
+// D16 returns the offset obtained by appending a 16-bit field to o.
+func (o Offset) D16() Offset {
+	return o.plus(2)
+}
+
+// D32 returns the offset obtained by appending a 32-bit field to o.
+func (o Offset) D32() Offset {
+	return o.plus(4)
+}
+
+// D64 returns the offset obtained by appending a 64-bit field to o.
+func (o Offset) D64() Offset {
+	return o.plus(8)
+}
+
+// D64 returns the offset obtained by appending a pointer field to o.
+func (o Offset) P() Offset {
+	if o.ptrSize == 0 {
+		panic("This offset has no defined pointer size")
+	}
+	return o.plus(uint64(o.ptrSize))
+}
+
+// Slice returns the offset obtained by appending a slice field to o.
+func (o Offset) Slice() Offset {
+	o = o.align_(o.sliceAlign)
+	o.off += 3 * uint64(o.ptrSize)
+	// There's been discussion of whether slices should be 2-word aligned to allow
+	// use of aligned 2-word load/store to prevent tearing, this is future proofing.
+	// In general, for purposes of struct layout (and very likely default C layout
+	// compatibility) the "size" of a Go type is rounded up to its alignment.
+	return o.Align(o.sliceAlign)
+}
+
+// String returns the offset obtained by appending a string field to o.
+func (o Offset) String() Offset {
+	o = o.align_(o.sliceAlign)
+	o.off += 2 * uint64(o.ptrSize)
+	return o // We "know" it needs no further alignment
+}
+
+// Interface returns the offset obtained by appending an interface field to o.
+func (o Offset) Interface() Offset {
+	o = o.align_(o.sliceAlign)
+	o.off += 2 * uint64(o.ptrSize)
+	return o // We "know" it needs no further alignment
+}
+
+// Offset returns the struct-aligned offset (size) of o.
+// This is at least as large as the current internal offset; it may be larger.
+func (o Offset) Offset() uint64 {
+	return o.Align(o.align).off
+}
+
+func (o Offset) PlusUncommon() Offset {
+	o.off += UncommonSize()
+	return o
+}
+
+// CommonOffset returns the Offset to the data after the common portion of type data structures.
+func CommonOffset(ptrSize int, twoWordAlignSlices bool) Offset {
+	return InitializedOffset(CommonSize(ptrSize), uint8(ptrSize), uint8(ptrSize), twoWordAlignSlices)
+}
diff --git a/src/internal/abi/export_test.go b/src/internal/abi/export_test.go
new file mode 100644
index 0000000..2a87e9d
--- /dev/null
+++ b/src/internal/abi/export_test.go
@@ -0,0 +1,14 @@
+// Copyright 2021 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
+
+func FuncPCTestFn()
+
+var FuncPCTestFnAddr uintptr // address of FuncPCTestFn, directly retrieved from assembly
+
+//go:noinline
+func FuncPCTest() uintptr {
+	return FuncPCABI0(FuncPCTestFn)
+}
diff --git a/src/internal/abi/funcpc.go b/src/internal/abi/funcpc.go
new file mode 100644
index 0000000..e038d36
--- /dev/null
+++ b/src/internal/abi/funcpc.go
@@ -0,0 +1,31 @@
+// 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.
+
+//go:build !gccgo
+
+package abi
+
+// FuncPC* intrinsics.
+//
+// CAREFUL: In programs with plugins, FuncPC* can return different values
+// for the same function (because there are actually multiple copies of
+// the same function in the address space). To be safe, don't use the
+// results of this function in any == expression. It is only safe to
+// use the result as an address at which to start executing code.
+
+// FuncPCABI0 returns the entry PC of the function f, which must be a
+// direct reference of a function defined as ABI0. Otherwise it is a
+// compile-time error.
+//
+// Implemented as a compile intrinsic.
+func FuncPCABI0(f interface{}) uintptr
+
+// FuncPCABIInternal returns the entry PC of the function f. If f is a
+// direct reference of a function, it must be defined as ABIInternal.
+// Otherwise it is a compile-time error. If f is not a direct reference
+// of a defined function, it assumes that f is a func value. Otherwise
+// the behavior is undefined.
+//
+// Implemented as a compile intrinsic.
+func FuncPCABIInternal(f interface{}) uintptr
diff --git a/src/internal/abi/funcpc_gccgo.go b/src/internal/abi/funcpc_gccgo.go
new file mode 100644
index 0000000..ad5fa52
--- /dev/null
+++ b/src/internal/abi/funcpc_gccgo.go
@@ -0,0 +1,21 @@
+// 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.
+
+// For bootstrapping with gccgo.
+
+//go:build gccgo
+
+package abi
+
+import "unsafe"
+
+func FuncPCABI0(f interface{}) uintptr {
+	words := (*[2]unsafe.Pointer)(unsafe.Pointer(&f))
+	return *(*uintptr)(unsafe.Pointer(words[1]))
+}
+
+func FuncPCABIInternal(f interface{}) uintptr {
+	words := (*[2]unsafe.Pointer)(unsafe.Pointer(&f))
+	return *(*uintptr)(unsafe.Pointer(words[1]))
+}
diff --git a/src/internal/abi/map.go b/src/internal/abi/map.go
new file mode 100644
index 0000000..e5b0a0b
--- /dev/null
+++ b/src/internal/abi/map.go
@@ -0,0 +1,14 @@
+// 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
+
+// Map constants common to several packages
+// runtime/runtime-gdb.py:MapTypePrinter contains its own copy
+const (
+	MapBucketCountBits = 3 // log2 of number of elements in a bucket.
+	MapBucketCount     = 1 << MapBucketCountBits
+	MapMaxKeyBytes     = 128 // Must fit in a uint8.
+	MapMaxElemBytes    = 128 // Must fit in a uint8.
+)
diff --git a/src/internal/abi/stack.go b/src/internal/abi/stack.go
new file mode 100644
index 0000000..8e3327e
--- /dev/null
+++ b/src/internal/abi/stack.go
@@ -0,0 +1,33 @@
+// 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 (
+	// StackNosplitBase is the base maximum number of bytes that a chain of
+	// NOSPLIT functions can use.
+	//
+	// This value must be multiplied by the stack guard multiplier, so do not
+	// use it directly. See runtime/stack.go:stackNosplit and
+	// cmd/internal/objabi/stack.go:StackNosplit.
+	StackNosplitBase = 800
+
+	// 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
+)
diff --git a/src/internal/abi/stub.s b/src/internal/abi/stub.s
new file mode 100644
index 0000000..5bad98d
--- /dev/null
+++ b/src/internal/abi/stub.s
@@ -0,0 +1,7 @@
+// 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.
+
+// This file silences errors about body-less functions
+// that are provided by intrinsics in the latest version of the compiler,
+// but may not be known to the bootstrap compiler.
diff --git a/src/internal/abi/symtab.go b/src/internal/abi/symtab.go
new file mode 100644
index 0000000..bf6ea82
--- /dev/null
+++ b/src/internal/abi/symtab.go
@@ -0,0 +1,106 @@
+// 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
+
+// A FuncFlag records bits about a function, passed to the runtime.
+type FuncFlag uint8
+
+const (
+	// FuncFlagTopFrame indicates a function that appears at the top of its stack.
+	// The traceback routine stop at such a function and consider that a
+	// successful, complete traversal of the stack.
+	// Examples of TopFrame functions include goexit, which appears
+	// at the top of a user goroutine stack, and mstart, which appears
+	// at the top of a system goroutine stack.
+	FuncFlagTopFrame FuncFlag = 1 << iota
+
+	// FuncFlagSPWrite indicates a function that writes an arbitrary value to SP
+	// (any write other than adding or subtracting a constant amount).
+	// The traceback routines cannot encode such changes into the
+	// pcsp tables, so the function traceback cannot safely unwind past
+	// SPWrite functions. Stopping at an SPWrite function is considered
+	// to be an incomplete unwinding of the stack. In certain contexts
+	// (in particular garbage collector stack scans) that is a fatal error.
+	FuncFlagSPWrite
+
+	// FuncFlagAsm indicates that a function was implemented in assembly.
+	FuncFlagAsm
+)
+
+// A FuncID identifies particular functions that need to be treated
+// specially by the runtime.
+// Note that in some situations involving plugins, there may be multiple
+// copies of a particular special runtime function.
+type FuncID uint8
+
+const (
+	// If you add a FuncID, you probably also want to add an entry to the map in
+	// ../../cmd/internal/objabi/funcid.go
+
+	FuncIDNormal FuncID = iota // not a special function
+	FuncID_abort
+	FuncID_asmcgocall
+	FuncID_asyncPreempt
+	FuncID_cgocallback
+	FuncID_debugCallV2
+	FuncID_gcBgMarkWorker
+	FuncID_goexit
+	FuncID_gogo
+	FuncID_gopanic
+	FuncID_handleAsyncEvent
+	FuncID_mcall
+	FuncID_morestack
+	FuncID_mstart
+	FuncID_panicwrap
+	FuncID_rt0_go
+	FuncID_runfinq
+	FuncID_runtime_main
+	FuncID_sigpanic
+	FuncID_systemstack
+	FuncID_systemstack_switch
+	FuncIDWrapper // any autogenerated code (hash/eq algorithms, method wrappers, etc.)
+)
+
+// ArgsSizeUnknown is set in Func.argsize to mark all functions
+// whose argument size is unknown (C vararg functions, and
+// assembly code without an explicit specification).
+// This value is generated by the compiler, assembler, or linker.
+const ArgsSizeUnknown = -0x80000000
+
+// IDs for PCDATA and FUNCDATA tables in Go binaries.
+//
+// These must agree with ../../../runtime/funcdata.h.
+const (
+	PCDATA_UnsafePoint   = 0
+	PCDATA_StackMapIndex = 1
+	PCDATA_InlTreeIndex  = 2
+	PCDATA_ArgLiveIndex  = 3
+
+	FUNCDATA_ArgsPointerMaps    = 0
+	FUNCDATA_LocalsPointerMaps  = 1
+	FUNCDATA_StackObjects       = 2
+	FUNCDATA_InlTree            = 3
+	FUNCDATA_OpenCodedDeferInfo = 4
+	FUNCDATA_ArgInfo            = 5
+	FUNCDATA_ArgLiveInfo        = 6
+	FUNCDATA_WrapInfo           = 7
+)
+
+// Special values for the PCDATA_UnsafePoint table.
+const (
+	UnsafePointSafe   = -1 // Safe for async preemption
+	UnsafePointUnsafe = -2 // Unsafe for async preemption
+
+	// UnsafePointRestart1(2) apply on a sequence of instructions, within
+	// which if an async preemption happens, we should back off the PC
+	// to the start of the sequence when resuming.
+	// We need two so we can distinguish the start/end of the sequence
+	// in case that two sequences are next to each other.
+	UnsafePointRestart1 = -3
+	UnsafePointRestart2 = -4
+
+	// Like UnsafePointRestart1, but back to function entry if async preempted.
+	UnsafePointRestartAtEntry = -5
+)
diff --git a/src/internal/abi/testdata/x.go b/src/internal/abi/testdata/x.go
new file mode 100644
index 0000000..cae103d
--- /dev/null
+++ b/src/internal/abi/testdata/x.go
@@ -0,0 +1,22 @@
+// Copyright 2021 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 x
+
+import "internal/abi"
+
+func Fn0() // defined in assembly
+
+func Fn1() {}
+
+var FnExpr func()
+
+func test() {
+	_ = abi.FuncPCABI0(Fn0)           // line 16, no error
+	_ = abi.FuncPCABIInternal(Fn0)    // line 17, error
+	_ = abi.FuncPCABI0(Fn1)           // line 18, error
+	_ = abi.FuncPCABIInternal(Fn1)    // line 19, no error
+	_ = abi.FuncPCABI0(FnExpr)        // line 20, error
+	_ = abi.FuncPCABIInternal(FnExpr) // line 21, no error
+}
diff --git a/src/internal/abi/testdata/x.s b/src/internal/abi/testdata/x.s
new file mode 100644
index 0000000..63c1385
--- /dev/null
+++ b/src/internal/abi/testdata/x.s
@@ -0,0 +1,6 @@
+// Copyright 2021 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.
+
+TEXT	·Fn0(SB), 0, $0-0
+	RET
diff --git a/src/internal/abi/type.go b/src/internal/abi/type.go
new file mode 100644
index 0000000..4794f5a
--- /dev/null
+++ b/src/internal/abi/type.go
@@ -0,0 +1,712 @@
+// 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
+
+import (
+	"unsafe"
+)
+
+// Type is the runtime representation of a Go type.
+//
+// Type is also referenced implicitly
+// (in the form of expressions involving constants and arch.PtrSize)
+// in cmd/compile/internal/reflectdata/reflect.go
+// and cmd/link/internal/ld/decodesym.go
+// (e.g. data[2*arch.PtrSize+4] references the TFlag field)
+// unsafe.OffsetOf(Type{}.TFlag) cannot be used directly in those
+// places because it varies with cross compilation and experiments.
+type Type struct {
+	Size_       uintptr
+	PtrBytes    uintptr // number of (prefix) bytes in the type that can contain pointers
+	Hash        uint32  // hash of type; avoids computation in hash tables
+	TFlag       TFlag   // extra type information flags
+	Align_      uint8   // alignment of variable with this type
+	FieldAlign_ uint8   // alignment of struct field with this type
+	Kind_       uint8   // enumeration for C
+	// function for comparing objects of this type
+	// (ptr to object A, ptr to object B) -> ==?
+	Equal func(unsafe.Pointer, unsafe.Pointer) bool
+	// GCData stores the GC type data for the garbage collector.
+	// If the KindGCProg bit is set in kind, GCData is a GC program.
+	// Otherwise it is a ptrmask bitmap. See mbitmap.go for details.
+	GCData    *byte
+	Str       NameOff // string form
+	PtrToThis TypeOff // type for pointer to this type, may be zero
+}
+
+// A Kind represents the specific kind of type that a Type represents.
+// The zero Kind is not a valid kind.
+type Kind uint
+
+const (
+	Invalid Kind = iota
+	Bool
+	Int
+	Int8
+	Int16
+	Int32
+	Int64
+	Uint
+	Uint8
+	Uint16
+	Uint32
+	Uint64
+	Uintptr
+	Float32
+	Float64
+	Complex64
+	Complex128
+	Array
+	Chan
+	Func
+	Interface
+	Map
+	Pointer
+	Slice
+	String
+	Struct
+	UnsafePointer
+)
+
+const (
+	// TODO (khr, drchase) why aren't these in TFlag?  Investigate, fix if possible.
+	KindDirectIface = 1 << 5
+	KindGCProg      = 1 << 6 // Type.gc points to GC program
+	KindMask        = (1 << 5) - 1
+)
+
+// TFlag is used by a Type to signal what extra type information is
+// available in the memory directly following the Type value.
+type TFlag uint8
+
+const (
+	// TFlagUncommon means that there is a data with a type, UncommonType,
+	// just beyond the shared-per-type common data.  That is, the data
+	// for struct types will store their UncommonType at one offset, the
+	// data for interface types will store their UncommonType at a different
+	// offset.  UncommonType is always accessed via a pointer that is computed
+	// using trust-us-we-are-the-implementors pointer arithmetic.
+	//
+	// For example, if t.Kind() == Struct and t.tflag&TFlagUncommon != 0,
+	// then t has UncommonType data and it can be accessed as:
+	//
+	//	type structTypeUncommon struct {
+	//		structType
+	//		u UncommonType
+	//	}
+	//	u := &(*structTypeUncommon)(unsafe.Pointer(t)).u
+	TFlagUncommon TFlag = 1 << 0
+
+	// TFlagExtraStar means the name in the str field has an
+	// extraneous '*' prefix. This is because for most types T in
+	// a program, the type *T also exists and reusing the str data
+	// saves binary size.
+	TFlagExtraStar TFlag = 1 << 1
+
+	// TFlagNamed means the type has a name.
+	TFlagNamed TFlag = 1 << 2
+
+	// TFlagRegularMemory means that equal and hash functions can treat
+	// this type as a single region of t.size bytes.
+	TFlagRegularMemory TFlag = 1 << 3
+)
+
+// NameOff is the offset to a name from moduledata.types.  See resolveNameOff in runtime.
+type NameOff int32
+
+// TypeOff is the offset to a type from moduledata.types.  See resolveTypeOff in runtime.
+type TypeOff int32
+
+// TextOff is an offset from the top of a text section.  See (rtype).textOff in runtime.
+type TextOff int32
+
+// String returns the name of k.
+func (k Kind) String() string {
+	if int(k) < len(kindNames) {
+		return kindNames[k]
+	}
+	return kindNames[0]
+}
+
+var kindNames = []string{
+	Invalid:       "invalid",
+	Bool:          "bool",
+	Int:           "int",
+	Int8:          "int8",
+	Int16:         "int16",
+	Int32:         "int32",
+	Int64:         "int64",
+	Uint:          "uint",
+	Uint8:         "uint8",
+	Uint16:        "uint16",
+	Uint32:        "uint32",
+	Uint64:        "uint64",
+	Uintptr:       "uintptr",
+	Float32:       "float32",
+	Float64:       "float64",
+	Complex64:     "complex64",
+	Complex128:    "complex128",
+	Array:         "array",
+	Chan:          "chan",
+	Func:          "func",
+	Interface:     "interface",
+	Map:           "map",
+	Pointer:       "ptr",
+	Slice:         "slice",
+	String:        "string",
+	Struct:        "struct",
+	UnsafePointer: "unsafe.Pointer",
+}
+
+func (t *Type) Kind() Kind { return Kind(t.Kind_ & KindMask) }
+
+func (t *Type) HasName() bool {
+	return t.TFlag&TFlagNamed != 0
+}
+
+func (t *Type) Pointers() bool { return t.PtrBytes != 0 }
+
+// IfaceIndir reports whether t is stored indirectly in an interface value.
+func (t *Type) IfaceIndir() bool {
+	return t.Kind_&KindDirectIface == 0
+}
+
+// isDirectIface reports whether t is stored directly in an interface value.
+func (t *Type) IsDirectIface() bool {
+	return t.Kind_&KindDirectIface != 0
+}
+
+func (t *Type) GcSlice(begin, end uintptr) []byte {
+	return unsafeSliceFor(t.GCData, int(end))[begin:]
+}
+
+// Method on non-interface type
+type Method struct {
+	Name NameOff // name of method
+	Mtyp TypeOff // method type (without receiver)
+	Ifn  TextOff // fn used in interface call (one-word receiver)
+	Tfn  TextOff // fn used for normal method call
+}
+
+// UncommonType is present only for defined types or types with methods
+// (if T is a defined type, the uncommonTypes for T and *T have methods).
+// Using a pointer to this struct reduces the overall size required
+// to describe a non-defined type with no methods.
+type UncommonType struct {
+	PkgPath NameOff // import path; empty for built-in types like int, string
+	Mcount  uint16  // number of methods
+	Xcount  uint16  // number of exported methods
+	Moff    uint32  // offset from this uncommontype to [mcount]Method
+	_       uint32  // unused
+}
+
+func (t *UncommonType) Methods() []Method {
+	if t.Mcount == 0 {
+		return nil
+	}
+	return (*[1 << 16]Method)(addChecked(unsafe.Pointer(t), uintptr(t.Moff), "t.mcount > 0"))[:t.Mcount:t.Mcount]
+}
+
+func (t *UncommonType) ExportedMethods() []Method {
+	if t.Xcount == 0 {
+		return nil
+	}
+	return (*[1 << 16]Method)(addChecked(unsafe.Pointer(t), uintptr(t.Moff), "t.xcount > 0"))[:t.Xcount:t.Xcount]
+}
+
+// addChecked returns p+x.
+//
+// The whySafe string is ignored, so that the function still inlines
+// as efficiently as p+x, but all call sites should use the string to
+// record why the addition is safe, which is to say why the addition
+// does not cause x to advance to the very end of p's allocation
+// and therefore point incorrectly at the next block in memory.
+func addChecked(p unsafe.Pointer, x uintptr, whySafe string) unsafe.Pointer {
+	return unsafe.Pointer(uintptr(p) + x)
+}
+
+// Imethod represents a method on an interface type
+type Imethod struct {
+	Name NameOff // name of method
+	Typ  TypeOff // .(*FuncType) underneath
+}
+
+// ArrayType represents a fixed array type.
+type ArrayType struct {
+	Type
+	Elem  *Type // array element type
+	Slice *Type // slice type
+	Len   uintptr
+}
+
+// Len returns the length of t if t is an array type, otherwise 0
+func (t *Type) Len() int {
+	if t.Kind() == Array {
+		return int((*ArrayType)(unsafe.Pointer(t)).Len)
+	}
+	return 0
+}
+
+func (t *Type) Common() *Type {
+	return t
+}
+
+type ChanDir int
+
+const (
+	RecvDir    ChanDir = 1 << iota         // <-chan
+	SendDir                                // chan<-
+	BothDir            = RecvDir | SendDir // chan
+	InvalidDir ChanDir = 0
+)
+
+// ChanType represents a channel type
+type ChanType struct {
+	Type
+	Elem *Type
+	Dir  ChanDir
+}
+
+type structTypeUncommon struct {
+	StructType
+	u UncommonType
+}
+
+// ChanDir returns the direction of t if t is a channel type, otherwise InvalidDir (0).
+func (t *Type) ChanDir() ChanDir {
+	if t.Kind() == Chan {
+		ch := (*ChanType)(unsafe.Pointer(t))
+		return ch.Dir
+	}
+	return InvalidDir
+}
+
+// Uncommon returns a pointer to T's "uncommon" data if there is any, otherwise nil
+func (t *Type) Uncommon() *UncommonType {
+	if t.TFlag&TFlagUncommon == 0 {
+		return nil
+	}
+	switch t.Kind() {
+	case Struct:
+		return &(*structTypeUncommon)(unsafe.Pointer(t)).u
+	case Pointer:
+		type u struct {
+			PtrType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	case Func:
+		type u struct {
+			FuncType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	case Slice:
+		type u struct {
+			SliceType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	case Array:
+		type u struct {
+			ArrayType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	case Chan:
+		type u struct {
+			ChanType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	case Map:
+		type u struct {
+			MapType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	case Interface:
+		type u struct {
+			InterfaceType
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	default:
+		type u struct {
+			Type
+			u UncommonType
+		}
+		return &(*u)(unsafe.Pointer(t)).u
+	}
+}
+
+// Elem returns the element type for t if t is an array, channel, map, pointer, or slice, otherwise nil.
+func (t *Type) Elem() *Type {
+	switch t.Kind() {
+	case Array:
+		tt := (*ArrayType)(unsafe.Pointer(t))
+		return tt.Elem
+	case Chan:
+		tt := (*ChanType)(unsafe.Pointer(t))
+		return tt.Elem
+	case Map:
+		tt := (*MapType)(unsafe.Pointer(t))
+		return tt.Elem
+	case Pointer:
+		tt := (*PtrType)(unsafe.Pointer(t))
+		return tt.Elem
+	case Slice:
+		tt := (*SliceType)(unsafe.Pointer(t))
+		return tt.Elem
+	}
+	return nil
+}
+
+// StructType returns t cast to a *StructType, or nil if its tag does not match.
+func (t *Type) StructType() *StructType {
+	if t.Kind() != Struct {
+		return nil
+	}
+	return (*StructType)(unsafe.Pointer(t))
+}
+
+// MapType returns t cast to a *MapType, or nil if its tag does not match.
+func (t *Type) MapType() *MapType {
+	if t.Kind() != Map {
+		return nil
+	}
+	return (*MapType)(unsafe.Pointer(t))
+}
+
+// ArrayType returns t cast to a *ArrayType, or nil if its tag does not match.
+func (t *Type) ArrayType() *ArrayType {
+	if t.Kind() != Array {
+		return nil
+	}
+	return (*ArrayType)(unsafe.Pointer(t))
+}
+
+// FuncType returns t cast to a *FuncType, or nil if its tag does not match.
+func (t *Type) FuncType() *FuncType {
+	if t.Kind() != Func {
+		return nil
+	}
+	return (*FuncType)(unsafe.Pointer(t))
+}
+
+// InterfaceType returns t cast to a *InterfaceType, or nil if its tag does not match.
+func (t *Type) InterfaceType() *InterfaceType {
+	if t.Kind() != Interface {
+		return nil
+	}
+	return (*InterfaceType)(unsafe.Pointer(t))
+}
+
+// Size returns the size of data with type t.
+func (t *Type) Size() uintptr { return t.Size_ }
+
+// Align returns the alignment of data with type t.
+func (t *Type) Align() int { return int(t.Align_) }
+
+func (t *Type) FieldAlign() int { return int(t.FieldAlign_) }
+
+type InterfaceType struct {
+	Type
+	PkgPath Name      // import path
+	Methods []Imethod // sorted by hash
+}
+
+func (t *Type) ExportedMethods() []Method {
+	ut := t.Uncommon()
+	if ut == nil {
+		return nil
+	}
+	return ut.ExportedMethods()
+}
+
+func (t *Type) NumMethod() int {
+	if t.Kind() == Interface {
+		tt := (*InterfaceType)(unsafe.Pointer(t))
+		return tt.NumMethod()
+	}
+	return len(t.ExportedMethods())
+}
+
+// NumMethod returns the number of interface methods in the type's method set.
+func (t *InterfaceType) NumMethod() int { return len(t.Methods) }
+
+type MapType struct {
+	Type
+	Key    *Type
+	Elem   *Type
+	Bucket *Type // internal type representing a hash bucket
+	// function for hashing keys (ptr to key, seed) -> hash
+	Hasher     func(unsafe.Pointer, uintptr) uintptr
+	KeySize    uint8  // size of key slot
+	ValueSize  uint8  // size of elem slot
+	BucketSize uint16 // size of bucket
+	Flags      uint32
+}
+
+// Note: flag values must match those used in the TMAP case
+// in ../cmd/compile/internal/reflectdata/reflect.go:writeType.
+func (mt *MapType) IndirectKey() bool { // store ptr to key instead of key itself
+	return mt.Flags&1 != 0
+}
+func (mt *MapType) IndirectElem() bool { // store ptr to elem instead of elem itself
+	return mt.Flags&2 != 0
+}
+func (mt *MapType) ReflexiveKey() bool { // true if k==k for all keys
+	return mt.Flags&4 != 0
+}
+func (mt *MapType) NeedKeyUpdate() bool { // true if we need to update key on an overwrite
+	return mt.Flags&8 != 0
+}
+func (mt *MapType) HashMightPanic() bool { // true if hash function might panic
+	return mt.Flags&16 != 0
+}
+
+func (t *Type) Key() *Type {
+	if t.Kind() == Map {
+		return (*MapType)(unsafe.Pointer(t)).Key
+	}
+	return nil
+}
+
+type SliceType struct {
+	Type
+	Elem *Type // slice element type
+}
+
+// funcType represents a function type.
+//
+// A *Type for each in and out parameter is stored in an array that
+// directly follows the funcType (and possibly its uncommonType). So
+// a function type with one method, one input, and one output is:
+//
+//	struct {
+//		funcType
+//		uncommonType
+//		[2]*rtype    // [0] is in, [1] is out
+//	}
+type FuncType struct {
+	Type
+	InCount  uint16
+	OutCount uint16 // top bit is set if last input parameter is ...
+}
+
+func (t *FuncType) In(i int) *Type {
+	return t.InSlice()[i]
+}
+
+func (t *FuncType) NumIn() int {
+	return int(t.InCount)
+}
+
+func (t *FuncType) NumOut() int {
+	return int(t.OutCount & (1<<15 - 1))
+}
+
+func (t *FuncType) Out(i int) *Type {
+	return (t.OutSlice()[i])
+}
+
+func (t *FuncType) InSlice() []*Type {
+	uadd := unsafe.Sizeof(*t)
+	if t.TFlag&TFlagUncommon != 0 {
+		uadd += unsafe.Sizeof(UncommonType{})
+	}
+	if t.InCount == 0 {
+		return nil
+	}
+	return (*[1 << 16]*Type)(addChecked(unsafe.Pointer(t), uadd, "t.inCount > 0"))[:t.InCount:t.InCount]
+}
+func (t *FuncType) OutSlice() []*Type {
+	outCount := uint16(t.NumOut())
+	if outCount == 0 {
+		return nil
+	}
+	uadd := unsafe.Sizeof(*t)
+	if t.TFlag&TFlagUncommon != 0 {
+		uadd += unsafe.Sizeof(UncommonType{})
+	}
+	return (*[1 << 17]*Type)(addChecked(unsafe.Pointer(t), uadd, "outCount > 0"))[t.InCount : t.InCount+outCount : t.InCount+outCount]
+}
+
+func (t *FuncType) IsVariadic() bool {
+	return t.OutCount&(1<<15) != 0
+}
+
+type PtrType struct {
+	Type
+	Elem *Type // pointer element (pointed at) type
+}
+
+type StructField struct {
+	Name   Name    // name is always non-empty
+	Typ    *Type   // type of field
+	Offset uintptr // byte offset of field
+}
+
+func (f *StructField) Embedded() bool {
+	return f.Name.IsEmbedded()
+}
+
+type StructType struct {
+	Type
+	PkgPath Name
+	Fields  []StructField
+}
+
+// Name is an encoded type Name with optional extra data.
+//
+// The first byte is a bit field containing:
+//
+//	1<<0 the name is exported
+//	1<<1 tag data follows the name
+//	1<<2 pkgPath nameOff follows the name and tag
+//	1<<3 the name is of an embedded (a.k.a. anonymous) field
+//
+// Following that, there is a varint-encoded length of the name,
+// followed by the name itself.
+//
+// If tag data is present, it also has a varint-encoded length
+// followed by the tag itself.
+//
+// If the import path follows, then 4 bytes at the end of
+// the data form a nameOff. The import path is only set for concrete
+// methods that are defined in a different package than their type.
+//
+// If a name starts with "*", then the exported bit represents
+// whether the pointed to type is exported.
+//
+// Note: this encoding must match here and in:
+//   cmd/compile/internal/reflectdata/reflect.go
+//   cmd/link/internal/ld/decodesym.go
+
+type Name struct {
+	Bytes *byte
+}
+
+// DataChecked does pointer arithmetic on n's Bytes, and that arithmetic is asserted to
+// be safe for the reason in whySafe (which can appear in a backtrace, etc.)
+func (n Name) DataChecked(off int, whySafe string) *byte {
+	return (*byte)(addChecked(unsafe.Pointer(n.Bytes), uintptr(off), whySafe))
+}
+
+// Data does pointer arithmetic on n's Bytes, and that arithmetic is asserted to
+// be safe because the runtime made the call (other packages use DataChecked)
+func (n Name) Data(off int) *byte {
+	return (*byte)(addChecked(unsafe.Pointer(n.Bytes), uintptr(off), "the runtime doesn't need to give you a reason"))
+}
+
+// IsExported returns "is n exported?"
+func (n Name) IsExported() bool {
+	return (*n.Bytes)&(1<<0) != 0
+}
+
+// HasTag returns true iff there is tag data following this name
+func (n Name) HasTag() bool {
+	return (*n.Bytes)&(1<<1) != 0
+}
+
+// IsEmbedded returns true iff n is embedded (an anonymous field).
+func (n Name) IsEmbedded() bool {
+	return (*n.Bytes)&(1<<3) != 0
+}
+
+// ReadVarint parses a varint as encoded by encoding/binary.
+// It returns the number of encoded bytes and the encoded value.
+func (n Name) ReadVarint(off int) (int, int) {
+	v := 0
+	for i := 0; ; i++ {
+		x := *n.DataChecked(off+i, "read varint")
+		v += int(x&0x7f) << (7 * i)
+		if x&0x80 == 0 {
+			return i + 1, v
+		}
+	}
+}
+
+// IsBlank indicates whether n is "_".
+func (n Name) IsBlank() bool {
+	if n.Bytes == nil {
+		return false
+	}
+	_, l := n.ReadVarint(1)
+	return l == 1 && *n.Data(2) == '_'
+}
+
+// writeVarint writes n to buf in varint form. Returns the
+// number of bytes written. n must be nonnegative.
+// Writes at most 10 bytes.
+func writeVarint(buf []byte, n int) int {
+	for i := 0; ; i++ {
+		b := byte(n & 0x7f)
+		n >>= 7
+		if n == 0 {
+			buf[i] = b
+			return i + 1
+		}
+		buf[i] = b | 0x80
+	}
+}
+
+// Name returns the tag string for n, or empty if there is none.
+func (n Name) Name() string {
+	if n.Bytes == nil {
+		return ""
+	}
+	i, l := n.ReadVarint(1)
+	return unsafeStringFor(n.DataChecked(1+i, "non-empty string"), l)
+}
+
+// Tag returns the tag string for n, or empty if there is none.
+func (n Name) Tag() string {
+	if !n.HasTag() {
+		return ""
+	}
+	i, l := n.ReadVarint(1)
+	i2, l2 := n.ReadVarint(1 + i + l)
+	return unsafeStringFor(n.DataChecked(1+i+l+i2, "non-empty string"), l2)
+}
+
+func NewName(n, tag string, exported, embedded bool) Name {
+	if len(n) >= 1<<29 {
+		panic("abi.NewName: name too long: " + n[:1024] + "...")
+	}
+	if len(tag) >= 1<<29 {
+		panic("abi.NewName: tag too long: " + tag[:1024] + "...")
+	}
+	var nameLen [10]byte
+	var tagLen [10]byte
+	nameLenLen := writeVarint(nameLen[:], len(n))
+	tagLenLen := writeVarint(tagLen[:], len(tag))
+
+	var bits byte
+	l := 1 + nameLenLen + len(n)
+	if exported {
+		bits |= 1 << 0
+	}
+	if len(tag) > 0 {
+		l += tagLenLen + len(tag)
+		bits |= 1 << 1
+	}
+	if embedded {
+		bits |= 1 << 3
+	}
+
+	b := make([]byte, l)
+	b[0] = bits
+	copy(b[1:], nameLen[:nameLenLen])
+	copy(b[1+nameLenLen:], n)
+	if len(tag) > 0 {
+		tb := b[1+nameLenLen+len(n):]
+		copy(tb, tagLen[:tagLenLen])
+		copy(tb[tagLenLen:], tag)
+	}
+
+	return Name{Bytes: &b[0]}
+}
diff --git a/src/internal/abi/unsafestring_go119.go b/src/internal/abi/unsafestring_go119.go
new file mode 100644
index 0000000..a710384
--- /dev/null
+++ b/src/internal/abi/unsafestring_go119.go
@@ -0,0 +1,32 @@
+// 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.
+
+//go:build !go1.20
+// +build !go1.20
+
+package abi
+
+import "unsafe"
+
+type (
+	stringHeader struct {
+		Data *byte
+		Len  int
+	}
+	sliceHeader struct {
+		Data *byte
+		Len  int
+		Cap  int
+	}
+)
+
+func unsafeStringFor(b *byte, l int) string {
+	h := stringHeader{Data: b, Len: l}
+	return *(*string)(unsafe.Pointer(&h))
+}
+
+func unsafeSliceFor(b *byte, l int) []byte {
+	h := sliceHeader{Data: b, Len: l, Cap: l}
+	return *(*[]byte)(unsafe.Pointer(&h))
+}
diff --git a/src/internal/abi/unsafestring_go120.go b/src/internal/abi/unsafestring_go120.go
new file mode 100644
index 0000000..93ff8ea
--- /dev/null
+++ b/src/internal/abi/unsafestring_go120.go
@@ -0,0 +1,18 @@
+// 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.
+
+//go:build go1.20
+// +build go1.20
+
+package abi
+
+import "unsafe"
+
+func unsafeStringFor(b *byte, l int) string {
+	return unsafe.String(b, l)
+}
+
+func unsafeSliceFor(b *byte, l int) []byte {
+	return unsafe.Slice(b, l)
+}