runtime,reflect: move zeroVal to internal/abi

Change-Id: I0e19e4aa2ea47a714e27b8d66c23c449e27861f2
GitHub-Last-Rev: 2d59b9589efcf4ade6cfd7c8feffc46bf9ba912c
GitHub-Pull-Request: golang/go#67014
Reviewed-on: https://go-review.googlesource.com/c/go/+/581395
Reviewed-by: Keith Randall <khr@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Joedian Reid <joedian@google.com>

8 files changed, 32 insertions, 35 deletions

diff --git a/src/internal/abi/runtime.go b/src/internal/abi/runtime.go
index 9b91cdf5ef..2a3181a48d 100644
--- a/src/internal/abi/runtime.go
+++ b/src/internal/abi/runtime.go
@@ -4,5 +4,8 @@
 
 package abi
 
-// ZeroValSize is the size in bytes of runtime.zeroVal.
+// ZeroValSize is the size in bytes of [ZeroVal].
 const ZeroValSize = 1024
+
+// ZeroVal is a region containing all zero bytes.
+var ZeroVal [ZeroValSize]byte
diff --git a/src/reflect/value.go b/src/reflect/value.go
index 4b936bf5bb..06f2c2b7da 100644
--- a/src/reflect/value.go
+++ b/src/reflect/value.go
@@ -1591,7 +1591,7 @@ func (v Value) IsZero() bool {
 			// v.ptr doesn't escape, as Equal functions are compiler generated
 			// and never escape. The escape analysis doesn't know, as it is a
 			// function pointer call.
-			return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&zeroVal[0]))
+			return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&abi.ZeroVal[0]))
 		}
 		if typ.TFlag&abi.TFlagRegularMemory != 0 {
 			// For some types where the zero value is a value where all bits of this type are 0
@@ -1617,7 +1617,7 @@ func (v Value) IsZero() bool {
 		// If the type is comparable, then compare directly with zero.
 		if typ.Equal != nil && typ.Size() <= abi.ZeroValSize {
 			// See noescape justification above.
-			return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&zeroVal[0]))
+			return typ.Equal(abi.NoEscape(v.ptr), unsafe.Pointer(&abi.ZeroVal[0]))
 		}
 		if typ.TFlag&abi.TFlagRegularMemory != 0 {
 			// For some types where the zero value is a value where all bits of this type are 0
@@ -2312,7 +2312,7 @@ func (v Value) Set(x Value) {
 	}
 	x = x.assignTo("reflect.Set", v.typ(), target)
 	if x.flag&flagIndir != 0 {
-		if x.ptr == unsafe.Pointer(&zeroVal[0]) {
+		if x.ptr == unsafe.Pointer(&abi.ZeroVal[0]) {
 			typedmemclr(v.typ(), v.ptr)
 		} else {
 			typedmemmove(v.typ(), v.ptr, x.ptr)
@@ -3280,7 +3280,7 @@ func Zero(typ Type) Value {
 	if t.IfaceIndir() {
 		var p unsafe.Pointer
 		if t.Size() <= abi.ZeroValSize {
-			p = unsafe.Pointer(&zeroVal[0])
+			p = unsafe.Pointer(&abi.ZeroVal[0])
 		} else {
 			p = unsafe_New(t)
 		}
@@ -3289,9 +3289,6 @@ func Zero(typ Type) Value {
 	return Value{t, nil, fl}
 }
 
-//go:linkname zeroVal runtime.zeroVal
-var zeroVal [abi.ZeroValSize]byte
-
 // New returns a Value representing a pointer to a new zero value
 // for the specified type. That is, the returned Value's Type is [PointerTo](typ).
 func New(typ Type) Value {
diff --git a/src/runtime/iface.go b/src/runtime/iface.go
index e280180665..28eb8fb5ec 100644
--- a/src/runtime/iface.go
+++ b/src/runtime/iface.go
@@ -391,7 +391,7 @@ func convT64(val uint64) (x unsafe.Pointer) {
 
 func convTstring(val string) (x unsafe.Pointer) {
 	if val == "" {
-		x = unsafe.Pointer(&zeroVal[0])
+		x = unsafe.Pointer(&abi.ZeroVal[0])
 	} else {
 		x = mallocgc(unsafe.Sizeof(val), stringType, true)
 		*(*string)(x) = val
@@ -402,7 +402,7 @@ func convTstring(val string) (x unsafe.Pointer) {
 func convTslice(val []byte) (x unsafe.Pointer) {
 	// Note: this must work for any element type, not just byte.
 	if (*slice)(unsafe.Pointer(&val)).array == nil {
-		x = unsafe.Pointer(&zeroVal[0])
+		x = unsafe.Pointer(&abi.ZeroVal[0])
 	} else {
 		x = mallocgc(unsafe.Sizeof(val), sliceType, true)
 		*(*[]byte)(x) = val
diff --git a/src/runtime/map.go b/src/runtime/map.go
index d97e209deb..9e8ae67a35 100644
--- a/src/runtime/map.go
+++ b/src/runtime/map.go
@@ -402,7 +402,7 @@ func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
 		if err := mapKeyError(t, key); err != nil {
 			panic(err) // see issue 23734
 		}
-		return unsafe.Pointer(&zeroVal[0])
+		return unsafe.Pointer(&abi.ZeroVal[0])
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -443,7 +443,7 @@ bucketloop:
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0])
+	return unsafe.Pointer(&abi.ZeroVal[0])
 }
 
 func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
@@ -463,7 +463,7 @@ func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool)
 		if err := mapKeyError(t, key); err != nil {
 			panic(err) // see issue 23734
 		}
-		return unsafe.Pointer(&zeroVal[0]), false
+		return unsafe.Pointer(&abi.ZeroVal[0]), false
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -504,7 +504,7 @@ bucketloop:
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0]), false
+	return unsafe.Pointer(&abi.ZeroVal[0]), false
 }
 
 // returns both key and elem. Used by map iterator.
@@ -553,7 +553,7 @@ bucketloop:
 
 func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointer {
 	e := mapaccess1(t, h, key)
-	if e == unsafe.Pointer(&zeroVal[0]) {
+	if e == unsafe.Pointer(&abi.ZeroVal[0]) {
 		return zero
 	}
 	return e
@@ -561,7 +561,7 @@ func mapaccess1_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) unsafe.Pointe
 
 func mapaccess2_fat(t *maptype, h *hmap, key, zero unsafe.Pointer) (unsafe.Pointer, bool) {
 	e := mapaccess1(t, h, key)
-	if e == unsafe.Pointer(&zeroVal[0]) {
+	if e == unsafe.Pointer(&abi.ZeroVal[0]) {
 		return zero, false
 	}
 	return e, true
diff --git a/src/runtime/map_fast32.go b/src/runtime/map_fast32.go
index 7e52240e77..06dcbcabc4 100644
--- a/src/runtime/map_fast32.go
+++ b/src/runtime/map_fast32.go
@@ -16,7 +16,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
 		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast32))
 	}
 	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0])
+		return unsafe.Pointer(&abi.ZeroVal[0])
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -47,7 +47,7 @@ func mapaccess1_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0])
+	return unsafe.Pointer(&abi.ZeroVal[0])
 }
 
 func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
@@ -56,7 +56,7 @@ func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
 		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast32))
 	}
 	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0]), false
+		return unsafe.Pointer(&abi.ZeroVal[0]), false
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -87,7 +87,7 @@ func mapaccess2_fast32(t *maptype, h *hmap, key uint32) (unsafe.Pointer, bool) {
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0]), false
+	return unsafe.Pointer(&abi.ZeroVal[0]), false
 }
 
 func mapassign_fast32(t *maptype, h *hmap, key uint32) unsafe.Pointer {
diff --git a/src/runtime/map_fast64.go b/src/runtime/map_fast64.go
index 2c365183cb..c8b34dd41b 100644
--- a/src/runtime/map_fast64.go
+++ b/src/runtime/map_fast64.go
@@ -16,7 +16,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
 		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_fast64))
 	}
 	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0])
+		return unsafe.Pointer(&abi.ZeroVal[0])
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -47,7 +47,7 @@ func mapaccess1_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0])
+	return unsafe.Pointer(&abi.ZeroVal[0])
 }
 
 func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
@@ -56,7 +56,7 @@ func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
 		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_fast64))
 	}
 	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0]), false
+		return unsafe.Pointer(&abi.ZeroVal[0]), false
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -87,7 +87,7 @@ func mapaccess2_fast64(t *maptype, h *hmap, key uint64) (unsafe.Pointer, bool) {
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0]), false
+	return unsafe.Pointer(&abi.ZeroVal[0]), false
 }
 
 func mapassign_fast64(t *maptype, h *hmap, key uint64) unsafe.Pointer {
diff --git a/src/runtime/map_faststr.go b/src/runtime/map_faststr.go
index d989190f71..38841aee4b 100644
--- a/src/runtime/map_faststr.go
+++ b/src/runtime/map_faststr.go
@@ -16,7 +16,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess1_faststr))
 	}
 	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0])
+		return unsafe.Pointer(&abi.ZeroVal[0])
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -39,7 +39,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 					return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+i*uintptr(t.ValueSize))
 				}
 			}
-			return unsafe.Pointer(&zeroVal[0])
+			return unsafe.Pointer(&abi.ZeroVal[0])
 		}
 		// long key, try not to do more comparisons than necessary
 		keymaybe := uintptr(abi.MapBucketCount)
@@ -74,7 +74,7 @@ func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
 				return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+keymaybe*uintptr(t.ValueSize))
 			}
 		}
-		return unsafe.Pointer(&zeroVal[0])
+		return unsafe.Pointer(&abi.ZeroVal[0])
 	}
 dohash:
 	hash := t.Hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
@@ -102,7 +102,7 @@ dohash:
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0])
+	return unsafe.Pointer(&abi.ZeroVal[0])
 }
 
 func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
@@ -111,7 +111,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 		racereadpc(unsafe.Pointer(h), callerpc, abi.FuncPCABIInternal(mapaccess2_faststr))
 	}
 	if h == nil || h.count == 0 {
-		return unsafe.Pointer(&zeroVal[0]), false
+		return unsafe.Pointer(&abi.ZeroVal[0]), false
 	}
 	if h.flags&hashWriting != 0 {
 		fatal("concurrent map read and map write")
@@ -134,7 +134,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 					return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+i*uintptr(t.ValueSize)), true
 				}
 			}
-			return unsafe.Pointer(&zeroVal[0]), false
+			return unsafe.Pointer(&abi.ZeroVal[0]), false
 		}
 		// long key, try not to do more comparisons than necessary
 		keymaybe := uintptr(abi.MapBucketCount)
@@ -169,7 +169,7 @@ func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
 				return add(unsafe.Pointer(b), dataOffset+abi.MapBucketCount*2*goarch.PtrSize+keymaybe*uintptr(t.ValueSize)), true
 			}
 		}
-		return unsafe.Pointer(&zeroVal[0]), false
+		return unsafe.Pointer(&abi.ZeroVal[0]), false
 	}
 dohash:
 	hash := t.Hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
@@ -197,7 +197,7 @@ dohash:
 			}
 		}
 	}
-	return unsafe.Pointer(&zeroVal[0]), false
+	return unsafe.Pointer(&abi.ZeroVal[0]), false
 }
 
 func mapassign_faststr(t *maptype, h *hmap, s string) unsafe.Pointer {
diff --git a/src/runtime/runtime.go b/src/runtime/runtime.go
index 6ec0369a7e..cc6f03d2a0 100644
--- a/src/runtime/runtime.go
+++ b/src/runtime/runtime.go
@@ -5,7 +5,6 @@
 package runtime
 
 import (
-	"internal/abi"
 	"internal/runtime/atomic"
 	"unsafe"
 )
@@ -297,5 +296,3 @@ func setCrashFD(fd uintptr) uintptr {
 var auxv []uintptr
 
 func getAuxv() []uintptr { return auxv } // accessed from x/sys/cpu; see issue 57336
-
-var zeroVal [abi.ZeroValSize]byte