internal/bytealg, runtime: provide linknames for pushed symbols

The internal/bytealg package defines several symbols in the runtime,
bytes, and strings packages in assembly, and the runtime package
defines symbols in reflect and sync/atomic. Currently, there's no
corresponding Go prototype for these symbols in the defining package.

We're going to start depending on Go prototypes in the same package as
their assembly definitions in order to provide ABI wrappers. Plus,
these are good documentation and colocate type information with
definitions, which could be useful for vet if it learned a little
about linkname.

This CL adds linknamed Go prototypes for all pushed symbols in
internal/bytealg and runtime.

For #27539.

Change-Id: I9b0c12d935a75bb6af46b6761180d451c00f11b8
Reviewed-on: https://go-review.googlesource.com/c/146820
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

src/internal/bytealg/compare_native.go

@@ -6,5 +6,14 @@
 
 package bytealg
 
+import _ "unsafe" // For go:linkname
+
 //go:noescape
 func Compare(a, b []byte) int
+
+// The declaration below generates ABI wrappers for functions
+// implemented in assembly in this package but declared in another
+// package.
+
+//go:linkname abigen_runtime_cmpstring runtime.cmpstring
+func abigen_runtime_cmpstring(a, b string) int

src/internal/bytealg/equal_native.go

@@ -4,11 +4,23 @@
 
 package bytealg
 
+import "unsafe"
+
 // Note: there's no equal_generic.go because every platform must implement at least memequal_varlen in assembly.
 
 //go:noescape
 func Equal(a, b []byte) bool
 
+// The declarations below generate ABI wrappers for functions
+// implemented in assembly in this package but declared in another
+// package.
+
 // The compiler generates calls to runtime.memequal and runtime.memequal_varlen.
 // In addition, the runtime calls runtime.memequal explicitly.
 // Those functions are implemented in this package.
+
+//go:linkname abigen_runtime_memequal runtime.memequal
+func abigen_runtime_memequal(a, b unsafe.Pointer, size uintptr) bool
+
+//go:linkname abigen_runtime_memequal_varlen runtime.memequal_varlen
+func abigen_runtime_memequal_varlen(a, b unsafe.Pointer) bool

src/runtime/race.go

@@ -496,3 +496,76 @@ func racereleasemergeg(gp *g, addr unsafe.Pointer) {
 func racefingo() {
 	racecall(&__tsan_finalizer_goroutine, getg().racectx, 0, 0, 0)
 }
+
+// The declarations below generate ABI wrappers for functions
+// implemented in assembly in this package but declared in another
+// package.
+
+//go:linkname abigen_sync_atomic_LoadInt32 sync/atomic.LoadInt32
+func abigen_sync_atomic_LoadInt32(addr *int32) (val int32)
+
+//go:linkname abigen_sync_atomic_LoadInt64 sync/atomic.LoadInt64
+func abigen_sync_atomic_LoadInt64(addr *int64) (val int64)
+
+//go:linkname abigen_sync_atomic_LoadUint32 sync/atomic.LoadUint32
+func abigen_sync_atomic_LoadUint32(addr *uint32) (val uint32)
+
+//go:linkname abigen_sync_atomic_LoadUint64 sync/atomic.LoadUint64
+func abigen_sync_atomic_LoadUint64(addr *uint64) (val uint64)
+
+//go:linkname abigen_sync_atomic_LoadUintptr sync/atomic.LoadUintptr
+func abigen_sync_atomic_LoadUintptr(addr *uintptr) (val uintptr)
+
+//go:linkname abigen_sync_atomic_LoadPointer sync/atomic.LoadPointer
+func abigen_sync_atomic_LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)
+
+//go:linkname abigen_sync_atomic_StoreInt32 sync/atomic.StoreInt32
+func abigen_sync_atomic_StoreInt32(addr *int32, val int32)
+
+//go:linkname abigen_sync_atomic_StoreInt64 sync/atomic.StoreInt64
+func abigen_sync_atomic_StoreInt64(addr *int64, val int64)
+
+//go:linkname abigen_sync_atomic_StoreUint32 sync/atomic.StoreUint32
+func abigen_sync_atomic_StoreUint32(addr *uint32, val uint32)
+
+//go:linkname abigen_sync_atomic_StoreUint64 sync/atomic.StoreUint64
+func abigen_sync_atomic_StoreUint64(addr *uint64, val uint64)
+
+//go:linkname abigen_sync_atomic_SwapInt32 sync/atomic.SwapInt32
+func abigen_sync_atomic_SwapInt32(addr *int32, new int32) (old int32)
+
+//go:linkname abigen_sync_atomic_SwapInt64 sync/atomic.SwapInt64
+func abigen_sync_atomic_SwapInt64(addr *int64, new int64) (old int64)
+
+//go:linkname abigen_sync_atomic_SwapUint32 sync/atomic.SwapUint32
+func abigen_sync_atomic_SwapUint32(addr *uint32, new uint32) (old uint32)
+
+//go:linkname abigen_sync_atomic_SwapUint64 sync/atomic.SwapUint64
+func abigen_sync_atomic_SwapUint64(addr *uint64, new uint64) (old uint64)
+
+//go:linkname abigen_sync_atomic_AddInt32 sync/atomic.AddInt32
+func abigen_sync_atomic_AddInt32(addr *int32, delta int32) (new int32)
+
+//go:linkname abigen_sync_atomic_AddUint32 sync/atomic.AddUint32
+func abigen_sync_atomic_AddUint32(addr *uint32, delta uint32) (new uint32)
+
+//go:linkname abigen_sync_atomic_AddInt64 sync/atomic.AddInt64
+func abigen_sync_atomic_AddInt64(addr *int64, delta int64) (new int64)
+
+//go:linkname abigen_sync_atomic_AddUint64 sync/atomic.AddUint64
+func abigen_sync_atomic_AddUint64(addr *uint64, delta uint64) (new uint64)
+
+//go:linkname abigen_sync_atomic_AddUintptr sync/atomic.AddUintptr
+func abigen_sync_atomic_AddUintptr(addr *uintptr, delta uintptr) (new uintptr)
+
+//go:linkname abigen_sync_atomic_CompareAndSwapInt32 sync/atomic.CompareAndSwapInt32
+func abigen_sync_atomic_CompareAndSwapInt32(addr *int32, old, new int32) (swapped bool)
+
+//go:linkname abigen_sync_atomic_CompareAndSwapInt64 sync/atomic.CompareAndSwapInt64
+func abigen_sync_atomic_CompareAndSwapInt64(addr *int64, old, new int64) (swapped bool)
+
+//go:linkname abigen_sync_atomic_CompareAndSwapUint32 sync/atomic.CompareAndSwapUint32
+func abigen_sync_atomic_CompareAndSwapUint32(addr *uint32, old, new uint32) (swapped bool)
+
+//go:linkname abigen_sync_atomic_CompareAndSwapUint64 sync/atomic.CompareAndSwapUint64
+func abigen_sync_atomic_CompareAndSwapUint64(addr *uint64, old, new uint64) (swapped bool)