cmd/internal/objabi: extract shared functionality from obj

Now only cmd/asm and cmd/compile depend on cmd/internal/obj. Changing
the assembler backends no longer requires reinstalling cmd/link or
cmd/addr2line.

There's also now one canonical definition of the object file format in
cmd/internal/objabi/doc.go, with a warning to update all three
implementations.

objabi is still something of a grab bag of unrelated code (e.g., flag
and environment variable handling probably belong in a separate "tool"
package), but this is still progress.

Fixes #15165.
Fixes #20026.

Change-Id: Ic4b92fac7d0d35438e0d20c9579aad4085c5534c
Reviewed-on: https://go-review.googlesource.com/40972
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

1 files changed, 0 insertions, 21 deletions

diff --git a/src/cmd/internal/obj/stack.go b/src/cmd/internal/obj/stack.go
deleted file mode 100644
index 687adf20f3..0000000000
--- a/src/cmd/internal/obj/stack.go
+++ /dev/null
@@ -1,21 +0,0 @@
-// Copyright 2011 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 obj
-
-// For the linkers. Must match Go definitions.
-// TODO(rsc): Share Go definitions with linkers directly.
-
-const (
-	STACKSYSTEM = 0
-	StackSystem = STACKSYSTEM
-	StackBig    = 4096
-	StackGuard  = 880*stackGuardMultiplier + StackSystem
-	StackSmall  = 128
-	StackLimit  = StackGuard - StackSystem - StackSmall
-)
-
-const (
-	StackPreempt = -1314 // 0xfff...fade
-)