[dev.link] cmd/internal/obj: sort ctxt.Data on AIX

On AIX, TOC symbols may be created and added to ctxt.Data
concurrently. To ensure reproducible builds, sort ctxt.Data.
This implements the same logic as WriteObjFile does for old
object files.

Change-Id: I2e6e2d7755352848981544a4fb68b828a188c2ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/201021
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/src/cmd/internal/obj/sym.go b/src/cmd/internal/obj/sym.go
index e72ec3e701ae17e475b5ef39e33bb9da591638d2..39d294183d6d57b0cabc912500cc7d01b1d5dedc 100644 (file)
--- a/src/cmd/internal/obj/sym.go
+++ b/src/cmd/internal/obj/sym.go
@@ -37,6 +37,7 @@ import (
        "fmt"
        "log"
        "math"
+       "sort"
 )
 
 func Linknew(arch *LinkArch) *Link {
@@ -167,6 +168,16 @@ func (ctxt *Link) NumberSyms(asm bool) {
                return
        }
 
+       if ctxt.Headtype == objabi.Haix {
+               // Data must be sorted to keep a constant order in TOC symbols.
+               // As they are created during Progedit, two symbols can be switched between
+               // two different compilations. Therefore, BuildID will be different.
+               // TODO: find a better place and optimize to only sort TOC symbols
+               sort.Slice(ctxt.Data, func(i, j int) bool {
+                       return ctxt.Data[i].Name < ctxt.Data[j].Name
+               })
+       }
+
        ctxt.pkgIdx = make(map[string]int32)
        ctxt.defs = []*LSym{}
        ctxt.nonpkgdefs = []*LSym{}