cmd/internal/obj: hoist constant slice out of function called in loop

It's all local to a single file and responsible for 1.7% of total
space allocated summed over compilation of the bent benchmarks.

Showing nodes accounting for 27.16GB, 27.04% of 100.44GB total
Dropped 1622 nodes (cum <= 0.50GB)
Showing top 10 nodes out of 321
      flat  flat%   sum%        cum   cum%
    4.87GB  4.85%  4.85%     4.87GB  4.85%  cmd/compile/internal/objw.init
    4.79GB  4.77%  9.62%     4.81GB  4.79%  runtime.allocm
    4.72GB  4.70% 14.32%     4.72GB  4.70%  cmd/compile/internal/types.newType
    3.10GB  3.09% 17.41%     3.17GB  3.15%  cmd/compile/internal/ssagen.InitConfig
    1.86GB  1.85% 19.26%     2.61GB  2.60%  cmd/compile/internal/ssa.cse

    1.72GB  1.71% 20.97%     2.25GB  2.24%  cmd/internal/obj.(*Link).traverseFuncAux

    1.66GB  1.65% 22.62%     1.66GB  1.65%  runtime.malg
    1.61GB  1.61% 24.23%     1.64GB  1.63%  cmd/compile/internal/ssa.schedule
    1.42GB  1.41% 25.64%     1.42GB  1.41%  cmd/compile/internal/ir.NewNameAt

Change-Id: Id18ee3b83cb23a7042d59714a0c1ca074e7bc7a8
Reviewed-on: https://go-review.googlesource.com/c/go/+/437297
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: David Chase <drchase@google.com>

diff --git a/src/cmd/internal/obj/sym.go b/src/cmd/internal/obj/sym.go
index 40e5377a3d7fed34577de4dd045a3890a09334b2..b3eeedb59d00e1a85f5a988b6ba10ca75839e350 100644 (file)
--- a/src/cmd/internal/obj/sym.go
+++ b/src/cmd/internal/obj/sym.go
@@ -349,6 +349,7 @@ func (ctxt *Link) traverseSyms(flag traverseFlag, fn func(*LSym)) {
                }
        }
        lists := [][]*LSym{ctxt.Text, ctxt.Data}
+       files := ctxt.PosTable.FileTable()
        for _, list := range lists {
                for _, s := range list {
                        if flag&traverseDefs != 0 {
@@ -365,7 +366,7 @@ func (ctxt *Link) traverseSyms(flag traverseFlag, fn func(*LSym)) {
                                        f := func(parent *LSym, aux *LSym) {
                                                fn(aux)
                                        }
-                                       ctxt.traverseFuncAux(flag, s, f)
+                                       ctxt.traverseFuncAux(flag, s, f, files)
                                }
                        }
                        if flag&traversePcdata != 0 && s.Type == objabi.STEXT {
@@ -382,7 +383,7 @@ func (ctxt *Link) traverseSyms(flag traverseFlag, fn func(*LSym)) {
        }
 }
 
-func (ctxt *Link) traverseFuncAux(flag traverseFlag, fsym *LSym, fn func(parent *LSym, aux *LSym)) {
+func (ctxt *Link) traverseFuncAux(flag traverseFlag, fsym *LSym, fn func(parent *LSym, aux *LSym), files []string) {
        fninfo := fsym.Func()
        pc := &fninfo.Pcln
        if flag&traverseAux == 0 {
@@ -395,7 +396,6 @@ func (ctxt *Link) traverseFuncAux(flag traverseFlag, fsym *LSym, fn func(parent
                        fn(fsym, d)
                }
        }
-       files := ctxt.PosTable.FileTable()
        usedFiles := make([]goobj.CUFileIndex, 0, len(pc.UsedFiles))
        for f := range pc.UsedFiles {
                usedFiles = append(usedFiles, f)
@@ -435,6 +435,7 @@ func (ctxt *Link) traverseFuncAux(flag traverseFlag, fsym *LSym, fn func(parent
 // Traverse aux symbols, calling fn for each sym/aux pair.
 func (ctxt *Link) traverseAuxSyms(flag traverseFlag, fn func(parent *LSym, aux *LSym)) {
        lists := [][]*LSym{ctxt.Text, ctxt.Data}
+       files := ctxt.PosTable.FileTable()
        for _, list := range lists {
                for _, s := range list {
                        if s.Gotype != nil {
@@ -445,7 +446,7 @@ func (ctxt *Link) traverseAuxSyms(flag traverseFlag, fn func(parent *LSym, aux *
                        if s.Type != objabi.STEXT {
                                continue
                        }
-                       ctxt.traverseFuncAux(flag, s, fn)
+                       ctxt.traverseFuncAux(flag, s, fn, files)
                }
        }
 }