[dev.link] cmd/link: minor perf tweak for PropagateLoaderChangesToSymbols

When fixing up relocations in PropagateLoaderChangesToSymbols, don't
reallocate the target sym.Symbol relocation slice if it already has
the desired size (this gets rid of some unneeded allocations).

Change-Id: I05287772c18cab861c2df805fa9497103fb00dcc
Reviewed-on: https://go-review.googlesource.com/c/go/+/224420
Reviewed-by: Jeremy Faller <jeremy@golang.org>

diff --git a/src/cmd/link/internal/loader/loader.go b/src/cmd/link/internal/loader/loader.go
index 77b072bcf0fabcfbdeb90e0bb4e1603654c94db0..a916c50f19ddb4bbd97328ea227e64f952cbfe15 100644 (file)
--- a/src/cmd/link/internal/loader/loader.go
+++ b/src/cmd/link/internal/loader/loader.go
@@ -1977,7 +1977,9 @@ func (l *Loader) PropagateLoaderChangesToSymbols(toconvert []Sym, syms *sym.Symb
                s := l.Syms[cand]
                relocs := l.Relocs(cand)
                rslice = relocs.ReadAll(rslice)
-               s.R = make([]sym.Reloc, len(rslice))
+               if len(s.R) != len(rslice) {
+                       s.R = make([]sym.Reloc, len(rslice))
+               }
                l.convertRelocations(rslice, s, true)
        }