[dev.link] cmd/link: revise representation of dwarfp

Change linker DWARF generation to move away from emitting a single
giant list of DWARF symbols, and instead emit a list of descriptors,
with each descriptor holding the symbols for a specific DWARF section.

While placing all DWARF symbols in a single lists does come in handy
in certain instances, it also creates a lot of confusion and weird
code in other cases, specifically where we want to perform operations
on a section-by-section basis (resulting in code that tries to
re-discover section boundaries by walking/inspecting the list).

Change-Id: I4dac81bd38cba903c9fd7004d613597e76dfb77a
Reviewed-on: https://go-review.googlesource.com/c/go/+/228780
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 11 insertions, 6 deletions

diff --git a/src/cmd/link/internal/ld/lib.go b/src/cmd/link/internal/ld/lib.go
index c400d80a18..b71bef22f4 100644
--- a/src/cmd/link/internal/ld/lib.go
+++ b/src/cmd/link/internal/ld/lib.go
@@ -2820,14 +2820,19 @@ func (ctxt *Link) loadlibfull() {
 	pclntabFirstFunc = ctxt.loader.Syms[pclntabFirstFunc2]
 	pclntabLastFunc = ctxt.loader.Syms[pclntabLastFunc2]
 
-	// Populate dwarfp from dwarfp2. If we see a symbol index on dwarfp2
+	// Populate dwarfp from dwarfp2. If we see a symbol index
 	// whose loader.Syms entry is nil, something went wrong.
-	for _, symIdx := range dwarfp2 {
-		s := ctxt.loader.Syms[symIdx]
-		if s == nil {
-			panic(fmt.Sprintf("nil sym for dwarfp2 element %d", symIdx))
+	for _, si := range dwarfp2 {
+		syms := make([]*sym.Symbol, 0, len(si.syms))
+		for _, symIdx := range si.syms {
+			s := ctxt.loader.Syms[symIdx]
+			if s == nil {
+				panic(fmt.Sprintf("nil sym for dwarfp2 element %d", symIdx))
+			}
+			s.Attr |= sym.AttrLocal
+			syms = append(syms, s)
 		}
-		dwarfp = append(dwarfp, s)
+		dwarfp = append(dwarfp, dwarfSecInfo2{syms: syms})
 	}
 }