cmd/link: fix name section of WebAssembly binary

Chrome and Node.js were not showing the names of WebAssembly
functions any more. This was due to the name section containing
names also for import functions, which is redundant.

Change-Id: I2f2b2d0b5bd7a59b34f108d2fd7b6ba2eb26f9c9
Reviewed-on: https://go-review.googlesource.com/118976
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/cmd/link/internal/wasm/asm.go b/src/cmd/link/internal/wasm/asm.go
index b7beaa5d2fcec8f78ffa28256e9a75e3a6d6119c..96d9cbd71efb1b47d6f2e932f32d27a58c601717 100644 (file)
--- a/src/cmd/link/internal/wasm/asm.go
+++ b/src/cmd/link/internal/wasm/asm.go
@@ -177,7 +177,7 @@ func asmb(ctxt *ld.Link) {
        writeCodeSec(ctxt, fns)
        writeDataSec(ctxt)
        if !*ld.FlagS {
-               writeNameSec(ctxt, append(hostImports, fns...))
+               writeNameSec(ctxt, len(hostImports), fns)
        }
 
        ctxt.Out.Flush()
@@ -409,14 +409,14 @@ var nameRegexp = regexp.MustCompile(`[^\w\.]`)
 // writeNameSec writes an optional section that assigns names to the functions declared by the "func" section.
 // The names are only used by WebAssembly stack traces, debuggers and decompilers.
 // TODO(neelance): add symbol table of DATA symbols
-func writeNameSec(ctxt *ld.Link, fns []*wasmFunc) {
+func writeNameSec(ctxt *ld.Link, firstFnIndex int, fns []*wasmFunc) {
        sizeOffset := writeSecHeader(ctxt, sectionCustom)
        writeName(ctxt.Out, "name")
 
        sizeOffset2 := writeSecHeader(ctxt, 0x01) // function names
        writeUleb128(ctxt.Out, uint64(len(fns)))
        for i, fn := range fns {
-               writeUleb128(ctxt.Out, uint64(i))
+               writeUleb128(ctxt.Out, uint64(firstFnIndex+i))
                writeName(ctxt.Out, fn.Name)
        }
        writeSecSize(ctxt, sizeOffset2)