cmd/link: reduce alignment for some funcdata symbols

Funcdata like opendefer info and traceback arginfo are varints or
bytes. There is no need to align them.

GC liveness map and inline tree have 32-bit fields, so continue
align them to 4 bytes.

Change-Id: I9d5dd750a926c65a910efe5817f9f5c473019bc6
Reviewed-on: https://go-review.googlesource.com/c/go/+/353469
Trust: Cherry Mui <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>

diff --git a/src/cmd/link/internal/ld/symtab.go b/src/cmd/link/internal/ld/symtab.go
index 8dec78e01746ce0e92a6209144a36b9d2be5eaca..76cca41d25775c1a017a61a82ef85280432d0407 100644 (file)
--- a/src/cmd/link/internal/ld/symtab.go
+++ b/src/cmd/link/internal/ld/symtab.go
@@ -537,6 +537,7 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
                        continue
                }
 
+               align := int32(1)
                name := ldr.SymName(s)
                switch {
                case strings.HasPrefix(name, "go.importpath.") && ctxt.UseRelro():
@@ -571,14 +572,17 @@ func (ctxt *Link) symtab(pcln *pclntab) []sym.SymKind {
                case strings.HasPrefix(name, "gcargs."),
                        strings.HasPrefix(name, "gclocals."),
                        strings.HasPrefix(name, "gclocals·"),
-                       ldr.SymType(s) == sym.SGOFUNC && s != symgofunc,
-                       strings.HasSuffix(name, ".opendefer"),
+                       ldr.SymType(s) == sym.SGOFUNC && s != symgofunc: // inltree, see pcln.go
+                       // GC stack maps and inltrees have 32-bit fields.
+                       align = 4
+                       fallthrough
+               case strings.HasSuffix(name, ".opendefer"),
                        strings.HasSuffix(name, ".arginfo0"),
                        strings.HasSuffix(name, ".arginfo1"):
+                       // These are just bytes, or varints, use align 1 (set before the switch).
                        symGroupType[s] = sym.SGOFUNC
                        ldr.SetAttrNotInSymbolTable(s, true)
                        ldr.SetCarrierSym(s, symgofunc)
-                       align := int32(4)
                        if a := ldr.SymAlign(s); a < align {
                                ldr.SetSymAlign(s, align)
                        } else {