From 193daab9889708f7a20ff46efe0fa4b2bf0468d3 Mon Sep 17 00:00:00 2001 From: Russ Cox Date: Wed, 24 Sep 2014 16:55:26 -0400 Subject: cmd/cc, cmd/ld, runtime: disallow conservative data/bss objects In linker, refuse to write conservative (array of pointers) as the garbage collection type for any variable in the data/bss GC program. In the linker, attach the Go type to an already-read C declaration during dedup. This gives us Go types for C globals for free as long as the cmd/dist-generated Go code contains the declaration. (Most runtime C declarations have a corresponding Go declaration. Both are bss declarations and so the linker dedups them.) In cmd/dist, add a few more C files to the auto-Go-declaration list in order to get Go type information for the C declarations into the linker. In C compiler, mark all non-pointer-containing global declarations and all string data as NOPTR. This allows them to exist in C files without any corresponding Go declaration. Count C function pointers as "non-pointer-containing", since we have no heap-allocated C functions. In runtime, add NOPTR to the remaining pointer-containing declarations, none of which refer to Go heap objects. In runtime, also move os.Args and syscall.envs data into runtime-owned variables. Otherwise, in programs that do not import os or syscall, the runtime variables named os.Args and syscall.envs will be missing type information. I believe that this CL eliminates the final source of conservative GC scanning in non-SWIG Go programs, and therefore... Fixes #909. LGTM=iant R=iant CC=golang-codereviews https://golang.org/cl/149770043 --- src/liblink/objfile.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'src/liblink/objfile.c') diff --git a/src/liblink/objfile.c b/src/liblink/objfile.c index 9b1e1b7a8f..15d602df92 100644 --- a/src/liblink/objfile.c +++ b/src/liblink/objfile.c @@ -550,7 +550,7 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn) static int ndup; char *name; Reloc *r; - LSym *s, *dup; + LSym *s, *dup, *typ; Pcln *pc; Auto *a; @@ -586,7 +586,9 @@ readsym(Link *ctxt, Biobuf *f, char *pkg, char *pn) s->type = t; if(s->size < size) s->size = size; - s->gotype = rdsym(ctxt, f, pkg); + typ = rdsym(ctxt, f, pkg); + if(typ != nil) // if bss sym defined multiple times, take type from any one def + s->gotype = typ; rddata(f, &s->p, &s->np); s->maxp = s->np; n = rdint(f); -- cgit v1.3