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

1 files changed, 0 insertions, 23 deletions

diff --git a/src/runtime/malloc.c b/src/runtime/malloc.c
index 60d20a992d..b79c30b720 100644
--- a/src/runtime/malloc.c
+++ b/src/runtime/malloc.c
@@ -329,29 +329,6 @@ runtime·MHeap_SysAlloc(MHeap *h, uintptr n)
 	return p;
 }
 
-// Runtime stubs.
-
-static void*
-cnew(Type *typ, intgo n)
-{
-	if(n < 0 || (typ->size > 0 && n > MaxMem/typ->size))
-		runtime·throw("runtime: allocation size out of range");
-	return runtime·mallocgc(typ->size*n, typ, typ->kind&KindNoPointers ? FlagNoScan : 0);
-}
-
-// same as runtime·new, but callable from C
-void*
-runtime·cnew(Type *typ)
-{
-	return cnew(typ, 1);
-}
-
-void*
-runtime·cnewarray(Type *typ, intgo n)
-{
-	return cnew(typ, n);
-}
-
 void
 runtime·setFinalizer_m(void)
 {