• Russ Cox's avatar
    cmd/cc, cmd/ld, runtime: disallow conservative data/bss objects · 193daab9
    Russ Cox authored
    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
    193daab9
asm_386.s 42.8 KB