cmd/ld: move instruction selection + layout into compilers, assemblers

- new object file reader/writer (liblink/objfile.c)
- remove old object file writing routines
- add pcdata iterator
- remove all trace of "line number stack" and "path fragments" from
  object files, linker (!!!)
- dwarf now writes a single "compilation unit" instead of one per package

This CL disables the check for chains of no-split functions that
could overflow the stack red zone. A future CL will attack the problem
of reenabling that check (issue 6931).

This CL is just the liblink and cmd/ld changes.
There are minor associated adjustments in CL 37030045.
Each depends on the other.

R=golang-dev, dave, iant
CC=golang-dev
https://codereview.appspot.com/39680043

1 files changed, 0 insertions, 12 deletions

diff --git a/src/cmd/6l/obj.c b/src/cmd/6l/obj.c
index ac3273f93..a2f146574 100644
--- a/src/cmd/6l/obj.c
+++ b/src/cmd/6l/obj.c
@@ -92,11 +92,6 @@ archinit(void)
 			INITRND = 4096;
 		break;
 	case Hdarwin:		/* apple MACH */
-		/*
-		 * OS X system constant - offset from 0(GS) to our TLS.
-		 * Explained in ../../pkg/runtime/cgo/gcc_darwin_amd64.c.
-		 */
-		ctxt->tlsoffset = 0x8a0;
 		machoinit();
 		HEADR = INITIAL_MACHO_HEADR;
 		if(INITRND == -1)
@@ -111,13 +106,6 @@ archinit(void)
 	case Hnetbsd:		/* netbsd */
 	case Hopenbsd:		/* openbsd */
 	case Hdragonfly:	/* dragonfly */
-		/*
-		 * ELF uses TLS offset negative from FS.
-		 * Translate 0(FS) and 8(FS) into -16(FS) and -8(FS).
-		 * Also known to ../../pkg/runtime/sys_linux_amd64.s
-		 * and ../../pkg/runtime/cgo/gcc_linux_amd64.c.
-		 */
-		ctxt->tlsoffset = -16;
 		elfinit();
 		HEADR = ELFRESERVE;
 		if(INITTEXT == -1)