The point of GOOBJ=2 was to have an active test of the cmd/internal/obj code.
Now we have end-to-end tests of the assembler, and soon the compiler,
so we don't need this halfway test on by default anymore.
(It's still possible to enable during debugging with the
environment variable.)

The problem it causes on the builders is that this particular testing
mode ends up with both the C process and the Go objwriter subprocess
having the same very large Prog list in memory simultaneously,
which causes basically a 2x memory blowup. In large programs
(such as the one generated by test/rotate.go) this is significant.

Disabling GOOBJ=2 should help with the current dev.cc builder
failures.

Change-Id: I1b11e4f29ea575659f02d2234242a904f7c867e4
Reviewed-on: https://go-review.googlesource.com/4832
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Conflicts:
	src/cmd/dist/build.go

Change-Id: I98a4b5e010bee91507b85bb8efd9c74e1a1f649c

Now:

	0x0000 00000 (/tmp/x.s:2)	MULLU	R6,R3,(R7, R6)

The space is a little odd but I'd rather fix the usual printing to add spaces
than delete that one. But in a different CL, once C is gone.

Change-Id: I344e0b06eedaaf53cd79d370fa13c444a1e69c81
Reviewed-on: https://go-review.googlesource.com/4647
Reviewed-by: Rob Pike <r@golang.org>

This isn't everything, but it's a start.
Still producing bit-identical compiler output.

The semantics of the old back ends is preserved,
even when they are probably buggy.
There are some TODOs in gc/gsubr.c to
remove special cases to preserve bugs in 5g and 8g.

Change-Id: I28ae295fbfc94ef9df43e13ab96bd6fc2f194bc4
Reviewed-on: https://go-review.googlesource.com/3802
Reviewed-by: Austin Clements <austin@google.com>

Change-Id: I6a119109c8dea7fecb32de2c4b1b5ba54bc485be
Reviewed-on: https://go-review.googlesource.com/4100
Reviewed-by: Rob Pike <r@golang.org>

CL 2118 makes the assumption that all references to runtime.tlsg
should be accompanied by a declaration of runtime.tlsg if its type
should be a normal variable, instead of a placeholder for TLS
relocation.

Because if runtime.tlsg is not declared by the runtime package,
the type of runtime.tlsg will be zero, so fix the check in liblink
to look for 0 instead of STLSBSS (the type will be initialized by
cmd/ld, but cmd/ld doesn't run during assembly).

Change-Id: I691ac5c3faea902f8b9a0b963e781b22e7b269a7
Reviewed-on: https://go-review.googlesource.com/4030
Reviewed-by: David Crawshaw <crawshaw@golang.org>

warning: src/liblink/list5.c:171 format mismatch lld INT, arg 4
warning: src/liblink/list9.c:175 format mismatch lld INT, arg 4
warning: src/liblink/list6.c:211 format mismatch lld INT, arg 4
warning: src/liblink/list8.c:205 format mismatch lld INT, arg 4

Change-Id: I745ea852d8b58ecbbd32723e2a67aa784a729ff8
Reviewed-on: https://go-review.googlesource.com/4112
Reviewed-by: Minux Ma <minux@golang.org>

liblink:
 - set dummy value for ctxt->tlsoffset.
cmd/ld:
 - always do external linking when using cgo on darwin/arm,
   as our linker might not generate codesign-compatible binary.
cmd/5l:
 - support generate ARM Mach-O binaries
 - add machoreloc1() that translate our internal relocation to
   macho relocations used by external linking.

Change-Id: Ic5454aeb87009aaf8f1453ec7fe33e6da55d5f06
Reviewed-on: https://go-review.googlesource.com/3273
Reviewed-by: David Crawshaw <crawshaw@golang.org>

In the old code, liblink, cmd/ld and runtime all have code determine
whether runtime.tlsg is an actual variable or a placeholder for TLS
relocation. This change consolidate them into one: the runtime/tls_arm.s
will ultimately determine the type of that variable.

Change-Id: I3b3f80791a1db4c2b7318f81a115972cd2237e43
Reviewed-on: https://go-review.googlesource.com/2118
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>

cmd/internal/obj reconverted using rsc.io/c2go rev 2a95256.

- Brings in new, more regular Prog, Addr definitions

- Add Prog* argument to oclass in liblink/asm[68].c, for c2go conversion.
- Update objwriter for change in TEXT size encoding.
- Merge 5a, 6a, 8a, 9a changes into new5a, new6a, new8a, new9a (by hand).

- Add +build ignore to cmd/asm/internal/{addr,arch,asm}, cmd/asm.
  They need to be updated for the changes.

- Reenable verifyAsm in cmd/go.
- Reenable GOOBJ=2 mode by default in liblink.

All architectures build successfully again.

Change-Id: I2c845c5d365aa484b570476898171bee657b626d
Reviewed-on: https://go-review.googlesource.com/3963
Reviewed-by: Rob Pike <r@golang.org>