code review 134990043: runtime: fix nacl build

runtime: fix nacl build

The NaCl "system calls" were assumed to have a compatible
return convention with the C compiler, and we were using
tail jumps to those functions. Don't do that anymore.

Correct mistake introduced in newstackcall duringconversion
from (SP) to (FP) notation. (Actually this fix, in asm_amd64p32.s,
slipped into the C compiler change, but update the name to
match what go vet wants.)

Correct computation of caller stack pointer in morestack:
on amd64p32, the saved PC is the size of a uintreg, not uintptr.
This may not matter, since it's been like this for a while,
but uintreg is the correct one. (And on non-NaCl they are the same.)

This will allow the NaCl build to get much farther.
It will probably still not work completely.
There's a bug in 6l that needs fixing too.

[rsc, 2014-08-28 02:50:05]

Hello minux (cc: golang-codereviews@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go/

[rsc, 2014-08-28 02:50:12]

*** Submitted as https://code.google.com/p/go/source/detail?r=d51c319e0f20 ***

runtime: fix nacl build

The NaCl "system calls" were assumed to have a compatible
return convention with the C compiler, and we were using
tail jumps to those functions. Don't do that anymore.

Correct mistake introduced in newstackcall duringconversion
from (SP) to (FP) notation. (Actually this fix, in asm_amd64p32.s,
slipped into the C compiler change, but update the name to
match what go vet wants.)

Correct computation of caller stack pointer in morestack:
on amd64p32, the saved PC is the size of a uintreg, not uintptr.
This may not matter, since it's been like this for a while,
but uintreg is the correct one. (And on non-NaCl they are the same.)

This will allow the NaCl build to get much farther.
It will probably still not work completely.
There's a bug in 6l that needs fixing too.

TBR=minux
CC=golang-codereviews
https://codereview.appspot.com/134990043

[gobot, 2014-08-28 13:25:36]

This CL appears to have broken the freebsd-amd64-race builder.
See http://build.golang.org/log/bf8f8f12552e30b2c336971574c18efddcfaef4d

[minux, 2014-08-28 23:23:06]

LGTM.

https://codereview.appspot.com/134990043/diff/80001/src/pkg/runtime/asm_amd64...
File src/pkg/runtime/asm_amd64p32.s (right):

https://codereview.appspot.com/134990043/diff/80001/src/pkg/runtime/asm_amd64...
src/pkg/runtime/asm_amd64p32.s:278: LEAL	fv+0(FP), AX	// our caller's SP
why change this?