Russ Cox [Fri, 14 Nov 2014 17:09:42 +0000 (12:09 -0500)]
[dev.garbage] all: merge dev.power64 (7667e41f3ced) into dev.garbage
Now the only difference between dev.cc and dev.garbage
is the runtime conversion on the one side and the
garbage collection on the other. They both have the
same set of changes from default and dev.power64.
Austin Clements [Thu, 13 Nov 2014 18:34:20 +0000 (13:34 -0500)]
[dev.power64] 6g,8g: remove unnecessary and incorrect reg use scanning
Previously, the 6g and 8g registerizers scanned for used
registers beyond the end of a region being considered for
registerization. This ancient artifact was copied from the C
compilers, where it was probably necessary to track implicitly
used registers. In the Go compilers it's harmless (because it
can only over-restrict the set of available registers), but no
longer necessary because the Go compilers correctly track
register use/set information. The consequences of this extra
scan were (at least) that 1) we would not consider allocating
the AX register if there was a deferproc call in the future
because deferproc uses AX as a return register, so we see the
use of AX, but don't track that AX is set by the CALL, and 2)
we could not consider allocating the DX register if there was
a MUL in the future because MUL implicitly sets DX and (thanks
to an abuse of copyu in this code) we would also consider DX
used.
This commit fixes these problems by nuking this code.
Russ Cox [Wed, 12 Nov 2014 19:54:31 +0000 (14:54 -0500)]
[dev.cc] runtime: delete scalararg, ptrarg; rename onM to systemstack
Scalararg and ptrarg are not "signal safe".
Go code filling them out can be interrupted by a signal,
and then the signal handler runs, and if it also ends up
in Go code that uses scalararg or ptrarg, now the old
values have been smashed.
For the pieces of code that do need to run in a signal handler,
we introduced onM_signalok, which is really just onM
except that the _signalok is meant to convey that the caller
asserts that scalarg and ptrarg will be restored to their old
values after the call (instead of the usual behavior, zeroing them).
Scalararg and ptrarg are also untyped and therefore error-prone.
Go code can always pass a closure instead of using scalararg
and ptrarg; they were only really necessary for C code.
And there's no more C code.
For all these reasons, delete scalararg and ptrarg, converting
the few remaining references to use closures.
Once those are gone, there is no need for a distinction between
onM and onM_signalok, so replace both with a single function
equivalent to the current onM_signalok (that is, it can be called
on any of the curg, g0, and gsignal stacks).
The name onM and the phrase 'm stack' are misnomers,
because on most system an M has two system stacks:
the main thread stack and the signal handling stack.
Correct the misnomer by naming the replacement function systemstack.
Fix a few references to "M stack" in code.
The main motivation for this change is to eliminate scalararg/ptrarg.
Rick and I have already seen them cause problems because
the calling sequence m.ptrarg[0] = p is a heap pointer assignment,
so it gets a write barrier. The write barrier also uses onM, so it has
all the same problems as if it were being invoked by a signal handler.
We worked around this by saving and restoring the old values
and by calling onM_signalok, but there's no point in keeping this nice
home for bugs around any longer.
This CL also changes funcline to return the file name as a result
instead of filling in a passed-in *string. (The *string signature is
left over from when the code was written in and called from C.)
That's arguably an unrelated change, except that once I had done
the ptrarg/scalararg/onM cleanup I started getting false positives
about the *string argument escaping (not allowed in package runtime).
The compiler is wrong, but the easiest fix is to write the code like
Go code instead of like C code. I am a bit worried that the compiler
is wrong because of some use of uninitialized memory in the escape
analysis. If that's the reason, it will go away when we convert the
compiler to Go. (And if not, we'll debug it the next time.)
Russ Cox [Tue, 11 Nov 2014 22:05:55 +0000 (17:05 -0500)]
[dev.cc] runtime: convert signal handlers from C to Go
This code overused macros and could not be
converted automatically. Instead a new sigctxt
type had to be defined for each os/arch combination,
with a common (implicit) interface used by the
arch-specific signal handler code.
[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]
Russ Cox [Tue, 11 Nov 2014 06:29:05 +0000 (01:29 -0500)]
[dev.cc] cmd/dist: adjust for build process without cmd/cc
[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]
- Remove references to C compiler directories.
- Remove generation of special header files.
- Remove generation of Go source files from C declarations.
- Compile Go sources before rest of package (was after),
so that Go compiler can write go_asm.h for use in assembly.
- Move TLS information from cmd/dist (was embedding in output)
to src/runtime/go_tls.h, which it can be maintained directly.
LGTM=r
R=r, dave
CC=austin, golang-codereviews, iant, khr
https://golang.org/cl/172960043
Russ Cox [Tue, 11 Nov 2014 06:28:26 +0000 (01:28 -0500)]
[dev.cc] liblink: resolve bss vs other conflict regardless of order found
If the linker finds the same name given a BSS and a non-BSS
symbol, the assumption is that the non-BSS symbol is the
true one, and the BSS symbol is just the best Go can do toward
an "extern" declaration. This has always been the case,
as long as the object files were read in the right order.
The old code worked when the BSS symbol is found before
the non-BSS symbol. This CL adds equivalent logic for when
the non-BSS symbol is found before the BSS symbol.
This comes up when Go must refer to symbols defined in
host object files.
Russ Cox [Tue, 11 Nov 2014 06:27:55 +0000 (01:27 -0500)]
[dev.cc] cmd/go: adjust go, cgo builds & disable cc
[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]
Make gcToolchain.cc return an error (no C compiler!).
Adjust expectations of cgo, now that cgo does not write any C files
(no C compiler!).
For packages with .s files, invoke Go compiler with -asmhdr go_asm.h
so that assembly files can use it. This applies to all packages but is only
needed today by package runtime.
Russ Cox [Tue, 11 Nov 2014 06:27:30 +0000 (01:27 -0500)]
[dev.cc] cmd/gc: changes for removing runtime C code
[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]
export.c, lex.c:
Add -asmhdr flag to write assembly header file with struct
field offsets and const values. cmd/dist used to construct this
file by interpreting output from the C compiler.
Generate it from the Go definitions instead.
Also, generate the form we need directly, instead of relying
on cmd/dist for reprocessing.
lex.c, obj.c:
If the C compiler accepted #pragma cgo_xxx, recognize
a directive //go:cgo_xxx instead. The effect is the same as
in the C compiler: accumulate text into a buffer and emit in the
output file, where the linker will find and use it.
lex.c, obj.c:
Accept //go:linkname to control the external symbol name
used for a particular top-level Go variable. This makes it
possible to refer to C symbol names but also symbols from
other packages. It has always been possible to do this from
C and assembly. To drive home the point that this should not
be done lightly, require import "unsafe" in any file containing
//go:linkname.
plive.c, reflect.c, subr.c:
Hard-code that interfaces contain only pointers.
This means code handling multiword values in the garbage
collector and the stack copier can be deleted instead of being
converted. This change is already present in the dev.garbage
branch.
Russ Cox [Tue, 11 Nov 2014 06:23:19 +0000 (01:23 -0500)]
[dev.cc] cmd/cgo: generate only Go source files
[This CL is part of the removal of C code from package runtime.
See golang.org/s/dev.cc for an overview.]
We changed cgo to write the actual function wrappers in Go
for Go 1.4. The only code left in C output files was the definitions
for pointers to C data and the #pragma cgo directives.
Write both of those to Go outputs instead, using the new
compiler directives introduced in CL 169360043.
Russ Cox [Mon, 10 Nov 2014 02:14:36 +0000 (21:14 -0500)]
[dev.cc] create new branch
This branch is for work on converting the remaining C code in
package runtime to Go and then deleting the cc, 5c, 6c, and 8c
directories. It is targeted to land at the beginning of the 1.5 cycle.
The conversion will proceed one GOOS/GOARCH combination
at a time; red lines on the dashboard are expected and okay.
Once Linux and OS X are converted, help with other systems
will be most welcome.
Adam Langley [Sun, 9 Nov 2014 01:12:23 +0000 (17:12 -0800)]
lib/codereview: fix with more recent hg revisions.
I've Mercurial version 3.2 and hg submit fails with:
File "/home/agl/devel/go/lib/codereview/codereview.py", line 3567, in get_hg_status
ret = hg_commands.status(fui, self.repo, *[], **{'rev': [rev], 'copies': True})
File "/usr/lib/python2.7/site-packages/mercurial/commands.py", line 5714, in status
fm = ui.formatter('status', opts)
File "/home/agl/devel/go/lib/codereview/codereview.py", line 3464, in formatter
return plainformatter(self, topic, opts)
File "/usr/lib/python2.7/site-packages/mercurial/formatter.py", line 57, in __init__
if ui.debugflag:
AttributeError: 'FakeMercurialUI' object has no attribute 'debugflag'
This change dumbly adds a boolean debugflag and that seems to work.
Austin Clements [Fri, 7 Nov 2014 15:43:55 +0000 (10:43 -0500)]
[dev.power64] 5g: fix mistaken bit-wise AND in regopt
Replace a bit-wise AND with a logical one. This happened to
work before because bany returns 0 or 1, but the intent here
is clearly logical (and this makes 5g match with 6g and 8g).
Russ Cox [Fri, 7 Nov 2014 00:56:55 +0000 (19:56 -0500)]
cmd/objdump, cmd/pprof: factor disassembly into cmd/internal/objfile
Moving so that new Go 1.4 pprof can use it.
The old 'GNU objdump workalike' mode for 'go tool objdump'
is now gone, as are the tests for that mode. It was used only
by pre-Go 1.4 pprof. You can still specify an address range on
the command line; you just get the same output format as
you do when dumping the entire binary (without an address
limitation).
Austin Clements [Thu, 6 Nov 2014 19:37:39 +0000 (14:37 -0500)]
[dev.power64] gc: fix etype of strings
The etype of references to strings was being incorrectly set
to TINT32 on all platforms. Change it to TSTRING. It seems
this doesn't matter for compilation, since x86 uses LEA
instructions to load string addresses and arm and power64
disassemble the string into its constituent pieces (with the
correct types), but it helps when debugging.
Keith Randall [Thu, 6 Nov 2014 17:30:41 +0000 (09:30 -0800)]
runtime: don't stop bitmap dump at BitsDead
Stack bitmaps need to be scanned past any BitsDead entries.
Object bitmaps will not have any BitsDead in them (bitmap extraction stops at
the first BitsDead entry in makeheapobjbv). data/bss bitmaps also have no BitsDead entries.
Keith Randall [Thu, 6 Nov 2014 04:25:20 +0000 (20:25 -0800)]
os/exec: tell lsof not to block
For some reason lsof is now hanging on my workstation
without the -b (avoid blocking in the kernel) option.
Adding -b makes the test pass and shouldn't hurt.
I don't know how recent the -b option is. If the builders
are ok with it, it's probably ok.
Russ Cox [Thu, 6 Nov 2014 04:01:48 +0000 (23:01 -0500)]
runtime: avoid gentraceback of self on user goroutine stack
Gentraceback may grow the stack.
One of the gentraceback wrappers may grow the stack.
One of the gentraceback callback calls may grow the stack.
Various stack pointers are stored in various stack locations
as type uintptr during the execution of these calls.
If the stack does grow, these stack pointers will not be
updated and will start trying to decode stack memory that
is no longer valid.
It may be possible to change the type of the stack pointer
variables to be unsafe.Pointer, but that's pretty subtle and
may still have problems, even if we catch every last one.
An easier, more obviously correct fix is to require that
gentraceback of the currently running goroutine must run
on the g0 stack, not on the goroutine's own stack.
Not doing this causes faults when you set
StackFromSystem = 1
StackFaultOnFree = 1
The new check in gentraceback will catch future lapses.
The more general problem is calling getcallersp but then
calling a function that might relocate the stack, which would
invalidate the result of getcallersp. Add note to stubs.go
declaration of getcallersp explaining the problem, and
check all existing calls to getcallersp. Most needed fixes.
This affects Callers, Stack, and nearly all the runtime
profiling routines. It does not affect stack copying directly
nor garbage collection.
LGTM=khr
R=khr, bradfitz
CC=golang-codereviews, r
https://golang.org/cl/167060043
Rob Pike [Wed, 5 Nov 2014 22:57:46 +0000 (09:57 +1100)]
bufio: don't loop generating empty tokens
The new rules for split functions mean that we are exposed
to the common bug of a function that loops forever at EOF.
Pick these off by shutting down the scanner if too many
consecutive empty tokens are delivered.
Austin Clements [Wed, 5 Nov 2014 20:36:47 +0000 (15:36 -0500)]
[dev.power64] 6g: don't create variables for indirect addresses
Previously, mkvar treated, for example, 0(AX) the same as AX.
As a result, a move to an indirect address would be marked as
*setting* the register, rather than just using it, resulting
in unnecessary register moves. Fix this by not producing
variables for indirect addresses.
LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/164610043
Austin Clements [Wed, 5 Nov 2014 20:14:47 +0000 (15:14 -0500)]
5g: don't generate reg variables for direct-called functions
The test intended to skip direct calls when creating
registerization variables was testing p->to.type instead of
p->to.name, so it always failed, causing regopt to create
unnecessary variables for these names.
Russ Cox [Wed, 5 Nov 2014 19:42:54 +0000 (14:42 -0500)]
[dev.garbage] cmd/gc, runtime: add locks around print statements
Now each C printf, Go print, or Go println is guaranteed
not to be interleaved with other calls of those functions.
This should help when debugging concurrent failures.
Austin Clements [Tue, 4 Nov 2014 21:34:56 +0000 (16:34 -0500)]
[dev.power64] gc: convert Bits to a uint64 array
So far all of our architectures have had at most 32 registers,
so we've been able to use entry 0 in the Bits uint32 array
directly as a register mask. Power64 has 64 registers, so
this converts Bits to a uint64 array so we can continue to use
entry 0 directly as a register mask on Power64.
Rick Hudson [Tue, 4 Nov 2014 18:31:34 +0000 (13:31 -0500)]
[dev.garbage] runtime: Add gc mark verification pass.
This adds an independent mark phase to the GC that can be used to
verify the the default concurrent mark phase has found all reachable
objects. It uses the upper 2 bits of the boundary nibble to encode
the mark leaving the lower bits to encode the boundary and the
normal mark bit.
Ian Lance Taylor [Tue, 4 Nov 2014 18:20:35 +0000 (10:20 -0800)]
test: comment out failing cases from sinit.go
One failing case this removes is:
var bytes = []byte("hello, world")
var copy_bytes = bytes
We could handle this in the compiler, but it requires special
case for a variable that is initialized to the value of a
variable that is initialized to a string literal converted to
[]byte. This seems an unlikely case--it never occurs in the
standrd library--and it seems unnecessary to write the code to
handle it.
If we do want to support this case, one approach is
https://golang.org/cl/171840043.
The other failing cases are of the form
var bx bool
var copy_bx = bx
The compiler used to initialize copy_bx to false. However,
that led to issue 7665, since bx may be initialized in non-Go
code. The compiler no longer assumes that bx must be false,
so copy_bx can not be statically initialized.
We can fix these with https://golang.org/cl/169040043
if we also pass -complete to the compiler as part of this
test. This is OK but it's too late in the release cycle.