We also rename the constants related to unsafe-points: currently, they
follow the same naming scheme as the PCDATA table indexes, but are not
PCDATA table indexes.
For #59670.
Change-Id: I06529fecfae535be5fe7d9ac56c886b9106c74fd
Reviewed-on: https://go-review.googlesource.com/c/go/+/485497
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Austin Clements <austin@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This GODEBUG flag disables the freezetheworld call during fatal panic.
freezetheworld asks the scheduler to stop running goroutines on all Ms.
This is normally useful, as it ensures we can collect a traceback from
every goroutine. However, it can be frustrating when debugging the
scheduler itself, as it significantly changes the scheduler state from
when the panic started.
Setting this flag has some disadvantages. Most notably, running
goroutines will not traceback in the standard output (though they may be
included in the final SIGQUIT loop). Additionally, we may missing
concurrently created goroutines when looping over allgs (CL 270861 made
this safe, but still racy). The final state of all goroutines will also
be further removed from the time of panic, as they continued to run for
a while.
One unfortunate part of this flag is the final SIGQUIT loop in the
runtime leaves every thread in the signal handler at exit. This is a bit
frustrating in gdb, which doesn't understand how to step beyond
sigtramp. The data is still there, but you must manually walk.
Change-Id: Ie6bd3ac521fcababea668196b60cf225a0be1a00
Reviewed-on: https://go-review.googlesource.com/c/go/+/478975
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Allow GODEBUG users to report how many times a setting
resulted in non-default behavior.
Record non-default-behaviors for all existing GODEBUGs.
Also rework tests to ensure that runtime is in sync with runtime/metrics.All,
and generate docs mechanically from metrics.All.
For #56986.
Change-Id: Iefa1213e2a5c3f19ea16cd53298c487952ef05a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/453618
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Long ago we decided that panic(nil) was too unlikely to bother
making a special case for purposes of recover. Unfortunately,
it has turned out not to be a special case. There are many examples
of code in the Go ecosystem where an author has written panic(nil)
because they want to panic and don't care about the panic value.
Using panic(nil) in this case has the unfortunate behavior of
making recover behave as though the goroutine isn't panicking.
As a result, code like:
func f() {
defer func() {
if err := recover(); err != nil {
log.Fatalf("panicked! %v", err)
}
}()
call1()
call2()
}
looks like it guarantees that call2 has been run any time f returns,
but that turns out not to be strictly true. If call1 does panic(nil),
then f returns "successfully", having recovered the panic, but
without calling call2.
Instead you have to write something like:
func f() {
done := false
defer func() {
if err := recover(); !done {
log.Fatalf("panicked! %v", err)
}
}()
call1()
call2()
done = true
}
which defeats nearly the whole point of recover. No one does this,
with the result that almost all uses of recover are subtly broken.
One specific broken use along these lines is in net/http, which
recovers from panics in handlers and sends back an HTTP error.
Users discovered in the early days of Go that panic(nil) was a
convenient way to jump out of a handler up to the serving loop
without sending back an HTTP error. This was a bug, not a feature.
Go 1.8 added panic(http.ErrAbortHandler) as a better way to access the feature.
Any lingering code that uses panic(nil) to abort an HTTP handler
without a failure message should be changed to use http.ErrAbortHandler.
Programs that need the old, unintended behavior from net/http
or other packages can set GODEBUG=panicnil=1 to stop the run-time error.
Uses of recover that want to detect panic(nil) in new programs
can check for recover returning a value of type *runtime.PanicNilError.
Because the new GODEBUG is used inside the runtime, we can't
import internal/godebug, so there is some new machinery to
cross-connect those in this CL, to allow a mutable GODEBUG setting.
That won't be necessary if we add any other mutable GODEBUG settings
in the future. The CL also corrects the handling of defaulted GODEBUG
values in the runtime, for #56986.
Fixes#25448.
Change-Id: I2b39c7e83e4f7aa308777dabf2edae54773e03f5
Reviewed-on: https://go-review.googlesource.com/c/go/+/461956
Reviewed-by: Robert Griesemer <gri@google.com>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
The conversion T(x) is implemented as *(*T)(x). Accordingly, runtime
panic messages for (*T)(x) are made more general.
Fixes#46505.
Change-Id: I76317c0878b6a5908299506d392eed50d7ef6523
Reviewed-on: https://go-review.googlesource.com/c/go/+/430415
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Jenny Rakoczy <jenny@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
gp is a user G running on the same M as getg(), so it is a fine proxy
for gp.m.
Change-Id: I9aa1dd283ecf28878eeedd7da4ded5c901809832
Reviewed-on: https://go-review.googlesource.com/c/go/+/418576
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
* The gp argument to canpanic is always equivalent to getg(), so no need
to pass it at all.
* gp must not be nil or _g_.m would have crashed, so no need to check
for nil.
* Use acquirem to better reason about preemption.
Change-Id: Ic7dc8dc1e56ab4c1644965f6aeba16807cdb2df4
Reviewed-on: https://go-review.googlesource.com/c/go/+/418575
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Michael Pratt <mpratt@google.com>
When compiling package runtime, cmd/compile logically has two copies
of package runtime: the actual source files being compiled, and the
internal description used for emitting compiler-generated calls.
Notably, CL 393715 will cause the compiler's write barrier validation
to start recognizing that compiler-generated calls are actually calls
to the corresponding functions from the source package. And today,
there are some code paths in nowritebarrierrec code paths that
actually end up generating code to call panicshift or panicdivide.
In preparation, this CL marks those functions as
//go:yeswritebarrierrec. We probably want to actually cleanup those
code paths to avoid these calls actually (e.g., explicitly convert
shift count expressions to an unsigned integer type). But for now,
this at least unblocks CL 393715 while preserving the status quo.
Updates #51734.
Change-Id: I01f89adb72466c0260a9cd363e3e09246e39cff9
Reviewed-on: https://go-review.googlesource.com/c/go/+/406316
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Panic avoids any write barriers in the runtime by checking first
and throwing if called inappropriately, so it is "okay". Adding
this annotation repairs recursive write barrier checking, which
becomes more thorough when the local package naming convention
is changed from "" to the actual package name.
This CL is a prerequisite for a pending code cleanup,
https://go-review.googlesource.com/c/go/+/393715
Updates #51734.
Change-Id: If831a3598c6c8cd37a8e9ba269f822cd81464a13
Reviewed-on: https://go-review.googlesource.com/c/go/+/405900
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: David Chase <drchase@google.com>
This gives explicit names to the possible states of throwing (-1, 0, 1).
m.throwing is now one of:
throwTypeOff: not throwing, previously == 0
throwTypeUser: user throw, previously == -1
throwTypeRuntime: runtime throw, previously == 1
For runtime throws, we now always include frame metadata and system
goroutines regardless of GOTRACEBACK to aid in debugging the runtime.
For user throws, we no longer include frame metadata or runtime frames,
unless GOTRACEBACK=system or higher.
For #51485.
Change-Id: If252e2377a0b6385ce7756b937929be4273a56c0
Reviewed-on: https://go-review.googlesource.com/c/go/+/390421
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Austin Clements <austin@google.com>
"User" throws are throws due to some invariant broken by the application.
"System" throws are due to some invariant broken by the runtime,
environment, etc (i.e., not the fault of the application).
This CL sends "user" throws through the new fatal. Currently this
function is identical to throw, but with a different name to clearly
differentiate the throw type in the stack trace, and hopefully be a bit
more clear to users what it means.
This CL changes a few categories of throw to fatal:
1. Concurrent map read/write.
2. Deadlock detection.
3. Unlock of unlocked sync.Mutex.
4. Inconsistent results from syscall.AllThreadsSyscall.
"Thread exhaustion" and "out of memory" (usually address space full)
throws are additional throws that are arguably the fault of user code,
but I've left off for now because there is no specific invariant that
they have broken to get into these states.
For #51485
Change-Id: I713276a6c290fd34a6563e6e9ef378669d74ae32
Reviewed-on: https://go-review.googlesource.com/c/go/+/390420
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
In issue #17671, there are a endless loop if printing
the panic value panics, CL 30358 has fixed that.
As issue #52257 pointed out, above change should not
discard the value from panic while panicking.
With this CL, when we recover from a panic in error.Error()
or stringer.String(), and the recovered value is string,
then we can print it normally.
Fixes#52257
Change-Id: Icfcc4a1a390635de405eea04904b4607ae9e3055
Reviewed-on: https://go-review.googlesource.com/c/go/+/399874
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
A future change to gofmt will rewrite
// Doc comment.
//go:foo
to
// Doc comment.
//
//go:foo
Apply that change preemptively to all comments (not necessarily just doc comments).
For #51082.
Change-Id: Iffe0285418d1e79d34526af3520b415a12203ca9
Reviewed-on: https://go-review.googlesource.com/c/go/+/384260
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
And then revert the bootstrap cmd directories and certain testdata.
And adjust tests as needed.
Not reverting the changes in std that are bootstrapped,
because some of those changes would appear in API docs,
and we want to use any consistently.
Instead, rewrite 'any' to 'interface{}' in cmd/dist for those directories
when preparing the bootstrap copy.
A few files changed as a result of running gofmt -w
not because of interface{} -> any but because they
hadn't been updated for the new //go:build lines.
Fixes#49884.
Change-Id: Ie8045cba995f65bd79c694ec77a1b3d1fe01bb09
Reviewed-on: https://go-review.googlesource.com/c/go/+/368254
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Recent changes to runtime enabled crashdumps, which under some
circumstances apparently might result in memory being uploaded to
Microsoft. A change like this should go through the proper proposals
process where we can discuss how to gate it and what all of its
implications are.
This reverts CL 307372 and its cleanup CL 360617.
Change-Id: If2e74015899d746831da40546c82eacacdf739e1
Reviewed-on: https://go-review.googlesource.com/c/go/+/362454
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Run-TryBot: Jason A. Donenfeld <Jason@zx2c4.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Fix two defer bugs related to adding/removing open defer entries.
The bugs relate to the way that we add and remove open defer entries
from the defer chain. At the point of a panic, when we want to start
processing defer entries in order during the panic process, we need to
add entries to the defer chain for stack frames with open defers, since
the normal fast-defer code does not add these entries. We do this by
calling addOneOpenDeferFrame() at the beginning of each time around the
defer loop in gopanic(). Those defer entries get sorted with other open
and non-open-coded defer frames.
However, the tricky part is that we also need to remove defer entries if
they end not being needed because of a recover (which means we are back
to executing the defer code inline at function exits). But we need
to deal with multiple panics and in-process defers on the stack, so we
can't just remove all open-coded defers from the the defer chain during
a recover.
The fix (and new invariant) is that we should not add any open-coded
defers to the defer chain that are higher up the stack than an open-coded
defer that is in progress. We know that open-coded defer will still be
run until completed, and when it is completed, then a more outer frame
will be added (if there is one). This fits with existing code in gopanic
that only removes open-coded defer entries up to any defer in progress.
These bugs were because of the previous inconsistency between adding and
removing open defer entries, which meant that stale defer entries could
be left on the list, in these unusual cases with both recursive
panics plus multiple independent (non-nested) cases of panic & recover.
The test for #48898 was difficult to add to defer_test.go (while keeping
the failure mode), so I added as a go/test/fixedbug test instead.
Fixes#43920
Updates #43941Fixes#48898
Change-Id: I593b77033e08c33094315abf8089fbc4cab07376
Reviewed-on: https://go-review.googlesource.com/c/go/+/356011
Trust: Dan Scales <danscales@google.com>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Austin Clements <austin@google.com>
This change provides ability to create dumps on Windows that can be used by
"dlv core" command. Currently only full dumps can be correctly read by Delve.
Below are the steps to create and use the dumps.
1. Configure Windows OS to collect dumps before running the program.
Instructions on how to do the configuration are here:
https://docs.microsoft.com/en-us/windows/win32/wer/collecting-user-mode-dumps.
In order for Delve to read the dump, set the DumpType to full dump, i.e. DumpType=2.
2. Go program only generates dumps when the environment variable GOTRACEBACK
is set to crash. Run command "set GOTRACEBACK=crash" before running the program.
3. Dump files will be generated in %LOCALAPPDATA%\CrashDumps
4. Use Delve command "dlv core" to open the dump, e.g.: "dlv core a.exe a.exe.3840.dmp".
Fixes#20498
Change-Id: Ib9aa82e7aea9da19594dc49348876997b24e9600
Reviewed-on: https://go-review.googlesource.com/c/go/+/307372
Run-TryBot: Alessandro Arzilli <alessandro.arzilli@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Patrik Nyblom <pnyb@google.com>
Trust: Alex Brainman <alex.brainman@gmail.com>
_g_, _p_, and _m_ are primarily vestiges of the C version of the
runtime, while today we prefer Go-style variable names (generally gp,
pp, and mp).
This change replaces all remaining uses of _m_ with mp. There are very
few remaining and all replacements are trivial.
[git-generate]
cd src/runtime
rf 'mv canpanic._m_ canpanic.mp'
GOOS=solaris \
rf 'mv semasleep._m_ semasleep.mp'
GOOS=aix GOARCH=ppc64 \
rf 'mv semasleep._m_ semasleep.mp'
Change-Id: I83690f7b4d4dc57557963100e9a2560ff343f3e8
Reviewed-on: https://go-review.googlesource.com/c/go/+/307813
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
A subsequent change will alter the semantics of _func.entry.
To make that change obvious and clear, change _func.entry to a method,
and rename the field to _func.entryPC.
Change-Id: I05d66b54d06c5956d4537b0729ddf4290c3e2635
Reviewed-on: https://go-review.googlesource.com/c/go/+/351460
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
CL 339396 allowed stack copying on entry to and during freedefer, but
this introduced a subtle bug: if d is heap-allocated, and d.link
points to a stack-allocated defer, stack copying during freedefer can
briefly introduce a stale pointer, which the garbage collector can
discover and panic about. This happens because d has already been
unlinked from the defer chain when freedefer is called, so stack
copying won't update stack pointers in it.
Fix this by making freedefer nosplit again and immediately clearing
d.link.
This should fix the longtest builders, which currently fail on
GOMAXPROCS=2 runtime -cpu=1,2,4 -quick in the TestDeferHeapAndStack
test.
This seems like the simplest fix, but it just deals with the subtlety
rather than eliminating it. Really, every call site of freedefer (of
which there are surprisingly many) has hidden subtlety between
unlinking the defer and calling freedefer. We could consolidate the
subtlety into each call site by requiring that they unlink the defer
and set d.link to nil before calling freedefer. freedefer could check
this condition like it checks that various other fields have already
been zeroed. A more radical option is to replace freedefer with
"popDefer", which would both pop the defer off the link and take care
of freeing it. There would still be a brief moment of subtlety, but it
would be in one place, in popDefer. Annoyingly, *almost* every call to
freedefer just pops the defer from the head of the G's list, but
there's one place when handling open-coded defers where we have to
remove a defer from the middle of the list. I'm inclined to first fix
that subtlety by only expanding open-coded defer records when they're
at the head of the defer list, and then revisit the popDefer idea.
Change-Id: I3130d2542c01a421a5d60e8c31f5379263219627
Reviewed-on: https://go-review.googlesource.com/c/go/+/339730
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Currently, freedefer manually zeros all the fields in the _defer
because simply assigning _defer{} used to cause a nosplit stack
overflow. freedefer is no longer nosplit, so go back to the simpler,
more robust code.
Change-Id: I881f557bab3b1ee7ab29b68e7fb56d0fe6d35d8d
Reviewed-on: https://go-review.googlesource.com/c/go/+/339669
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Currently, deferreturn runs deferred functions by backing up its
return PC to the deferreturn call, and then effectively tail-calling
the deferred function (via jmpdefer). The effect of this is that the
deferred function appears to be called directly from the deferee, and
when it returns, the deferee calls deferreturn again so it can run the
next deferred function if necessary.
This unusual flow control leads to a large number of special cases and
complications all over the tool chain.
This used to be necessary because deferreturn copied the deferred
function's argument frame directly into its caller's frame and then
had to invoke that call as if it had been called from its caller's
frame so it could access it arguments. But now that we've simplified
defer processing so the runtime only deals with argument-less
closures, this approach is no longer necessary.
This CL simplifies all of this by making deferreturn simply call
deferred functions in a loop.
This eliminates the need for jmpdefer, so we can delete a bunch of
per-architecture assembly code.
This eliminates several special cases on Wasm, since it couldn't
support these calling shenanigans directly and thus had to simulate
the loop a different way. Now Wasm can largely work the way the other
platforms do.
This eliminates the per-architecture Ginsnopdefer operation. On PPC64,
this was necessary to reload the TOC pointer after the tail call
(since TOC pointers in general make tail calls impossible). The tail
call is gone, and in the case where we do force a jump to the
deferreturn call when recovering from an open-coded defer, we go
through gogo (via runtime.recovery), which handles the TOC. On other
platforms, we needed a NOP so traceback didn't get confused by seeing
the return to the CALL instruction, rather than the usual return to
the instruction following the CALL instruction. Now we don't inject a
return to the CALL instruction at all, so this NOP is also
unnecessary.
The one potential effect of this is that deferreturn could now appear
in stack traces from deferred functions. However, this could already
happen from open-coded defers, so we've long since marked deferreturn
as a "wrapper" so it gets elided not only from printed stack traces,
but from runtime.Callers*.
This is a retry of CL 337652 because we had to back out its parent.
There are no changes in this version.
Change-Id: I3f54b7fec1d7ccac71cc6cf6835c6a46b7e5fb6c
Reviewed-on: https://go-review.googlesource.com/c/go/+/339397
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Prior to regabi, the compiler passed defer arguments to the runtime as
untyped values on the stack. This meant a lot of defer-related runtime
functions had to be very careful not to grow the stack or allow
preemption since the stack could not be safely scanned or moved.
However, with regabi, every defer is now simply a func() from the
runtime's perspective, which means we no longer have untyped values on
the stack when we enter defer-related runtime code.
Hence, this CL removes a lot of the now-unnecessary carefulness in the
defer implementation. Specifically, deferreturn no longer needs to be
nosplit because it doesn't copy untyped defer arguments to its
caller's frame (we also update some stale comments in deferreturn).
freedefer no longer needs to be nosplit because it's none of its
callers are deeply nosplit. And newdefer and freedefer no longer need
to switch to the systemstack on their slow paths to avoid stack
growth.
deferprocStack is the only function that still needs to be nosplit,
but that's because the compiler calls it with uninitialized live
pointer slots on the stack (maybe we should change that, but that's a
very different fix).
This is a retry of CL 337651, which was rolled back. This version
disables preemption in newdefer and freedefer while they hold the
current P.
Change-Id: Ibf469addc0b69dc3ba9a3d1a5e0c2804b7b4b244
Reviewed-on: https://go-review.googlesource.com/c/go/+/339396
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This reverts CL 227652.
I'm reverting CL 337651 and this builds on top of it.
Change-Id: I03ce363be44c2a3defff2e43e7b1aad83386820d
Reviewed-on: https://go-review.googlesource.com/c/go/+/338709
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Currently, deferreturn runs deferred functions by backing up its
return PC to the deferreturn call, and then effectively tail-calling
the deferred function (via jmpdefer). The effect of this is that the
deferred function appears to be called directly from the deferee, and
when it returns, the deferee calls deferreturn again so it can run the
next deferred function if necessary.
This unusual flow control leads to a large number of special cases and
complications all over the tool chain.
This used to be necessary because deferreturn copied the deferred
function's argument frame directly into its caller's frame and then
had to invoke that call as if it had been called from its caller's
frame so it could access it arguments. But now that we've simplified
defer processing so the runtime only deals with argument-less
closures, this approach is no longer necessary.
This CL simplifies all of this by making deferreturn simply call
deferred functions in a loop.
This eliminates the need for jmpdefer, so we can delete a bunch of
per-architecture assembly code.
This eliminates several special cases on Wasm, since it couldn't
support these calling shenanigans directly and thus had to simulate
the loop a different way. Now Wasm can largely work the way the other
platforms do.
This eliminates the per-architecture Ginsnopdefer operation. On PPC64,
this was necessary to reload the TOC pointer after the tail call
(since TOC pointers in general make tail calls impossible). The tail
call is gone, and in the case where we do force a jump to the
deferreturn call when recovering from an open-coded defer, we go
through gogo (via runtime.recovery), which handles the TOC. On other
platforms, we needed a NOP so traceback didn't get confused by seeing
the return to the CALL instruction, rather than the usual return to
the instruction following the CALL instruction. Now we don't inject a
return to the CALL instruction at all, so this NOP is also
unnecessary.
The one potential effect of this is that deferreturn could now appear
in stack traces from deferred functions. However, this could already
happen from open-coded defers, so we've long since marked deferreturn
as a "wrapper" so it gets elided not only from printed stack traces,
but from runtime.Callers*.
Change-Id: Ie9f700cd3fb774f498c9edce363772a868407bf7
Reviewed-on: https://go-review.googlesource.com/c/go/+/337652
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
Prior to regabi, the compiler passed defer arguments to the runtime as
untyped values on the stack. This meant a lot of defer-related runtime
functions had to be very careful not to grow the stack or allow
preemption since the stack could not be safely scanned or moved.
However, with regabi, every defer is now simply a func() from the
runtime's perspective, which means we no longer have untyped values on
the stack when we enter defer-related runtime code.
Hence, this CL removes a lot of the now-unnecessary carefulness in the
defer implementation. Specifically, deferreturn no longer needs to be
nosplit because it doesn't copy untyped defer arguments to its
caller's frame (we also update some stale comments in deferreturn).
freedefer no longer needs to be nosplit because it's none of its
callers are deeply nosplit. And newdefer and freedefer no longer need
to switch to the systemstack on their slow paths to avoid stack
growth.
deferprocStack is the only function that still needs to be nosplit,
but that's because the compiler calls it with uninitialized live
pointer slots on the stack (maybe we should change that, but that's a
very different fix).
Change-Id: I1156ec90bff2613fe4b48b84b375943349ce637d
Reviewed-on: https://go-review.googlesource.com/c/go/+/337651
Trust: Austin Clements <austin@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
Prior to regabi, a deferred function could have any signature, so the
runtime always manipulated them as funcvals. Now, a deferred function
is always func(). Hence, this CL makes the runtime's manipulation of
deferred functions more type-safe by using func() directly instead of
*funcval.
Change-Id: Ib55f38ed49107f74149725c65044e4690761971d
Reviewed-on: https://go-review.googlesource.com/c/go/+/337650
Trust: Austin Clements <austin@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
Currently, deferproc stores the caller SP as a uintptr in a local
variable across a call to newdefer, but newdefer could grow the stack
and invalidate this saved SP, causing deferproc to store a stale SP in
the defer record. This would lead to us later failing to match that
defer to its calling frame, and we wouldn't run the defer at the right
time (or possibly at all).
It turns out this isn't crashing horribly right now only because the
compiler happens to only materialize the result of getcallersp when
this variable is used, *after* the call to newdefer. But this is
clearly on thin ice, so this CL moves the getcallersp() to the place
where we actually need the result.
Change-Id: Iae8ab226e03e4482f16acfb965885f0bd83a13b0
Reviewed-on: https://go-review.googlesource.com/c/go/+/337649
Trust: Austin Clements <austin@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
Temprary revert CL 325918.
Delve relies on the _defer.fn.fn field to get defer frames.
CL 325918 changes the type of _defer.fn to func(), which no
longer has an fn field.
Change-Id: If6c71b15a27bac579593f5273c9a49715e6e35b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/327775
Trust: Cherry Mui <cherryyz@google.com>
Trust: Dan Scales <danscales@google.com>
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Reviewed-by: Dan Scales <danscales@google.com>
Now that deferred functions are always argumentless and defer
records are no longer with arguments, defer record can be fixed
size (just the _defer struct). This allows us to simplify the
allocation of defer records, specifically, remove the defer
classes and the pools of different sized defers.
Change-Id: Icc4b16afc23b38262ca9dd1f7369ad40874cf701
Reviewed-on: https://go-review.googlesource.com/c/go/+/326062
Trust: Cherry Mui <cherryyz@google.com>
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TryBot-Result: Go Bot <gobot@golang.org>
Now that deferred functions are always argumentless, we don't
need the metadata for the frame size, number of arguments, and
the information about each argument.
Change-Id: I99e75248a22bda6efbdf2012a2f35beca4c18fd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/326061
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Than McIntosh <thanm@google.com>
As deferred function now always has zero arguments, _defer.siz is
always 0 and can be removed.
Change-Id: Ibb89f65b2f9d2ba4aeabe50438cc3d4b6a88320b
Reviewed-on: https://go-review.googlesource.com/c/go/+/325921
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
deferproc was not allowed to split stack because it had a special
stack layout, where the go'd function's arguments were passed on
stack but not included in the signature (therefore the stack map).
Now it no longer has argument, so it does not need to be nosplit.
Change-Id: I6d4b5302bd6fea6642bb4202984d86e3ebbc9054
Reviewed-on: https://go-review.googlesource.com/c/go/+/325920
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
Previously it takes a *funcval, as it can be any function types.
Now it must be func(). Make it so.
Change-Id: I04273047b024386f55dbbd5fbda4767cbee7ac93
Reviewed-on: https://go-review.googlesource.com/c/go/+/325918
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
newproc/deferproc takes a siz argument for the go'd/deferred
function's argument size. Now it is always zero. Remove the
argument.
Change-Id: If1bb8d427e34015ccec0ba10dbccaae96757fa8c
Reviewed-on: https://go-review.googlesource.com/c/go/+/325917
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
Now that defer/go wrapping is used, deferred/go'd functions are
always argumentless. Remove the code handling arguments.
This CL is mostly removing the fallback code path. There are more
cleanups to be done, in later CLs.
Change-Id: I87bfd3fb2d759fbeb6487b8125c0f6992863d6e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/325915
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
Hardwire regabidefers to true. Remove it from GOEXPERIMENTs.
Fallback paths are not cleaned up in this CL. That will be done
in later CLs.
Change-Id: Iec1112a1e55d5f6ef70232a5ff6e702f649071c4
Reviewed-on: https://go-review.googlesource.com/c/go/+/325913
Trust: Cherry Mui <cherryyz@google.com>
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Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
deferreturn has a dummy argument, that is only used for getting
the caller's SP. When generating deferreturn calls, the compiler
does not pass an actual argument or reserve its stack space.
Also, the current code is written with the assumption about where
the argument's address is on the stack. Currently this is correct
for both ABI0 and the register ABI, but it may change in the
future (e.g. if we remove dedicated spill slots). Remove the
argument.
Also remove the argument for getargp.
Change-Id: I96d07efa79a9c1a53ef3fc5adbecc11877e99dc1
Reviewed-on: https://go-review.googlesource.com/c/go/+/309329
Trust: Cherry Zhang <cherryyz@google.com>
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Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Currently, we have boolean and integral constants for GOEXPERIMENTs in
various places. Consolidate these into automatically generated
constants in the internal/goexperiment package.
Change-Id: I42a49aba2a3b4c722fedea23a613162cd8a67bee
Reviewed-on: https://go-review.googlesource.com/c/go/+/307818
Trust: Austin Clements <austin@google.com>
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Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
This change eliminates the use of funcPC to determine if an PC is in
abort. Using funcPC for this purpose is problematic when using plugins
because symbols no longer have unique PCs. funcPC also grabs the wrapper
for runtime.abort which isn't what we want for the new register ABI, so
rather than mark runtime.abort as ABIInternal, use funcID.
For #40724.
Change-Id: I2730e99fe6f326d22d64a10384828b94f04d101a
Reviewed-on: https://go-review.googlesource.com/c/go/+/307391
Trust: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>
David Chase
Austin Clements
Michael Pratt
Russ Cox
Matthew Dempsky
Daniel Martí
hopehook
Jason A. Donenfeld
Dan Scales
Zhi Zheng
Josh Bleecher Snyder
Michael Anthony Knyszek
Cherry Mui