Rob Pike [Tue, 21 Mar 2017 03:24:26 +0000 (20:24 -0700)]
encoding/gob: document the extra byte after a singleton
This paragraph has been added, as the notion was missing from the
documentation.
If a value is passed to Encode and the type is not a struct (or pointer to struct,
etc.), for simplicity of processing it is represented as a struct of one field.
The only visible effect of this is to encode a zero byte after the value, just as
after the last field of an encoded struct, so that the decode algorithm knows when
the top-level value is complete.
Fixes #16978
Change-Id: I5f008e792d1b6fe80d2e026a7ff716608889db32
Reviewed-on: https://go-review.googlesource.com/38414 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Rob Pike [Tue, 21 Mar 2017 03:18:02 +0000 (20:18 -0700)]
text/template,html/template: state that Funcs must happen before parsing
Any method that affects the parse must happen before parsing.
This obvious point is clear, but it's not clear to some that the
set of defined functions affect the parse.
Fixes #18971
Change-Id: I8b7f8c8cf85b028c18e5ca3b9797de92ea910669
Reviewed-on: https://go-review.googlesource.com/38413 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Previously, we handled recursive interfaces by deferring typechecking
of interface methods, while eagerly expanding interface embeddings.
This CL switches to eagerly evaluating interface methods, and
deferring expanding interface embeddings to dowidth. This allows us to
detect recursive interface embeddings with the same mechanism used for
detecting recursive struct embeddings.
Updates #16369.
Change-Id: If4c0320058047f8a2d9b52b9a79de47eb9887f95
Reviewed-on: https://go-review.googlesource.com/38391
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
Jakob Borg [Mon, 13 Mar 2017 23:21:51 +0000 (08:21 +0900)]
net/http: fix ProxyFromEnvironment panic on invalid $NO_PROXY value
Given an entry in $no_proxy like ":1" we would interpret it as an empty
host name and a port number, then check the first character of the host
name for dots. This would then cause an index out of range panic. This
change simply skips these entries, as the following checks would anyway
have returned false.
Pascal S. de Kloe [Wed, 16 Nov 2016 15:35:42 +0000 (16:35 +0100)]
encoding/json: reduce unmarshal mallocs for unmapped fields
JSON decoding performs poorly for unmapped and ignored fields. We noticed better
performance when unmarshalling unused fields. The loss comes mostly from calls
to scanner.error as described at #17914.
benchmark old ns/op new ns/op delta
BenchmarkIssue10335-8 431 408 -5.34%
BenchmarkUnmapped-8 1744 1314 -24.66%
benchmark old allocs new allocs delta
BenchmarkIssue10335-8 4 3 -25.00%
BenchmarkUnmapped-8 18 4 -77.78%
benchmark old bytes new bytes delta
BenchmarkIssue10335-8 320 312 -2.50%
BenchmarkUnmapped-8 568 344 -39.44%
Matthew Dempsky [Sat, 11 Mar 2017 00:03:56 +0000 (16:03 -0800)]
cmd/compile: sort CFG blocks in PC order during liveness
This CL changes the order that liveness analysis visits CFG blocks to
PC order, rather than RPO. This doesn't meaningfully change anything
except that the PCDATA_StackMapIndex values will be assigned in PC
order too.
However, this does have the benefit that the subsequent CL to port
liveness analysis to the SSA CFG (which has blocks in PC order) will
now pass toolstash-check.
Michael Munday [Mon, 20 Mar 2017 21:31:35 +0000 (17:31 -0400)]
cmd/internal/obj/s390x: cleanup objz.go
This CL deletes some unnecessary code in objz.go that existed to
support instruction scheduling. It's likely instruction scheduling
will never be done in this part of the backend so this code can
just be deleted.
This file can probably be cleaned up a bit more, but I think this
is a good start.
Passes: go build -toolexec 'toolstash -cmp' -a std.
cmd/go, cmd/compile: always optimize when building runtime
When optimizations are disabled, the compiler
cannot eliminate enough write barriers to satisfy
the runtime's nowritebarrier and nowritebarrierrec
annotations.
Enforce that requirement, and for convenience,
have cmd/go elide -N when compiling the runtime.
This came up in practice for me when running
toolstash -cmp. When toolstash -cmp detected
mismatches, it recompiled with -N, which caused
runtime compilation failures.
CL 27254 changed a constant string to a byte array
in encoding/hex and got significant performance
improvements.
hex.Encode used the string twice in a single function.
The rewrite rules lower constant strings into components.
The pointer component requires an aux symbol.
The existing implementation created a new aux symbol every time.
As a result, constant string pointers were never CSE'd.
Tighten then moved the pointer calculation next to the uses, i.e.
into the loop.
The re-use of aux syms enabled by this CL
occurs 3691 times during make.bash.
This CL should not go in without CL 38338
or something like it.
Robert Griesemer [Mon, 20 Mar 2017 20:08:26 +0000 (13:08 -0700)]
cmd/gofmt: clarify doc string even more
Since "columns of alignment" are terminated whenever indentation
changes from one line to the next, alignment with spaces will work
independent of the actually chosen tab width. Don't mention tab width
anymore.
Follow-up on https://golang.org/cl/38374/.
For #19618.
Change-Id: I58e47dfde57834f56a98d9119670757a12fb9c41
Reviewed-on: https://go-review.googlesource.com/38379 Reviewed-by: Rob Pike <r@golang.org>
Brad Fitzpatrick [Mon, 20 Mar 2017 16:44:34 +0000 (16:44 +0000)]
net/http: deflake TestServerAllowsBlockingRemoteAddr more
As noted in https://github.com/golang/go/issues/19161#issuecomment-287554171,
CL 37771 (adding use of the new httptest.Server.Client to all net/http
tests) accidentally reverted DisableKeepAlives for this test. For
many tests, DisableKeepAlives was just present to prevent goroutines
from staying active after the test exited. In this case it might
actually be important. (We'll see)
Updates #19161
Change-Id: I11f889f86c932b51b11846560b68dbe5993cdfc3
Reviewed-on: https://go-review.googlesource.com/38373 Reviewed-by: Michael Munday <munday@ca.ibm.com>
Austin Clements [Thu, 16 Mar 2017 21:02:24 +0000 (17:02 -0400)]
runtime: disallow malloc or panic in scavenge
Mallocs and panics in the scavenge path are particularly nasty because
they're likely to silently self-deadlock on the mheap.lock. Avoid
sinking lots of time into debugging these issues in the future by
turning these into immediate throws.
Austin Clements [Tue, 7 Mar 2017 21:38:29 +0000 (16:38 -0500)]
runtime: introduce a type for lfstacks
The lfstack API is still a C-style API: lfstacks all have unhelpful
type uint64 and the APIs are package-level functions. Make the code
more readable and Go-style by creating an lfstack type with methods
for push, pop, and empty.
I noted in CL 38327 that the SSA test API felt a bit
clunky after the ssa.Func/ssa.Cache/ssa.Config refactoring,
and promised to clean it up once the dust settled.
The dust has settled.
Along the way, this CL fixes a potential latent bug,
in which the amd64 test context was used for all dummy Syslook calls.
The lone SSA test using the s390x context did not depend on the
Syslook context being correct, so the bug did not arise in practice.
This reduces the number of calls back into the
gc Type routines, which will help performance
in a concurrent backend.
It also reduces the number of callsites
that must be considered in making the transition.
Passes toolstash-check -all. No compiler performance changes.
cmd/compile: separate ssa.Frontend and ssa.TypeSource
Prior to this CL, the ssa.Frontend field was responsible
for providing types to the backend during compilation.
However, the types needed by the backend are few and static.
It makes more sense to use a struct for them
and to hang that struct off the ssa.Config,
which is the correct home for readonly data.
Now that Types is a struct, we can clean up the names a bit as well.
This has the added benefit of allowing early construction
of all types needed by the backend.
This will be useful for concurrent backend compilation.
Passes toolstash-check -all. No compiler performance change.
Updates #15756
Change-Id: I021658c8cf2836d6a22bbc20cc828ac38c7da08a
Reviewed-on: https://go-review.googlesource.com/38336 Reviewed-by: Matthew Dempsky <mdempsky@google.com>
cmd/compile: move Frontend field from ssa.Config to ssa.Func
Suggested by mdempsky in CL 38232.
This allows us to use the Frontend field
to associate frontend state and information
with a function.
See the following CL in the series for examples.
This is a giant CL, but it is almost entirely routine refactoring.
The ssa test API is starting to feel a bit unwieldy.
I will clean it up separately, once the dust has settled.
cmd/compile: evaluate config as needed in rewrite rules
Prior to this CL, config was an explicit argument
to the SSA rewrite rules, and rules that needed
a Frontend got at it via config.
An upcoming CL moves Frontend from Config to Func,
so rules can no longer reach Frontend via Config.
Passing a Frontend as an argument to the rewrite rules
causes a 2-3% regression in compile times.
This CL takes a different approach:
It treats the variable names "config" and "fe"
as special and calculates them as needed.
The "as needed part" is also important to performance:
If they are calculated eagerly, the nilchecks themselves
cause a regression.
This introduces a little bit of magic into the rewrite
generator. However, from the perspective of the rules,
the config variable was already more or less magic.
And it makes the upcoming changes much clearer.
Matthew Dempsky [Fri, 17 Mar 2017 20:35:31 +0000 (13:35 -0700)]
cmd/compile: eliminate direct uses of gc.Thearch in backends
This CL changes the GOARCH.Init functions to take gc.Thearch as a
parameter, which gc.Main supplies.
Additionally, the x86 backend is refactored to decide within Init
whether to use the 387 or SSE2 instruction generators, rather than for
each individual SSA Value/Block.
Robert Griesemer [Fri, 17 Mar 2017 04:13:29 +0000 (21:13 -0700)]
strconv: replace small int string table with constant string
This reduces memory use yet still provides the significant
performance gain seen when using a fast path for small integers.
Improvement of this CL comparing to code without fast path:
name old time/op new time/op delta
FormatIntSmall-8 35.6ns ± 1% 4.5ns ± 1% -87.30% (p=0.008 n=5+5)
AppendIntSmall-8 17.4ns ± 1% 9.4ns ± 3% -45.70% (p=0.008 n=5+5)
For comparison, here's the improvement before this CL to code without
fast path (1% better for FormatIntSmall):
name old time/op new time/op delta
FormatIntSmall-8 35.6ns ± 1% 4.0ns ± 3% -88.64% (p=0.008 n=5+5)
AppendIntSmall-8 17.4ns ± 1% 8.2ns ± 1% -52.80% (p=0.008 n=5+5)
Thus, the code in this CL performs slower for small integers using fast
path then the prior version, but this is relative to an already very fast
version:
name old time/op new time/op delta
FormatIntSmall-8 4.05ns ± 3% 4.52ns ± 1% +11.81% (p=0.008 n=5+5)
AppendIntSmall-8 8.21ns ± 1% 9.45ns ± 3% +15.05% (p=0.008 n=5+5)
Measured on 2.3 GHz Intel Core i7 running macOS Sierra 10.12.3.
Overall, it's still ~88% faster than without fast path for small integers,
so probably worth it as it removes 100 global string slices in favor of
a single string.
Credits: This is based on the original (but cleaned up) version of the
code by Aliaksandr Valialkin (https://go-review.googlesource.com/c/37963/).
Change-Id: Icda78679c8c14666d46257894e9fa3d7f35e58b8
Reviewed-on: https://go-review.googlesource.com/38319 Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Alexander Menzhinsky [Fri, 3 Mar 2017 12:57:19 +0000 (15:57 +0300)]
cmd/go: fix race libraries rebuilding by `go test -i`
`go test -i -race` adds the "sync/atomic" package to every package dependency tree
that makes buildIDs different from packages installed with `go install -race`
and causes cache rebuilding.
Fixes #19133
Fixes #19151
Change-Id: I0536c6fa41b0d20fe361b5d35b3c0937b146d07d
Reviewed-on: https://go-review.googlesource.com/37598 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Alexey Neganov [Tue, 14 Mar 2017 18:11:42 +0000 (21:11 +0300)]
mime: handling invalid mime media parameters
Sometimes it's necessary to deal with emails that do not follow the specification; in particular, it's possible to download such email via gmail.
When the existing implementation handle invalid mime media parameters, it returns nils and error, although there is a valid media type, which may be returned.
If this behavior changes, it may not affect any existing programs, but it will help to parse some emails.
Fixes #19498
Change-Id: Ieb2fdbddfd93857faee941d2aa49d59e286d57fd
Reviewed-on: https://go-review.googlesource.com/38190 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
cmd/compile: rearrange fields between ssa.Func, ssa.Cache, and ssa.Config
This makes ssa.Func, ssa.Cache, and ssa.Config fulfill
the roles laid out for them in CL 38160.
The only non-trivial change in this CL is how cached
values and blocks get IDs. Prior to this CL, their IDs were
assigned as part of resetting the cache, and only modified
IDs were reset. This required knowing how many values and
blocks were modified, which required a tight coupling between
ssa.Func and ssa.Config. To eliminate that coupling,
we now zero values and blocks during reset,
and assign their IDs when they are used.
Since unused values and blocks have ID == 0,
we can efficiently find the last used value/block,
to avoid zeroing everything.
Bulk zeroing is efficient, but not efficient enough
to obviate the need to avoid zeroing everything every time.
As a happy side-effect, ssa.Func.Free is no longer necessary.
DebugHashMatch and friends now belong in func.go.
They have been left in place for clarity and review.
I will move them in a subsequent CL.
Passes toolstash -cmp. No compiler performance impact.
No change in 'go test cmd/compile/internal/ssa' execution time.
We could likely also eliminate the "assignment count mismatch" prefix now
without losing any information, but that string is matched by a number of
tests.
Change-Id: Ie6fc8a7bbd0ebe841d53e66e5c2f49868decf761
Reviewed-on: https://go-review.googlesource.com/38313 Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
8-bit args is a special case - the Go code is really fast because
it is just a single table lookup. So I've disabled that for now.
Intrinsics were actually slower:
LeadingZeros8-4 1.22ns ± 3% 1.58ns ± 1% +29.56% (p=0.000 n=10+10)
Update #18616
Change-Id: Ia9c289b9ba59c583ea64060470315fd637e814cf
Reviewed-on: https://go-review.googlesource.com/38311
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
Steve Francia [Thu, 9 Feb 2017 20:33:13 +0000 (15:33 -0500)]
doc: reorganize the contribution guidelines into a guide
Updates #17802
Change-Id: I65ea0f4cde973604c04051e7eb25d12e4facecd3
Reviewed-on: https://go-review.googlesource.com/36626 Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Chris Broadfoot <cbro@golang.org>
Cherry Zhang [Tue, 14 Mar 2017 01:51:08 +0000 (21:51 -0400)]
cmd/compile: use type information in Aux for Store size
Remove size AuxInt in Store, and alignment in Move/Zero. We still
pass size AuxInt to Move/Zero, as it is used for partial Move/Zero
lowering (e.g. cmd/compile/internal/ssa/gen/386.rules:288).
SizeAndAlign is gone.
Cherry Zhang [Tue, 14 Feb 2017 02:27:53 +0000 (21:27 -0500)]
cmd/compile: add a test for writebarrier pass with single-block loop
The old writebarrier implementation fails to handle single-block
loop where a memory Phi value depends on the write barrier store
in the same block. The new implementation (CL 36834) doesn't have
this problem. Add a test to ensure it.
Fix #19067.
Change-Id: Iab13c6817edc12be8a048d18699b4450fa7ed712
Reviewed-on: https://go-review.googlesource.com/36940 Reviewed-by: David Chase <drchase@google.com>
Cherry Zhang [Mon, 6 Feb 2017 04:43:31 +0000 (23:43 -0500)]
cmd/compile: move write barrier insertion to SSA
When the compiler insert write barriers, the frontend makes
conservative decisions at an early stage. This sometimes have
false positives because of the lack of information, for example,
writes on stack. SSA's writebarrier pass identifies writes on
stack and eliminates write barriers for them.
This CL moves write barrier insertion into SSA. The frontend no
longer makes decisions about write barriers, and simply does
normal assignments and emits normal Store ops when building SSA.
SSA writebarrier pass inserts write barrier for Stores when needed.
There, it has better information about the store because Phi and
Copy propagation are done at that time.
This CL only changes StoreWB to Store in gc/ssa.go. A followup CL
simplifies SSA building code.
Cherry Zhang [Thu, 9 Feb 2017 14:46:44 +0000 (09:46 -0500)]
cmd/compile: pass types on SSA Store/Move/Zero ops
For SSA Store/Move/Zero ops, attach the type of the value being
stored to the op as the Aux field. This type will be used for
write barrier insertion (in a followup CL). Since SSA passes
do not accurately propagate types of values (because of type
casting), we can't simply use type of the store's arguments
for write barrier insertion.
Keith Randall [Tue, 14 Mar 2017 20:25:12 +0000 (13:25 -0700)]
cmd/compile: intrinsics for math/bits.TrailingZerosX
Implement math/bits.TrailingZerosX using intrinsics.
Generally reorganize the intrinsic spec a bit.
The instrinsics data structure is now built at init time.
This will make doing the other functions in math/bits easier.
Update sys.CtzX to return int instead of uint{64,32} so it
matches math/bits.TrailingZerosX.
Improve the intrinsics a bit for amd64. We don't need the CMOV
for <64 bit versions.
Update #18616
Change-Id: Ic1c5339c943f961d830ae56f12674d7b29d4ff39
Reviewed-on: https://go-review.googlesource.com/38155
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@golang.org>
Martin Möhrmann [Sat, 25 Feb 2017 22:50:56 +0000 (23:50 +0100)]
runtime: make complex division c99 compatible
- changes tests to check that the real and imaginary part of the go complex
division result is equal to the result gcc produces for c99
- changes complex division code to satisfy new complex division test
- adds float functions isNan, isFinite, isInf, abs and copysign
in the runtime package
Austin Clements [Fri, 10 Mar 2017 15:59:39 +0000 (10:59 -0500)]
runtime: print user stack on other threads during GOTRACBEACK=crash
Currently, when printing tracebacks of other threads during
GOTRACEBACK=crash, if the thread is on the system stack we print only
the header for the user goroutine and fail to print its stack. This
happens because we passed the g0 to traceback instead of curg. The g0
never has anything set in its gobuf, so traceback doesn't print
anything.
Fix this by passing _g_.m.curg to traceback instead of the g0.
Fixes #19494.
Change-Id: Idfabf94d6a725e9cdf94a3923dead6455ef3b217
Reviewed-on: https://go-review.googlesource.com/38012
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
Austin Clements [Wed, 15 Mar 2017 18:48:23 +0000 (14:48 -0400)]
runtime: make GOTRACEBACK=crash crash promptly in cgo binaries
GOTRACEBACK=crash works by bouncing a SIGQUIT around the process
sched.mcount times. However, sched.mcount includes the extra Ms
allocated by oneNewExtraM for cgo callbacks. Hence, if there are any
extra Ms that don't have real OS threads, we'll try to send SIGQUIT
more times than there are threads to catch it. Since nothing will
catch these extra signals, we'll fall back to blocking for five
seconds before aborting the process.
Avoid this five second delay by subtracting out the number of extra Ms
when sending SIGQUITs.
Of course, in a cgo binary, it's still possible for the SIGQUIT to go
to a cgo thread and cause some other failure mode. This does not fix
that.
Change-Id: I4fbf3c52dd721812796c4c1dcb2ab4cb7026d965
Reviewed-on: https://go-review.googlesource.com/38182
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
cmd/compile: check labels and gotos before building SSA
This CL introduces yet another compiler pass,
which checks for correct control flow constructs
prior to converting from AST to SSA form.
It cannot be integrated with walk, since walk rewrites
switch and select statements on the fly.
To reduce code duplication, this CL also does some
minor refactoring.
With this pass in place, the AST to SSA converter
can now stop generating SSA for any known-dead code.
This minor savings pays for the minor cost of the new pass.
Cherry Zhang [Mon, 13 Mar 2017 12:24:46 +0000 (08:24 -0400)]
cmd/link: on PPC64, put plt stubs at beginning of Textp
Put call stubs at the beginning (instead of the end). So the
trampoline pass knows the addresses of the stubs, and it can
insert trampolines when necessary.
cmd/compile: define roles for ssa.Func, ssa.Config, and ssa.Cache
The line between ssa.Func and ssa.Config has blurred.
Concurrent compilation in the backend will require more precision.
This CL lays out an (aspirational) organization.
The implementation will come in follow-up CLs,
once the organization is settled.
ssa.Config holds basic compiler configuration,
mostly arch-specific information.
It is configured once, early on, and is readonly,
so it is safe for concurrent use.
ssa.Func is a single-shot object used for
compiling a single Func. It is not concurrency-safe
and not re-usable.
ssa.Cache is a multi-use object used to avoid
expensive allocations during compilation.
Each ssa.Func is given an ssa.Cache to use.
ssa.Cache is not concurrency-safe.
Change-Id: Id02809b6f3541541cac6c27bbb598834888ce1cc
Reviewed-on: https://go-review.googlesource.com/38160 Reviewed-by: Keith Randall <khr@golang.org>
David Chase [Tue, 7 Mar 2017 19:45:46 +0000 (14:45 -0500)]
cmd/compile: put spills in better places
Previously we always issued a spill right after the op
that was being spilled. This CL pushes spills father away
from the generator, hopefully pushing them into unlikely branches.
For example:
x = ...
if unlikely {
call ...
}
... use x ...
Used to compile to
x = ...
spill x
if unlikely {
call ...
restore x
}
It now compiles to
x = ...
if unlikely {
spill x
call ...
restore x
}
This is particularly useful for code which appends, as the only
call is an unlikely call to growslice. It also helps for the
spills needed around write barrier calls.
The basic algorithm is walk down the dominator tree following a
path where the block still dominates all of the restores. We're
looking for a block that:
1) dominates all restores
2) has the value being spilled in a register
3) has a loop depth no deeper than the value being spilled
The walking-down code is iterative. I was forced to limit it to
searching 100 blocks so it doesn't become O(n^2). Maybe one day
we'll find a better way.
I had to delete most of David's code which pushed spills out of loops.
I suspect this CL subsumes most of the cases that his code handled.
Generally positive performance improvements, but hard to tell for sure
with all the noise. (compilebench times are unchanged.)
Philip Hofer [Tue, 14 Mar 2017 21:00:38 +0000 (14:00 -0700)]
cmd/compile/internal/gc: mark generated wrappers as DUPOK
Interface wrapper functions now get compiled eagerly in some cases.
Consequently, they may be present in multiple translation units.
Mark them as DUPOK, just like closures.
Fixes #19548
Fixes #19550
Change-Id: Ibe74adb5a62dbf6447db37fde22dcbb3479969ef
Reviewed-on: https://go-review.googlesource.com/38156 Reviewed-by: David Chase <drchase@google.com>
Matthew Dempsky [Thu, 9 Mar 2017 20:15:41 +0000 (12:15 -0800)]
cmd/compile: refactor liveness analysis for moving to SSA
In the SSA CFG, TEXT, RET, and JMP instructions correspond to Blocks,
not Values. Rework liveness analysis so that progeffects only cares
about Progs that result from Values, and handle Blocks separately.
Daniel Martí [Fri, 10 Mar 2017 17:15:46 +0000 (17:15 +0000)]
*.bash: always use the same string equality operator
POSIX Shell only supports = to compare variables inside '[' tests. But
this is Bash, where == is an alias for =. In practice they're the same,
but the current form is inconsisnent and breaks POSIX for no good
reason.
Change-Id: I38fa7a5a90658dc51acc2acd143049e510424ed8
Reviewed-on: https://go-review.googlesource.com/38031 Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
cmd/compile: eliminate fmtmode and fmtpkgpfx globals
The fmtmode and fmtpkgpfx globals stand in the
way of making the compiler more concurrent (#15756).
This CL removes them.
The natural way to eliminate a global is to explicitly
thread it as a parameter through all function calls.
However, most of the functions in gc/fmt.go
get called indirectly, by way of fmt format strings,
so there's nowhere natural to add a parameter.
Since there are only a few fmtmode modes,
use named types to distinguish between modes.
For example, fmtNodeErr, fmtNodeDbg, and fmtNodeTypeId
are all gc.Node, but they print in different modes.
Varying the type allows us to thread mode through fmt.
Handle fmtpkgpfx by converting it to a printing mode,
FTypeIdName, and using the same type-based approach.
To avoid a loss of readability and danger of bugs
from introducing conversions at all call sites,
instead add a helper that systematically modifies the args.
The only remaining gc/fmt.go global is dumpdepth.
Since that is used for debugging only,
it that can be handled with a global mutex,
or some similarly basic, if inefficient, protection.
Passes toolstash -cmp. No compiler performance impact.
For future reference, other options for threading state
that were considered and rejected:
* Wrapping values in structs, such as:
type fmtNode struct {
n *Node
mode fmtMode
}
This reduces the proliferation of types, and supports
easily adding extra local parameters.
However, putting such a struct into an interface{} allocates.
This is unacceptable in this particular area of code.
* Passing state via precision, such as:
fmt.Fprintf("%*v", mode, n)
where mode is the state encoded as an integer.
This avoids extra allocations, but it is out of keeping
with the intended semantics of precision, and is less readable.
* Modify the fmt package to support setting/getting context
via fmt.State. Unavailable due to Go 1 compatibility,
and probably the wrong solution anyway.
* Give up on package fmt. This would be a huge readability
regression and cause high code churn.
* Attempt a de-novo rewrite that circumvents these problems.
Too high a risk of bugs, with insufficient reward for the effort,
particularly since long term plans call for elimination
of gc.Node.