This gets the Go command out of the business of thinking it understands
compiler debug flags, and allows the compiler to turn down its worker
concurrency instead of failing and forcing the user to do the very
same thing. Debug flags that are obviously safe for concurrency
(at least to me) are tagged; probably there's more.
Change-Id: I59bb19861d8a654a9cfd2364ee78c8628212f82e
Reviewed-on: https://go-review.googlesource.com/c/go/+/448359
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Benchmarking suggests about a 14-17% reduction in user build time,
about 3.5-7.8% reduction for wall time. This helps most builds
because small packages are common. Latest benchmarks (after the last
round of improvement):
(12 processors) https://perf.golang.org/search?q=upload:20221102.20
(GOMAXPROCS=2) https://perf.golang.org/search?q=upload:20221103.1
(48 processors) https://perf.golang.org/search?q=upload:20221102.19
(The number of compiler workers is capped at min(4, GOMAXPROCS))
An earlier, similar version of this CL at one point observed a 27%
reduction in user build time (building 40+ benchmarks, 20 times), but
the current form is judged to be the most reliable; it may be
profitable to tweak the numbers slightly later, and/or to adjust the
number of compiler workers.
We've talked about doing this in the past, the "new"(ish) metrics
package makes it a more tractable proposition.
The method here is:
1. If os.Getenv("GOGC") is empty, then increase GOGC to a large value,
calculated to grow the heap to 32 + 4 * compile_parallelism before a
GC occurs (e.g., on a >= 4 processor box, 64M). In practice,
sometimes GC occurs before that, but this still results in fewer GCs
and saved time. This is "heap goal".
2. Use a finalizer to approximately detect when GC occurs, and use
runtime metrics to track progress towards the goal heap size,
readjusting GOGC to retarget it as necessary. Reset GOGC to 100 when
the heap is "close enough" to the goal.
One feared failure mode of doing this is that the finalizer will be
slow to run and the heap will grow exceptionally large before GOGC is
reset; I monitored the heap size at reset and exit across several
boxes with a variety of processor counts and extra noise
(including several builds in parallel, including a laptop with a busy
many-tabs browser running) and overshoot effectively does not occur.
In some cases the compiler's heap grows so rapidly that estimated live
exceeds the GC goal, but this is not delayed-finalizer overshoot; the
compiler is just using that much memory. In a small number of cases
(3% of GCs in make.bash) the new goal is larger than predicted by as
much as 38%, so check for that and redo the adjustment.
I considered instead using the maximum heap size limit +
GC-detecting-finalizer + reset instead, but to me that seemed like it
might have a worse bad-case outcome; if the reset is delayed, it's
possible the GC would start running frequently, making it harder to
run the finalizer, reach 50% utilization, and the extra GCs would
lose the advantage. This might also perform badly in the case that a
rapidly growing heap outruns goal. In practice, this sort of
overshoot hasn't been observed, and a goal of 64M is small enough to
tolerate plenty of overshoot anyway.
This version of the CL includes a comment urging anyone who sees the
code and thinks it would work for them, to update a bug (to be
created if the CL is approved) with information about their
situation/experience, so that we may consider creating some more
official and reliable way of obtaining the same result.
Change-Id: I45df1c927c1a7d7503ade1abd1a3300e27516633
Reviewed-on: https://go-review.googlesource.com/c/go/+/436235
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This adds a -d debug flag "fmahash" for hashcode search for
floating point architecture-dependent problems. This variable has no
effect on architectures w/o fused-multiply-add.
This was rebased onto the GOSSAHASH renovation so that this could have
its own dedicated environment variable, and so that it would be
cheap (a nil check) to check it in the normal case.
Includes a basic test of the trigger plumbing.
Sample use (on arm64, ppc64le, s390x):
% GOCOMPILEDEBUG=fmahash=001110110 \
go build -o foo cmd/compile/internal/ssa/testdata/fma.go
fmahash triggered main.main:24 101111101101111001110110
GOFMAHASH triggered main.main:20 010111010000101110111011
1.0000000000000002 1.0000000000000004 -2.220446049250313e-16
exit status 1
The intended use is in conjunction with github.com/dr2chase/gossahash,
which will probably acquire a flag "-fma" to streamline its use. This
tool+use was inspired by an ad hoc use of this technique "in anger"
to debug this very problem. This is also a dry-run for using this
same technique to identify code sensitive to loop variable
lifetime/capture, should we make that change.
Example intended use, with current search tool (using old environment
variable), for a test example:
gossahash -e GOFMAHASH GOMAGIC=GOFMAHASH go run fma.go
Trying go args=[...], env=[GOFMAHASH=1 GOMAGIC=GOFMAHASH]
go failed (81 distinct triggers): exit status 1
Trying go args=[...], env=[GOFMAHASH=11 GOMAGIC=GOFMAHASH]
go failed (39 distinct triggers): exit status 1
Trying go args=[...], env=[GOFMAHASH=011 GOMAGIC=GOFMAHASH]
go failed (18 distinct triggers): exit status 1
Trying go args=[...], env=[GOFMAHASH=0011 GOMAGIC=GOFMAHASH]
Trying go args=[...], env=[GOFMAHASH=1011 GOMAGIC=GOFMAHASH]
...
Trying go args=[...], env=[GOFMAHASH=0110111011 GOMAGIC=GOFMAHASH]
Trying go args=[...], env=[GOFMAHASH=1110111011 GOMAGIC=GOFMAHASH]
go failed (2 distinct triggers): exit status 1
Trigger string is 'GOFMAHASH triggered math.qzero:427 111111101010011110111011', repeated 6 times
Trigger string is 'GOFMAHASH triggered main.main:20 010111010000101110111011', repeated 1 times
Trying go args=[...], env=[GOFMAHASH=01110111011 GOMAGIC=GOFMAHASH]
go failed (1 distinct triggers): exit status 1
Trigger string is 'GOFMAHASH triggered main.main:20 010111010000101110111011', repeated 1 times
Review GSHS_LAST_FAIL.0.log for failing run
FINISHED, suggest this command line for debugging:
GOSSAFUNC='main.main:20 010111010000101110111011' \
GOFMAHASH=01110111011 GOMAGIC=GOFMAHASH go run fma.go
Change-Id: Ifa22dd8f1c37c18fc8a4f7c396345a364bc367d5
Reviewed-on: https://go-review.googlesource.com/c/go/+/394754
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: David Chase <drchase@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Currently in PGO we use a percentage threshold to determine if a
callsite is hot. This CL uses a different method -- treating the
hottest callsites that make up cumulatively top X% of total edge
weights as hot (X=95 for now). This default might work better for
a wider range of profiles. (The absolute threshold can still be
changed by a flag.)
For #55022.
Change-Id: I7e3b6f0c3cf23f9a89dd5994c10075b498bf14ee
Reviewed-on: https://go-review.googlesource.com/c/go/+/447016
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Currently, with PGO, the inliner uses node weights to decide if a
function is inlineable (with a larger budget). But the actual
inlining is determined by the weight of the call edge. There is a
discrepancy that, if a callee node is hot but the call edge is not,
it would not inlined, and marking the callee inlineable would of
no use.
Instead of using two kinds of weights, we just use the edge
weights to decide inlineability. If a function is the callee of a
hot call edge, its inlineability is determined with a larger
threshold. For a function that exceeds the regular inlining budget,
it is still inlined only when the call edge is hot, as it would
exceed the regular inlining cost for non-hot call sites, even if
it is marked inlineable.
For #55022.
Change-Id: I93fa9919fc6bcbb394e6cfe54ec96a96eede08f7
Reviewed-on: https://go-review.googlesource.com/c/go/+/447015
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Randomized feature enable/disable might be something we use to
help users debug any problems with changed loop variable capture,
and there's another CL that would like to use it to help in
locating places where "fused" multiply add instructions change
program behavior.
This CL:
- adds the ability to include an integer parameter (e.g. line number)
- replumbed the environment variable into a flag to simplify go build cache management
- but added an environment variable to allow flag setting through the environment
- which adds the possibility of switching on a different variable
(if there's one built-in for variable capture, it shouldn't be GOSSAHASH)
- cleaned up the checking code
- adds tests for all the intended behavior
- removes the case for GSHS_LOGFILE; TBD whether we'll need to put that back
or if there is another way.
Change-Id: I8503e1bb3dbc4a743aea696e04411ea7ab884787
Reviewed-on: https://go-review.googlesource.com/c/go/+/443063
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Run-TryBot: David Chase <drchase@google.com>
Also removes no-longer-needed "Any" field from compiler's DebugFlags.
Test/use case for this is the fmahash CL.
Change-Id: I214f02c91f30fc2ce53caf75fa5e2b905dd33429
Reviewed-on: https://go-review.googlesource.com/c/go/+/445495
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: David Chase <drchase@google.com>
Shape-based stenciling in unified IR is done by converting type argument
to its underlying type. So it agressively check that type argument is
not a TFORW. However, for recursive instantiated type argument, it may
still be a TFORW when shapifying happens. Thus the assertion failed,
causing the compiler crashing.
To fix it, just allow fully instantiated type when shapifying.
Fixes#54512Fixes#54722
Change-Id: I527e3fd696388c8a37454e738f0324f0c2ec16cb
Reviewed-on: https://go-review.googlesource.com/c/go/+/426335
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
In CL 424734, I implemented pointer shaping for unified IR. Evidently
though, we didn't have any test cases that check that uses of
pointer-shaped expressions were handled correctly.
In the reported test case, the struct field "children items[*node[T]]"
gets shaped to "children items[go.shape.*uint8]" (underlying type
"[]go.shape.*uint8"); and so the expression "n.children[i]" has type
"go.shape.*uint8" and the ".items" field selection expression fails.
The fix implemented in this CL is that any expression of derived type
now gets an explicit "reshape" operation applied to it, to ensure it
has the appropriate type for its context. E.g., the "n.children[i]"
OINDEX expression above gets "reshaped" from "go.shape.*uint8" to
"*node[go.shape.int]", allowing the field selection to succeed.
This CL also adds a "-d=reshape" compiler debugging flag, because I
anticipate debugging reshaping operations will be something to come up
again in the future.
Fixes#54535.
Change-Id: Id847bd8f51300d2491d679505ee4d2e974ca972a
Reviewed-on: https://go-review.googlesource.com/c/go/+/424936
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: hopehook <hopehook@qq.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
The Go object file references (some of) symbols from other
packages by indices, not by names. The linker doesn't need the
symbol names to do the linking. The names are included in the
object file so it is self-contained and tools (objdump, nm) can
read the referenced symbol names. Including the names increases
object file size. Add a flag to disable it on demand (off by
default).
Change-Id: I143a0eb656997497c750b8eb1541341b2aee8f30
Reviewed-on: https://go-review.googlesource.com/c/go/+/404297
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Unified IR quirks mode existed to help bootstrap unified IR by forcing
it to produce bit-for-bit identical output to the original gc noder
and typechecker. However, I believe it's far enough along now to stand
on its own, plus we have good test coverage of generics already for
-G=3 mode.
Change-Id: I8bf412c8bb5d720eadeac3fe31f49dc73679da70
Reviewed-on: https://go-review.googlesource.com/c/go/+/385998
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
This adds a debugging hook for optionally calling a "maymorestack"
function in the prologue of any function that might call morestack
(whether it does at run time or not). The maymorestack function will
let us improve lock checking and add debugging modes that stress
function preemption and stack growth.
Passes toolstash-check -all (except on js/wasm, where toolstash
appears to be broken)
Fixes#48297.
Change-Id: I27197947482b329af75dafb9971fc0d3a52eaf31
Reviewed-on: https://go-review.googlesource.com/c/go/+/359795
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This moves and slightly generalizes the -d debug flag parser from
cmd/compile/internal/base to cmd/internal/objabi so that we can use
the same debug flag syntax in other tools.
This makes a few minor tweaks to implementation details. The flag
itself is now just a flag.Value that gets constructed explicitly,
rather than at init time, and we've cleaned up the implementation a
little (e.g., using a map instead of a linear search of a slice). The
help text is now automatically alphabetized. Rather than describing
the values of some flags in the help text footer, we simply include it
in the flags' help text and make sure multi-line help text renders
sensibly.
For #48297.
Change-Id: Id373ee3b767e456be483fb28c110d025149be532
Reviewed-on: https://go-review.googlesource.com/c/go/+/359956
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Originally, overloading -d=inlfuncswithclosures=0 to enable quirks
mode was convenient because toolstash -cmp doesn't provide a way to
pass different gcflags to the installed vs stashed toolchains. Prior
to unified IR being merged, the stashed toolchain wouldn't know about
or accept any unified-specific flags.
However, this concern is no longer applicable since unified IR has
been merged, and the TestUnifiedCompare test can easily specify
different flag sets for the baseline and experiment build configs.
This CL adds a new -d=unifiedquirks flag to enable quirks mode, so
that it's possible to test unified IR with -d=inlfuncswithclosures=0
without also affecting a bunch of other compilation details.
Change-Id: Id1932f332822622aa8617278e82ec6d1a53b1b46
Reviewed-on: https://go-review.googlesource.com/c/go/+/329733
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
This CL extends the unified export data format's existing sync
mechanism to save writer stacks, controlled by the -d=syncframes debug
flag. This allows readers to provide more details when reporting
desync errors, which should simplify development of the data format
and the various reader/writer implementations.
For example, CL 328051 updated reader and writer, but missed making a
similar change to the linker (fix in CL 328054). Re-reviewing the CL
in isolation after the failure, it was not immediately obvious what
was going wrong. But the pair of stack traces below identifies exactly
what happened: it should have updated linker.relocFuncExt to write out
the new sync marker too.
```
data sync error: package "internal/abi", section 6, index 4, offset 536
found UseReloc, written at:
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/encoder.go:221: (*encoder).reloc +0x44
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/linker.go:214: (*linker).relocFuncExt +0x580
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/linker.go:233: (*linker).relocTypeExt +0x234
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/linker.go:161: (*linker).relocObj +0x2198
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/linker.go:64: (*linker).relocIdx +0x196
expected ImplicitTypes, reading at:
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/reader.go:796: (*reader).implicitTypes +0x36
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/reader.go:810: (*reader).addBody +0x81
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/reader.go:727: (*reader).funcExt +0x542
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/reader.go:651: (*reader).method +0x324
/home/mdempsky/wd/go/src/cmd/compile/internal/noder/reader.go:557: (*pkgReader).objIdx +0x2704
```
Change-Id: I911193edd2a965f81b7459f15fb613a773584685
Reviewed-on: https://go-review.googlesource.com/c/go/+/328909
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
This CL adds a new -d=unified debug flag, which controls whether
unified IR mode is used.
Change-Id: Iaa5f3cc0a24b9881aeec5317cd6b462b4a7b6fc9
Reviewed-on: https://go-review.googlesource.com/c/go/+/327054
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
This moves all remaining GOEXPERIMENT flags into the objabi.Experiment
struct, drops the "_enabled" from their name, and makes them all bool
typed.
We also drop DebugFlags.Fieldtrack because the previous CL shifted the
one test that used it to use GOEXPERIMENT instead.
Change-Id: I3406fe62b1c300bb4caeaffa6ca5ce56a70497fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/302389
Trust: Austin Clements <austin@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Added a flag '-d=inlfuncswithclosures=1' to allow inlining functions with
closures, and change the default to off for now, until #44370 is fixed.
Updates #44370.
Change-Id: Ic17723aa5c091d91f5f5004d8b63ec7125257acf
Reviewed-on: https://go-review.googlesource.com/c/go/+/296049
Run-TryBot: Dan Scales <danscales@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Dan Scales <danscales@google.com>
The compiler currently has two modes for compilation: one where it
compiles each function as it sees them, and another where it enqueues
them all into a work queue. A subsequent CL is going to reorder
function compilation to ensure that functions are always compiled
before any non-trivial function literals they enclose, and this will
be easier if we always use the compile work queue.
Also, fewer compilation modes makes things simpler to reason about.
Change-Id: Ie090e81f7476c49486296f2b90911fa0a466a5dd
Reviewed-on: https://go-review.googlesource.com/c/go/+/283313
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Trust: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Add compiler support for emitting ABI wrappers by creating real IR as
opposed to introducing ABI aliases. At the moment these are "no-op"
wrappers in the sense that they make a simple call (using the existing
ABI) to their target. The assumption here is that once late call
expansion can handle both ABI0 and the "new" ABIInternal (register
version), it can expand the call to do the right thing.
Note that the runtime contains functions that do not strictly follow
the rules of the current Go ABI0; this has been handled in most cases
by treating these as ABIInternal instead (these changes have been made
in previous patches).
Generation of ABI wrappers (as opposed to ABI aliases) is currently
gated by GOEXPERIMENT=regabi -- wrapper generation is on by default if
GOEXPERIMENT=regabi is set and off otherwise (but can be turned on
using "-gcflags=all=-abiwrap -ldflags=-abiwrap"). Wrapper generation
currently only workd on AMD64; explicitly enabling wrapper for other
architectures (via the command line) is not supported.
Also in this patch are a few other command line options for debugging
(tracing and/or limiting wrapper creation). These will presumably go
away at some point.
Updates #27539, #40724.
Change-Id: I1ee3226fc15a3c32ca2087b8ef8e41dbe6df4a75
Reviewed-on: https://go-review.googlesource.com/c/go/+/270863
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Trust: Than McIntosh <thanm@google.com>
Move Flag, Debug, Ctxt, Exit, and error messages to
new package cmd/compile/internal/base.
These are the core functionality that everything in gc uses
and which otherwise prevent splitting any other code
out of gc into different packages.
A minor milestone: the compiler source code
no longer contains the string "yy".
[git-generate]
cd src/cmd/compile/internal/gc
rf '
mv atExit AtExit
mv Ctxt atExitFuncs AtExit Exit base.go
mv lineno Pos
mv linestr FmtPos
mv flusherrors FlushErrors
mv yyerror Errorf
mv yyerrorl ErrorfAt
mv yyerrorv ErrorfVers
mv noder.yyerrorpos noder.errorAt
mv Warnl WarnfAt
mv errorexit ErrorExit
mv base.go debug.go flag.go print.go cmd/compile/internal/base
'
: # update comments
sed -i '' 's/yyerrorl/ErrorfAt/g; s/yyerror/Errorf/g' *.go
: # bootstrap.go is not built by default so invisible to rf
sed -i '' 's/Fatalf/base.Fatalf/' bootstrap.go
goimports -w bootstrap.go
: # update cmd/dist to add internal/base
cd ../../../dist
sed -i '' '/internal.amd64/a\
"cmd/compile/internal/base",
' buildtool.go
gofmt -w buildtool.go
Change-Id: I59903c7084222d6eaee38823fd222159ba24a31a
Reviewed-on: https://go-review.googlesource.com/c/go/+/272250
Trust: Russ Cox <rsc@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
2020-11-25 16:39:54 +00:00
Renamed from src/cmd/compile/internal/gc/debug.go (Browse further)
