Use sym.Size, instead of len(sym.P), to decide whether a
content-addressable symbol is "short" and hashed as Hashed64.
So we don't dedup a small symbol with a gigantic almost-zero
symbol.
Fixes#42140.
Change-Id: Ic65869e1eaf51947517b3ece49c8b0be1b94bb75
Reviewed-on: https://go-review.googlesource.com/c/go/+/264337
Trust: Cherry Zhang <cherryyz@google.com>
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This creates space for a different kind of extension field
in LSym without making the struct any larger.
(There are many LSym, so we care about keeping the struct small.)
Change-Id: Ib16edb9e15f54c2a7351c8b875e19684058711e5
Reviewed-on: https://go-review.googlesource.com/c/go/+/243943
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Type namedata symbols are for type/field/method names and package
paths. We can use content-addressable symbol mechanism for them.
Change-Id: I923fda17b7094c7a0e46aad7c450622eb3826294
Reviewed-on: https://go-review.googlesource.com/c/go/+/257960
Trust: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
I think they are no longer experimental status. Might as well promote
them to permanent.
Change-Id: Id1259601b3dd2061dd60df86ee48080bfb575d2f
Reviewed-on: https://go-review.googlesource.com/c/go/+/249857
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
CL 245485 introduced a map for used files in a function. When
numbering symbols, make sure we traverse the files in
deterministic order.
Should fix longtest builders.
Change-Id: I1006bc5425116ab40e33a61e8f5acd1bdb4abad9
Reviewed-on: https://go-review.googlesource.com/c/go/+/247997
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
In order to prevent renumbering of filenames in pclntab generation, use
the per-package file list (previously only used for DWARF generation) as
file-indices. This is the largest step to eliminate renumbering of
filenames in pclntab.
Note, this is probably not the final state of the file table within the
object file. In this form, the linker loads all filenames for all
objects. I'll move to storing the filenames as regular string
symbols,and defaulting all string symbols to using the larger hash value
to make generation of pcln simplest, and most memory friendly.
Change-Id: I23daafa3f4b4535076e23100200ae0e7163aafe0
Reviewed-on: https://go-review.googlesource.com/c/go/+/245485
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
For content-addressable symbols with relocations, we build a
content hash based on its content and relocations. Depending on
the category of the referenced symbol, we choose different hash
algorithms such that the hash is globally consistent.
For now, we only support content-addressable symbols with
relocations when the current package's import path is known, so
that the symbol names are fully expanded. Otherwise, if the
referenced symbol is a named symbol whose name is not fully
expanded, the hash won't be globally consistent, and can cause
erroneous collisions. This is fine for now, as the deduplication
is just an optimization, not a requirement for correctness (until
we get to type descriptors).
Change-Id: I639e4e03dd749b5d71f0a55c2525926575b1ac30
Reviewed-on: https://go-review.googlesource.com/c/go/+/243142
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
For now, we only do this for symbols without relocations.
Mark static temps "local", as they are not referenced across DSO
boundaries. And deduplicating a local symbol and a non-local
symbol can be problematic.
Change-Id: I0a3dc4138aaeea7fd4f326998f32ab6305da8e4b
Reviewed-on: https://go-review.googlesource.com/c/go/+/243141
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
For symbols of size 8 bytes or below, we can map them to 64-bit
hash values using the identity function. There is no need to use
longer and more expensive hash functions.
For them, we introduce another pseudo-package, PkgIdxHashed64. It
is like PkgIdxHashed except that the hash function is different.
Note that the hash value is not affected with trailing zeros,
e.g. "A" and "A\0\0\0" have the same hash value. This allows
deduplicating a few more symbols. When deduplicating them, we
need to keep the longer one.
Change-Id: Iad0c2e9e569b6a59ca6a121fb8c8f0c018c6da03
Reviewed-on: https://go-review.googlesource.com/c/go/+/242362
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Fill in the data at compile time, and get rid of the preprocess
function in the linker.
We need to be careful with symbol alignment: data symbols are
generally naturally aligned, except for string symbols which are
not aligned. When deduplicating two symbols with same content but
different alignments, we need to keep the biggest alignment.
Change-Id: I4bd96adfdc5f704b5bf3a0e723457c9bfe16a684
Reviewed-on: https://go-review.googlesource.com/c/go/+/242081
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
This CL introduces content-addressable symbols (a.k.a. hashed
symbols) to object files. Content-addressable symbols are
identified and referenced by their content hashes, instead of by
names.
In the object file, a new pseudo-package index PkgIdxHashed is
introduced, for content-addressable symbols, and a new block is
added to store their hashes. The hashes are used by the linker to
identify and deduplicate the symbols.
For now, we only support content-addressable symbols that are
always locally defined (i.e. no cross-package references).
As a proof of concept, make string constant symbols content-
addressable.
Change-Id: Iaf53efd74c0ffb54fa95f784628cc84e95844536
Reviewed-on: https://go-review.googlesource.com/c/go/+/242079
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Mark compiler-generated ".stmp_%d" and "<fn>.stkobj" symbols as
AttrStatic, so as to tell the linker that they do not need to be
inserted into its name lookup tables.
Change-Id: I59ffd11659b2c54c2d0ad41275d05c3f919e3b88
Reviewed-on: https://go-review.googlesource.com/c/go/+/240497
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Merge conflicts are mostly recently changed nm/objdump output
format and its tests. Resolved easily (mostly just using the
format on master branch).
Change-Id: I99d8410a9a02947ecf027d9cae5762861562baf5
Currently, the compiler generates a fingerprint for each package,
which is used by the linker for index consistency check.
When building plugin or shared object, currently the linker also
generates a hash, by hashing the export data. At run time, when
a package is referenced by multiple DSOs, this hash is compared
to ensure consistency.
It would be good if we can unify this two hashes. This way, the
linker doesn't need to read the export data (which is intended
for the compiler only, and is not always available for the
linker). The export data hash is sufficient for both purposes.
It is consistent with the current hash geneated by the linker.
And the export data includes indices for exported symbols, so its
hash can be used to catch index mismatches.
Updates #33820.
Change-Id: I2bc0d74930746f54c683a10dfd695d50ea3f5a38
Reviewed-on: https://go-review.googlesource.com/c/go/+/236118
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Now we have ctxt.IsAsm, use that, instead of passing in a
parameter.
Change-Id: I81dedbe6459424fa9a4c2bfbd9abd83d83f3a107
Reviewed-on: https://go-review.googlesource.com/c/go/+/234492
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
We are not going to merge to master until Go 1.16 cycle. The old
object support can go now.
Change-Id: I93e6f584974c7749d0a0c2e7a96def35134dc566
Reviewed-on: https://go-review.googlesource.com/c/go/+/231918
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
The new object files use indices for symbol references, instead
of names. Fundamental to the design, it requires that the
importing and imported packages have consistent view of symbol
indices. The Go command should already ensure this, when using
"go build". But in case it goes wrong, it could lead to obscure
errors like run-time crashes. It would be better to check the
index consistency at build time.
To do that, we add a fingerprint to each object file, which is
a hash of symbol indices. In the object file it records the
fingerprints of all imported packages, as well as its own
fingerprint. At link time, the linker checks that a package's
fingerprint matches the fingerprint recorded in the importing
packages, and issue an error if they don't match.
This CL does the first part: introducing the fingerprint in the
object file, and propagating fingerprints through
importing/exporting by the compiler. It is not yet used by the
linker. Next CL will do.
Change-Id: I0aa372da652e4afb11f2867cb71689a3e3f9966e
Reviewed-on: https://go-review.googlesource.com/c/go/+/229617
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Add back the newobj flag, renamed to go115newobj, for feature
gating. The flag defaults to true.
This essentially reverts CL 206398 as well as CL 220060.
The old object format isn't working yet. Will fix in followup CLs.
Change-Id: I1ace2a9cbb1a322d2266972670d27bda4e24adbc
Reviewed-on: https://go-review.googlesource.com/c/go/+/224623
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Switch the primary subprogram die DWARF symbol emitted by the compiler
from named+dupOK to anonymous aux. This should help performance wise
by not having to add these symbols to the linker's symbol name lookup
tables.
Change-Id: Idf66662b8bf60b3dee9a55e6cd5137b24a9f5ab6
Reviewed-on: https://go-review.googlesource.com/c/go/+/223669
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Generalize symbol traversal code for aux symbols to allow for client
control over whether the walk incldues symbols referenced by
relocations on visited aux syms. This is not needed just yet but will
be required in order to support anonymous aux syms that have
relocations.
Change-Id: I898c1f398213c8d9d777dd3c40524a013b25e348
Reviewed-on: https://go-review.googlesource.com/c/go/+/223668
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Convert DWARF .debug_line symbols to anonymous aux syms, so as
to save space in object files and reduce the number of symbols
that have to be added to the linker's lookup tables.
Change-Id: I5b350f036e21a7a7128cb08148ab7c243aaf0d0b
Reviewed-on: https://go-review.googlesource.com/c/go/+/223018
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
For compiler developers interested in seeing DWARF generation details,
this patch provides symbol "debug asm" dumps for DWARF aux symbols
when -S=2 is in effect.
Change-Id: I5a0b6b65ce7b708948cbbf23c6b0d279bd4f8d9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/223017
Reviewed-by: Jeremy Faller <jeremy@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
There are more cleanups to do, but I want to keep this CL mostly
a pure deletion.
Change-Id: Icd2ff0a4b648eb4adf3d29386542617e49620818
Reviewed-on: https://go-review.googlesource.com/c/go/+/206398
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Compiler-generated function references (e.g. call to
runtime.newobject) appear frequently. We assign special indices
for them, so they don't need to be referenced by name.
Change-Id: I2072594cbc56c9e1037a26e4aae12e68c2436e9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/202085
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Jeremy Faller <jeremy@golang.org>
In assembly we always reference symbols by name. But for static
symbols, as they are reachable only within the current file, we
can assign them local indices and use the indices to reference
them. The index is only meaningful locally, and it is fine.
Change-Id: I16e011cd41575ef703ceb6f35899e5fa58fbcf1e
Reviewed-on: https://go-review.googlesource.com/c/go/+/201997
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
When building a program that links against Go shared libraries,
it needs to reference symbols defined in the shared library. At
compile time, we don't know where the shared library boundary is.
If we reference a symbol in package p by index, and package p is
actually part of a shared library, we cannot resolve the index at
link time, as the linker doesn't see the object file of p.
So when linking against Go shared libraries, always use named
reference for now.
To do this, the compiler needs to know whether we will be linking
against Go shared libraries. The -dynlink flag kind of indicates
that (as the document says), but currently it is actually
overloaded: it is also used when building a plugin or a shared
library, which is self-contained (if -linkshared is not otherwise
specified) and could use index for symbol reference. So we
introduce another compiler flag, -linkshared, specifically for
linking against Go shared libraries. The go command will pass
this flag if its -linkshared flag is specified
("go build -linkshared").
There may be better way to handle this. For example, we can
put the symbol indices in a special section in the shared library
that the linker can read. Or we can generate some per-package
description file to include the indices. (Currently we generate
a .shlibname file for each package that is included in a shared
library, which contains the path of the library. We could
consider extending this.) That said, this CL is a stop-gap
solution. And it is no worse than the old object files.
If we were to redesign the build system so that the shared
library boundary is known at compile time, we could use indices
for symbol references that do not cross shared library boundary,
as well as doing other things better.
Change-Id: I9c02aad36518051cc4785dbe25c4b4cef8f3faeb
Reviewed-on: https://go-review.googlesource.com/c/go/+/201818
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
Add InlTree to the FuncInfo aux symbol in new object files.
In the linker, change InlinedCall.Func from a Symbol to a string,
as we only use its Name. (There was a use of Func.File, but that
use is not correct anyway.) So we don't need to create a Symbol
if not necessary.
Change-Id: I38ce568ae0934cd9cb6d0b30599f1c8d75444fc9
Reviewed-on: https://go-review.googlesource.com/c/go/+/200098
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
On AIX, TOC symbols may be created and added to ctxt.Data
concurrently. To ensure reproducible builds, sort ctxt.Data.
This implements the same logic as WriteObjFile does for old
object files.
Change-Id: I2e6e2d7755352848981544a4fb68b828a188c2ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/201021
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
If -newobj is set, write object file in new format, which uses
indices for symbol references instead of symbol names. The file
format is described at the beginning of
cmd/internal/goobj2/objfile.go.
A new package, cmd/internal/goobj2, is introduced for reading and
writing new object files. (The package name is temporary.) It is
written in a way that trys to make the encoding as regular as
possible, and the reader and writer as symmetric as possible.
This is incomplete, and currently nothing will consume the new
object file.
Change-Id: Ifefedbf6456d760d15a9f40a28af6486c93100fe
Reviewed-on: https://go-review.googlesource.com/c/go/+/196030
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
We are planning to use indices for symbol references, instead of
symbol names. Here we assign indices to symbols defined in the
package being compiled, and propagate the indices to the
dependent packages in the export data.
A symbol is referenced by a tuple, (package index, symbol index).
Normally, for a given symbol, this index is unique, and the
symbol index is globally consistent (but with exceptions, see
below). The package index is local to a compilation. For example,
when compiling the fmt package, fmt.Println gets assigned index
25, then all packages that reference fmt.Println will refer it
as (X, 25) with some X. X is the index for the fmt package, which
may differ in different compilations.
There are some symbols that do not have clear package affiliation,
such as dupOK symbols and linknamed symbols. We cannot give them
globally consistent indices. We categorize them as non-package
symbols, assign them with package index 1 and a symbol index that
is only meaningful locally.
Currently nothing will consume the indices.
All this is behind a flag, -newobj. The flag needs to be set for
all builds (-gcflags=all=-newobj -asmflags=all=-newobj), or none.
Change-Id: I18e489c531e9a9fbc668519af92c6116b7308cab
Reviewed-on: https://go-review.googlesource.com/c/go/+/196029
Reviewed-by: Than McIntosh <thanm@google.com>
Currently, obj.Ctxt's symbol table does not distinguish between ABI0
and ABIInternal symbols. This is *almost* okay, since a given symbol
name in the final object file is only going to belong to one ABI or
the other, but it requires that the compiler mark a Sym as being a
function symbol before it retrieves its LSym. If it retrieves the LSym
first, that LSym will be created as ABI0, and later marking the Sym as
a function symbol won't change the LSym's ABI.
Marking a Sym as a function symbol before looking up its LSym sounds
easy, except Syms have a dual purpose: they are used just as interned
strings (every function, variable, parameter, etc with the same
textual name shares a Sym), and *also* to store state for whatever
package global has that name. As a result, it's easy to slip up and
look up an LSym when a Sym is serving as the name of a local variable,
and then later mark it as a function when it's serving as the global
with the name.
In general, we were careful to avoid this, but #29610 demonstrates one
case where we messed up. Because of on-demand importing from indexed
export data, it's possible to compile a method wrapper for a type
imported from another package before importing an init function from
that package. If the argument of the method is named "init", the
"init" LSym will be created as a data symbol when compiling the
wrapper, before it gets marked as a function symbol.
To fix this, we separate obj.Ctxt's symbol tables for ABI0 and
ABIInternal symbols. This way, the compiler will simply get a
different LSym once the Sym takes on its package-global meaning as a
function.
This fixes the above ordering issue, and means we no longer need to go
out of our way to create the "init" function early and mark it as a
function symbol.
Fixes#29610.
Updates #27539.
Change-Id: Id9458b40017893d46ef9e4a3f9b47fc49e1ce8df
Reviewed-on: https://go-review.googlesource.com/c/157017
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
CL 56950 correctly identified code with checks that were impossible.
But instead of correcting the checks it deleted them.
This CL corrects the code to check what was meant.
Change-Id: Ic89222184ee4fa5cacccae12d750601a9438ac8d
Reviewed-on: https://go-review.googlesource.com/78113
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
All of these are uints of different sizes, so checking >= 0 or < 0 are
effectively no-ops.
Found with staticcheck.
Change-Id: I16ac900eb7007bc8f9018b302136d42e483a4180
Reviewed-on: https://go-review.googlesource.com/56950
Reviewed-by: Matt Layher <mdlayher@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Matt Layher <mdlayher@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This CL adds initial support for concurrent backend compilation.
BACKGROUND
The compiler currently consists (very roughly) of the following phases:
1. Initialization.
2. Lexing and parsing into the cmd/compile/internal/syntax AST.
3. Translation into the cmd/compile/internal/gc AST.
4. Some gc AST passes: typechecking, escape analysis, inlining,
closure handling, expression evaluation ordering (order.go),
and some lowering and optimization (walk.go).
5. Translation into the cmd/compile/internal/ssa SSA form.
6. Optimization and lowering of SSA form.
7. Translation from SSA form to assembler instructions.
8. Translation from assembler instructions to machine code.
9. Writing lots of output: machine code, DWARF symbols,
type and reflection info, export data.
Phase 2 was already concurrent as of Go 1.8.
Phase 3 is planned for eventual removal;
we hope to go straight from syntax AST to SSA.
Phases 5–8 are per-function; this CL adds support for
processing multiple functions concurrently.
The slowest phases in the compiler are 5 and 6,
so this offers the opportunity for some good speed-ups.
Unfortunately, it's not quite that straightforward.
In the current compiler, the latter parts of phase 4
(order, walk) are done function-at-a-time as needed.
Making order and walk concurrency-safe proved hard,
and they're not particularly slow, so there wasn't much reward.
To enable phases 5–8 to be done concurrently,
when concurrent backend compilation is requested,
we complete phase 4 for all functions
before starting later phases for any functions.
Also, in reality, we automatically generate new
functions in phase 9, such as method wrappers
and equality and has routines.
Those new functions then go through phases 4–8.
This CL disables concurrent backend compilation
after the first, big, user-provided batch of
functions has been compiled.
This is done to keep things simple,
and because the autogenerated functions
tend to be small, few, simple, and fast to compile.
USAGE
Concurrent backend compilation still defaults to off.
To set the number of functions that may be backend-compiled
concurrently, use the compiler flag -c.
In future work, cmd/go will automatically set -c.
Furthermore, this CL has been intentionally written
so that the c=1 path has no backend concurrency whatsoever,
not even spawning any goroutines.
This helps ensure that, should problems arise
late in the development cycle,
we can simply have cmd/go set c=1 always,
and revert to the original compiler behavior.
MUTEXES
Most of the work required to make concurrent backend
compilation safe has occurred over the past month.
This CL adds a handful of mutexes to get the rest of the way there;
they are the mutexes that I didn't see a clean way to avoid.
Some of them may still be eliminable in future work.
In no particular order:
* gc.funcsymsmu. The global funcsyms slice is populated
lazily when we need function symbols for closures.
This occurs during gc AST to SSA translation.
The function funcsym also does a package lookup,
which is a source of races on types.Pkg.Syms;
funcsymsmu also covers that package lookup.
This mutex is low priority: it adds a single global,
it is in an infrequently used code path, and it is low contention.
Since funcsyms may now be added in any order,
we must sort them to preserve reproducible builds.
* gc.largeStackFramesMu. We don't discover until after SSA compilation
that a function's stack frame is gigantic.
Recording that error happens basically never,
but it does happen concurrently.
Fix with a low priority mutex and sorting.
* obj.Link.hashmu. ctxt.hash stores the mapping from
types.Syms (compiler symbols) to obj.LSyms (linker symbols).
It is accessed fairly heavily through all the phases.
This is the only heavily contended mutex.
* gc.signatlistmu. The global signatlist map is
populated with types through several of the concurrent phases,
including notably via ngotype during DWARF generation.
It is low priority for removal.
* gc.typepkgmu. Looking up symbols in the types package
happens a fair amount during backend compilation
and DWARF generation, particularly via ngotype.
This mutex helps us to avoid a broader mutex on types.Pkg.Syms.
It has low-to-moderate contention.
* types.internedStringsmu. gc AST to SSA conversion and
some SSA work introduce new autotmps.
Those autotmps have their names interned to reduce allocations.
That interning requires protecting types.internedStrings.
The autotmp names are heavily re-used, and the mutex
overhead and contention here are low, so it is probably
a worthwhile performance optimization to keep this mutex.
TESTING
I have been testing this code locally by running
'go install -race cmd/compile'
and then doing
'go build -a -gcflags=-c=128 std cmd'
for all architectures and a variety of compiler flags.
This obviously needs to be made part of the builders,
but it is too expensive to make part of all.bash.
I have filed #19962 for this.
REPRODUCIBLE BUILDS
This version of the compiler generates reproducible builds.
Testing reproducible builds also needs automation, however,
and is also too expensive for all.bash.
This is #19961.
Also of note is that some of the compiler flags used by 'toolstash -cmp'
are currently incompatible with concurrent backend compilation.
They still work fine with c=1.
Time will tell whether this is a problem.
NEXT STEPS
* Continue to find and fix races and bugs,
using a combination of code inspection, fuzzing,
and hopefully some community experimentation.
I do not know of any outstanding races,
but there probably are some.
* Improve testing.
* Improve performance, for many values of c.
* Integrate with cmd/go and fine tune.
* Support concurrent compilation with the -race flag.
It is a sad irony that it does not yet work.
* Minor code cleanup that has been deferred during
the last month due to uncertainty about the
ultimate shape of this CL.
PERFORMANCE
Here's the buried lede, at last. :)
All benchmarks are from my 8 core 2.9 GHz Intel Core i7 darwin/amd64 laptop.
First, going from tip to this CL with c=1 has almost no impact.
name old time/op new time/op delta
Template 195ms ± 3% 194ms ± 5% ~ (p=0.370 n=30+29)
Unicode 86.6ms ± 3% 87.0ms ± 7% ~ (p=0.958 n=29+30)
GoTypes 548ms ± 3% 555ms ± 4% +1.35% (p=0.001 n=30+28)
Compiler 2.51s ± 2% 2.54s ± 2% +1.17% (p=0.000 n=28+30)
SSA 5.16s ± 3% 5.16s ± 2% ~ (p=0.910 n=30+29)
Flate 124ms ± 5% 124ms ± 4% ~ (p=0.947 n=30+30)
GoParser 146ms ± 3% 146ms ± 3% ~ (p=0.150 n=29+28)
Reflect 354ms ± 3% 352ms ± 4% ~ (p=0.096 n=29+29)
Tar 107ms ± 5% 106ms ± 3% ~ (p=0.370 n=30+29)
XML 200ms ± 4% 201ms ± 4% ~ (p=0.313 n=29+28)
[Geo mean] 332ms 333ms +0.10%
name old user-time/op new user-time/op delta
Template 227ms ± 5% 225ms ± 5% ~ (p=0.457 n=28+27)
Unicode 109ms ± 4% 109ms ± 5% ~ (p=0.758 n=29+29)
GoTypes 713ms ± 4% 721ms ± 5% ~ (p=0.051 n=30+29)
Compiler 3.36s ± 2% 3.38s ± 3% ~ (p=0.146 n=30+30)
SSA 7.46s ± 3% 7.47s ± 3% ~ (p=0.804 n=30+29)
Flate 146ms ± 7% 147ms ± 3% ~ (p=0.833 n=29+27)
GoParser 179ms ± 5% 179ms ± 5% ~ (p=0.866 n=30+30)
Reflect 431ms ± 4% 429ms ± 4% ~ (p=0.593 n=29+30)
Tar 124ms ± 5% 123ms ± 5% ~ (p=0.140 n=29+29)
XML 243ms ± 4% 242ms ± 7% ~ (p=0.404 n=29+29)
[Geo mean] 415ms 415ms +0.02%
name old obj-bytes new obj-bytes delta
Template 382k ± 0% 382k ± 0% ~ (all equal)
Unicode 203k ± 0% 203k ± 0% ~ (all equal)
GoTypes 1.18M ± 0% 1.18M ± 0% ~ (all equal)
Compiler 3.98M ± 0% 3.98M ± 0% ~ (all equal)
SSA 8.28M ± 0% 8.28M ± 0% ~ (all equal)
Flate 230k ± 0% 230k ± 0% ~ (all equal)
GoParser 287k ± 0% 287k ± 0% ~ (all equal)
Reflect 1.00M ± 0% 1.00M ± 0% ~ (all equal)
Tar 190k ± 0% 190k ± 0% ~ (all equal)
XML 416k ± 0% 416k ± 0% ~ (all equal)
[Geo mean] 660k 660k +0.00%
Comparing this CL to itself, from c=1 to c=2
improves real times 20-30%, costs 5-10% more CPU time,
and adds about 2% alloc.
The allocation increase comes from allocating more ssa.Caches.
name old time/op new time/op delta
Template 202ms ± 3% 149ms ± 3% -26.15% (p=0.000 n=49+49)
Unicode 87.4ms ± 4% 84.2ms ± 3% -3.68% (p=0.000 n=48+48)
GoTypes 560ms ± 2% 398ms ± 2% -28.96% (p=0.000 n=49+49)
Compiler 2.46s ± 3% 1.76s ± 2% -28.61% (p=0.000 n=48+46)
SSA 6.17s ± 2% 4.04s ± 1% -34.52% (p=0.000 n=49+49)
Flate 126ms ± 3% 92ms ± 2% -26.81% (p=0.000 n=49+48)
GoParser 148ms ± 4% 107ms ± 2% -27.78% (p=0.000 n=49+48)
Reflect 361ms ± 3% 281ms ± 3% -22.10% (p=0.000 n=49+49)
Tar 109ms ± 4% 86ms ± 3% -20.81% (p=0.000 n=49+47)
XML 204ms ± 3% 144ms ± 2% -29.53% (p=0.000 n=48+45)
name old user-time/op new user-time/op delta
Template 246ms ± 9% 246ms ± 4% ~ (p=0.401 n=50+48)
Unicode 109ms ± 4% 111ms ± 4% +1.47% (p=0.000 n=44+50)
GoTypes 728ms ± 3% 765ms ± 3% +5.04% (p=0.000 n=46+50)
Compiler 3.33s ± 3% 3.41s ± 2% +2.31% (p=0.000 n=49+48)
SSA 8.52s ± 2% 9.11s ± 2% +6.93% (p=0.000 n=49+47)
Flate 149ms ± 4% 161ms ± 3% +8.13% (p=0.000 n=50+47)
GoParser 181ms ± 5% 192ms ± 2% +6.40% (p=0.000 n=49+46)
Reflect 452ms ± 9% 474ms ± 2% +4.99% (p=0.000 n=50+48)
Tar 126ms ± 6% 136ms ± 4% +7.95% (p=0.000 n=50+49)
XML 247ms ± 5% 264ms ± 3% +6.94% (p=0.000 n=48+50)
name old alloc/op new alloc/op delta
Template 38.8MB ± 0% 39.3MB ± 0% +1.48% (p=0.008 n=5+5)
Unicode 29.8MB ± 0% 30.2MB ± 0% +1.19% (p=0.008 n=5+5)
GoTypes 113MB ± 0% 114MB ± 0% +0.69% (p=0.008 n=5+5)
Compiler 443MB ± 0% 447MB ± 0% +0.95% (p=0.008 n=5+5)
SSA 1.25GB ± 0% 1.26GB ± 0% +0.89% (p=0.008 n=5+5)
Flate 25.3MB ± 0% 25.9MB ± 1% +2.35% (p=0.008 n=5+5)
GoParser 31.7MB ± 0% 32.2MB ± 0% +1.59% (p=0.008 n=5+5)
Reflect 78.2MB ± 0% 78.9MB ± 0% +0.91% (p=0.008 n=5+5)
Tar 26.6MB ± 0% 27.0MB ± 0% +1.80% (p=0.008 n=5+5)
XML 42.4MB ± 0% 43.4MB ± 0% +2.35% (p=0.008 n=5+5)
name old allocs/op new allocs/op delta
Template 379k ± 0% 378k ± 0% ~ (p=0.421 n=5+5)
Unicode 322k ± 0% 321k ± 0% ~ (p=0.222 n=5+5)
GoTypes 1.14M ± 0% 1.14M ± 0% ~ (p=0.548 n=5+5)
Compiler 4.12M ± 0% 4.11M ± 0% -0.14% (p=0.032 n=5+5)
SSA 9.72M ± 0% 9.72M ± 0% ~ (p=0.421 n=5+5)
Flate 234k ± 1% 234k ± 0% ~ (p=0.421 n=5+5)
GoParser 316k ± 1% 315k ± 0% ~ (p=0.222 n=5+5)
Reflect 980k ± 0% 979k ± 0% ~ (p=0.095 n=5+5)
Tar 249k ± 1% 249k ± 1% ~ (p=0.841 n=5+5)
XML 392k ± 0% 391k ± 0% ~ (p=0.095 n=5+5)
From c=1 to c=4, real time is down ~40%, CPU usage up 10-20%, alloc up ~5%:
name old time/op new time/op delta
Template 203ms ± 3% 131ms ± 5% -35.45% (p=0.000 n=50+50)
Unicode 87.2ms ± 4% 84.1ms ± 2% -3.61% (p=0.000 n=48+47)
GoTypes 560ms ± 4% 310ms ± 2% -44.65% (p=0.000 n=50+49)
Compiler 2.47s ± 3% 1.41s ± 2% -43.10% (p=0.000 n=50+46)
SSA 6.17s ± 2% 3.20s ± 2% -48.06% (p=0.000 n=49+49)
Flate 126ms ± 4% 74ms ± 2% -41.06% (p=0.000 n=49+48)
GoParser 148ms ± 4% 89ms ± 3% -39.97% (p=0.000 n=49+50)
Reflect 360ms ± 3% 242ms ± 3% -32.81% (p=0.000 n=49+49)
Tar 108ms ± 4% 73ms ± 4% -32.48% (p=0.000 n=50+49)
XML 203ms ± 3% 119ms ± 3% -41.56% (p=0.000 n=49+48)
name old user-time/op new user-time/op delta
Template 246ms ± 9% 287ms ± 9% +16.98% (p=0.000 n=50+50)
Unicode 109ms ± 4% 118ms ± 5% +7.56% (p=0.000 n=46+50)
GoTypes 735ms ± 4% 806ms ± 2% +9.62% (p=0.000 n=50+50)
Compiler 3.34s ± 4% 3.56s ± 2% +6.78% (p=0.000 n=49+49)
SSA 8.54s ± 3% 10.04s ± 3% +17.55% (p=0.000 n=50+50)
Flate 149ms ± 6% 176ms ± 3% +17.82% (p=0.000 n=50+48)
GoParser 181ms ± 5% 213ms ± 3% +17.47% (p=0.000 n=50+50)
Reflect 453ms ± 6% 499ms ± 2% +10.11% (p=0.000 n=50+48)
Tar 126ms ± 5% 149ms ±11% +18.76% (p=0.000 n=50+50)
XML 246ms ± 5% 287ms ± 4% +16.53% (p=0.000 n=49+50)
name old alloc/op new alloc/op delta
Template 38.8MB ± 0% 40.4MB ± 0% +4.21% (p=0.008 n=5+5)
Unicode 29.8MB ± 0% 30.9MB ± 0% +3.68% (p=0.008 n=5+5)
GoTypes 113MB ± 0% 116MB ± 0% +2.71% (p=0.008 n=5+5)
Compiler 443MB ± 0% 455MB ± 0% +2.75% (p=0.008 n=5+5)
SSA 1.25GB ± 0% 1.27GB ± 0% +1.84% (p=0.008 n=5+5)
Flate 25.3MB ± 0% 26.9MB ± 1% +6.31% (p=0.008 n=5+5)
GoParser 31.7MB ± 0% 33.2MB ± 0% +4.61% (p=0.008 n=5+5)
Reflect 78.2MB ± 0% 80.2MB ± 0% +2.53% (p=0.008 n=5+5)
Tar 26.6MB ± 0% 27.9MB ± 0% +5.19% (p=0.008 n=5+5)
XML 42.4MB ± 0% 44.6MB ± 0% +5.20% (p=0.008 n=5+5)
name old allocs/op new allocs/op delta
Template 380k ± 0% 379k ± 0% -0.39% (p=0.032 n=5+5)
Unicode 321k ± 0% 321k ± 0% ~ (p=0.841 n=5+5)
GoTypes 1.14M ± 0% 1.14M ± 0% ~ (p=0.421 n=5+5)
Compiler 4.12M ± 0% 4.14M ± 0% +0.52% (p=0.008 n=5+5)
SSA 9.72M ± 0% 9.76M ± 0% +0.37% (p=0.008 n=5+5)
Flate 234k ± 1% 234k ± 1% ~ (p=0.690 n=5+5)
GoParser 316k ± 0% 317k ± 1% ~ (p=0.841 n=5+5)
Reflect 981k ± 0% 981k ± 0% ~ (p=1.000 n=5+5)
Tar 250k ± 0% 249k ± 1% ~ (p=0.151 n=5+5)
XML 393k ± 0% 392k ± 0% ~ (p=0.056 n=5+5)
Going beyond c=4 on my machine tends to increase CPU time and allocs
without impacting real time.
The CPU time numbers matter, because when there are many concurrent
compilation processes, that will impact the overall throughput.
The numbers above are in many ways the best case scenario;
we can take full advantage of all cores.
Fortunately, the most common compilation scenario is incremental
re-compilation of a single package during a build/test cycle.
Updates #15756
Change-Id: I6725558ca2069edec0ac5b0d1683105a9fff6bea
Reviewed-on: https://go-review.googlesource.com/40693
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
There were only two versions, 0 and 1,
and the only user of version 1 was the assembler,
to indicate that a symbol was static.
Rename LSym.Version to Static,
and add it to LSym.Attributes.
Simplify call-sites.
Passes toolstash-check.
Change-Id: Iabd39918f5019cce78f381d13f0481ae09f3871f
Reviewed-on: https://go-review.googlesource.com/41201
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
obj.Linksymfmt is no longer referenced by any packages in cmd/...
Change-Id: Id4d9213d1577e13580b60755dbf7da313b17cb0e
Reviewed-on: https://go-review.googlesource.com/41171
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Now only cmd/asm and cmd/compile depend on cmd/internal/obj. Changing
the assembler backends no longer requires reinstalling cmd/link or
cmd/addr2line.
There's also now one canonical definition of the object file format in
cmd/internal/objabi/doc.go, with a warning to update all three
implementations.
objabi is still something of a grab bag of unrelated code (e.g., flag
and environment variable handling probably belong in a separate "tool"
package), but this is still progress.
Fixes#15165.
Fixes#20026.
Change-Id: Ic4b92fac7d0d35438e0d20c9579aad4085c5534c
Reviewed-on: https://go-review.googlesource.com/40972
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
A prior CL eliminated the last reference to Ctxt.Hash
from the compiler.
Change-Id: Ic97ff84ed1a14e0c93fb0e8ec0b2617c3397c0e8
Reviewed-on: https://go-review.googlesource.com/40699
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
It is zeroed pointlessly and never read.
Change-Id: I65390501a878f545122ec558cb621b91e394a538
Reviewed-on: https://go-review.googlesource.com/40406
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
There are some LSyms that are lazily initialized,
and which cannot be made eagerly initialized,
such as elements of a constant pool.
To avoid needing a mutex to protect the internals of
those LSyms, this CL introduces LookupInit,
which allows an LSym to be initialized only once.
By itself this is not fully concurrency-safe,
but Ctxt.Hash will need mutex protection anyway,
and that will be enough to support one-time LSym initialization.
Passes toolstash-check -all.
Updates #15756
Change-Id: Id7248dfdc4dfbdfe425fa31d0c0045018eeea1fa
Reviewed-on: https://go-review.googlesource.com/39990
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This is a straightforward refactoring,
to reduce the scope of upcoming changes.
The symbol size and AttrLocal=true was not
set universally, but it appears not to matter,
since toolstash -cmp is happy.
Passes toolstash-check -all.
Change-Id: I7f8392f939592d3a1bc6f61dec992f5661f42fca
Reviewed-on: https://go-review.googlesource.com/39791
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
It was simply a wrapper around Link.Lookup.
Unwrap everything.
CL prepared using eg with template:
package p
import "cmd/internal/obj"
func before(ctxt *obj.Link, name string, version int) *obj.LSym {
return obj.Linklookup(ctxt, name, version)
}
func after(ctxt *obj.Link, name string, version int) *obj.LSym {
return ctxt.Lookup(name, version)
}
Then one comment in cmd/asm/internal/asm/parse.go
was manually updated (and gofmt'ed!),
and func Linklookup deleted.
Passes toolstash-check (as a sanity measure).
Change-Id: Icc4d56b0b2b5c8888d3184c1898c48359ea1e638
Reviewed-on: https://go-review.googlesource.com/39715
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
The meaning of Version=1 was overloaded: it was reserved for file name
symbols (to avoid conflicts with non-file name symbols), but was also
used to mean "give me a fresh version number for this symbol."
With the new inlining tree, the same file name symbol can appear in
multiple entries, but each one would become a distinct symbol with its
own version number.
Now, we avoid duplicating symbols by using Version=0 for file name
symbols and we avoid conflicts with other symbols by prefixing the
symbol name with "gofile..".
Change-Id: I8d0374053b8cdb6a9ca7fb71871b69b4dd369a9c
Reviewed-on: https://go-review.googlesource.com/37234
Run-TryBot: David Lazar <lazard@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Russ Cox <rsc@golang.org>
This replaces the src.Pos LineHist-based position tracking with
the syntax.Pos implementation and updates all uses.
The LineHist table is not used anymore - the respective code is still
there but should be removed eventually. CL forthcoming.
Passes toolstash -cmp when comparing to the master repo (with the
exception of a couple of swapped assembly instructions, likely due
to different instruction scheduling because the line-based sorting
has changed; though this is won't affect correctness).
The sizes of various important compiler data structures have increased
significantly (see the various sizes_test.go files); this is probably
the reason for an increase of compilation times (to be addressed). Here
are the results of compilebench -count 5, run on a "quiet" machine (no
apps running besides a terminal):
name old time/op new time/op delta
Template 256ms ± 1% 280ms ±15% +9.54% (p=0.008 n=5+5)
Unicode 132ms ± 1% 132ms ± 1% ~ (p=0.690 n=5+5)
GoTypes 891ms ± 1% 917ms ± 2% +2.88% (p=0.008 n=5+5)
Compiler 3.84s ± 2% 3.99s ± 2% +3.95% (p=0.016 n=5+5)
MakeBash 47.1s ± 1% 47.2s ± 2% ~ (p=0.841 n=5+5)
name old user-ns/op new user-ns/op delta
Template 309M ± 1% 326M ± 2% +5.18% (p=0.008 n=5+5)
Unicode 165M ± 1% 168M ± 4% ~ (p=0.421 n=5+5)
GoTypes 1.14G ± 2% 1.18G ± 1% +3.47% (p=0.008 n=5+5)
Compiler 5.00G ± 1% 5.16G ± 1% +3.12% (p=0.008 n=5+5)
Change-Id: I241c4246cdff627d7ecb95cac23060b38f9775ec
Reviewed-on: https://go-review.googlesource.com/34273
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
