This is mostly a copy-paste jobs from the linker to generate the debug
information in the compiler instead of the linker. The new data is
inserted into the debug line numbers symbol defined in CL 188238.
Generating the debug information BEFORE deadcode results in one subtle
difference, and that is that the state machine needs to be reset at the
end of every function's debug line table. The reasoning is that
generating the table AFTER dead code allows the producer and consumer of
the table to agree on the state of the state machine, and since these
blocks will (eventually) be concatenated in the linker, we don't KNOW
the state of the state machine unless we reset it. So,
generateDebugLinesSymbol resets the state machine at the end of every
function.
Right now, we don't do anything with this line information, or the file
table -- we just populate the symbols.
Change-Id: If9103eda6cc5f1f7a11e7e1a97184a060a4ad7fb
Reviewed-on: https://go-review.googlesource.com/c/go/+/188317
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
As we move the debug_line generation into the compiler, we need to
upgrade the notion of compilationUnit to not just be on a per package
basis. That won't be the case as it will be impossible for all
compilationUnits to have the same set of files names used to build the
debug_lines table. (For example, assembled files in a package don't know
about any files but themselves, so the debug_lines table could only
reference themseves. As such, we need to break the 1:1 relationship
between compUnit and package.)
Change-Id: I2e517bb6c01de0115bbf777af828a2fe59c09ce8
Reviewed-on: https://go-review.googlesource.com/c/go/+/189618
Run-TryBot: Jeremy Faller <jeremy@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Renaming the method makes clear, both to readers and to vet,
that this method is not the implementation of io.Seeker:
it cannot fail.
Working toward making the tree vet-safe instead of having
so many exceptions in cmd/vet/all/whitelist.
For #31916.
Change-Id: I3e6ad7264cb0121b4b76935450cccb71d533e96b
Reviewed-on: https://go-review.googlesource.com/c/go/+/176108
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
In CL 173938, the linker's object file reader was switched over to
selectively create strings backed with read-only mmap'd memory.
In the process a call to r.rd.Offset() was added to readSymName(),
which greatly increased the number of system calls (Offset does a
seek system call).
This patch changes the object file reader so that all reads are done
directly from the mmap'd data if it is present, and adds logic to keep
track of the offset within the rodata consumed so far. Doing this gets
rid of the calls to r.rd.Offset() and the corresponding seek system
calls.
Also as part of this change, hoist the calls to objabi.PathToPrefix
up into the initial setup code for object reading, and store the
result in the reader (since objabi.PathToPrefix was also coming up
as hot in the profile).
Numbers for this change from compilebench:
benchmark old ns/op new ns/op delta
BenchmarkTemplate 172053975 170357597 -0.99%
BenchmarkUnicode 64564850 64333653 -0.36%
BenchmarkGoTypes 627931042 628043673 +0.02%
BenchmarkCompiler 2982468893 2924575043 -1.94%
BenchmarkSSA 9701681721 9799342557 +1.01%
BenchmarkFlate 106847240 107509414 +0.62%
BenchmarkGoParser 132082319 130734905 -1.02%
BenchmarkReflect 386810586 383036621 -0.98%
BenchmarkTar 154360072 152670594 -1.09%
BenchmarkXML 217725693 216858727 -0.40%
BenchmarkLinkCompiler 908813802 734363234 -19.20%
BenchmarkStdCmd 32378532486 31222542974 -3.57%
Fixes#31898.
Change-Id: Ibf253a52ce9213325f42b1c2b20d0410f5c88c3b
Reviewed-on: https://go-review.googlesource.com/c/go/+/176039
Reviewed-by: Cherry Zhang <cherryyz@google.com>
When reading symbol names from an object file, if a name does not
need fixup (conversion of "". to package path), then generate
a string whose backing store is in read-only memory (from an mmap
of the object file), avoiding the need for an allocation. This
yields a modest reduction in total linker heap use.
Change-Id: I95719c93026b6cc82eb6947a9d14063cf3a6679c
Reviewed-on: https://go-review.googlesource.com/c/go/+/173938
Run-TryBot: Than McIntosh <thanm@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Add a couple of additional entries to the white list used to screen
out errors for builtin functions; these correspond to cases
that appear to come up only on the plan9 builder.
Updates #31503.
Change-Id: I48ab942ab2894240efe651ec7b7eace7aa5cb45e
Reviewed-on: https://go-review.googlesource.com/c/go/+/172986
Reviewed-by: David du Colombier <0intro@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This resurrects CL 121198, except that this time we map read-only.
In case that we need to apply relocations to the symbol's
content that is backed by read-only memory, we do our own copy-
on-write. This can happen if we failed to mmap the output file,
or we build for Wasm.
Memory profile for building k8s.io/kubernetes/cmd/kube-apiserver
on Linux/AMD64:
Old (before this sequence of CLs):
inuse_space 1598.75MB total
669.87MB 41.90% 41.90% 669.87MB 41.90% cmd/link/internal/objfile.(*objReader).readSlices
New:
inuse_space 1280.45MB total
441.18MB 34.46% 34.46% 441.18MB 34.46% cmd/link/internal/objfile.(*objReader).readSlices
Change-Id: I6b4d29d6eee9828089ea3120eb38c212db21330b
Reviewed-on: https://go-review.googlesource.com/c/go/+/170741
Run-TryBot: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This CL adds a new attribute, TOPFRAME, which can be used to mark
functions that should be treated as being at the top of the call
stack. The function `runtime.goexit` has been marked this way on
architectures that use a link register.
This will stop programs that use DWARF to unwind the call stack
from unwinding past `runtime.goexit` on architectures that use a
link register. For example, it eliminates "corrupt stack?"
warnings when generating a backtrace that hits `runtime.goexit`
in GDB on s390x.
Similar code should be added for non-link-register architectures
(i.e. amd64, 386). They mark the top of the call stack slightly
differently to link register architectures so I haven't added
that code (they need to mark "rip" as undefined).
Fixes#24385.
Change-Id: I15b4c69ac75b491daa0acf0d981cb80eb06488de
Reviewed-on: https://go-review.googlesource.com/c/go/+/169726
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Update the recently-added '-strictdups' sanity checking to avoid
failing the link in cases where we have objects feeding into the link
with a mix of command line flags (and in particular some with "-N" and
some without). This scenario will trigger errors/warnings due to
inlinable functions and wrapper functions that have different sizes
due to presence or lack of optimization.
Update #31034.
Change-Id: I1dd9e37c2f9bea5da0ab82e32e6fc210aebf6a65
Reviewed-on: https://go-review.googlesource.com/c/go/+/169160
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Introduce a new linker command line option "-strictdups", which
enables sanity checking of "ok to duplicate" symbols, especially
DWARF info symbols. Acceptable values are 0 (no checking) 1 (issue
warnings) and 2 (issue a fatal error checks fail).
Currently if we read a DWARF symbol (such as "go.info.PKG.FUNCTION")
from one object file, and then encounter the same symbol later on
while reading another object file, we simply discard the second one
and move on with the link, since the two should in theory be
identical.
If as a result of a compiler bug we wind up with symbols that are not
identical, this tends to (silently) result in incorrect DWARF
generation, which may or may not be discovered depending on who is
consuming the DWARF and what's being done with it.
When this option is turned on, at the point where a duplicate
symbol is detected in the object file reader, we check to make sure
that the length/contents of the symbol are the same as the previously
read symbol, and print a descriptive warning (or error) if not.
For the time being this can be used for one-off testing to find
problems; at some point it would be nice if we can enable it by
default.
Updates #30908.
Change-Id: I64c4e07c326b4572db674ff17c93307e2eec607c
Reviewed-on: https://go-review.googlesource.com/c/go/+/168410
Run-TryBot: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
Work involved in getting a stack trace is divided between
runtime.Callers and runtime.CallersFrames.
Before this CL, runtime.Callers returns a pc per runtime frame.
runtime.CallersFrames is responsible for expanding a runtime frame
into potentially multiple user frames.
After this CL, runtime.Callers returns a pc per user frame.
runtime.CallersFrames just maps those to user frame info.
Entries in the result of runtime.Callers are now pcs
of the calls (or of the inline marks), not of the instruction
just after the call.
Fixes#29007Fixes#28640
Update #26320
Change-Id: I1c9567596ff73dc73271311005097a9188c3406f
Reviewed-on: https://go-review.googlesource.com/c/152537
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
When CL 147160 introduced function ABIs encoded as symbol versions in
the linker, it became slightly more complicated to look up derived
DWARF symbols. It fixed this by introducing a dwarfFuncSym function to
hide this logic, but missed one derived lookup that was done in the
object reader itself. As a result, we lost the isStmt tables from the
compiler, so every PC was marked as a statement in the DWARF info.
Fix this by moving this derived lookup out of the object reader and
into the DWARF code and calling dwarfFuncSym to get the correctly
versioned symbol.
Should fix the linux-amd64-longtest builder.
Updates #27539.
Change-Id: If40d5ba28bab1918ac4ad18fbb5103666b6d978b
Reviewed-on: https://go-review.googlesource.com/c/149605
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
This repurposes the "version" field of a symbol reference in the Go
object file format to be an ABI field. Currently, this is just 0 or 1
depending on whether the symbol is static (the linker turns it into a
different internal version number), so it's already only tenuously a
symbol version. We change this to be -1 for static symbols and
otherwise by the ABI number.
This also adds a separate list of ABI alias symbols to be recorded in
the object file. The ABI aliases must be a separate list and not just
part of the symbol definitions because it's possible to have a symbol
defined in one package and the alias "defined" in a different package.
For example, this can happen if a symbol is defined in assembly in one
package and stubbed in a different package. The stub triggers the
generation of the ABI alias, but in a different package from the
definition.
For #27539.
Change-Id: I015c9fe54690c027de6ef77e22b5585976a01587
Reviewed-on: https://go-review.googlesource.com/c/147157
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
The DIEs for global variables were all assigned to the first emitted
compile unit in debug_info, regardless of what it was. Move them
instead to their respective compile units.
Change-Id: If794fa0ba4702f5b959c6e8c16119b16e7ecf6d8
Reviewed-on: https://go-review.googlesource.com/137235
Reviewed-by: Than McIntosh <thanm@google.com>
Splits part of dwarfgeneratedebugsyms into a new function,
dwarfGenerateDebugInfo which is called between deadcode elimination
and type name mangling.
This function takes care of collecting and processing the DIEs for
all functions and package-level variables and also generates DIEs
for all types used in the program.
Fixes#23733
Change-Id: I75ef0608fbed2dffc3be7a477f1b03e7e740ec61
Reviewed-on: https://go-review.googlesource.com/111237
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Currently, the linker generates one huge DWARF compilation unit for
the entire Go binary. This commit creates a separate compilation unit
and line table per Go package.
We temporarily lose compilation unit PC range information, since it's
now discontiguous, so harder to emit. We'll bring it back in the next
commit.
Beyond being "more traditional", this has various technical
advantages:
* It should speed up line table lookup, since that requires a
sequential scan of the line table. With this change, a debugger can
first locate the per-package line table and then scan only that line
table.
* Once we emit compilation unit PC ranges again, this should also
speed up various other debugger reverse PC lookups.
* It puts us in a good position to move more DWARF generation into the
compiler, which could produce at least the CU header, per-function
line table fragments, and per-function frame unwinding info that the
linker could simply paste together.
* It will let us record a per-package compiler command-line flags
(#22168).
Change-Id: Ibac642890984636b3ef1d4b37fe97f4453c2cc84
Reviewed-on: https://go-review.googlesource.com/69973
Run-TryBot: Austin Clements <austin@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
For #22095
Change-Id: Ie9ae84c758af99ac7daed26d0b3e3b0a47599edd
Reviewed-on: https://go-review.googlesource.com/67315
Run-TryBot: David Crawshaw <crawshaw@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2017-10-06 13:33:15 +00:00
Renamed from src/cmd/link/internal/ld/objfile.go (Browse further)
