Also fix 64-bit DWARF to read a 64-bit abbrev offset in the
compilation unit.
Change-Id: Idc22e59ffb354d58e9973b62fdbd342acf695859
Reviewed-on: https://go-review.googlesource.com/71171
Reviewed-by: Austin Clements <austin@google.com>
This is a subset of https://golang.org/cl/20022 with only the copyright
header lines, so the next CL will be smaller and more reviewable.
Go policy has been single space after periods in comments for some time.
The copyright header template at:
https://golang.org/doc/contribute.html#copyright
also uses a single space.
Make them all consistent.
Change-Id: Icc26c6b8495c3820da6b171ca96a74701b4a01b0
Reviewed-on: https://go-review.googlesource.com/20111
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
To return DWARF attribute values, debug/dwarf maps the DWARF attribute
value classes to Go types. Unfortunately, this mapping is ambiguous in
a way that makes it impossible to correctly interpret some DWARF
attributes as of DWARF 4. For example, AttrStartScope can be either a
constant or a rangelistptr. The attribute is interpreted differently
depending on its class, but debug/dwarf maps both classes to int64, so
the caller can't distinguish them from the Go type.
AttrDataMemberLocation is similar.
To address this, this change adds a field to type Field that indicates
the exact DWARF attribute value class of that field's value. This
makes it possible to distinguish value classes that can't be
distinguished by their Go type alone.
The root of this type ambiguity was DWARF itself. For example, DWARF 2
made no distinction between constants that were just constants and
constants that were section offsets because no attribute could have
both meanings. Hence, the single int64 type was sufficient. To avoid
introducing just another layer of ambiguity, this change takes pains
to canonicalize ambiguous classes in DWARF 2 and 3 files into the
unambiguous classes of DWARF 4.
Of course, there's no guarantee that future DWARF versions won't do
the same thing again and further subdivide the DWARF 4 classes. This
change gets ahead of this somewhat by distinguishing the various *ptr
classes even though the encoding does not. If there's some other form
of split, we can handle this in a backwards-compatible way by
introducing, for example, a Class5 field and type.
Change-Id: I4ef96d1223b0fd7f96ecf44fcc0e704a36af02b4
Reviewed-on: https://go-review.googlesource.com/8502
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Many headers in DWARF sections have a "unit length" that can be either
4 bytes or 12 bytes and indicates both the length of the unit and
whether the unit is in 32-bit or 64-bit format.
Currently, we implement unit length parsing in four different places.
Add a "unitLength" method to buf that parses a unit length and use it
in these four places.
Change-Id: I7950b91caaa92aa5e19aa63debc8ae46178ecc4d
Reviewed-on: https://go-review.googlesource.com/7281
Reviewed-by: Nigel Tao <nigeltao@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This factors out the code for finding which unit contains an offset in
the "info" section. The new code also replaces linear search with a
binary search. The line table reader will also need this
functionality.
Change-Id: I2076e4fc6719b6f06fd2796cbbc7548ec1876cb3
Reviewed-on: https://go-review.googlesource.com/6733
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Ian Lance Taylor
Brad Fitzpatrick
Austin Clements
Russ Cox