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>
These new methods help find the compilation unit to pass to the
LineReader method in order to find the line information for a PC.
The Ranges method also helps identify the specific function for a PC,
needed to determine the function name.
This uses the .debug.ranges section if necessary, and changes the object
file format packages to pass in the section contents if available.
Change-Id: I5ebc3d27faaf1a126ffb17a1e6027efdf64af836
Reviewed-on: https://go-review.googlesource.com/20769
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The tree's pretty inconsistent about single space vs double space
after a period in documentation. Make it consistently a single space,
per earlier decisions. This means contributors won't be confused by
misleading precedence.
This CL doesn't use go/doc to parse. It only addresses // comments.
It was generated with:
$ perl -i -npe 's,^(\s*// .+[a-z]\.) +([A-Z]),$1 $2,' $(git grep -l -E '^\s*//(.+\.) +([A-Z])')
$ go test go/doc -update
Change-Id: Iccdb99c37c797ef1f804a94b22ba5ee4b500c4f7
Reviewed-on: https://go-review.googlesource.com/20022
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Dave Day <djd@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Currently, if the .debug_abbrev section of an ELF file contains
attributes that aren't known to the dwarf package and that have form
formSecOffset, the dwarf package will fail to open the DWARF data with
an error like "decoding dwarf section abbrev at offset 0x17: cannot
determine class of unknown attribute with formSecOffset". For the most
part, the class is implied by the form encoded in the abbrev section,
but formSecOffset can imply many different DWARF classes. Hence,
debug/dwarf disambiguates these using a table of known attributes.
However, it will reject the entire image if it encounters an attribute
it can't determine the class of. This is particularly unfortunate
because the caller may never even uses the offending attribute.
Fix this by introducing a ClassUnknown attribute class to use as a
fallback in these cases. This allows the dwarf package to load the
DWARF data and isolates the problem to just the affected attributes.
Fixes#12592.
Change-Id: I766227b136e9757f8b89c0b3ab8e9ddea899d94f
Reviewed-on: https://go-review.googlesource.com/14541
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: jcd . <jcd@golang.org>
When AttrByteSize is not present for a type, we can still determine the
size in two more cases: when the type is a Typedef referring to another
type, and when the type is a pointer and we know the default address
size.
entry.go: return after setting an error if the offset is out of range.
Change-Id: I63a922ca4e4ad2fc9e9be3e5b47f59fae7d0eb5c
Reviewed-on: https://go-review.googlesource.com/9663
Reviewed-by: Austin Clements <austin@google.com>
Currently, Entry has a Val method that looks up an attribute and
returns its value. Now that Field has more fields than the attribute
and its value, it's useful to return the whole Field and let the
caller retrieve the parts it needs.
This change adds an AttrField method to Entry that does the same
lookup at Val, but returns the whole *Field rather than just the
value.
Change-Id: Ic629744c14c0e09d7528fa1026b0e1857789948c
Reviewed-on: https://go-review.googlesource.com/8503
Reviewed-by: Ian Lance Taylor <iant@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>
Currently, the only way to know the Go type of an attribute of some
DWARF attribute class was to read the dwarf package code (or
experiment). This makes it hard to go from the DWARF specification to
writing code that uses the dwarf package.
Fix this by adding a table to the documentation comment of the Field
type that gives the correspondence between DWARF attribute classes and
Go types.
Change-Id: I57c678a551fa1eb46f8207085d5a53d44985e3e7
Reviewed-on: https://go-review.googlesource.com/7280
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
The debug/dwarf and encoding/asn1 examples were added in 2009, a few
months before Go added implicit semicolons, and never updated.
The go/ast node types have always been named just "Expr", "Stmt", and
"Decl", so the comments about "ExprNode", "StmtNode", and "DeclNode"
were likely just mistaken because the interface tag methods are
"exprNode", "stmtNode", and "declNode", respectively.
Change-Id: I9d138cc3a16c1a51453da1406914d7b320bf6270
Reviewed-on: https://go-review.googlesource.com/7980
Reviewed-by: Brad Fitzpatrick <bradfitz@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