Previously, the debug line parser would keep attempting to read data
even if it had run out of data to read. This meant errors in parsing
would often end up being reported as something else, such as an unknown
version or malformed directory/filename table. This patch fixes the
issues by using the Cursor API to capture errors.
Reviewed by: labath
Differential Revision: https://reviews.llvm.org/D83043
Previously, if there was an error whilst parsing the operands of an
extended opcode, the operands would be treated as zero and printed. This
could potentially be slightly confusing. This patch changes the
behaviour to print the raw bytes instead.
Reviewed by: ikudrin
Differential Revision: https://reviews.llvm.org/D81570
This is a natural extension of the previous changes to use the Cursor
class independently in the standard and extended opcode paths, and in
turn allows delaying error handling until the entire line has been
printed in verbose mode, removing interleaved output in some cases.
Reviewed by: MaskRay, JDevlieghere
Differential Revision: https://reviews.llvm.org/D81562
Summary:
This makes the code easier to reason about, as it will behave the same
way regardless of whether there is any more data coming after the
presumed end of the prologue.
Reviewers: jhenderson, dblaikie, probinson, ikudrin
Subscribers: hiraditya, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77557
The new line printing for debug line verbose output was inconsistent.
For new rows in the matrix, a blank line followed, whilst the
DW_LNS_copy opcode actually resulted in two blank lines. There was also
potential inconsistency in the blank lines at the end of the table. This
patch mostly resolves these issues - no blank lines appear in the output
except for a single line after the prologue and at table end to separate
it from any subsquent table, plus some instances after error messages.
Also add a unit test for verbose output to test the fine details of new
line placement and other aspects of verbose output.
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D81102
Verbose and non-verbose parsing of .debug_line produced their output at
different points in the program. The most obvious impact of this was
that error messages were produced at different times, but it also
potentially reduced what clients could do by customising the stream or
warning/error handlers.
This change makes the two variants consistent by printing non-verbose
output inline, the same as verbose output.
Testing of the error messages has been modified to check the messages
always appear in the same location to illustrate the behaviour.
Reviewed by: JDevlieghere, dblaikie, MaskRay, labath
Differential Revision: https://reviews.llvm.org/D80989
The flushes previously existed to help ensure consistent error message
output when stdout and stderr were passed to the same location. This is
no longer necessary as errs() is now tied to outs().
Reviewed by: dblaikie, MaskRay, JDevlieghere, labath
Differential Revision: https://reviews.llvm.org/D80803
Previously, if an extended opcode was truncated, it would manifest as an
"unexpected line op length error" which wasn't quite accurate. This
change checks for errors any time data is read whilst parsing an
extended opcode, and reports any errors detected.
Reviewed by: MaskRay, labath, aprantl
Differential Revision: https://reviews.llvm.org/D80797
Like non-verbose output, so that it is easy to recognize the `Line,Column,File,ISA,Discriminator` column values.
Reviewed By: JDevlieghere, jhenderson
Differential Revision: https://reviews.llvm.org/D80874
This will ensure that nothing can ever start parsing data from a future
sequence and part-read data will be returned as 0 instead.
Reviewed by: aprantl, labath
Differential Revision: https://reviews.llvm.org/D80796
The debug_line_invalid.test test case was previously using the
interpreted line table dumping to identify which opcodes have been
parsed. This change moves to looking for the expected opcodes
explicitly. This is probably a little clearer and also allows for
testing some cases that wouldn't be easily identifiable from the
interpreted table.
Reviewed by: MaskRay
Differential Revision: https://reviews.llvm.org/D80795
Summary:
Without this we could silently accept an invalid prologue because the
default DataExtractor behavior is to return an empty string when
reaching the end of file. And empty string is also used to terminate
these lists.
This makes the parsing code slightly more complicated, but this
complexity will go away once the parser starts working with truncating
data extractors. The reason I am doing it this way is because without
this, the truncation would regress the quality of error messages (right
now, we produce bad error messages only near EOF, but truncation would
make everything behave as if it was near EOF).
Reviewers: dblaikie, probinson, jhenderson
Subscribers: hiraditya, MaskRay, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77555
The patch was reverted in 69da40033 because of test failures on windows.
The problem was the unpredictable order of some of the error messages,
which I've tried to strenghten in that patch.
It turns out this is not possible to do in verbose mode because there
the data is being writted as it is being parsed. No amount of flushing
(as I've done in the non-verbose mode) will help that. Indeed, even
without any buffering the warning messages can end in the middle of a
line in non-verbose mode.
In this patch, I have reverted the changes which tested the relative
position of the warning message, except for the messages about
unsupported initial length, which are the ones I really wanted to test,
and which do come out reasonably.
The original commit message was:
This patch if motivated by D74560, specifically the subthread about what
to print upon encountering reserved initial length values.
If the debug_line prologue has an unsupported version, we skip parsing
the rest of the data. If we encounter an reserved initial length field,
we don't even parse the version. However, we still print out all members
(with value 0) in the dump function.
This patch introduces early exits in the Prologue::dump function so that
we print only the fields that were parsed successfully. In case of an
unsupported version, we skip printing all subsequent prologue fields --
because we don't even know if this version has those fields. In case of a
reserved unit length, we don't print anything -- if the very first field
of the prologue is invalid, it's hard to say if we even have a prologue
to begin with.
Note that the user will still be able to see the invalid/reserved
initial length value in the error message. I've modified (reordered)
debug_line_invalid.test to show that the error message comes straight
after the debug_line offset. I've also added some flush() calls to the
dumping code to ensure this is the case in all situations (without that,
the warnings could get out of sync if the output was not a terminal -- I
guess this is why std::iostreams have the tie() function).
Reviewers: jhenderson, ikudrin, dblaikie
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75043
Summary:
This patch if motivated by D74560, specifically the subthread about what
to print upon encountering reserved initial length values.
If the debug_line prologue has an unsupported version, we skip parsing
the rest of the data. If we encounter an reserved initial length field,
we don't even parse the version. However, we still print out all members
(with value 0) in the dump function.
This patch introduces early exits in the Prologue::dump function so that
we print only the fields that were parsed successfully. In case of an
unsupported version, we skip printing all subsequent prologue fields --
because we don't even know if this version has those fields. In case of a
reserved unit length, we don't print anything -- if the very first field
of the prologue is invalid, it's hard to say if we even have a prologue
to begin with.
Note that the user will still be able to see the invalid/reserved
initial length value in the error message. I've modified (reordered)
debug_line_invalid.test to show that the error message comes straight
after the debug_line offset. I've also added some flush() calls to the
dumping code to ensure this is the case in all situations (without that,
the warnings could get out of sync if the output was not a terminal -- I
guess this is why std::iostreams have the tie() function).
Reviewers: jhenderson, ikudrin, dblaikie
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75043
The DWARFv2-4 specification for the line table header states that the
include directories and file name tables both end with a single null
byte. Prior to this change, the parser did not detect if this byte was
missing, because it also stopped reading the tables once it reached the
prologue end, as claimed by the header_length field. This change adds a
check that the terminator has been seen at the end of each table.
Reviewed by: dblaikie, MaskRay
Differential Revision: https://reviews.llvm.org/D74413
The number of standard opcodes is defined to be opcode_base - 1, so a
value of 0 for the opcode_base caused a crash as an attempt was made to
reserve many entries in a vector. This change fixes the crash, by
issuing a warning and skipping reading of standard opcode lengths in the
event of an opcode_base of 0.
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D74309
Also remove some test duplication and add a test case that shows the
maximum version is rejected (this also shows that the value in the error
message is actually in decimal, and not just missing an 0x prefix).
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D74403
The DebugInfo/dwarfdump-invalid-line-table test used a pre-canned binary
generated by a fuzzer to demonstrate a bug fix. Unfortunately, the
binary is rigid and requires hand-editing if we change behaviour, such
as rejecting certain properties within it (as I plan on doing in another
change).
Rather than hand-edit the binary, I have replaced it with two tests. The
first tests the high-level code path from the debug line parser that
produces the same error as this test previously did, and the second is a
set of unit test cases that comprehensively cover the
FormValue::skipValue method, which in turn covers the area that the
original bug fix touched.
Reviewed by: MaskRay, dblaikie
Differential Revision: https://reviews.llvm.org/D74202
Many of the debug line prologue errors are not inherently fatal. In most
cases, we can make reasonable assumptions and carry on. This patch does
exactly that. In the case of length problems, the approach of "assume
stated length is correct" is taken which means the offset might need
adjusting.
This is a relanding of b94191fe, fixing an LLD test and the LLDB build.
Reviewed by: dblaikie, labath
Differential Revision: https://reviews.llvm.org/D72158
Many of the debug line prologue errors are not inherently fatal. In most
cases, we can make reasonable assumptions and carry on. This patch does
exactly that. In the case of length problems, the approach of "the
claimed length is correct" is taken to be consistent with other
instances such as the SectionParser, which ignores the read length.
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D72158
A subsequent patch will change how an invalid file name table is handled
to allow parsing to continue. This patch adds a test case that will
demonstrate a difference in behaviour with that change between invalid
file tables where the error is before the end of the stated prologue
length and where the error occurs after the stated length.
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D72157
It is possible to try to keep parsing a debug line program even when the
length of an extended opcode does not match what is expected for that
opcode. This patch changes what was previously a fatal error to be
non-fatal. The parser now continues by assuming the the claimed length
is correct, even if it means moving the offset backwards.
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D72155
Unlike most of our errors in the debug line parser, the "no end of
sequence" message was missing any reference to which line table it
refererred to. This change adds the offset to this message.
Reviewed by: dblaikie
Differential Revision: https://reviews.llvm.org/D72443
The V5 directory and filename tables had checks in to make sure we
hadn't read past the end of the line table prologue. Since previous
changes to the data extractor class ensure we never read past the end,
these checks are now redundant, so this patch removes them.
There is still a check to show that the whole prologue remains within
the prologue length.
Reviewed By: JDevlieghere
Differential Revision: https://reviews.llvm.org/D71768
This removes the need to duplicate the LASTONLY check pattern and the
last part of the NONFATAL pattern in the modified test.
Reviewed By: MaskRay, JDevlieghere
Differential Revision: https://reviews.llvm.org/D71757
The line tables in debug_line_malformed.s had contents that varied more
than was necessary for the testing, making it harder to follow what was
important. This patch normalises them so that they all share
more-or-less the same body. Additionally, it makes the testing for what
was printed more consistent, to show that the right parts of the line
table prologue and body are/are not parsed and printed.
Reviewed By: JDevlieghere
Differential Revision: https://reviews.llvm.org/D71755
Some of the tables in debug_line_malformed.s were not being checked in
the NONFATAL checks in debug_line_invalid.test (only the warnings coming
from them were being checked). This made the test harder to follow.
Additionally, a later change will change the way the errors are handled
such that more of the line table will be printed. That will require
checks for these tables (or something equivalent) so that the difference
in behaviour can be observed. This patch adds checks for the three
tables that were missing checks.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D71753
This patch adds and improves comments in the debug_line_invalid.test and
its associated input file so that it is easier to follow. It uses '##'
to make comments stand out from lit and FileCheck commands.
It also reflows some commands so that the lines are not so long and are
easier to read and fixes some copy/paste errors.
Reviewed by: JDevlieghere
Differential Revision: https://reviews.llvm.org/D71752
This patch exnteds the error handling in the debug line parser to get
rid of the existing MD5 assertion. I want to reuse the debug line parser
from LLVM in LLDB where we cannot crash on invalid input.
Differential revision: https://reviews.llvm.org/D64544
llvm-svn: 366762
Reviewed by: dblaikie, JDevlieghere, espindola
Differential Revision: https://reviews.llvm.org/D44560
Summary:
The .debug_line parser previously reported errors by printing to stderr and
return false. This is not particularly helpful for clients of the library code,
as it prevents them from handling the errors in a manner based on the calling
context. This change switches to using llvm::Error and callbacks to indicate
what problems were detected during parsing, and has updated clients to handle
the errors in a location-specific manner. In general, this means that they
continue to do the same thing to external users. Below, I have outlined what
the known behaviour changes are, relating to this change.
There are two levels of "errors" in the new error mechanism, to broadly
distinguish between different fail states of the parser, since not every
failure will prevent parsing of the unit, or of subsequent unit. Malformed
table errors that prevent reading the remainder of the table (reported by
returning them) and other minor issues representing problems with parsing that
do not prevent attempting to continue reading the table (reported by calling a
specified callback funciton). The only example of this currently is when the
last sequence of a unit is unterminated. However, I think it would be good to
change the handling of unrecognised opcodes to report as minor issues as well,
rather than just printing to the stream if --verbose is used (this would be a
subsequent change however).
I have substantially extended the DwarfGenerator to be able to handle
custom-crafted .debug_line sections, allowing for comprehensive unit-testing
of the parser code. For now, I am just adding unit tests to cover the basic
error reporting, and positive cases, and do not currently intend to test every
part of the parser, although the framework should be sufficient to do so at a
later point.
Known behaviour changes:
- The dump function in DWARFContext now does not attempt to read subsequent
tables when searching for a specific offset, if the unit length field of a
table before the specified offset is a reserved value.
- getOrParseLineTable now returns a useful Error if an invalid offset is
encountered, rather than simply a nullptr.
- The parse functions no longer use `WithColor::warning` directly to report
errors, allowing LLD to call its own warning function.
- The existing parse error messages have been updated to not specifically
include "warning" in their message, allowing consumers to determine what
severity the problem is.
- If the line table version field appears to have a value less than 2, an
informative error is returned, instead of just false.
- If the line table unit length field uses a reserved value, an informative
error is returned, instead of just false.
- Dumping of .debug_line.dwo sections is now implemented the same as regular
.debug_line sections.
- Verbose dumping of .debug_line[.dwo] sections now prints the prologue, if
there is a prologue error, just like non-verbose dumping.
As a helper for the generator code, I have re-added emitInt64 to the
AsmPrinter code. This previously existed, but was removed way back in r100296,
presumably because it was dead at the time.
This change also requires a change to LLD, which will be committed separately.
llvm-svn: 331971
James Henderson