Summary: One of the cases handled by ValueObjectChild::UpdateValue() uses the entire width of the parent's scalar value as the size of the child, and extracts the child by calling Scalar::ExtractBitfield(). This seems valid but APInt::trunc(), APInt::sext() and APInt::zext() assert that the bit field must not have the same size as the parent scalar. Replacing those calls with sextOrTrunc(), zextOrTrunc(), sextOrSelf() and zextOrSelf() fixes the assertion failures.
Reviewers: uweigand, labath
Subscribers: labath, lldb-commits
Differential Revision: http://reviews.llvm.org/D20355
llvm-svn: 270062
Recommit modified version of r266311 including build bot regression fix.
This differs from the original r266311 by:
- Fixing Scalar::Promote to correctly zero- or sign-extend value depending
on signedness of the *source* type, not the target type.
- Omitting a few stand-alone fixes that were already committed separately.
llvm-svn: 266422
Currently, the DataExtractor::GetMaxU64Bitfield and GetMaxS64Bitfield
routines assume the incoming "bitfield_bit_offset" parameter uses
little-endian bit numbering, i.e. a bitfield_bit_offset 0 refers to
a bitfield whose least-significant bit coincides with the least-
significant bit of the surrounding integer.
On many big-endian systems, however, the big-endian bit numbering
is used for bit fields. Here, a bitfield_bit_offset 0 refers to
a bitfield whose most-significant bit conincides with the most-
significant bit of the surrounding integer.
Now, in principle LLDB could arbitrarily choose which semantics of
bitfield_bit_offset to use. However, there are two problems with
the current approach:
- When parsing DWARF, LLDB decodes bit offsets in little-endian
bit numbering on LE systems, but in big-endian bit numbering
on BE systems. Passing those offsets later on into the
DataExtractor routines gives incorrect results on BE.
- In the interim, LLDB's type layer combines byte and bit offsets
into a single number. I.e. instead of recording bitfields by
specifying the byte offset and byte size of the surrounding
integer *plus* the bit offset of the bit field within that field,
it simply records a single bit offset number.
Now, note that converting from byte offset + bit offset to a
single offset value and back is well-defined if we either use
little-endian byte order *and* little-endian bit numbering,
or use big-endian byte order *and* big-endian bit numbering.
Any other combination will yield incorrect results.
Therefore, the simplest approach would seem to be to always use
the bit numbering that matches the system byte order. This makes
storing a single bit offset valid, and makes the existing DWARF
code correct. The only place to fix is to teach DataExtractor
to use big-endian bit numbering on big endian systems.
However, there is only additional caveat: we also get bit offsets
from LLDB synthetic bitfields. While the exact semantics of those
doesn't seem to be well-defined, from test cases it appears that
the intent was for the user-provided synthetic bitfield offset to
always use little-endian bit numbering. Therefore, on a big-endian
system we now have to convert those to big-endian bit numbering
to remain consistent.
Differential Revision: http://reviews.llvm.org/D18982
llvm-svn: 266312
The Scalar implementation and a few other places in LLDB directly
access the internal implementation of APInt values using the
getRawData method. Unfortunately, pretty much all of these places
do not handle big-endian systems correctly. While on little-endian
machines, the pointer returned by getRawData can simply be used as
a pointer to the integer value in its natural format, no matter
what size, this is not true on big-endian systems: getRawData
actually points to an array of type uint64_t, with the first element
of the array always containing the least-significant word of the
integer. This means that if the bitsize of that integer is smaller
than 64, we need to add an offset to the pointer returned by
getRawData in order to access the value in its natural type, and
if the bitsize is *larger* than 64, we actually have to swap the
constituent words before we can access the value in its natural type.
This patch fixes every incorrect use of getRawData in the code base.
For the most part, this is done by simply removing uses of getRawData
in the first place, and using other APInt member functions to operate
on the integer data.
This can be done in many member functions of Scalar itself, as well
as in Symbol/Type.h and in IRInterpreter::Interpret. For the latter,
I've had to add a Scalar::MakeUnsigned routine to parallel the existing
Scalar::MakeSigned, e.g. in order to implement an unsigned divide.
The Scalar::RawUInt, Scalar::RawULong, and Scalar::RawULongLong
were already unused and can be simply removed. I've also removed
the Scalar::GetRawBits64 function and its few users.
The one remaining user of getRawData in Scalar.cpp is GetBytes.
I've implemented all the cases described above to correctly
implement access to the underlying integer data on big-endian
systems. GetData now simply calls GetBytes instead of reimplementing
its contents.
Finally, two places in the clang interface code were also accessing
APInt.getRawData in order to actually construct a byte representation
of an integer. I've changed those to make use of a Scalar instead,
to avoid having to re-implement the logic there.
The patch also adds a couple of unit tests verifying correct operation
of the GetBytes routine as well as the conversion routines. Those tests
actually exposed more problems in the Scalar code: the SetValueFromData
routine didn't work correctly for 128- and 256-bit data types, and the
SChar routine should have an explicit "signed char" return type to work
correctly on platforms where char defaults to unsigned.
Differential Revision: http://reviews.llvm.org/D18981
llvm-svn: 266311
Summary: This also fixes an infinite recursion between lldb_private::operator>> () and Scalar::operator>>= ().
Reviewers: sagar, tberghammer, labath
Subscribers: lldb-commits
Differential Revision: http://reviews.llvm.org/D16868
Patch by Marianne Mailhot-Sarrasin
llvm-svn: 260239
Bryan Chan