This reverts commit r238350, effectively reapplying r238349 after fixing
(all?) the problems, all somehow related to how I was using
`AlignedArrayCharUnion<>` inside `DIEValue`:
- MSVC can only handle `sizeof()` on types, not values. Change the
assert.
- GCC doesn't know the `is_trivially_copyable` type trait. Instead of
asserting it, add destructors.
- Call placement new even when constructing POD (i.e., the pointers).
- Instead of copying the char buffer, copy the casted classes.
I've left in a couple of `static_assert`s that I think both MSVC and GCC
know how to handle. If the bots disagree with me, I'll remove them.
- Check that the constructed type is either standard layout or a
pointer. This protects against a programming error: we really want
the "small" `DIEValue`s to be small and simple, so don't
accidentally change them not to be.
- Similarly, check that the size of the buffer is no bigger than a
`uint64_t` or a pointer. (I thought checking against
`sizeof(uint64_t)` would be good enough, but Chandler suggested that
pointers might sometimes be bigger than that in the context of
sanitizers.)
I've also committed r238359 in the meantime, which introduces a
DIEValue.def to simplify dispatching between the various types (thanks
to a review comment by David Blaikie). Without that, this commit would
be almost unintelligible.
Here's the original commit message:
--
Change `DIEValue` to be stored/passed/etc. by value, instead of
reference. It's now a discriminated union, with a `Val` field storing
the actual type. The classes that used to inherit from `DIEValue` no
longer do. There are two categories of these:
- Small values fit in a single pointer and are stored by value.
- Large values require auxiliary storage, and are stored by reference.
The only non-mechanical change is to tools/dsymutil/DwarfLinker.cpp. It
was relying on `DIEInteger`s being passed around by reference, so I
replaced that assumption with a `PatchLocation` type that stores a safe
reference to where the `DIEInteger` lives instead.
This commit causes a temporary regression in memory usage, since I've
left merging `DIEAbbrevData` into `DIEValue` for a follow-up commit. I
measured an increase from 845 MB to 879 MB, around 3.9%. The follow-up
drops it lower than the starting point, and I've only recently brought
the memory this low anyway, so I'm committing these changes separately
to keep them incremental. (I also considered swapping the commits, but
the other one first would cause a lot more code churn.)
(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)
--
llvm-svn: 238362
This reverts commit r238349, since it caused some errors on bots:
- std::is_trivially_copyable isn't available until GCC 5.0.
- It was complaining about strict aliasing with my use of
ArrayCharUnion.
llvm-svn: 238350
Change `DIEValue` to be stored/passed/etc. by value, instead of
reference. It's now a discriminated union, with a `Val` field storing
the actual type. The classes that used to inherit from `DIEValue` no
longer do. There are two categories of these:
- Small values fit in a single pointer and are stored by value.
- Large values require auxiliary storage, and are stored by reference.
The only non-mechanical change is to tools/dsymutil/DwarfLinker.cpp. It
was relying on `DIEInteger`s being passed around by reference, so I
replaced that assumption with a `PatchLocation` type that stores a safe
reference to where the `DIEInteger` lives instead.
This commit causes a temporary regression in memory usage, since I've
left merging `DIEAbbrevData` into `DIEValue` for a follow-up commit. I
measured an increase from 845 MB to 879 MB, around 3.9%. The follow-up
drops it lower than the starting point, and I've only recently brought
the memory this low anyway, so I'm committing these changes separately
to keep them incremental. (I also considered swapping the commits, but
the other one first would cause a lot more code churn.)
(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)
llvm-svn: 238349
This starts merging MCSection and MCSectionData.
There are a few issues with the current split between MCSection and
MCSectionData.
* It optimizes the the not as important case. We want the production
of .o files to be really fast, but the split puts the information used
for .o emission in a separate data structure.
* The ELF/COFF/MachO hierarchy is not represented in MCSectionData,
leading to some ad-hoc ways to represent the various flags.
* It makes it harder to remember where each item is.
The attached patch starts merging the two by moving the alignment from
MCSectionData to MCSection.
Most of the patch is actually just dropping 'const', since
MCSectionData is mutable, but MCSection was not.
llvm-svn: 237936
DWARF standard claims that each compilation/type unit header in
.debug_info/.debug_types section must be followed by corresponding
compile/type unit DIE, possibly with its children. Two situations
are possible:
* compile/type unit DIE is missing because DWARF producer failed to
emit it.
* DWARF parser failed to parse unit DIE correctly, for instance if it
contains some unsupported attributes (see r237721, for instance).
In either of these cases, the library, and the tools that use it
(llvm-dwarfdump, llvm-symbolizer) should not crash. Insert appropriate
checks to protect against this.
llvm-svn: 237733
The code this patch removes was there to make sure the text sections went
before the dwarf sections. That is necessary because MachO uses offsets
relative to the start of the file, so adding a section can change relaxations.
The dwarf sections were being printed at the start just to produce symbols
pointing at the start of those sections.
The underlying issue was fixed in r231898. The dwarf sections are now printed
when they are about to be used, which is after we printed the text sections.
To make sure we don't regress, the patch makes the MachO streamer assert
if CodeGen puts anything unexpected after the DWARF sections.
llvm-svn: 232842
Before this patch code wanting to create temporary labels for a given entity
(function, cu, exception range, etc) had to keep its own counter to have stable
symbol names.
createTempSymbol would still add a suffix to make sure a new symbol was always
returned, but it kept a single counter. Because of that, if we were to use
just createTempSymbol("cu_begin"), the label could change from cu_begin42 to
cu_begin43 because some other code started using temporary labels.
Simplify this by just keeping one counter per prefix and removing the various
specialized counters.
llvm-svn: 232535
The information gathering part of the patch stores a bit more information
than what is strictly necessary for these 2 sections. The rest will
become useful when we start emitting __apple_* type accelerator tables.
llvm-svn: 232342
Also, after looking at the raw_svector_stream internals, increase the
size of the SmallString used with it to prevent heap allocation.
Issue found by the Asan bot.
llvm-svn: 232335
This code comes with a lot of cruft that is meant to mimic darwin's
dsymutil behavior. A much simpler approach (described in the numerous
FIXMEs that I put in there) gives the right output for the vast
majority of cases. The extra corner cases that are handled differently
need to be investigated: they seem to correctly handle debug info that
is in the input, but that info looks suspicious in the first place.
Anyway, the current code needs to handle this, but I plan to revisit it
as soon as the big round of validation against the classic dsymutil is
over.
llvm-svn: 232333
The debug map embedded by ld64 in binaries conatins function sizes.
These sizes are less precise than the ones given by the debug information
(byte granularity vs linker atom granularity), but they might cover code
that is referenced in the line table but not in the DIE tree (that might
very well be a compiler bug that I need to investigate later).
Anyway, extracting that information is necessary to be able to mimic
dsymutil's behavior exactly.
llvm-svn: 232300
There is no need to look into the location expressions to transfer them,
the only modification to apply is to patch their base address to reflect
the linked function address.
llvm-svn: 232267
This actually shares most of its implementation with the generation
of the debug_ranges (the absence of 'a' is not a typo) contribution
for the unit's DW_AT_ranges attribute.
llvm-svn: 232246
The ID can eg. de used in MCSymbol names to differentiate the ones
that need to be created for every unit.
The ID is a constructor parameter and not a static class member so
there is no issue with counter updates if we decide to thread that
code.
llvm-svn: 232245
Next time, when I fix a typo, I'll take the time to reread the whole
comment instead of waiting for the commit email to realize that there
is another one two words later...
llvm-svn: 232234
Nothing fancy, just a straightforward offset to apply to the original
debug_ranges entries to get them in line with the linked addresses.
llvm-svn: 232232
We recorded the forward references in the CU that holds the referenced
DIE, but this is wrong as those will get resoled *after* the CU that
holds the reference. Record the references in their originating CU along
with a pointer to the remote CU to be able to compute the fixed up
offset at the right time.
llvm-svn: 232193
The typo got unnoticed because we were testing only on Dwarf 2. Add a
Dwarf4 test that exercises the code path, and also tests some newer
FORMs that the other test doesn't cover.
llvm-svn: 232191
This reverts commit r231957.
IntervalMap currently doesn't support keys more aligned than host pointers
and I've been using it with uint64_t keys. This asserts on some 32bits
systems.
Revert while I work on an IntervalMap generalization.
llvm-svn: 231967
Gather the function ranges [low_pc, high_pc) during DIE selection and
store them along with the offset to apply to them to get the linked
addresses.
This is just the data collection part, it comes with no tests. That
information will be used in multiple followup commits to perform the
relocation of line tables and range sections among other things, and
these commits will add tests.
llvm-svn: 231957
DW_AT_low_pc on functions is taken care of by the relocation processing, but
DW_AT_high_pc and DW_AT_low_pc on other lexical scopes need special handling.
llvm-svn: 231955
Doing this gets function's low_pc and global variable's locations right
in the output debug info. It also could get right other attributes
that need to be relocated (in linker terms), but I don't know of any
other than the address attributes.
This doesn't fixup low_pc attributes in compile_unit, lexical_block
or inlined subroutine, nor does it get right high_pc attributes
for function. This will come in a subsequent commit.
llvm-svn: 231544
Reference attributes are mainly handled by just creating DIEEntry
attributes for them. There is a special case for DW_FORM_ref_addr
attributes though, because the DIEEntry code needs a DwarfDebug
code to emit them (and we don't have one as we do no CodeGen).
In that case, just use DIEInteger attributes with the right form.
llvm-svn: 231531
The start offset of a linked unit is known before starting to clone
its DIEs. Handling DW_FORM_ref_addr attributes requires that this
offset is set while cloning the unit. Split CompileUnit::computeOffsets()
into setStartOffset() and computeNextUnitOffset() and call them
repsectively before cloning the DIEs and right after.
llvm-svn: 231530
This commit adds code to emit DIE trees that have been pruned from the
parts that haven't been marked as kept in the previous pass.
It works by 'cloning' the input DIE tree (as read by libDebugInfoDwarf)
into a tree of DIE objects. Cloning the DIEs means essentially cloning
their attributes. The code in this commit does only handle scalar and
block attributes (scalar because they are trivial, blocks because they
can't be easily replaced by a scalr placeholder), all the other ones
are replaced by placeholder zero values and will be handled in
further commits.
The added tests mostly check that the DIE tree has the correct layout and
also verify that a few chosen scalar and block attributes correctly make
their way into the output.
llvm-svn: 231300
This class is responsible for getting the linked data to the
disk in the appropriate form. Today it it an empty shell that
just instantiates an MC layer.
As we do not put anything in the resulting file yet, we just
check it has the right architecture (and check that -o does
the right thing).
To be able to create all the components, this commit adds a
few dependencies to llvm-dsymutil, namely all-targets, MC and
AsmPrinter.
Also add a -no-output option, so that tests that do not need
the binary result can continue to run even if they do not have
the required target linked in.
llvm-svn: 230824
