argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
Note: I accidentally committed a bogus older version of this patch previously.
llvm-svn: 218787
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.
Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.
By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.
The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)
This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.
What this patch doesn't do:
This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.
http://reviews.llvm.org/D4919
rdar://problem/17994491
Thanks to dblaikie and dexonsmith for reviewing this patch!
llvm-svn: 218778
No functional change. Pre-emptive refactoring before I start pushing
some of this subprogram creation down into DWARFCompileUnit so I can
build different subprograms in the skeleton unit from the dwo unit for
adding -gmlt-like data to the skeleton.
llvm-svn: 218713
r218129 omits DW_TAG_subprograms which have no inlined subroutines when
emitting -gmlt data. This makes -gmlt very low cost for -O0 builds.
Darwin's dsymutil reasonably considers a CU empty if it has no
subprograms (which occurs with the above optimization in -O0 programs
without any force_inline function calls) and drops the line table, CU,
and everything in this situation, making backtraces impossible.
Until dsymutil is modified to account for this, disable this
optimization on Darwin to preserve the desired functionality.
(see r218545, which should be reverted after this patch, for other
discussion/details)
Footnote:
In the long term, it doesn't look like this scheme (of simplified debug
info to describe inlining to enable backtracing) is tenable, it is far
too size inefficient for optimized code (the DW_TAG_inlined_subprograms,
even once compressed, are nearly twice as large as the line table
itself (also compressed)) and we'll be considering things like Cary's
two level line table proposal to encode all this information directly in
the line table.
llvm-svn: 218702
To reduce the size of -gmlt data, skip the subprograms without any
inlined subroutines. Since we've now got the ability to make these
determinations in the backend (funnily enough - we added the flag so we
wouldn't produce ranges under -gmlt, but with this change we use the
flag, but go back to producing ranges under -gmlt).
Instead, just produce CU ranges to inform the consumer which parts of
the code are described by this CU's line table. Tools could inspect the
line table directly to compute the range, but the CU ranges only seem to
be about 0.5% of object/executable size, so I'm not too worried about
teaching llvm-symbolizer that trick just yet - it's certainly a possible
piece of future work.
Update an llvm-symbolizer test just to demonstrate that this schema is
acceptable there (if it wasn't, the compiler-rt tests would catch this,
but good to have an in-llvm-tree test for llvm-symbolizer's behavior
here)
Building the clang binary with -gmlt with this patch reduces the total
size of object files by 5.1% (5.56% without ranges) without compression
and the executable by 4.37% (4.75% without ranges).
llvm-svn: 218129
Summary:
This will allow to request the creation of a forward delacred variable
at is point of use (for imported declarations, this will be
DwarfDebug::constructImportedEntityDIE) rather than having to put the
forward decl in a retention list.
Note that getOrCreateGlobalVariable returns the actual definition DIE when the
routine creates a declaration and a definition DIE. If you agree this is the
right behavior, then I'll have a followup patch that registers the definition
in the DIE map instead of the declaration as it is today (this 'breaks' only
one test, where we test that the imported entity is the declaration). I'm
not sure what's best here, but it's easy enough for a consumer to follow the
DW_AT_specification link to get to the declaration, whereas it takes more
work to find the actual definition from a declaration DIE.
Reviewers: echristo, dblaikie, aprantl
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5381
llvm-svn: 218126
And since it /looked/ like the DwarfStrSectionSym was unused, I tried
removing it - but then it turned out that DwarfStringPool was
reconstructing the same label (and expecting it to have already been
emitted) and uses that.
So I kept it around, but wanted to pass it in to users - since it seemed
a bit silly for DwarfStringPool to have it passed in and returned but
itself have no use for it. The only two users don't handle strings in
both .dwo and .o files so they only ever need the one symbol - no need
to keep it (and have an unused symbol) in the DwarfStringPool used for
fission/.dwo.
Refactor a bunch of accelerator table usage to remove duplication so I
didn't have to touch 4-5 callers.
llvm-svn: 217628
So that the two operations in DwarfDebug couldn't get separated (because
I accidentally separated them in some work in progress), put them
together. While we're here, move DwarfUnit::addRange to
DwarfCompileUnit, since it's not relevant to type units.
llvm-svn: 217468
PrevSection/PrevCU are used to detect holes in the address range of a CU
to ensure the DW_AT_ranges does not include those holes. When we see a
function with no debug info, though it may be in the same range as the
prior and subsequent functions, there should be a gap in the CU's
ranges. By setting PrevCU to null in that case, the range would not be
extended to cover the gap.
llvm-svn: 217466
DW_TAG_lexical_scopes inform debuggers about the instruction range for
which a given variable (or imported declaration/module/etc) is valid. If
the scope doesn't itself contain any such entities, it's a waste of
space and should be omitted.
We were correctly doing this for entirely empty leaves, but not for
intermediate nodes.
Reduces total (not just debug sections) .o file size for a bootstrap
-gmlt LLVM by 22% and bootstrap -gmlt clang executable by 13%. The wins
for a full -g build will be less as a % (and in absolute terms), but
should still be substantial - with some of that win being fewer
relocations, thus more substantiall reducing link times than fewer bytes
alone would have.
llvm-svn: 216861
This makes the emptiness of the scope with regards to variables and
nested scopes is the same as with regards to imported entities. Just
check if we had nothing at all before we build the node.
llvm-svn: 216840
First of many steps to improve lexical scope construction (to omit
trivial lexical scopes - those without any direct variables). To that
end it's easier not to create imported entities directly into the
lexical scope node, but to build them, then add them if necessary.
llvm-svn: 216838
Rushed when I realized I hadn't committed the FreeDeleter for a clang
change I'd committed, and didn't check that I had things lying around in
my client.
Apologies for the noise.
llvm-svn: 216792
Somewhat unnoticed in the original implementation of discriminators, but
it could cause instructions to end up in new, small,
DW_TAG_lexical_blocks due to the use of DILexicalBlock to track
discriminator changes.
Instead, use DILexicalBlockFile which we already use to track file
changes without introducing new scopes, so it works well to track
discriminator changes in the same way.
llvm-svn: 216239
buildLocationLists easier to read.
The previous implementation conflated the merging of individual pieces
and the merging of entire DebugLocEntries.
By splitting this functionality into two separate functions the intention
of the code should be clearer.
llvm-svn: 215383
Due to an unnecessary special case, inlined arguments that happened to
be from the same function as they were inlined into were misclassified
as non-inline arguments and would overwrite the non-inlined arguments.
Assert that we never overwrite a function's arguments, and stop
misclassifying inlined arguments as non-inline arguments to fix this
issue.
Excuse the rather crappy test case - handcrafted IR might do better, or
someone who understands better how to tickle the inliner to create a
recursive inlining situation like this (though it may also be necessary
to tickle the variable in a particular way to cause it to be recorded in
the MMI side table and go down this particular path for location
information).
llvm-svn: 215157
This was coming in weird debug info that had variables (and hence
debug_locs) but was in GMLT mode (because it was missing the 13th field
of the compile_unit metadata) so no ranges were constructed. We should
always have at least one range for any CU with a debug_loc in it -
because the range should cover the debug_loc.
The assertion just ensures that the "!= 1" range case inside the
subsequent loop doesn't get entered for the case where there are no
ranges at all, which should never reach here in the first place.
llvm-svn: 214939
This simplifies construction and usage while making the data structure
smaller. It was a holdover from the days when we didn't have a separate
DebugLocList and all we had was a flat list of DebugLocEntries.
llvm-svn: 214933
Originally reverted in r213432 with flakey failures on an ASan self-host
build. After reduction it seems to be the same issue fixed in r213805
(ArgPromo + DebugInfo: Handle updating debug info over multiple
applications of argument promotion) and r213952 (by having
LiveDebugVariables strip dbg_value intrinsics in functions that are not
described by debug info). Though I cannot explain why this failure was
flakey...
llvm-svn: 214761
variables (for example, by-value struct arguments passed in registers, or
large integer values split across several smaller registers).
On the IR level, this adds a new type of complex address operation OpPiece
to DIVariable that describes size and offset of a variable fragment.
On the DWARF emitter level, all pieces describing the same variable are
collected, sorted and emitted as DWARF expressions using the DW_OP_piece
and DW_OP_bit_piece operators.
http://reviews.llvm.org/D3373
rdar://problem/15928306
What this patch doesn't do / Future work:
- This patch only adds the backend machinery to make this work, patches
that change SROA and SelectionDAG's type legalizer to actually create
such debug info will follow. (http://reviews.llvm.org/D2680)
- Making the DIVariable complex expressions into an argument of dbg.value
will reduce the memory footprint of the debug metadata.
- The sorting/uniquing of pieces should be moved into DebugLocEntry,
to facilitate the merging of multi-piece entries.
llvm-svn: 214576
Per feedback on r214111, we are going to use null to represent unspecified
parameter. If the type array is {null}, it means a function that returns void;
If the type array is {null, null}, it means a variadic function that returns
void. In summary if we have more than one element in the type array and the last
element is null, it is a variadic function.
rdar://17628609
llvm-svn: 214189
The enum types array by design contains pointers to MDNodes rather than DIRefs.
Unique them when handling the enum types in DwarfDebug.
rdar://17628609
llvm-svn: 214139
DITypeArray is an array of DITypeRef, at its creation, we will create
DITypeRef (i.e use the identifier if the type node has an identifier).
This is the last patch to unique the type array of a subroutine type.
rdar://17628609
llvm-svn: 214132
This is the second of a series of patches to handle type uniqueing of the
type array for a subroutine type.
For vector and array types, getElements returns the array of subranges, so it
is a better name than getTypeArray. Even for class, struct and enum types,
getElements returns the members, which can be subprograms.
setArrays can set up to two arrays, the second is the templates.
This commit should have no functionality change.
llvm-svn: 214112
Adrian Prantl