Emit the number of bytes in a `.debug_loc` entry directly. The old code
created temp labels (expensive), emitted the difference between them,
and then emitted one on each side of the relevant bytes.
(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`
(the optimized version of ld64's `-save-temps` when linking the
`verify-uselistorder` executable in an LTO bootstrap). I've hacked
`MCContext::Allocate()` to just call `malloc()` instead of using the
`BumpPtrAllocator` so that the heap profile is easier to read. As far
as peak memory is concerned, `MCContext::Allocate()` is equivalent to a
leak, since it only gets freed at process teardown.
In my heap profile, this patch drops memory usage of
`DwarfDebug::emitDebugLoc()` from 132.56 MB (11.4%) down to 29.86 MB
(2.7%) at peak memory. Some of that must be noise from `SmallVector`
(or other) allocations -- peak memory only dropped from 1160 MB down to
1100 MB -- but this nevertheless shaves 5% off the top.)
llvm-svn: 236629
Finish off PR23080 by renaming the debug info IR constructs from `MD*`
to `DI*`. The last of the `DIDescriptor` classes were deleted in
r235356, and the last of the related typedefs removed in r235413, so
this has all baked for about a week.
Note: If you have out-of-tree code (like a frontend), I recommend that
you get everything compiling and tests passing with the *previous*
commit before updating to this one. It'll be easier to keep track of
what code is using the `DIDescriptor` hierarchy and what you've already
updated, and I think you're extremely unlikely to insert bugs. YMMV of
course.
Back to *this* commit: I did this using the rename-md-di-nodes.sh
upgrade script I've attached to PR23080 (both code and testcases) and
filtered through clang-format-diff.py. I edited the tests for
test/Assembler/invalid-generic-debug-node-*.ll by hand since the columns
were off-by-three. It should work on your out-of-tree testcases (and
code, if you've followed the advice in the previous paragraph).
Some of the tests are in badly named files now (e.g.,
test/Assembler/invalid-mdcompositetype-missing-tag.ll should be
'dicompositetype'); I'll come back and move the files in a follow-up
commit.
llvm-svn: 236120
Delete subclasses of (the already deleted) `DIType` in favour of
directly using pointers from the `Metadata` hierarchy.
While `DICompositeType` wraps `MDCompositeTypeBase` and `DIDerivedType`
wraps `MDDerivedTypeBase`, most uses of each really meant the more
specific `MDCompositeType` and `MDDerivedType`.
llvm-svn: 235351
The version of `constructTypeDIE()` for `MDSubroutineType` is unrelated
to (and has different callers than) the `MDCompositeType`. Split the
two in half.
This simplifies an upcoming patch to delete `DICompositeType`. There
shouldn't be any real functionality change here. `createTypeDIE()` is
`cast<>`'ing where it didn't need to before, but that function in turn
is only called for true `MDCompositeType`s.
llvm-svn: 235349
This is the last major parent class, so I'll probably start deleting
classes in batches now. Looks like many of the references to the DI*
hierarchy were updated organically along the way.
llvm-svn: 235331
This commit removes `DebugLocList` and replaces it with
`DebugLocStream`.
- `DebugLocEntry` no longer contains its byte/comment streams.
- The `DebugLocEntry` list for a variable/inlined-at pair is allocated
on the stack, and released right after `DebugLocEntry::finalize()`
(possible because of the refactoring in r231023). Now, only one
list is in memory at a time now.
- There's a single unified stream for the `.debug_loc` section that
persists, stored in the new `DebugLocStream` data structure.
The last point is important: this collapses the nested `SmallVector<>`s
from `DebugLocList` into unified streams. We previously had something
like the following:
vec<tuple<Label, CU,
vec<tuple<BeginSym, EndSym,
vec<Value>,
vec<char>,
vec<string>>>>>
A `SmallVector` can avoid allocations, but is statically fairly large
for a vector: three pointers plus the size of the small storage, which
is the number of elements in small mode times the element size).
Nesting these is expensive, since an inner vector's size contributes to
the element size of an outer one. (Nesting any vector is expensive...)
In the old data structure, the outer vector's *element* size was 632B,
excluding allocation costs for when the middle and inner vectors
exceeded their small sizes. 312B of this was for the "three" pointers
in the vector-tree beneath it. If you assume 1M functions with an
average of 10 variable/inlined-at pairs each (in an LTO scenario),
that's almost 6GB (besides inner allocations), with almost 3GB for the
"three" pointers.
This came up in a heap profile a little while ago of a `clang -flto -g`
bootstrap, with `DwarfDebug::collectVariableInfo()` using something like
10-15% of the total memory.
With this commit, we have:
tuple<vec<tuple<Label, CU, Offset>>,
vec<tuple<BeginSym, EndSym, Offset, Offset>>,
vec<char>,
vec<string>>
The offsets are used to create `ArrayRef` slices of adjacent
`SmallVector`s. This reduces the number of vectors to four (unrelated
to the number of variable/inlined-at pairs), and caps the number of
allocations at the same number.
Besides saving memory and limiting allocations, this is NFC.
I don't know my way around this code very well yet, but I wonder if we
could go further: why stream to a side-table, instead of directly to the
output stream?
llvm-svn: 235229
Stop storing the `MDLocalVariable` in the `DebugLocEntry::Value`s. We
generate the list of `DebugLocEntry`s separately for each
variable/inlined-at pair, so the variable never actually changes here.
This is effectively NFC (aside from saving some memory and CPU time).
llvm-svn: 235202
We can calculate the variable type up front before calling
`DebugLocEntry::finalize()`. In fact, since we only care about the type
if it's an `MDBasicType`, don't even bother resolving it using the type
identifier map.
llvm-svn: 235201
Delete `DIRef<>`, and replace the remaining uses of it with
`TypedDebugNodeRef<>`. To minimize code churn, I've added typedefs from
`MDTypeRef` to `DITypeRef` (etc.).
llvm-svn: 235071
Continuing PR23080, gut `DIType` and its various subclasses, leaving
behind thin wrappers around the pointer types in the new debug info
hierarchy.
llvm-svn: 235064
Remove 'inlinedAt:' from MDLocalVariable. Besides saving some memory
(variables with it seem to be single largest `Metadata` contributer to
memory usage right now in -g -flto builds), this stops optimization and
backend passes from having to change local variables.
The 'inlinedAt:' field was used by the backend in two ways:
1. To tell the backend whether and into what a variable was inlined.
2. To create a unique id for each inlined variable.
Instead, rely on the 'inlinedAt:' field of the intrinsic's `!dbg`
attachment, and change the DWARF backend to use a typedef called
`InlinedVariable` which is `std::pair<MDLocalVariable*, MDLocation*>`.
This `DebugLoc` is already passed reliably through the backend (as
verified by r234021).
This commit removes the check from r234021, but I added a new check
(that will survive) in r235048, and changed the `DIBuilder` API in
r235041 to require a `!dbg` attachment whose 'scope:` is in the same
`MDSubprogram` as the variable's.
If this breaks your out-of-tree testcases, perhaps the script I used
(mdlocalvariable-drop-inlinedat.sh) will help; I'll attach it to PR22778
in a moment.
llvm-svn: 235050
Gut the `DIDescriptor` wrappers around `MDLocalScope` subclasses. Note
that `DILexicalBlock` wraps `MDLexicalBlockBase`, not `MDLexicalBlock`.
llvm-svn: 234850
Gut all the non-pointer API from the variable wrappers, except an
implicit conversion from `DIGlobalVariable` to `DIDescriptor`. Note
that if you're updating out-of-tree code, `DIVariable` wraps
`MDLocalVariable` (`MDVariable` is a common base class shared with
`MDGlobalVariable`).
llvm-svn: 234840
Completely gut `DIExpression`, turning it into a simple wrapper around
`MDExpression *`. There are two bits of magic left:
- It's constructed from `const MDExpression*` but convertible to
`MDExpression*`.
- It's default-constructed to `nullptr`.
Otherwise, it should behave quite like a raw pointer. Once I've done
the same to the rest of the `DIDescriptor` subclasses, I'll come back to
delete them entirely (and update call sites as necessary to deal with
the missing magic).
llvm-svn: 234832
This reverts commit r234717, reapplying r234698 (in spirit).
As described in r234717, the original `Verifier` check had a
use-after-free. Instead of storing pointers to "interesting" debug info
intrinsics whose bit piece expressions should be verified once we have
typerefs, do a second traversal. I've added a testcase to catch the
`llc` crasher.
Original commit message:
Verifier: Check for incompatible bit piece expressions
Convert an assertion into a `Verifier` check. Bit piece expressions
must fit inside the variable, and mustn't be the entire variable.
Catching this in the verifier will help us find bugs sooner, and makes
`DIVariable::getSizeInBits()` dead code.
llvm-svn: 234776
This reverts commit r234698.
This caused a use-after-free: `QueuedBitPieceExpressions` holds onto
references to `DbgInfoIntrinsic`s and references them past where they're
deleted (this is because the verifier is run as a function pass, and
then `verifyTypeRefs()` is called during `doFinalization()`).
I'll include a reduced crasher for `llc` when I recommit the check.
llvm-svn: 234717
Convert an assertion into a `Verifier` check. Bit piece expressions
must fit inside the variable, and mustn't be the entire variable.
Catching this in the verifier will help us find bugs sooner, and makes
`DIVariable::getSizeInBits()` dead code.
llvm-svn: 234698
Replace all uses of `DITypedArray<>` with `MDTupleTypedArrayWrapper<>`
and `MDTypeRefArray`. The APIs are completely different, but the
provided functionality is the same: treat an `MDTuple` as if it's an
array of a particular element type.
To simplify this patch a bit, I've temporarily typedef'ed
`DebugNodeArray` to `DIArray` and `MDTypeRefArray` to `DITypeArray`.
I've also temporarily conditionalized the accessors to check for null --
eventually these should be changed to asserts and the callers should
check for null themselves.
There's a tiny accompanying patch to clang.
llvm-svn: 234290
Remove special iterators from `DIExpression` in favour of same in
`MDExpression`. There should be no functionality change here.
Note that the APIs are slightly different: `getArg(unsigned)` counts
from 0, not 1, in the `MDExpression` version of the iterator.
llvm-svn: 234285
Remove `DIDescriptor::Verify()` and the `Verify()`s from subclasses.
They had already been gutted, and just did an `isa<>` check.
In a couple of cases I've temporarily dropped the check entirely, but
subsequent commits are going to disallow conversions to the
`DIDescriptor`s directly from `MDNode`, so the checks will come back in
another form soon enough.
llvm-svn: 234201
As a follow-up to r234021, assert that a debug info intrinsic variable's
`MDLocalVariable::getInlinedAt()` always matches the
`MDLocation::getInlinedAt()` of its `!dbg` attachment.
The goal here is to get rid of `MDLocalVariable::getInlinedAt()`
entirely (PR22778), but I'll let these assertions bake for a while
first.
If you have an out-of-tree backend that just broke, you're probably
attaching the wrong `DebugLoc` to a `DBG_VALUE` instruction. The one
you want is the location that was attached to the corresponding
`@llvm.dbg.declare` or `@llvm.dbg.value` call that you started with.
llvm-svn: 234038
Pervasively use the types provided by the debug info hierarchy rather
than `MDNode` in `LexicalScopes`.
I noticed (again, I guess, based on comments in the implementation?)
that `DILexicalBlockFile::getScope()` returns something different from
`DILexicalBlockFile::getContext()`. I created a local helper for
getting the same logic from `MDLexicalBlockFile` called
`getScopeOfScope()`. I still don't really understand it, but I've added
some FIXMEs and I'll come back to it (I suspect the way we encode these
objects isn't really ideal).
Note that my previous commit r233610 accidentally changed behaviour in
`findLexicalScope()` -- it transitioned from a call to
`DILexicalBlockFile::getScope()` to `MDLexicalBlockFile::getScope()`
(sounds right, doesn't it?) -- so I've fixed that as a drive-by. No
tests failed with my error, so it looks like we're missing some coverage
here... when I come back to understand the logic, I'll see if I can add
some.
Other than the fix to `findLexicalScope()`, no functionality change.
llvm-svn: 233640
Don't use `DebugLoc::getFnDebugLoc()`, which creates new `MDLocation`s,
in the backend. We just want to grab the subprogram here anyway.
llvm-svn: 233601
There is now a canonical symbol at the end of a section that different
passes can request.
This also allows us to assert that we don't switch back to a section whose
end symbol has already been printed.
llvm-svn: 233026
`DL` might be null, so check for that before using accessors. A WIP
patch to make `DIDescriptors` more strict fails otherwise.
As a bonus, I think the logic is easier to follow now (despite the extra
nesting depth).
llvm-svn: 232836
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
This lets us pass the symbol to the constructor and avoid the mutable field.
This also opens the way for outputting the symbol only when needed, instead
of outputting them at the start of the file.
llvm-svn: 231859
This makes code that uses section relative expressions (debug info) simpler and
less brittle.
This is still a bit awkward as the symbol is created late and has to be
stored in a mutable field.
I will move the symbol creation earlier in the next patch.
llvm-svn: 231802
