This commit changes how inline information is stored in SILDebugScope
from a tree to a linear chain of inlined call sites (similar to what
LLVM is using). This makes creating inlined SILDebugScopes slightly
more expensive, but makes lowering SILDebugScopes into LLVM metadata
much faster because entire inlined-at chains can now be cached. This
means that SIL is no longer preserve the inlining history (i.e., ((a
was inlined into b) was inlined into c) is represented the same as (a
was inlined into (b was inlined into c)), but this information was not
used by anyone.
On my late 2012 i7 iMac, this saves about 4 seconds when compiling the
RelWithDebInfo x86_64 swift standard library — or 40% of IRGen time.
rdar://problem/28311051
This fixes a crash while building the Swift standard library when
partial specializations are enabled.
Eventually we should get rid of needing the DeclContext in the mangled
typename at all, and this is one step towards that goal.
rdar://problem/31253373
llvm r283043 and possibly other recent changes switch to use StringRef
instead of char* pointers. Update Swift to match. In some cases, this is
a clear improvement. It would be good to assess the impact on memory use,
particularly for the Filename component of source locations.
Note that the change to SILLocation::isNull fixes an apparent bug where
the location was treated as null when the filename was *not* null.
The Darwin linker won't process the debug info if the source file name
is invalid so there is no point in having a fallback implemented there.
<rdar://problem/25130236>
This saves ~4 seconds of a -r --no-assertions stdlib build and lowers
the contribution of llvm::SourceMgr::getLineAndColumn() to the total
runtime from 6% to 2%.
<rdar://problem/27016577>
It is not valid LLVM IR to have a function call without a location to an
inlinable function inside a function with debug info — this makes it impossible
to construct inline information.
This patch adds an assertion and fixes up several places across IRGen where
such a situation could happen.
rdar://problem/26955467
explosion schema rather than from the debug type information and retire
a bunch of heuristics that are no longer necessary.
To enable this, this commit also includes a bugfix to debug info for
opaque data structures with the correct size and alignment information.
<rdar://problem/21470869+22707597>
This reapplies ad4f065ad6 and 7e489db9 after fixing the problem
uncovered by this commit in 5726370c1.
explosion schema rather than from the debug type information and retire
a bunch of heuristics that are no longer necessary.
To enable this, this commit also includes a bugfix to debug info for
opaque data structures with the correct size and alignment information.
<rdar://problem/21470869+22707597>
Recent versions of LLDB can deal with line 0 locations much better and
due to a subtle bug in the heuristic instructions immediately following
the prologue could end up without debug locations which can cause serious
problems for the LLVM inliner when constructing inline debug scope info.
<rdar://problem/24394944>
Correct format:
```
//===--- Name of file - Description ----------------------------*- Lang -*-===//
```
Notes:
* Comment line should be exactly 80 chars.
* Padding: Pad with dashes after "Description" to reach 80 chars.
* "Name of file", "Description" and "Lang" are all optional.
* In case of missing "Lang": drop the "-*-" markers.
* In case of missing space: drop one, two or three dashes before "Name of file".
The drivers for this change are providing a simpler API to SIL pass
authors, having a more efficient of the in-memory representation,
and ruling out an entire class of common bugs that usually result
in hard-to-debug backend crashes.
Summary
-------
SILInstruction
Old New
+---------------+ +------------------+ +-----------------+
|SILInstruction | |SILInstruction | |SILDebugLocation |
+---------------+ +------------------+ +-----------------+
| ... | | ... | | ... |
|SILLocation | |SILDebugLocation *| -> |SILLocation |
|SILDebugScope *| +------------------+ |SILDebugScope * |
+---------------+ +-----------------+
We’re introducing a new class SILDebugLocation which represents the
combination of a SILLocation and a SILDebugScope.
Instead of storing an inline SILLocation and a SILDebugScope pointer,
SILInstruction now only has one SILDebugLocation pointer. The APIs of
SILBuilder and SILDebugLocation guarantees that every SILInstruction
has a nonempty SILDebugScope.
Developer-visible changes include:
SILBuilder
----------
In the old design SILBuilder populated the InsertedInstrs list to
allow setting the debug scopes of all built instructions in bulk
at the very end (as the responsibility of the user). In the new design,
SILBuilder now carries a "current debug scope" state and immediately
sets the debug scope when an instruction is inserted.
This fixes a use-after-free issue with with SIL passes that delete
instructions before destroying the SILBuilder that created them.
Because of this, SILBuilderWithScopes no longer needs to be a template,
which simplifies its call sites.
SILInstruction
--------------
It is neither possible or necessary to manually call setDebugScope()
on a SILInstruction any more. The function still exists as a private
method, but is only used when splicing instructions from one function
to another.
Efficiency
----------
In addition to dropping 20 bytes from each SILInstruction,
SILDebugLocations are now allocated in the SILModule's bump pointer
allocator and are uniqued by SILBuilder. Unfortunately repeat compiles
of the standard library already vary by about 5% so I couldn’t yet
produce reliable numbers for how much this saves overall.
rdar://problem/22017421
