Summary:
-debug-info-kind=constructor reduces the amount of class debug info that
is emitted; this patch switches to using this as the default.
Constructor homing emits the complete type info for a class only when the
constructor is emitted, so it is expected that there will be some classes that
are not defined in the debug info anymore because they are never constructed,
and we shouldn't need debug info for these classes.
I compared the PDB files for clang, and there are 273 class types that are defined with `=limited`
but not with `=constructor` (out of ~60,000 total class types).
We've looked at a number of the types that are no longer defined with =constructor. The vast
majority of cases are something like class A is used as a parameter in a member function of
some other class B, which is emitted. But the function that uses class A is never called, and class A
is never constructed, and therefore isn't emitted in the debug info.
Bug: https://bugs.llvm.org/show_bug.cgi?id=46537
Subscribers: aprantl, cfe-commits, lldb-commits
Tags: #clang, #lldb
Differential Revision: https://reviews.llvm.org/D79147
The -fsplit-dwarf-inlining option does not conform to DWARF5 standard.
It creates children for Skeleton compilation unit. We need default behavior
to be DWARF5 compatible. Thus set default state for -fsplit-dwarf-inlining
into "false".
Differential Revision: https://reviews.llvm.org/D71304
Summary:
The changes in D59673 made the choice redundant, since we can achieve
single-file split DWARF just by not setting an output file name.
Like llc we can also derive whether to enable Split DWARF from whether
-split-dwarf-file is set, so we don't need the flag at all anymore.
The test CodeGen/split-debug-filename.c distinguished between having set
or not set -enable-split-dwarf with -split-dwarf-file, but we can
probably just always emit the metadata into the IR.
The flag -split-dwarf wasn't used at all anymore.
Reviewers: dblaikie, echristo
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D63167
llvm-svn: 364479
Summary:
With Split DWARF the resulting object file (then called skeleton CU)
contains the file name of another ("DWO") file with the debug info.
This can be a problem for remote compilation, as it will contain the
name of the file on the compilation server, not on the client.
To use Split DWARF with remote compilation, one needs to either
* make sure only relative paths are used, and mirror the build directory
structure of the client on the server,
* inject the desired file name on the client directly.
Since llc already supports the latter solution, we're just copying that
over. We allow setting the actual output filename separately from the
value of the DW_AT_[GNU_]dwo_name attribute in the skeleton CU.
Fixes PR40276.
Reviewers: dblaikie, echristo, tejohnson
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D59673
llvm-svn: 363496
Summary:
This is the first in a series of changes trying to align clang -cc1
flags for Split DWARF with those of llc. The unfortunate side effect of
having -split-dwarf-output for single file Split DWARF will disappear
again in a subsequent change.
The change is the result of a discussion in D59673.
Reviewers: dblaikie, echristo
Reviewed By: dblaikie
Differential Revision: https://reviews.llvm.org/D63130
llvm-svn: 363494
Summary:
When -gsplit-dwarf is used together with other -g options, in most cases
the computed debug info level is decided by the last -g option, with one
special case (see below). This patch drops that special case and thus
makes it easy to reason about:
// If a lower debug level -g comes after -gsplit-dwarf, in some cases
// -gsplit-dwarf is cancelled.
-gsplit-dwarf -g0 => 0
-gsplit-dwarf -gline-directives-only => DebugDirectivesOnly
-gsplit-dwarf -gmlt -fsplit-dwarf-inlining => 1
-gsplit-dwarf -gmlt -fno-split-dwarf-inlining => 1 + split
// If -gsplit-dwarf comes after -g options, with this patch, the net
// effect is 2 + split for all combinations
-g0 -gsplit-dwarf => 2 + split
-gline-directives-only -gsplit-dwarf => 2 + split
-gmlt -gsplit-dwarf -fsplit-dwarf-inlining => 2 + split
-gmlt -gsplit-dwarf -fno-split-dwarf-inlining => 1 + split (before) 2 + split (after)
The last case has been changed. In general, if the user intends to lower
debug info level, place that -g option after -gsplit-dwarf.
Some context:
In gcc, the last of -gsplit-dwarf -g0 -g1 -g2 -g3 -ggdb[0-3] -gdwarf-*
... decides the debug info level (-gsplit-dwarf -gdwarf-* have level 2).
It is a bit unfortunate that -gsplit-dwarf -gdwarf-* ... participate in
the level computation but that is the status quo.
Reviewers: dblaikie, echristo, probinson
Reviewed By: dblaikie, probinson
Subscribers: probinson, aprantl, jdoerfert, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D59923
llvm-svn: 358544
Effectively reverts r337612. The issues that cropped up with the last
attempt appear to have gone away.
Differential Revision: https://reviews.llvm.org/D59008
llvm-svn: 357285
In gcc, -gsplit-dwarf is handled in gcc/gcc.c as a spec
(ASM_FINAL_SPEC): objcopy --extract-dwo + objcopy --strip-dwo. In
gcc/opts.c, -gsplit_dwarf has the same semantic of a -g. Except for the
availability of the external command 'objcopy', nothing precludes the
feature working on other ELF OSes. llvm doesn't use objcopy, so it doesn't
have to exclude other OSes.
llvm-svn: 357150
The DWARF5 specification says(Appendix F.1):
"The sections that do not require relocation, however, can be
written to the relocatable object (.o) file but ignored by the
linker or they can be written to a separate DWARF object (.dwo)
file that need not be accessed by the linker."
The first part describes a single file split DWARF feature and there
is no way to trigger this behavior atm.
Fortunately, no many changes are required to keep *.dwo sections
in a .o, the patch does that.
Differential revision: https://reviews.llvm.org/D52296
llvm-svn: 346837
Since -gsplit-dwarf is specified on a backend compile (in ThinLTO
parlance) it isn't passed during the frontend compile (because no ELF
object/dwo file is produced then), yet the -fno-split-dwarf-inlining
value needs to be encoded in the LLVM DebugInfo metadata to have
effect...
So let it be specified & it'll be silently ignored if -gsplit-dwarf
isn't used in the end, otherwise it'll be used on a per-cu basis
depending on where it's specified in the frontend compile actions.
llvm-svn: 301684
Since Split DWARF needs to name the actual .dwo file that is generated,
it can't be known at the time the llvm::Module is produced as it may be
merged with other Modules before the object is generated and that object
may be generated with any name.
By passing the Split DWARF file name when LLVM is producing object code
the .dwo file name in the object file can match correctly.
The support for Split DWARF for implicit modules remains the same -
using metadata to store the dwo name and dwo id so that potentially
multiple skeleton CUs referring to different dwo files can be generated
from one llvm::Module.
llvm-svn: 301063
I tested the cases involving split-dwarf + gmlt +
no-split-dwarf-inlining, but didn't verify the simpler case without
gmlt.
The logic is, admittedly, a little hairy, but seems about as simple as I
could wrangle it.
llvm-svn: 280290
If the inline info is not duplicated into the skeleton CU, then there's
value in using -gsplit-dwarf and -gmlt together (to keep all those extra
subprograms out of the skeleton CU, while also producing smaller .dwo
files)
llvm-svn: 279687
Adds driver options named -glldb and -gsce to mean -g plus tuning for
lldb and SCE debuggers respectively; the existing -ggdb option does
the same for gdb. Existing options -ggdb0, -ggdb1 etc. unpack into
-ggdb -g<N>. (There will not be -glldb<N> or -gsce<N> options.) The
tuning gets a target-specific default in the driver, and is passed
into cc1 with the new -debugger-tuning option.
As fallout, fixes where '-gsplit-dwarf -g0' would ignore the -g0 part
on Linux.
Differential Revision: http://reviews.llvm.org/D15651
llvm-svn: 256104
With this change, most 'g' options are rejected by CompilerInvocation.
They remain only as Driver options. The new way to request debug info
from cc1 is with "-debug-info-kind={line-tables-only|limited|standalone}"
and "-dwarf-version={2|3|4}". In the absence of a command-line option
to specify Dwarf version, the Toolchain decides it, rather than placing
Toolchain-specific logic in CompilerInvocation.
Also fix a bug in the Windows compatibility argument parsing
in which the "rightmost argument wins" principle failed.
Differential Revision: http://reviews.llvm.org/D13221
llvm-svn: 249655
It doesn't make any sense to enable -gmlt with -gsplit-dwarf, since
-gmlt is designed for on-line symbolication (and -gsplit-dwarf normally
emits all the -gmlt data into the .o anyway - so there's nothing to
split out except redundant/duplicate info).
With this change they override each other, -gmlt -gsplit-dwarf is the
same as -gsplit-dwarf and -gsplit-dwarf -gmlt is the same as -gmlt.
llvm-svn: 243694
integrated assembler then go ahead and still split the dwarf anyhow.
Add two tests, one to exercise existing behavior of not splitting
when we're just emitting assembly files and the other to test
that we split when we're not in integrated as mode.
llvm-svn: 183355
to want to propagate some information through the module into
the back end and so need to pass it through to codegen.
Also make the methods file static so we can use them in other places.
llvm-svn: 175916
Amy Huang