[CLANG][DWARF] Do not emit -ggnu-pubnames for LLDB tuning, unless -ggnu-pubnames is specified. (#83331)

When -gsplit-dwarf is passed in clang emmmits -ggnu-pubnames which
results in
.debug_gnu_pub

[CLANG][DWARF] Do not emit -ggnu-pubnames for LLDB tuning, unless -ggnu-pubnames is specified. (#83331)

When -gsplit-dwarf is passed in clang emmmits -ggnu-pubnames which
results in
.debug_gnu_pubnames/..debug_gnu_pubtypes being generated.
This is used by GDB, but not by LLDB.
Changed so that these sections are not emitted for LLDB tuning, unless
flag
is passed explicitly.

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Revert "[CLANG][DWARF] Do not emit -ggnu-pubnames for split dwarf version 5." (#83214)

Reverts llvm/llvm-project#82840

[CLANG][DWARF] Do not emit -ggnu-pubnames for split dwarf version 5. (#82840)

When -gsplit-dwarf is passed in clang emmmits -ggnu-pubnames which
results in
.debug_gnu_pubnames/..debug_gnu_pubtypes

[CLANG][DWARF] Do not emit -ggnu-pubnames for split dwarf version 5. (#82840)

When -gsplit-dwarf is passed in clang emmmits -ggnu-pubnames which
results in
.debug_gnu_pubnames/..debug_gnu_pubtypes being generated.
This is used by GDB, but not by LLDB.
Changed so that these sections are not emitted for LLDB tuning.

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[Driver][test] Add --rocm-path or -nogpuinc/-nogpulib to some AMDGPU tests

An upcoming change D156363 will change -### to exit with code 1
if hasErrorOccurred. Some AMDGPU tests would exit with code

[Driver][test] Add --rocm-path or -nogpuinc/-nogpulib to some AMDGPU tests

An upcoming change D156363 will change -### to exit with code 1
if hasErrorOccurred. Some AMDGPU tests would exit with code 1.

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Revert D156363 "[Driver] -###: exit with code 1 if hasErrorOccurred"

This reverts commit 8c3550b1a78fde7bf28f420da8447d9fde37017f.

clang/test/Driver/fsanitize.c has a mysterious failure worth
inves

Revert D156363 "[Driver] -###: exit with code 1 if hasErrorOccurred"

This reverts commit 8c3550b1a78fde7bf28f420da8447d9fde37017f.

clang/test/Driver/fsanitize.c has a mysterious failure worth
investigation.

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[Driver] -###: exit with code 1 if hasErrorOccurred

The exit code for -### is inconsistent. Unrecognized options lead to
exit code 1, as expected. However, most others errors (including invalid
opti

[Driver] -###: exit with code 1 if hasErrorOccurred

The exit code for -### is inconsistent. Unrecognized options lead to
exit code 1, as expected. However, most others errors (including invalid
option value) lead to exit code 0, differing from GCC and most utilities.

This is a longstanding quirk of -###, and we didn't fix it because many
driver tests need adjustment.

Change -### to be similar to -fdriver-only -v and exit with code 1.

This requires fixing many driver tests, but the end result gives us
stronger tests.

* Existing `RUN: %clang -### ...` tests usually don't use `CHECK-NOT: error:` or `--implicit-check-not=error:`.
If a change introduces an error, such a change usually cannot be detected.
* Many folks contributing new tests don't know `-fdriver-only -v`.
To test no driver error/warning for new tests, they can use the familiar `-### -Werror`
instead of `-fdriver-only -v -Werror`.

An incomplete list of prerequisite test improvement:

* 2f79bb10461d114783a1548201928549ace09755: add -nogpulib to some AMDGPU tests
* 9155e517e6e1cda474d0d0fa82f71696c325bc10: add --cuda-path= (test w/ and w/o /usr/local/cuda)
* 80765ede5bbcca1364c2d4ae06127011eaba6389: -mcpu=native may return either 0 or 1, depending on whether `--target=` specifies a native target
* abae53f43f0d1da8d8e421f4a628d7ec64d6e365: fix -fuse-ld=lld misuses (test w/o and w/o /usr/local/bin/ld.lld)

Reviewed By: jhuber6, yaxunl, dblaikie

Differential Revision: https://reviews.llvm.org/D156363

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Revert D156363 "[Driver] -###: exit with code 1 if hasErrorOccurred"

This reverts commit e39bf32b3bc2f0cc21d783ba789bd82553493875.

Some tests have different behaviors depent on whether certain dire

Revert D156363 "[Driver] -###: exit with code 1 if hasErrorOccurred"

This reverts commit e39bf32b3bc2f0cc21d783ba789bd82553493875.

Some tests have different behaviors depent on whether certain directories/files are present on the host.
An incomplete list from https://lab.llvm.org/buildbot/#/builders/109/builds/70149

csky-toolchain.c
riscv*-toolchain.c
fuchsia.*
hip-*
ohos.c

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[Driver] -###: exit with code 1 if hasErrorOccurred

The exit code for -### is inconsistent. Unrecognized options lead to
exit code 1, as expected. However, most others errors (including invalid
opti

[Driver] -###: exit with code 1 if hasErrorOccurred

The exit code for -### is inconsistent. Unrecognized options lead to
exit code 1, as expected. However, most others errors (including invalid
option value) lead to exit code 0, differing from GCC and most utilities.

This is a longstanding quirk of -###, and we didn't fix it because many
driver tests need adjustment.

Change -### to be similar to -fdriver-only -v and exit with code 1.

This requires fixing many driver tests, but the end result gives us
stronger tests.

* Existing `RUN: %clang -### ...` tests usually don't use `CHECK-NOT: error:` or `--implicit-check-not=error:`.
If a change introduces an error, such a change usually cannot be detected.
* Many folks contributing new tests don't know `-fdriver-only -v`.
To test no driver error/warning for new tests, they can use the familiar `-### -Werror`
instead of `-fdriver-only -v -Werror`.

Reviewed By: jhuber6, yaxunl, dblaikie

Differential Revision: https://reviews.llvm.org/D156363

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Reland [COFF] Support -gsplit-dwarf for COFF on Windows

This relands 3eee5aa528abd67bb6d057e25ce1980d0d38c445 with fixes.

Revert "[COFF] Support -gsplit-dwarf for COFF on Windows"

This reverts commit 3eee5aa528abd67bb6d057e25ce1980d0d38c445.

Breaks tests on mac, see https://reviews.llvm.org/D152785#4447118

[COFF] Support -gsplit-dwarf for COFF on Windows

D152340 has split WinCOFFObjectWriter to WinCOFFWriter. This patch adds
another WinCOFFWriter as DwoWriter to write Dwo sections to dwo file.
Driver

[COFF] Support -gsplit-dwarf for COFF on Windows

D152340 has split WinCOFFObjectWriter to WinCOFFWriter. This patch adds
another WinCOFFWriter as DwoWriter to write Dwo sections to dwo file.
Driver options are also updated accordingly to support -gsplit-dwarf in
CL mode.

e.g. $ clang-cl -c -gdwarf -gsplit-dwarf foo.c

Like what -gsplit-dwarf did in ELF, using this option will create DWARF object
(.dwo) file. DWARF debug info is split between COFF object and DWARF object
file. It can reduce the executable file size especially for large project.

Reviewed By: skan, MaskRay

Differential Revision: https://reviews.llvm.org/D152785

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[Driver][test] Exclude `-o /dev/null` test for Windows

lit changes /dev/null to a special filename, and `"-dumpdir" "/dev/null-"` will fail.

[Driver] Add -dumpdir and change -gsplit-dwarf .dwo names for linking

When the final phase is linking, Clang currently places `.dwo` files in the
current directory (like the `-c` behavior for multip

[Driver] Add -dumpdir and change -gsplit-dwarf .dwo names for linking

When the final phase is linking, Clang currently places `.dwo` files in the
current directory (like the `-c` behavior for multiple inputs).
Strangely, -fdebug-compilation-dir=/-ffile-compilation-dir= is considered, which
is untested.

GCC has a more useful behavior that derives auxiliary filenames from the final
output (-o).
```
gcc -c -g -gsplit-dwarf d/a.c d/b.c # a.dwo b.dwo
gcc -g -gsplit-dwarf d/a.c d/b.c -o e/x # e/x-a.dwo e/x-b.dwo
gcc -g -gsplit-dwarf d/a.c d/b.c # a-a.dwo a-b.dwo
```

Port a useful subset of GCC behaviors that are easy to describe to Clang.

* Add a driver and cc1 option -dumpdir
* When the final phase is link, add a default -dumpdir if not specified by the user
* Forward -dumpdir to -cc1 command lines
* tools::SplitDebugName prefers -dumpdir when constructing the .dwo filename

GCC provides -dumpbase. If we use just one of -dumpdir and -dumpbase,
-dumpbase isn't very useful as it appends a dash.

```
gcc -g -gsplit-dwarf -dumpdir e d/a.c # ea.dwo
gcc -g -gsplit-dwarf -dumpdir e/ d/a.c # e/a.dwo
gcc -g -gsplit-dwarf -dumpbase e d/a.c # e-a.dwo
gcc -g -gsplit-dwarf -dumpbase e/ d/a.c # e/-a.dwo
```

If we specify both `-dumpdir` and `-dumpbase`, we can avoid the influence of the
source filename when there is one input file.
```
gcc -g -gsplit-dwarf -dumpdir f/ -dumpbase x d/a.c # f/x.dwo
gcc -g -gsplit-dwarf -dumpdir f/ -dumpbase x d/a.c d/b.c # f/x-a.dwo f/x-b.dwo
```

Given the above examples, I think -dumpbase is not useful.

GCC -save-temps has interesting interaction with -dumpdir as -save-temps
generated files are considered auxiliary files like .dwo files.

For Clang, with this patch, -save-temps and -dumpdir are orthogonal, which is
easier to explain.

```
gcc -g -gsplit-dwarf d/a.c -o e/x -dumpdir f/ -save-temps=obj # e/a.{i,s,o,dwo}
gcc -g -gsplit-dwarf d/a.c -o e/x -save-temps=obj -dumpdir f/ # f/a.{i,s,o,dwo}

clang -g -gsplit-dwarf d/a.c -o e/x -save-temps=obj -dumpdir f/ # e/a.{i,s,o} f/a.dwo
```

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D149193

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Revert "DebugInfo: Fully integrate ctor type homing into 'limited' debug info"

Reverting to simplify some Google-internal rollout issues. Will recommit
in a week or two.

This reverts commit 517bbc6

Revert "DebugInfo: Fully integrate ctor type homing into 'limited' debug info"

Reverting to simplify some Google-internal rollout issues. Will recommit
in a week or two.

This reverts commit 517bbc64dbe493644eff8d55fd9566435e930520.

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DebugInfo: Fully integrate ctor type homing into 'limited' debug info

Simplify debug info back to just "limited" or "full" by rolling the ctor
type homing fully into the "limited" debug info.

Also

DebugInfo: Fully integrate ctor type homing into 'limited' debug info

Simplify debug info back to just "limited" or "full" by rolling the ctor
type homing fully into the "limited" debug info.

Also fix a bug I found along the way that was causing ctor type homing
to kick in even when something could be vtable homed (where vtable
homing is stronger/more effective than ctor homing) - fixing at the same
time as it keeps the tests (that were testing only "limited non ctor"
homing and now test ctor homing) passing.

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[DebugInfo] Switch to using constructor homing (-debug-info-kind=constructor) by default when debug info is enabled

Constructor homing reduces the amount of class type info that is emitted
by emitti

[DebugInfo] Switch to using constructor homing (-debug-info-kind=constructor) by default when debug info is enabled

Constructor homing reduces the amount of class type info that is emitted
by emitting conmplete type info for a class only when a constructor for
that class is emitted.

This will mainly reduce the amount of duplicate debug info in object
files. In Chrome enabling ctor homing decreased total build directory sizes
by about 30%.

It's also expected that some class types (such as unused classes)
will no longer be emitted in the debug info. This is fine, since we wouldn't
expect to need these types when debugging.

In some cases (e.g. libc++, https://reviews.llvm.org/D98750), classes
are used without calling the constructor. Since this is technically
undefined behavior, enabling constructor homing should be fine.
However Clang now has an attribute
`__attribute__((standalone_debug))` that can be used on classes to
ignore ctor homing.

Bug: https://bugs.llvm.org/show_bug.cgi?id=46537

Differential Revision: https://reviews.llvm.org/D106084

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Make -f[no-]split-dwarf-inlining CC1 default align with driver default (no inlining)

This makes CC1 and driver defaults consistent.
In addition, for more common cases (-g is specified without -gspli

Make -f[no-]split-dwarf-inlining CC1 default align with driver default (no inlining)

This makes CC1 and driver defaults consistent.
In addition, for more common cases (-g is specified without -gsplit-dwarf), users will not see -fno-split-dwarf-inlining in CC1 options.

Verified that the below is still true:

* `clang -g` => `splitDebugInlining: false` in DICompileUnit
* `clang -g -gsplit-dwarf` => `splitDebugInlining: false` in DICompileUnit
* `clang -g -gsplit-dwarf -fsplit-dwarf-inlining` => no `splitDebugInlining: false`

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D97706

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[Driver] -gsplit-dwarf: Produce .dwo regardless of -gN for IR input

This generalizes D94647 to IR input, as suggested by @tejohnson.
Ideally the driver should just forward split dwarf options, but d

[Driver] -gsplit-dwarf: Produce .dwo regardless of -gN for IR input

This generalizes D94647 to IR input, as suggested by @tejohnson.
Ideally the driver should just forward split dwarf options, but doing this currently will cause `clang -gsplit-dwarf -c a.c` to create a .dwo with just `.strtab`.

Reviewed By: dblaikie, tejohnson

Differential Revision: https://reviews.llvm.org/D94655

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[Driver] -gsplit-dwarf: Produce .dwo regardless of -gN for -fthinlto-index=

-g is an IR generation option while -gsplit-dwarf is an object file generation option.
For -gsplit-dwarf in the backend ph

[Driver] -gsplit-dwarf: Produce .dwo regardless of -gN for -fthinlto-index=

-g is an IR generation option while -gsplit-dwarf is an object file generation option.
For -gsplit-dwarf in the backend phase of a distributed ThinLTO (-fthinlto-index=) which does object file generation and no IR generation, -g should not be needed.

This patch makes `-fthinlto-index= -gsplit-dwarf` emit .dwo even in the absence of -g.
This should fix https://crbug.com/1158215 after D80391.

```
// Distributed ThinLTO usage
clang -g -O2 -c -flto=thin -fthin-link-bitcode=a.indexing.o a.c
clang -g -O2 -c -flto=thin -fthin-link-bitcode=b.indexing.o b.c
clang -fuse-ld=lld -Wl,--thinlto-index-only=a.rsp -Wl,--thinlto-prefix-replace=';lto/' -Wl,--thinlto-object-suffix-replace='.indexing.o;.o' a.indexing.o b.indexing.o
clang -gsplit-dwarf -O2 -c -fthinlto-index=lto/a.o.thinlto.bc a.o -o lto/a.o
clang -gsplit-dwarf -O2 -c -fthinlto-index=lto/b.o.thinlto.bc b.o -o lto/b.o
clang -fuse-ld=lld @a.rsp -o exe
```

Note: for implicit regular/Thin LTO, .dwo emission works without this patch:
`clang -flto=thin -gsplit-dwarf a.o b.o` passes `-plugin-opt=dwo_dir=` to the linker.
The linker forwards the option to LTO. LTOBackend.cpp emits `$dwo_dir/[01234].dwo`.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D94647

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Fix split-debug.c test on Windows

[Driver] Add -gno-split-dwarf which can disable debug fission

Currently when -gsplit-dwarf is specified (could be buried in a build system),
there is no convenient way to cancel debug fission withou

[Driver] Add -gno-split-dwarf which can disable debug fission

Currently when -gsplit-dwarf is specified (could be buried in a build system),
there is no convenient way to cancel debug fission without affecting the debug
information amount (all of -g0, -g1 -fsplit-dwarf-inlining and -gline-directives-only
can, but they affect the debug information amount).

Reviewed By: #debug-info, dblaikie

Differential Revision: https://reviews.llvm.org/D92809

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[Driver] Don't make -gsplit-dwarf imply -g2

RFC: http://lists.llvm.org/pipermail/cfe-dev/2020-May/065430.html
Agreement from GCC: https://sourceware.org/pipermail/gcc-patches/2020-May/545688.html

g

[Driver] Don't make -gsplit-dwarf imply -g2

RFC: http://lists.llvm.org/pipermail/cfe-dev/2020-May/065430.html
Agreement from GCC: https://sourceware.org/pipermail/gcc-patches/2020-May/545688.html

g_flags_Group options generally don't affect the amount of debugging
information. -gsplit-dwarf is an exception. Its order dependency with
other gN_Group options make it inconvenient in a build system:

* -g0 -gsplit-dwarf -> level 2
-gsplit-dwarf "upgrades" the amount of debugging information despite
the previous intention (-g0) to drop debugging information
* -g1 -gsplit-dwarf -> level 2
-gsplit-dwarf "upgrades" the amount of debugging information.
* If we have a higher-level -gN, -gN -gsplit-dwarf will supposedly decrease the
amount of debugging information. This happens with GCC -g3.

The non-orthogonality has confused many users. GCC 11 will change the semantics
(-gsplit-dwarf no longer implies -g2) despite the backwards compatibility break.
This patch matches its behavior.

New semantics:

* If there is a g_Group, allow split DWARF if useful
(none of: -g0, -gline-directives-only, -g1 -fno-split-dwarf-inlining)
* Otherwise, no-op.

To restore the original behavior, replace -gsplit-dwarf with -gsplit-dwarf -g.

Reviewed By: dblaikie

Differential Revision: https://reviews.llvm.org/D80391

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[test] Rewrite split-debug.c

Use generic ELF target triples.
Add missing coverage: -gsplit-dwarf=split -g -fsplit-dwarf-inlining
Reorganize and add comments.
Test -gno-pubnames

Support dwarf fission for wasm object files

Initial support for dwarf fission sections (-gsplit-dwarf) on wasm.
The most interesting change is support for writing 2 files (.o and .dwo) in the
wasm o

Support dwarf fission for wasm object files

Initial support for dwarf fission sections (-gsplit-dwarf) on wasm.
The most interesting change is support for writing 2 files (.o and .dwo) in the
wasm object writer. My approach moves object-writing logic into its own function
and calls it twice, swapping out the endian::Writer (W) in between calls.
It also splits the import-preparation step into its own function (and skips it when writing a dwo).

Differential Revision: https://reviews.llvm.org/D85685

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Revert "Switch to using -debug-info-kind=constructor as default (from =limited)"

This reverts commit 227db86a1b7dd6f96f7df14890fcd071bc4fe1f5.

Causing debug info errors in google3 LTO builds; also

Revert "Switch to using -debug-info-kind=constructor as default (from =limited)"

This reverts commit 227db86a1b7dd6f96f7df14890fcd071bc4fe1f5.

Causing debug info errors in google3 LTO builds; also causes a
debuginfo-test failure.

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