Rename parallelForEachN to just parallelFor

Patch created by running:

rg -l parallelForEachN | xargs sed -i '' -c 's/parallelForEachN/parallelFor/'

No behavior change.

Differential Revision: ht

Rename parallelForEachN to just parallelFor

Patch created by running:

rg -l parallelForEachN | xargs sed -i '' -c 's/parallelForEachN/parallelFor/'

No behavior change.

Differential Revision: https://reviews.llvm.org/D128140

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Print C-string literals in mapfile

This diff has the C-string literals printed into the mapfile in the symbol table like how ld64 does.

Here is what ld64's mapfile looks like with C-string literals

Print C-string literals in mapfile

This diff has the C-string literals printed into the mapfile in the symbol table like how ld64 does.

Here is what ld64's mapfile looks like with C-string literals:
```
# Path: out
# Arch: x86_64
# Object files:
[ 0] linker synthesized
[ 1] foo.o
# Sections:
# Address Size Segment Section
0x100003F7D 0x0000001D __TEXT __text
0x100003F9A 0x0000001E __TEXT __cstring
0x100003FB8 0x00000048 __TEXT __unwind_info
# Symbols:
# Address Size File Name
0x100003F7D 0x0000001D [ 1] _main
0x100003F9A 0x0000000E [ 1] literal string: Hello world!\n
0x100003FA8 0x00000010 [ 1] literal string: Hello, it's me\n
0x100003FB8 0x00000048 [ 0] compact unwind info
```

Here is what the new lld's Mach-O mapfile looks like:
```
# Path: /Users/rgr/local/llvm-project/build/Debug/tools/lld/test/MachO/Output/map-file.s.tmp/c-string-liter
al-out
# Arch: x86_64
# Object files:
[ 0] linker synthesized
[ 1] /Users/rgr/local/llvm-project/build/Debug/tools/lld/test/MachO/Output/map-file.s.tmp/c-string-literal
.o
# Sections:
# Address Size Segment Section
0x1000002E0 0x0000001D __TEXT __text
0x1000002FD 0x0000001D __TEXT __cstring
# Symbols:
# Address File Name
0x1000002E0 [ 1] _main
0x1000002FD [ 1] literal string: Hello world!\n
0x10000030B [ 1] literal string: Hello, it's me\n
```

Reviewed By: #lld-macho, int3

Differential Revision: https://reviews.llvm.org/D118077

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[lld][Macho] Include dead-stripped symbols in mapfile

ld64 outputs dead stripped symbols when using the -dead-strip flag. This change mimics that behavior for lld.

ld64's -dead_strip flag outputs:

[lld][Macho] Include dead-stripped symbols in mapfile

ld64 outputs dead stripped symbols when using the -dead-strip flag. This change mimics that behavior for lld.

ld64's -dead_strip flag outputs:
```
$ ld -map map basics.o -o out -dead_strip -L/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib -lSystem
$ cat map
# Path: out
# Arch: x86_64
# Object files:
[ 0] linker synthesized
[ 1] basics.o
# Sections:
# Address Size Segment Section
0x100003F97 0x00000021 __TEXT __text
0x100003FB8 0x00000048 __TEXT __unwind_info
0x100004000 0x00000008 __DATA_CONST __got
0x100008000 0x00000010 __DATA __ref_section
0x100008010 0x00000001 __DATA __common
# Symbols:
# Address Size File Name
0x100003F97 0x00000006 [ 1] _ref_local
0x100003F9D 0x00000001 [ 1] _ref_private_extern
0x100003F9E 0x0000000C [ 1] _main
0x100003FAA 0x00000006 [ 1] _no_dead_strip_globl
0x100003FB0 0x00000001 [ 1] _ref_from_no_dead_strip_globl
0x100003FB1 0x00000006 [ 1] _no_dead_strip_local
0x100003FB7 0x00000001 [ 1] _ref_from_no_dead_strip_local
0x100003FB8 0x00000048 [ 0] compact unwind info
0x100004000 0x00000008 [ 0] non-lazy-pointer-to-local: _ref_com
0x100008000 0x00000008 [ 1] _ref_data
0x100008008 0x00000008 [ 1] l_ref_data
0x100008010 0x00000001 [ 1] _ref_com

# Dead Stripped Symbols:
# Size File Name
<<dead>> 0x00000006 [ 1] _unref_extern
<<dead>> 0x00000001 [ 1] _unref_local
<<dead>> 0x00000007 [ 1] _unref_private_extern
<<dead>> 0x00000001 [ 1] _ref_private_extern_u
<<dead>> 0x00000008 [ 1] _unref_data
<<dead>> 0x00000008 [ 1] l_unref_data
<<dead>> 0x00000001 [ 1] _unref_com
```

Reviewed By: int3, #lld-macho, thevinster

Differential Revision: https://reviews.llvm.org/D114737

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[lld][macho] Stop grouping symbols by sections in mapfile.

As per [Bug 50689](https://bugs.llvm.org/show_bug.cgi?id=50689),

```
2. getSectionSyms() puts all the symbols into a map of section -> sym

[lld][macho] Stop grouping symbols by sections in mapfile.

As per [Bug 50689](https://bugs.llvm.org/show_bug.cgi?id=50689),

```
2. getSectionSyms() puts all the symbols into a map of section -> symbols, but this seems unnecessary. This was likely copied from the ELF port, which prints a section header before the list of symbols it contains. But the Mach-O map file doesn't print these headers.
```

This diff removes `getSectionSyms()` and keeps all symbols in a flat vector.

What does ld64's mapfile look like?
```
$ llvm-mc -filetype=obj -triple=x86_64-apple-darwin test.s -o test.o
$ llvm-mc -filetype=obj -triple=x86_64-apple-darwin foo.s -o foo.o
$ ld -map map test.o foo.o -o out -L/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/usr/lib -lSystem
```

```
[ 0] linker synthesized
[ 1] test.o
[ 2] foo.o
0x100003FB7 0x00000001 __TEXT __text
0x100003FB8 0x00000000 __TEXT obj
0x100003FB8 0x00000048 __TEXT __unwind_info
0x100004000 0x00000001 __DATA __common
0x100003FB7 0x00000001 [ 1] _main
0x100003FB8 0x00000000 [ 2] _foo
0x100003FB8 0x00000048 [ 0] compact unwind info
0x100004000 0x00000001 [ 1] _number
```

Perf numbers when linking chromium framework on a 16-Core Intel Xeon W Mac Pro:
```
base diff difference (95% CI)
sys_time 1.406 ± 0.020 1.388 ± 0.019 [ -1.9% .. -0.6%]
user_time 5.557 ± 0.023 5.914 ± 0.020 [ +6.2% .. +6.6%]
wall_time 4.455 ± 0.041 4.436 ± 0.035 [ -0.8% .. -0.0%]
samples 35 35
```

Reviewed By: #lld-macho, int3

Differential Revision: https://reviews.llvm.org/D114735

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[lld][MachO] Sort symbols in parallel in -map

source: https://bugs.llvm.org/show_bug.cgi?id=50689

When writing a map file, sort symbols in parallel using parallelSort.
Use address name to break tie

[lld][MachO] Sort symbols in parallel in -map

source: https://bugs.llvm.org/show_bug.cgi?id=50689

When writing a map file, sort symbols in parallel using parallelSort.
Use address name to break ties if two symbols have the same address.

Reviewed By: thakis, int3

Differential Revision: https://reviews.llvm.org/D104346

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[lld-macho][nfc] Put back shouldOmitFromOutput() asserts

I removed them in rG5de7467e982 but @thakis pointed out that
they were useful to keep, so here they are again. I've also converted
the `!isCo

[lld-macho][nfc] Put back shouldOmitFromOutput() asserts

I removed them in rG5de7467e982 but @thakis pointed out that
they were useful to keep, so here they are again. I've also converted
the `!isCoalescedWeak()` asserts into `!shouldOmitFromOutput()` asserts,
since the latter check subsumes the former.

Reviewed By: #lld-macho, thakis

Differential Revision: https://reviews.llvm.org/D104169

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[lld-macho] Reword comment for clarity

[lld-macho] Fix debug build

D103977 broke a bunch of stuff as I had only tested the release build
which eliminated asserts.

I've retained the asserts where possible, but I also removed a bunch
inst

[lld-macho] Fix debug build

D103977 broke a bunch of stuff as I had only tested the release build
which eliminated asserts.

I've retained the asserts where possible, but I also removed a bunch
instead of adding a whole lot of verbose ConcatInputSection casts.

show more ...

[lld/mac] Implement -dead_strip

Also adds support for live_support sections, no_dead_strip sections,
.no_dead_strip symbols.

Chromium Framework 345MB unstripped -> 250MB stripped
(vs 290MB unstripp

[lld/mac] Implement -dead_strip

Also adds support for live_support sections, no_dead_strip sections,
.no_dead_strip symbols.

Chromium Framework 345MB unstripped -> 250MB stripped
(vs 290MB unstripped -> 236M stripped with ld64).

Doing dead stripping is a bit faster than not, because so much less
data needs to be processed:

% ministat lld_*
x lld_nostrip.txt
+ lld_strip.txt
N Min Max Median Avg Stddev
x 10 3.929414 4.07692 4.0269079 4.0089678 0.044214794
+ 10 3.8129408 3.9025559 3.8670411 3.8642573 0.024779651
Difference at 95.0% confidence
-0.144711 +/- 0.0336749
-3.60967% +/- 0.839989%
(Student's t, pooled s = 0.0358398)

This interacts with many parts of the linker. I tried to add test coverage
for all added `isLive()` checks, so that some test will fail if any of them
is removed. I checked that the test expectations for the most part match
ld64's behavior (except for live-support-iterations.s, see the comment
in the test). Interacts with:
- debug info
- export tries
- import opcodes
- flags like -exported_symbol(s_list)
- -U / dynamic_lookup
- mod_init_funcs, mod_term_funcs
- weak symbol handling
- unwind info
- stubs
- map files
- -sectcreate
- undefined, dylib, common, defined (both absolute and normal) symbols

It's possible it interacts with more features I didn't think of,
of course.

I also did some manual testing:
- check-llvm check-clang check-lld work with lld with this patch
as host linker and -dead_strip enabled
- Chromium still starts
- Chromium's base_unittests still pass, including unwind tests

Implemenation-wise, this is InputSection-based, so it'll work for
object files with .subsections_via_symbols (which includes all
object files generated by clang). I first based this on the COFF
implementation, but later realized that things are more similar to ELF.
I think it'd be good to refactor MarkLive.cpp to look more like the ELF
part at some point, but I'd like to get a working state checked in first.

Mechanical parts:
- Rename canOmitFromOutput to wasCoalesced (no behavior change)
since it really is for weak coalesced symbols
- Add noDeadStrip to Defined, corresponding to N_NO_DEAD_STRIP
(`.no_dead_strip` in asm)

Fixes PR49276.

Differential Revision: https://reviews.llvm.org/D103324

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[lld/mac] Write every weak symbol only once in the output

Before this, if an inline function was defined in several input files,
lld would write each copy of the inline function the output. With thi

[lld/mac] Write every weak symbol only once in the output

Before this, if an inline function was defined in several input files,
lld would write each copy of the inline function the output. With this
patch, it only writes one copy.

Reduces the size of Chromium Framework from 378MB to 345MB (compared
to 290MB linked with ld64, which also does dead-stripping, which we
don't do yet), and makes linking it faster:

N Min Max Median Avg Stddev
x 10 3.9957051 4.3496981 4.1411121 4.156837 0.10092097
+ 10 3.908154 4.169318 3.9712729 3.9846753 0.075773012
Difference at 95.0% confidence
-0.172162 +/- 0.083847
-4.14165% +/- 2.01709%
(Student's t, pooled s = 0.0892373)

Implementation-wise, when merging two weak symbols, this sets a
"canOmitFromOutput" on the InputSection belonging to the weak symbol not put in
the symbol table. We then don't write InputSections that have this set, as long
as they are not referenced from other symbols. (This happens e.g. for object
files that don't set .subsections_via_symbols or that use .alt_entry.)

Some restrictions:
- not yet done for bitcode inputs
- no "comdat" handling (`kindNoneGroupSubordinate*` in ld64) --
Frame Descriptor Entries (FDEs), Language Specific Data Areas (LSDAs)
(that is, catch block unwind information) and Personality Routines
associated with weak functions still not stripped. This is wasteful,
but harmless.
- However, this does strip weaks from __unwind_info (which is needed for
correctness and not just for size)
- This nopes out on InputSections that are referenced form more than
one symbol (eg from .alt_entry) for now

Things that work based on symbols Just Work:
- map files (change in MapFile.cpp is no-op and not needed; I just
found it a bit more explicit)
- exports

Things that work with inputSections need to explicitly check if
an inputSection is written (e.g. unwind info).

This patch is useful in itself, but it's also likely also a useful foundation
for dead_strip.

I used to have a "canoncialRepresentative" pointer on InputSection instead of
just the bool, which would be handy for ICF too. But I ended up not needing it
for this patch, so I removed that again for now.

Differential Revision: https://reviews.llvm.org/D102076

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[lld-macho][nfc] Add accessors for commonly-used PlatformInfo fields

As discussed here: https://reviews.llvm.org/D100523#inline-951543

Reviewed By: #lld-macho, thakis, alexshap

Differential Revisi

[lld-macho][nfc] Add accessors for commonly-used PlatformInfo fields

As discussed here: https://reviews.llvm.org/D100523#inline-951543

Reviewed By: #lld-macho, thakis, alexshap

Differential Revision: https://reviews.llvm.org/D100978

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[lld][MachO] Add support for LC_VERSION_MIN_* load commands

This diff adds initial support for the legacy LC_VERSION_MIN_* load commands.

Test plan: make check-lld-macho

Differential revision: htt

[lld][MachO] Add support for LC_VERSION_MIN_* load commands

This diff adds initial support for the legacy LC_VERSION_MIN_* load commands.

Test plan: make check-lld-macho

Differential revision: https://reviews.llvm.org/D100523

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[lld-macho][NFC] Drop unnecessary macho:: namespace prefix on unambiguous references to Symbol

Within `lld/macho/`, only `InputFiles.cpp` and `Symbols.h` require the `macho::` namespace qualifier to

[lld-macho][NFC] Drop unnecessary macho:: namespace prefix on unambiguous references to Symbol

Within `lld/macho/`, only `InputFiles.cpp` and `Symbols.h` require the `macho::` namespace qualifier to disambiguate references to `class Symbol`.

Add braces to outer `for` of a 5-level single-line `if`/`for` nest.

Differential Revision: https://reviews.llvm.org/D99555

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fix comment typo to cycle bots

[lld-macho] Add more TimeTraceScopes

I added just enough to allow us to see a top-level breakdown of time taken. This
is the result of loading the time-trace output into `chrome:://tracing`:

https:

[lld-macho] Add more TimeTraceScopes

I added just enough to allow us to see a top-level breakdown of time taken. This
is the result of loading the time-trace output into `chrome:://tracing`:

https://gist.githubusercontent.com/int3/236c723cbb4b6fa3b2d340bb6395c797/raw/ef5e8234f3fdf609bf93b50f54f4e0d9bd439403/tracing.png

Reviewed By: oontvoo

Differential Revision: https://reviews.llvm.org/D99311

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[lld-macho] implement options -map

Implement command-line options -map

Reviewed By: int3, #lld-macho

Differential Revision: https://reviews.llvm.org/D98323