[lld-macho] Devirtualize TargetInfo::getRelocAttrs

This method is called on each relocation when parsing input files, so
the overhead of using virtual functions ends up being quite large. We
now ha

[lld-macho] Devirtualize TargetInfo::getRelocAttrs

This method is called on each relocation when parsing input files, so
the overhead of using virtual functions ends up being quite large. We
now have a single non-virtual method, which reads from the appropriate
array of relocation attributes set in the TargetInfo constructor.

This change results in a modest 2.3% reduction in link time for
chromium_framework measured on an x86-64 VPS, and 0.7% on an arm64 Mac.

N Min Max Median Avg Stddev
x 10 11.869417 12.032609 11.935041 11.938268 0.045802324
+ 10 11.581526 11.785265 11.649885 11.659507 0.054634834
Difference at 95.0% confidence
-0.278761 +/- 0.0473673
-2.33502% +/- 0.396768%
(Student's t, pooled s = 0.0504124)

Differential Revision: https://reviews.llvm.org/D130000

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[lld-macho] Handle user-provided dtrace symbols to avoid linking failure

This fixes https://github.com/llvm/llvm-project/issues/56238. ld64.lld currently does not generate __dof section in Mach-O, a

[lld-macho] Handle user-provided dtrace symbols to avoid linking failure

This fixes https://github.com/llvm/llvm-project/issues/56238. ld64.lld currently does not generate __dof section in Mach-O, and -no_dtrace_dof option is on by default. However when there are user-defined dtrace symbols, ld64.lld will treat them as undefined symbols, which causes the linking to fail because lld cannot find their definitions. This patch allows ld64.lld to rewrite the instructions calling dtrace symbols to instructions like nop as what ld64 does; therefore, when encountered with user-provided dtrace probes, the linking can still succeed.

I'm not sure whether support for dtrace is expected in lld, so for now I didn't add codes to make lld emit __dof section like ld64, and only made it possible to link with dtrace symbols provided. If this feature is needed, I can add that part in Dtrace.cpp & Dtrace.h.

Reviewed By: int3, #lld-macho

Differential Revision: https://reviews.llvm.org/D129062

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[lld-macho][nfc] Allow Defined symbols to be placed in binding sections

Previously, we only allowed this for DylibSymbols. However, in order to
properly support `-flat_namespace` as well as `-interp

[lld-macho][nfc] Allow Defined symbols to be placed in binding sections

Previously, we only allowed this for DylibSymbols. However, in order to
properly support `-flat_namespace` as well as `-interposable`, we need
to allow this for Defined symbols too. Therefore we hoist the
`lazyBindOffset` and the `stubsHelperIndex` into the parent Symbol
class.

The actual change to support interposition under `-flat_namespace` is in
{D119294}; the NFC changes here have been split out for easier review.

Perf regression isn't stat sig on my 3.2 GHz 16-Core Intel Xeon W linking
chromium_framework:

base diff difference (95% CI)
sys_time 1.227 ± 0.021 1.234 ± 0.031 [ -0.3% .. +1.5%]
user_time 3.665 ± 0.036 3.674 ± 0.035 [ -0.2% .. +0.7%]
wall_time 4.596 ± 0.055 4.609 ± 0.064 [ -0.3% .. +0.9%]
samples 34 47

Max RSS regression is barely stat sig:

base diff difference (95% CI)
time 1003664356.324 ± 15404053.912 1010380403.613 ± 10578309.455 [ +0.0% .. +1.3%]
samples 37 31

Reviewed By: modimo

Differential Revision: https://reviews.llvm.org/D121351

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Use true/false instead of 1/0 (NFC)

Identified by modernize-use-bool-literals.

[lld-macho] Try to unbreak build

Looks like the PointerUnion casting cares about const-ness...

[lld-macho] Preliminary support for ARM_RELOC_BR24

ARM_RELOC_BR24 is used for BL/BLX instructions from within ARM (i.e. not
Thumb) code. This diff just handles the basic case: branches from ARM to
A

[lld-macho] Preliminary support for ARM_RELOC_BR24

ARM_RELOC_BR24 is used for BL/BLX instructions from within ARM (i.e. not
Thumb) code. This diff just handles the basic case: branches from ARM to
ARM, or from ARM to Thumb where no shimming is required. (See comments
in ARM.cpp for why shims are required.)

Note: I will likely be deprioritizing ARM work for the near future to
focus on other parts of LLD. Apologies for the half-done state of this;
I'm just trying to wrap up what I've already worked on.

Reviewed By: #lld-macho, alexshap

Differential Revision: https://reviews.llvm.org/D101814

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[lld-macho] Initial scaffolding for ARM32 support

This just parses the `-arch armv7` and emits the right header flags.
The rest will be slowly fleshed out in upcoming diffs.

Reviewed By: #lld-macho

[lld-macho] Initial scaffolding for ARM32 support

This just parses the `-arch armv7` and emits the right header flags.
The rest will be slowly fleshed out in upcoming diffs.

Reviewed By: #lld-macho, gkm

Differential Revision: https://reviews.llvm.org/D101557

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