[MC] Replace getCurrentSection().first with getCurrentSectionOnly. NFC

[WebAssembly] Add segment RETAIN flag to support private retained data (#81539)

In WebAssembly, we have `WASM_SYMBOL_NO_STRIP` symbol flag to mark the
referenced content as retained. However, the f

[WebAssembly] Add segment RETAIN flag to support private retained data (#81539)

In WebAssembly, we have `WASM_SYMBOL_NO_STRIP` symbol flag to mark the
referenced content as retained. However, the flag is not enough to
express retained data that is not referenced by any symbol. This patch
adds a new segment flag`WASM_SEG_FLAG_RETAIN` to support "private"
linkage data that is retained by llvm.used.

This kind of data that is not referenced but must be retained is usually
used with encapsulation symbols (__start/__stop). Swift runtime uses
this technique and depends on the fact "all metadata sections in live
objects are retained", which was not guaranteed with `--gc-sections`
before this patch.

This is a revised version of https://reviews.llvm.org/D126950 (has been
reverted) based on @MaskRay's comments

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[llvm] Add missing StringExtras.h includes

In preparation for removing the `#include "llvm/ADT/StringExtras.h"`
from the header to source file of `llvm/Support/Error.h`, first add in
all the missing

[llvm] Add missing StringExtras.h includes

In preparation for removing the `#include "llvm/ADT/StringExtras.h"`
from the header to source file of `llvm/Support/Error.h`, first add in
all the missing includes that were previously included transitively
through this header.

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[MCParser] Use std::optional in WasmAsmParser.cpp (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-

[MCParser] Use std::optional in WasmAsmParser.cpp (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

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[WebAssembly][MC] Avoid the need for .size directives for functions

Warn if `.size` is specified for a function symbol. The size of a
function symbol is determined solely by its content.

I noticed

[WebAssembly][MC] Avoid the need for .size directives for functions

Warn if `.size` is specified for a function symbol. The size of a
function symbol is determined solely by its content.

I noticed this simplification was possible while debugging #57427, but
this change doesn't fix that specific issue.

Differential Revision: https://reviews.llvm.org/D132929

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[llvm] Don't use Optional::getValue (NFC)

[MC] De-capitalize SwitchSection. NFC

Add SwitchSection to return switchSection. The API will be removed soon.

[WebAssembly] Allow .data shorthand for .section .data,"",@

Cleanup MCParser headers

As usual with that header cleanup series, some implicit dependencies now need to
be explicit:

llvm/MC/MCParser/MCAsmParser.h no longer includes llvm/MC/MCParser/MCAsmLexer.

Cleanup MCParser headers

As usual with that header cleanup series, some implicit dependencies now need to
be explicit:

llvm/MC/MCParser/MCAsmParser.h no longer includes llvm/MC/MCParser/MCAsmLexer.h

Preprocessed lines to build llvm on my setup:
after: 1068185081
before: 1068324320

So no compile time benefit to expect, but we still get the looser coupling
between files which is great.

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119359

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Cleanup LLVMMC headers

There's a few relevant forward declarations in there that may require downstream
adding explicit includes:

llvm/MC/MCContext.h no longer includes llvm/BinaryFormat/ELF.h, llv

Cleanup LLVMMC headers

There's a few relevant forward declarations in there that may require downstream
adding explicit includes:

llvm/MC/MCContext.h no longer includes llvm/BinaryFormat/ELF.h, llvm/MC/MCSubtargetInfo.h, llvm/MC/MCTargetOptions.h
llvm/MC/MCObjectStreamer.h no longer include llvm/MC/MCAssembler.h
llvm/MC/MCAssembler.h no longer includes llvm/MC/MCFixup.h, llvm/MC/MCFragment.h

Counting preprocessed lines required to rebuild llvm-project on my setup:
before: 1052436830
after: 1049293745

Which is significant and backs up the change in addition to the usual benefits of
decreasing coupling between headers and compilation units.

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D119244

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[WebAssembly] Add TLS data segment flag: WASM_SEG_FLAG_TLS

Previously the linker was relying solely on the name of the segment
to imply TLS.

Differential Revision: https://reviews.llvm.org/D102202

Reland: "[lld][WebAssembly] Initial support merging string data"

This change was originally landed in: 5000a1b4b9edeb9e994f2a5b36da8d48599bea49
It was reverted in: 061e071d8c9b98526f35cad55a918a4f16

Reland: "[lld][WebAssembly] Initial support merging string data"

This change was originally landed in: 5000a1b4b9edeb9e994f2a5b36da8d48599bea49
It was reverted in: 061e071d8c9b98526f35cad55a918a4f1615afd4

This change adds support for a new WASM_SEG_FLAG_STRINGS flag in
the object format which works in a similar fashion to SHF_STRINGS
in the ELF world.

Unlike the ELF linker this support is currently limited:
- No support for SHF_MERGE (non-string merging)
- Always do full tail merging ("lo" can be merged with "hello")
- Only support single byte strings (p2align 0)

Like the ELF linker merging is only performed at `-O1` and above.

This fixes part of https://bugs.llvm.org/show_bug.cgi?id=48828,
although crucially it doesn't not currently support debug sections
because they are not represented by data segments (they are custom
sections)

Differential Revision: https://reviews.llvm.org/D97657

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Revert "[lld][WebAssembly] Initial support merging string data"

This reverts commit 5000a1b4b9edeb9e994f2a5b36da8d48599bea49.
Breaks tests, see https://reviews.llvm.org/D97657#2749151

Easily repros

Revert "[lld][WebAssembly] Initial support merging string data"

This reverts commit 5000a1b4b9edeb9e994f2a5b36da8d48599bea49.
Breaks tests, see https://reviews.llvm.org/D97657#2749151

Easily repros locally with `ninja check-llvm-mc-webassembly`.

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[lld][WebAssembly] Initial support merging string data

This change adds support for a new WASM_SEG_FLAG_STRINGS flag in
the object format which works in a similar fashion to SHF_STRINGS
in the ELF w

[lld][WebAssembly] Initial support merging string data

This change adds support for a new WASM_SEG_FLAG_STRINGS flag in
the object format which works in a similar fashion to SHF_STRINGS
in the ELF world.

Unlike the ELF linker this support is currently limited:
- No support for SHF_MERGE (non-string merging)
- Always do full tail merging ("lo" can be merged with "hello")
- Only support single byte strings (p2align 0)

Like the ELF linker merging is only performed at `-O1` and above.

This fixes part of https://bugs.llvm.org/show_bug.cgi?id=48828,
although crucially it doesn't not currently support debug sections
because they are not represented by data segments (they are custom
sections)

Differential Revision: https://reviews.llvm.org/D97657

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[WebAssembly] Use data sections by default

This allows data sections that don't start with `.data` to be
used/created.

Without this, clang's `__attribute__((section("foo")))` would
generate assembl

[WebAssembly] Use data sections by default

This allows data sections that don't start with `.data` to be
used/created.

Without this, clang's `__attribute__((section("foo")))` would
generate assembly that would not parse.

Differential Revision: https://reviews.llvm.org/D96233

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[WebAssembly] Support COMDAT sections in assembly syntax

This CL changes the asm syntax for section flags, making them more like ELF
(previously "passive" was the only option). Now we also allow "G"

[WebAssembly] Support COMDAT sections in assembly syntax

This CL changes the asm syntax for section flags, making them more like ELF
(previously "passive" was the only option). Now we also allow "G" to designate
COMDAT group sections. In these sections we set the appropriate comdat flag on
function symbols, and also avoid auto-creating a new section for them.

This also adds asm-based tests for the changes D92691 to go along with
the direct-to-object tests.

Differential Revision: https://reviews.llvm.org/D92952
This is a reland of rG4564553b8d8a with a fix to the lit pipeline in
llvm/test/MC/WebAssembly/comdat.ll

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Revert "[WebAssembly] Support COMDAT sections in assembly syntax"

This reverts commit 4564553b8d8ab81dc21431a35275581cb42329c8.
It broke several buildbots.

[WebAssembly] Support COMDAT sections in assembly syntax

This CL changes the asm syntax for section flags, making them more like ELF
(previously "passive" was the only option). Now we also allow "G"

[WebAssembly] Support COMDAT sections in assembly syntax

This CL changes the asm syntax for section flags, making them more like ELF
(previously "passive" was the only option). Now we also allow "G" to designate
COMDAT group sections. In these sections we set the appropriate comdat flag on
function symbols, and also avoid auto-creating a new section for them.

This also adds asm-based tests for the changes D92691 to go along with
the direct-to-object tests.

Differential Revision: https://reviews.llvm.org/D92952

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[lld][WebAssembly] Add test for TLS BSS data. NFC.

Differential Revision: https://reviews.llvm.org/D91231

[lld][WebAssembly] Convert TLS tests to asm format

Fix a corresponding bug in WasmAsmParser around parsing.tdata sections.

Differential Revision: https://reviews.llvm.org/D91113

[MC] De-capitalize MCStreamer::Emit{Bundle,Addrsig}* etc

So far, all non-COFF-related Emit* functions have been de-capitalized.

[MC] De-capitalize some MCStreamer::Emit* functions

[WebAssembly][lld] Fix crash when applying relocations to debug sections

Debug sections are special in that they can contain relocations against
symbols that are not present in the final output (i.e

[WebAssembly][lld] Fix crash when applying relocations to debug sections

Debug sections are special in that they can contain relocations against
symbols that are not present in the final output (i.e. not live).
However it is also possible to have R_WASM_TABLE_INDEX relocations
against symbols that don't have a table index assigned (since they are
not address taken by actual code.

Fixes: https://github.com/emscripten-core/emscripten/issues/9023

Differential Revision: https://reviews.llvm.org/D66435

llvm-svn: 369423

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[WebAssembly] Assembler: recognize .init_array as data section.

Reviewers: sbc100

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https:/

[WebAssembly] Assembler: recognize .init_array as data section.

Reviewers: sbc100

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D64602

llvm-svn: 366104

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[WebAssembly] Allow @object in .type directives.

Reviewers: sbc100

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.o

[WebAssembly] Allow @object in .type directives.

Reviewers: sbc100

Subscribers: dschuff, jgravelle-google, aheejin, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D63955

llvm-svn: 364688

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