Overhaul the TargetMachine and LLVMTargetMachine Classes (#111234)

Following discussions in #110443, and the following earlier discussions
in https://lists.llvm.org/pipermail/llvm-dev/2017-October/

Overhaul the TargetMachine and LLVMTargetMachine Classes (#111234)

Following discussions in #110443, and the following earlier discussions
in https://lists.llvm.org/pipermail/llvm-dev/2017-October/117907.html,
https://reviews.llvm.org/D38482, https://reviews.llvm.org/D38489, this
PR attempts to overhaul the `TargetMachine` and `LLVMTargetMachine`
interface classes. More specifically:
1. Makes `TargetMachine` the only class implemented under
`TargetMachine.h` in the `Target` library.
2. `TargetMachine` contains target-specific interface functions that
relate to IR/CodeGen/MC constructs, whereas before (at least on paper)
it was supposed to have only IR/MC constructs. Any Target that doesn't
want to use the independent code generator simply does not implement
them, and returns either `false` or `nullptr`.
3. Renames `LLVMTargetMachine` to `CodeGenCommonTMImpl`. This renaming
aims to make the purpose of `LLVMTargetMachine` clearer. Its interface
was moved under the CodeGen library, to further emphasis its usage in
Targets that use CodeGen directly.
4. Makes `TargetMachine` the only interface used across LLVM and its
projects. With these changes, `CodeGenCommonTMImpl` is simply a set of
shared function implementations of `TargetMachine`, and CodeGen users
don't need to static cast to `LLVMTargetMachine` every time they need a
CodeGen-specific feature of the `TargetMachine`.
5. More importantly, does not change any requirements regarding library
linking.

cc @arsenm @aeubanks

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[WebAssembly] Split WebAssemblyUtils to fix library layering for MC tools.

WebAssemblyUtils depends on CodeGen which depends on all middle end
optimization libraries.

This component is used by WebA

[WebAssembly] Split WebAssemblyUtils to fix library layering for MC tools.

WebAssemblyUtils depends on CodeGen which depends on all middle end
optimization libraries.

This component is used by WebAssembly's AsmParser, Disassembler, and
MCTargetDesc libraries. Because of this, any MC layer tool built with
WebAssembly support includes a larger portion of LLVM than it should.

To fix this I've created an MC only version of WebAssemblyTypeUtilities.cpp
in MCTargetDesc to be used by the MC components.

This shrinks llvm-objdump and llvm-mc on my local release+asserts
build by 5-6 MB.

Reviewed By: MaskRay, aheejin

Differential Revision: https://reviews.llvm.org/D144354

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[NFC][TargetParser] Remove llvm/ADT/Triple.h

I also ran `git clang-format` to get the headers in the right order for
the new location, which has changed the order of other headers in two
files.

[WebAssembly] Remove TODO comment for IAS, NFC

IAS has been enabled on WebAssembly since commit 0a55d3f557a74cfb459b24e442072302d5444baf.

[WebAssembly] Support clang -fwasm-exceptions for bitcode

This supports bitcode compilation using `clang -fwasm-exceptions`.

---

The current situation:

Currently the backend requires two options

[WebAssembly] Support clang -fwasm-exceptions for bitcode

This supports bitcode compilation using `clang -fwasm-exceptions`.

---

The current situation:

Currently the backend requires two options for Wasm EH:
`-wasm-enable-eh` and `-exception-model=wasm`. Wasm SjLj requires two
options as well: `-wasm-enable-sjlj` and `-exception-model=wasm`. When
using Wasm EH via Emscripten, you only need to pass `-fwasm-exceptions`,
and these options will be added within the clang driver. This
description will focus on the case of Wasm EH going forward, but Wasm
SjLj's case is similar.

When you pass `-fwasm-exceptions` to emcc and clang driver, the clang
driver adds these options to the command line that calls the clang
frontend (`clang -cc1`): `-mllvm -wasm-enable-eh` and
`-exception-model=wasm`. `-wasm-enable-eh` is prefixed with `-mllvm`, so
it is passed as is to the backend. But `-exception-model` is parsed and
processed within the clang frontend and stored in `LangOptions` class.
This info is later transferred to `TargetOptions` class, and then
eventually passed to `MCAsmInfo` class. All LLVM code queries this
`MCAsmInfo` to get the exception model.

---

Problem:

The problem is the whole `LangOptions` processing is bypassed when
compiling bitcode, so the information transfer of `LangOptions` ->
`TargetOptions` -> `MCAsmInfo` does not happen. They are all set to
`ExceptionHandling::None`, which is the default value.

---

What other targets do, and why we can't do the same:

Other targets support bitcode compilation by the clang driver, but they
can do that by using different triples. For example, X86 target supports
multiple triples, each of which has its own subclass of `MCAsmInfo`, so
it can hardcode the appropriate exception model within those subclasses'
constructors. But we don't have separate triples for each exception
mode: none, emscripten, and wasm.

---

What this CL does:

If we can figure out whether `-wasm-enable-eh` is passed to the backend,
we can programatically set the exception model from the backend, rather
than requiring it to be passed.

So we check `WasmEnableEH` and `WasmEnableSjLj` variables, which are
`cl::opt` for `-wasm-enable-eh` and `-wasm-enable-sjlj`, in
`WebAssemblyMCAsmInfo` constructor, and if either of them is set, we set
`MCAsmInfo.ExceptionType` to Wasm. `TargetOptions` cannot be updated
there, so we make sure they are the same later.

Fixes https://github.com/emscripten-core/emscripten/issues/15712.

Reviewed By: dschuff

Differential Revision: https://reviews.llvm.org/D115893

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[WebAssembly] Added R_WASM_FUNCTION_OFFSET_I64 for use with DWARF DW_AT_low_pc

Needed for wasm64, see discussion in https://reviews.llvm.org/D91203

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

[WebAssembly] Added R_WASM_FUNCTION_OFFSET_I64 for use with DWARF DW_AT_low_pc

Needed for wasm64, see discussion in https://reviews.llvm.org/D91203

Differential Revision: https://reviews.llvm.org/D91395

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[WebAssembly] Fixed DWARF DW_AT_low_pc encoded as 64-bit in wasm64

Also added general wasm64 DWARF test
Also added asserts for unsupported reloc combinations that triggered this bug.

Differential R

[WebAssembly] Fixed DWARF DW_AT_low_pc encoded as 64-bit in wasm64

Also added general wasm64 DWARF test
Also added asserts for unsupported reloc combinations that triggered this bug.

Differential Revision: https://reviews.llvm.org/D90503

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[Mips] Use appropriate private label prefix based on Mips ABI

MipsMCAsmInfo was using '$' prefix for Mips32 and '.L' for Mips64
regardless of -target-abi option. By passing MCTargetOptions to MCAsmI

[Mips] Use appropriate private label prefix based on Mips ABI

MipsMCAsmInfo was using '$' prefix for Mips32 and '.L' for Mips64
regardless of -target-abi option. By passing MCTargetOptions to MCAsmInfo
we can find out Mips ABI and pick appropriate prefix.

Tags: #llvm, #clang, #lldb

Differential Revision: https://reviews.llvm.org/D66795

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[WebAssembly] clang-tidy (NFC)

Summary:
This patch fixes clang-tidy warnings on wasm-only files.
The list of checks used is:
`-*,clang-diagnostic-*,llvm-*,misc-*,-misc-unused-parameters,readability-

[WebAssembly] clang-tidy (NFC)

Summary:
This patch fixes clang-tidy warnings on wasm-only files.
The list of checks used is:
`-*,clang-diagnostic-*,llvm-*,misc-*,-misc-unused-parameters,readability-identifier-naming,modernize-*`
(LLVM's default .clang-tidy list is the same except it does not have
`modernize-*`. But I've seen in multiple CLs in LLVM the modernize style
was recommended and code was fixed based on the style, so I added it as
well.)

The common fixes are:
- Variable names start with an uppercase letter
- Function names start with a lowercase letter
- Use `auto` when you use casts so the type is evident
- Use inline initialization for class member variables
- Use `= default` for empty constructors / destructors
- Use `using` in place of `typedef`

Reviewers: sbc100, tlively, aardappel

Subscribers: dschuff, sunfish, jgravelle-google, yurydelendik, kripken, MatzeB, mgorny, rupprecht, llvm-commits

Differential Revision: https://reviews.llvm.org/D57500

llvm-svn: 353075

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Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the ne

Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636

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[WebAssembly] Remove ELF file support.

This support was partial and temporary. Now that we have
wasm object file support its no longer needed.

Differential Revision: https://reviews.llvm.org/D4874

[WebAssembly] Remove ELF file support.

This support was partial and temporary. Now that we have
wasm object file support its no longer needed.

Differential Revision: https://reviews.llvm.org/D48744

llvm-svn: 337222

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Remove \brief commands from doxygen comments.

We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they ar

Remove \brief commands from doxygen comments.

We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by

for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done

Differential Revision: https://reviews.llvm.org/D46290

llvm-svn: 331272

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[WebAssembly] Add exception handling option and feature

Summary:
Add a llc command line option and WebAssembly architecture feature for
exception handling.

Reviewers: dschuff

Subscribers: jfb, sbc

[WebAssembly] Add exception handling option and feature

Summary:
Add a llc command line option and WebAssembly architecture feature for
exception handling.

Reviewers: dschuff

Subscribers: jfb, sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D43683

llvm-svn: 326004

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Unbreak build of the wasm backend after r300463.

llvm-svn: 300479

[WebAssembly] Add skeleton MC support for the Wasm container format

This just adds the basic skeleton for supporting a new object file format.
All of the actual encoding will be implemented in follo

[WebAssembly] Add skeleton MC support for the Wasm container format

This just adds the basic skeleton for supporting a new object file format.
All of the actual encoding will be implemented in followup patches.

Differential Revision: https://reviews.llvm.org/D26722

llvm-svn: 295803

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[NFC] Header cleanup

Removed some unused headers, replaced some headers with forward class declarations.

Found using simple scripts like this one:
clear && ack --cpp -l '#include "llvm/ADT/IndexedM

[NFC] Header cleanup

Removed some unused headers, replaced some headers with forward class declarations.

Found using simple scripts like this one:
clear && ack --cpp -l '#include "llvm/ADT/IndexedMap.h"' | xargs grep -L 'IndexedMap[<]' | xargs grep -n --color=auto 'IndexedMap'

Patch by Eugene Kosov <claprix@yandex.ru>

Differential Revision: http://reviews.llvm.org/D19219

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266595

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[WebAssembly] Don't create a needless .note.GNU-stack section

WebAssembly's stack will never be executable by default, so it isn't
necessary to declare .note.GNU-stack sections to request a non-exec

[WebAssembly] Don't create a needless .note.GNU-stack section

WebAssembly's stack will never be executable by default, so it isn't
necessary to declare .note.GNU-stack sections to request a non-executable
stack.

Differential Revision: http://reviews.llvm.org/D15969

llvm-svn: 257962

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WebAssembly: use .skip instead of .zero directive

.zero is confusing when used with two arguments. Documentation:

This directive emits SIZE 0-valued bytes. SIZE must be an absolute
expression.

WebAssembly: use .skip instead of .zero directive

.zero is confusing when used with two arguments. Documentation:

This directive emits SIZE 0-valued bytes. SIZE must be an absolute
expression. This directive is actually an alias for the '.skip'
directive so in can take an optional second argument of the value to
store in the bytes instead of zero. Using '.zero' in this way would be
confusing however.

Ref: https://sourceware.org/bugzilla/show_bug.cgi?id=18353

Hexagon and Sparc do the same, and it's all the same to WebAssembly so
let's pick the less confusing of the two.

llvm-svn: 257111

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[WebAssembly] Use the default private label prefixes.

The MC assembler doesn't like using the empty string as a private label
prefix because then it treats all labels as private. This commit reverts

[WebAssembly] Use the default private label prefixes.

The MC assembler doesn't like using the empty string as a private label
prefix because then it treats all labels as private. This commit reverts
back to the default prefix, which is .L, which is common in ELF targets
and consistent with the LLVM name mangler.

llvm-svn: 257083

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[WebAssembly] Switch to a more traditional assembly syntax

This new syntax is built around putting each instruction on its own line
in a "mnemonic op, op, op" like syntax. It also uses conventional

[WebAssembly] Switch to a more traditional assembly syntax

This new syntax is built around putting each instruction on its own line
in a "mnemonic op, op, op" like syntax. It also uses conventional data
section directives like ".byte" and so on rather than requiring everything
to be in hierarchical S-expression format. This is a more natural syntax
for a ".s" file format from the perspective of LLVM MC and related tools,
while remaining easy to translate into other forms as needed.

llvm-svn: 249364

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WebAssembly: add small FIXME for AsmPrinter.

Suggested by @sunfish as a follow-up to r245982.

llvm-svn: 245996

WebAssembly: comment out .globl when printing textual assembly

Do the same for .weak (not implemented for now, but may as well to it). Update comment string to two semicolons.

llvm-svn: 245982

WebAssembly: more MCAsmInfo nits.

Summary: As suggested by sunfish.

Subscribers: jfb, llvm-commits, sunfish

Differential Revision: http://reviews.llvm.org/D11544

llvm-svn: 243339

WebAssembly: minor MCAsmInfo fixes

Summary:
Fix pointer / callee-save stack sto size.
Update comment character to be LISP-ish.

Subscribers: llvm-commits, sunfish, jfb

Differential Revision: http:/

WebAssembly: minor MCAsmInfo fixes

Summary:
Fix pointer / callee-save stack sto size.
Update comment character to be LISP-ish.

Subscribers: llvm-commits, sunfish, jfb

Differential Revision: http://reviews.llvm.org/D11537

llvm-svn: 243326

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[WebAssembly] Initial WebAssembly backend

This WebAssembly backend is just a skeleton at this time and is not yet
functional.

llvm-svn: 241022