Cleanup includes: DebugInfo & CodeGen

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D121332

[CodeGen] Use = default (NFC)

Identified with modernize-use-equals-default

[CodeGen] Use default member initialization (NFC)

Identified with modernize-use-default-member-init.

[MCAsmInfo] Support UsesCFIForDebug for targets with no exception handling

This change enables emitting CFI unwind information for debugging purpose
for targets with MCAsmInfo::ExceptionsType == Exc

[MCAsmInfo] Support UsesCFIForDebug for targets with no exception handling

This change enables emitting CFI unwind information for debugging purpose
for targets with MCAsmInfo::ExceptionsType == ExceptionHandling::None.

Currently generating CFI unwind information is entangled with supporting
the exceptions, even when AsmPrinter explicitly recognizes that the unwind
tables are being generated as debug information.

In fact, the unwind information is not generated even if we specify
--force-dwarf-frame-section, unless exceptions are enabled. The LIT test
llvm/test/CodeGen/AMDGPU/debug_frame.ll demonstrates this behavior.

Enable this option for AMDGPU to prepare for future patches which add
complete CFI support.

Reviewed By: dblaikie, MaskRay

Differential Revision: https://reviews.llvm.org/D78778

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[NFC] Refactor how CFI section types are represented in AsmPrinter

In terms of readability, the `enum CFIMoveType` didn't better document what it
intends to convey i.e. the type of CFI section that

[NFC] Refactor how CFI section types are represented in AsmPrinter

In terms of readability, the `enum CFIMoveType` didn't better document what it
intends to convey i.e. the type of CFI section that gets emitted.

Reviewed By: dblaikie, MaskRay

Differential Revision: https://reviews.llvm.org/D76519

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Revert D76519 "[NFC] Refactor how CFI section types are represented in AsmPrinter"

This reverts commit 0ce723cb228bc1d1a0f5718f3862fb836145a333.

D76519 was not quite NFC. If we see a CFISection::De

Revert D76519 "[NFC] Refactor how CFI section types are represented in AsmPrinter"

This reverts commit 0ce723cb228bc1d1a0f5718f3862fb836145a333.

D76519 was not quite NFC. If we see a CFISection::Debug function before a
CFISection::EH one (-fexceptions -fno-asynchronous-unwind-tables), we may
incorrectly pick CFISection::Debug and emit a `.cfi_sections .debug_frame`.
We should use .eh_frame instead.

This scenario is untested.

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[NFC] Refactor how CFI section types are represented in AsmPrinter

In terms of readability, the `enum CFIMoveType` didn't better document what it
intends to convey i.e. the type of CFI section that

[NFC] Refactor how CFI section types are represented in AsmPrinter

In terms of readability, the `enum CFIMoveType` didn't better document what it
intends to convey i.e. the type of CFI section that gets emitted.

Reviewed By: dblaikie, MaskRay

Differential Revision: https://reviews.llvm.org/D76519

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[NFC] Delete the redundant member 'shouldEmitMoves' from DwarfCFIException class

The data member 'shouldEmitMoves' is only used in DwarfCFIException::beginFunction()
and 'shouldEmitCFI' in DwarfCFIE

[NFC] Delete the redundant member 'shouldEmitMoves' from DwarfCFIException class

The data member 'shouldEmitMoves' is only used in DwarfCFIException::beginFunction()
and 'shouldEmitCFI' in DwarfCFIExceptionBase serves its purpose.

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D101155

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Exception support for basic block sections

This is part of the Propeller framework to do post link code layout optimizations. Please see the RFC here: https://groups.google.com/forum/#!msg/llvm-dev/

Exception support for basic block sections

This is part of the Propeller framework to do post link code layout optimizations. Please see the RFC here: https://groups.google.com/forum/#!msg/llvm-dev/ef3mKzAdJ7U/1shV64BYBAAJ and the detailed RFC doc here: https://github.com/google/llvm-propeller/blob/plo-dev/Propeller_RFC.pdf

This patch provides exception support for basic block sections by splitting the call-site table into call-site ranges corresponding to different basic block sections. Still all landing pads must reside in the same basic block section (which is guaranteed by the the core basic block section patch D73674 (ExceptionSection) ). Each call-site table will refer to the landing pad fragment by explicitly specifying @LPstart (which is omitted in the normal non-basic-block section case). All these call-site tables will share their action and type tables.

The C++ ABI somehow assumes that no landing pads point directly to LPStart (which works in the normal case since the function begin is never a landing pad), and uses LP.offset = 0 to specify no landing pad. In the case of basic block section where one section contains all the landing pads, the landing pad offset relative to LPStart could actually be zero. Thus, we avoid zero-offset landing pads by inserting a **nop** operation as the first non-CFI instruction in the exception section.

**Background on Exception Handling in C++ ABI**
https://github.com/itanium-cxx-abi/cxx-abi/blob/master/exceptions.pdf

Compiler emits an exception table for every function. When an exception is thrown, the stack unwinding library queries the unwind table (which includes the start and end of each function) to locate the exception table for that function.

The exception table includes a call site table for the function, which is used to guide the exception handling runtime to take the appropriate action upon an exception. Each call site record in this table is structured as follows:

| CallSite | --> Position of the call site (relative to the function entry)
| CallSite length | --> Length of the call site.
| Landing Pad | --> Position of the landing pad (relative to the landing pad fragment’s begin label)
| Action record offset | --> Position of the first action record

The call site records partition a function into different pieces and describe what action must be taken for each callsite. The callsite fields are relative to the start of the function (as captured in the unwind table).

The landing pad entry is a reference into the function and corresponds roughly to the catch block of a try/catch statement. When execution resumes at a landing pad, it receives an exception structure and a selector value corresponding to the type of the exception thrown, and executes similar to a switch-case statement. The landing pad field is relative to the beginning of the procedure fragment which includes all the landing pads (@LPStart). The C++ ABI requires all landing pads to be in the same fragment. Nonetheless, without basic block sections, @LPStart is the same as the function @Start (found in the unwind table) and can be omitted.

The action record offset is an index into the action table which includes information about which exception types are caught.

**C++ Exceptions with Basic Block Sections**
Basic block sections break the contiguity of a function fragment. Therefore, call sites must be specified relative to the beginning of the basic block section. Furthermore, the unwinding library should be able to find the corresponding callsites for each section. To do so, the .cfi_lsda directive for a section must point to the range of call-sites for that section.
This patch introduces a new **CallSiteRange** structure which specifies the range of call-sites which correspond to every section:

`struct CallSiteRange {
// Symbol marking the beginning of the precedure fragment.
MCSymbol *FragmentBeginLabel = nullptr;
// Symbol marking the end of the procedure fragment.
MCSymbol *FragmentEndLabel = nullptr;
// LSDA symbol for this call-site range.
MCSymbol *ExceptionLabel = nullptr;
// Index of the first call-site entry in the call-site table which
// belongs to this range.
size_t CallSiteBeginIdx = 0;
// Index just after the last call-site entry in the call-site table which
// belongs to this range.
size_t CallSiteEndIdx = 0;
// Whether this is the call-site range containing all the landing pads.
bool IsLPRange = false;
};`

With N basic-block-sections, the call-site table is partitioned into N call-site ranges.

Conceptually, we emit the call-site ranges for sections sequentially in the exception table as if each section has its own exception table. In the example below, two sections result in the two call site ranges (denoted by LSDA1 and LSDA2) placed next to each other. However, their call-sites will refer to records in the shared Action Table. We also emit the header fields (@LPStart and CallSite Table Length) for each call site range in order to place the call site ranges in separate LSDAs. We note that with -basic-block-sections, The CallSiteTableLength will not actually represent the length of the call site table, but rather the reference to the action table. Since the only purpose of this field is to locate the action table, correctness is guaranteed.

Finally, every call site range has one @LPStart pointer so the landing pads of each section must all reside in one section (not necessarily the same section). To make this easier, we decide to place all landing pads of the function in one section (hence the `IsLPRange` field in CallSiteRange).

| @LPStart | ---> Landing pad fragment ( LSDA1 points here)
| CallSite Table Length | ---> Used to find the action table.
| CallSites |
| … |
| … |
| @LPStart | ---> Landing pad fragment ( LSDA2 points here)
| CallSite Table Length |
| CallSites |
| … |
| … |
…
…
| Action Table |
| Types Table |

Reviewed By: MaskRay

Differential Revision: https://reviews.llvm.org/D73739

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Call Frame Information (CFI) Handling for Basic Block Sections

This patch handles CFI with basic block sections, which unlike DebugInfo does
not support ranges. The DWARF standard explicitly require

Call Frame Information (CFI) Handling for Basic Block Sections

This patch handles CFI with basic block sections, which unlike DebugInfo does
not support ranges. The DWARF standard explicitly requires emitting separate
CFI Frame Descriptor Entries for each contiguous fragment of a function. Thus,
the CFI information for all callee-saved registers (possibly including the
frame pointer, if necessary) have to be emitted along with redefining the
Call Frame Address (CFA), viz. where the current frame starts.

CFI directives are emitted in FDE’s in the object file with a low_pc, high_pc
specification. So, a single FDE must point to a contiguous code region unlike
debug info which has the support for ranges. This is what complicates CFI for
basic block sections.

Now, what happens when we start placing individual basic blocks in unique
sections:

* Basic block sections allow the linker to randomly reorder basic blocks in the
address space such that a given basic block can become non-contiguous with the
original function.
* The different basic block sections can no longer share the cfi_startproc and
cfi_endproc directives. So, each basic block section should emit this
independently.
* Each (cfi_startproc, cfi_endproc) directive will result in a new FDE that
caters to that basic block section.
* Now, this basic block section needs to duplicate the information from the
entry block to compute the CFA as it is an independent entity. It cannot refer
to the FDE of the original function and hence must duplicate all the stuff that
is needed to compute the CFA on its own.
* We are working on a de-duplication patch that can share common information in
FDEs in a CIE (Common Information Entry) and we will present this as a follow up
patch. This can significantly reduce the duplication overhead and is
particularly useful when several basic block sections are created.
* The CFI directives are emitted similarly for registers that are pushed onto
the stack, like callee saved registers in the prologue. There are cfi
directives that emit how to retrieve the value of the register at that point
when the push happened. This has to be duplicated too in a basic block that is
floated as a separate section.

Differential Revision: https://reviews.llvm.org/D79978

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[AsmPrinter][MCStreamer] De-capitalize EmitInstruction and EmitCFI*

[cfi] Add flag to always generate .debug_frame

This adds a flag to LLVM and clang to always generate a .debug_frame
section, even if other debug information is not being generated. In
situations whe

[cfi] Add flag to always generate .debug_frame

This adds a flag to LLVM and clang to always generate a .debug_frame
section, even if other debug information is not being generated. In
situations where .eh_frame would normally be emitted, both .debug_frame
and .eh_frame will be used.

Differential Revision: https://reviews.llvm.org/D67216

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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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Move TargetLoweringObjectFile from CodeGen to Target to fix layering

It's implemented in Target & include from other Target headers, so the
header should be in Target.

llvm-svn: 328392

MachineFunction: Return reference from getFunction(); NFC

The Function can never be nullptr so we can return a reference.

llvm-svn: 320884

Remove redundant includes from lib/CodeGen.

llvm-svn: 320619

Fix a bunch more layering of CodeGen headers that are in Target

All these headers already depend on CodeGen headers so moving them into
CodeGen fixes the layering (since CodeGen depends on Target, n

Fix a bunch more layering of CodeGen headers that are in Target

All these headers already depend on CodeGen headers so moving them into
CodeGen fixes the layering (since CodeGen depends on Target, not the
other way around).

llvm-svn: 318490

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Move TargetFrameLowering.h to CodeGen where it's implemented

This header already includes a CodeGen header and is implemented in
lib/CodeGen, so move the header there to match.

This fixes a link er

Move TargetFrameLowering.h to CodeGen where it's implemented

This header already includes a CodeGen header and is implemented in
lib/CodeGen, so move the header there to match.

This fixes a link error with modular codegeneration builds - where a
header and its implementation are circularly dependent and so need to be
in the same library, not split between two like this.

llvm-svn: 317379

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Move Object format code to lib/BinaryFormat.

This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various type

Move Object format code to lib/BinaryFormat.

This creates a new library called BinaryFormat that has all of
the headers from llvm/Support containing structure and layout
definitions for various types of binary formats like dwarf, coff,
elf, etc as well as the code for identifying a file from its
magic.

Differential Revision: https://reviews.llvm.org/D33843

llvm-svn: 304864

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PR 31534: When emitting both DWARF unwind tables and debug information,
do not use .cfi_sections. This requires checking if any non-declaration
function in the module needs an unwind table.

llvm-svn

PR 31534: When emitting both DWARF unwind tables and debug information,
do not use .cfi_sections. This requires checking if any non-declaration
function in the module needs an unwind table.

llvm-svn: 291172

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Emit .cfi_sections before the first .cfi_startproc

GNU as rejects input where .cfi_sections is used after .cfi_startproc,
if the new section differs from the old. Adjust our output to always
emit .c

Emit .cfi_sections before the first .cfi_startproc

GNU as rejects input where .cfi_sections is used after .cfi_startproc,
if the new section differs from the old. Adjust our output to always
emit .cfi_sections before the first .cfi_startproc to minimize necessary
code.

Differential Revision: https://reviews.llvm.org/D28011

llvm-svn: 290817

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Move most EH from MachineModuleInfo to MachineFunction

Recommitting r288293 with some extra fixes for GlobalISel code.

Most of the exception handling members in MachineModuleInfo is actually
per fu

Move most EH from MachineModuleInfo to MachineFunction

Recommitting r288293 with some extra fixes for GlobalISel code.

Most of the exception handling members in MachineModuleInfo is actually
per function data (talks about the "current function") so it is better
to keep it at the function instead of the module.

This is a necessary step to have machine module passes work properly.

Also:
- Rename TidyLandingPads() to tidyLandingPads()
- Use doxygen member groups instead of "//===- EH ---"... so it is clear
where a group ends.
- I had to add an ugly const_cast at two places in the AsmPrinter
because the available MachineFunction pointers are const, but the code
wants to call tidyLandingPads() in between
(markFunctionEnd()/endFunction()).

Differential Revision: https://reviews.llvm.org/D27227

llvm-svn: 288405

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Temporarily Revert "Move most EH from MachineModuleInfo to MachineFunction"

This apprears to have broken the global isel bot:
http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-globalisel_buil

Temporarily Revert "Move most EH from MachineModuleInfo to MachineFunction"

This apprears to have broken the global isel bot:
http://lab.llvm.org:8080/green/job/clang-stage1-cmake-RA-globalisel_build/5174/console

This reverts commit r288293.

llvm-svn: 288322

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Move most EH from MachineModuleInfo to MachineFunction

Most of the exception handling members in MachineModuleInfo is actually
per function data (talks about the "current function") so it is better

Move most EH from MachineModuleInfo to MachineFunction

Most of the exception handling members in MachineModuleInfo is actually
per function data (talks about the "current function") so it is better
to keep it at the function instead of the module.

This is a necessary step to have machine module passes work properly.

Also:
- Rename TidyLandingPads() to tidyLandingPads()
- Use doxygen member groups instead of "//===- EH ---"... so it is clear
where a group ends.
- I had to add an ugly const_cast at two places in the AsmPrinter
because the available MachineFunction pointers are const, but the code
wants to call tidyLandingPads() in between
(markFunctionEnd()/endFunction()).

Differential Revision: https://reviews.llvm.org/D27227

llvm-svn: 288293

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Move the Mangler from the AsmPrinter down to TLOF and clean up the
TLOF API accordingly.

llvm-svn: 281708