[AsmPrinter] Reintroduce full AsmPrinterHandler API (#122297)

This restores the functionality of AsmPrinterHandlers to what it was
prior to https://github.com/llvm/llvm-project/pull/96785. The attem

[AsmPrinter] Reintroduce full AsmPrinterHandler API (#122297)

This restores the functionality of AsmPrinterHandlers to what it was
prior to https://github.com/llvm/llvm-project/pull/96785. The attempted
hack there of adding a duplicate DebugHandlerBase handling added a lot
of hidden state and assumptions, which just segfaulted when we tried to
continuing using this API. Instead, this just goes back to the old
design, but adds a separate array for the basic EH handles. The
duplicate array is identical to the other array of handler, but which
doesn't get their begin/endInstruction callbacks called. This still
saves the negligible but measurable amount of virtual function calls as
was the goal of #96785, while restoring the API to the pre-LLVM-19
status quo.

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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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[AsmPrinter] Remove timers (#97046)

Timers are an out-of-line function call and a global variable access,
here twice per emitted instruction. At this granularity, not only the
time results become

[AsmPrinter] Remove timers (#97046)

Timers are an out-of-line function call and a global variable access,
here twice per emitted instruction. At this granularity, not only the
time results become skewed, but the timers also add a performance
overhead when profiling is disabled. Also outside of the innermost loop,
timers add a measurable overhead. As this is quite expensive for a
mostly unused profiling facility, remove the timers.

Fixes #39650.

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[AsmPrinter] Reduce AsmPrinterHandlers virt. fn calls (#96785)

Currently, an AsmPrinterHandler has several methods that allow to
dynamically hook in unwind or debug info emission, e.g. at begin/end

[AsmPrinter] Reduce AsmPrinterHandlers virt. fn calls (#96785)

Currently, an AsmPrinterHandler has several methods that allow to
dynamically hook in unwind or debug info emission, e.g. at begin/end of
every function or instruction. The class hierarchy and the actually
overridden functions are as follows:

(SymSz=setSymbolSize, mFE=markFunctionEnd, BBS=BasicBlockSection,
FL=Funclet; b=beginX, e=endX)
SymSz Mod Fn mFE BBS FL Inst
AsmPrinterHandler - - - - - - -
` PseudoProbeHandler - - - - - - -
` WinCFGuard - e e - - - -
` EHStreamer - - - - - - -
` DwarfCFIException - e be - be - -
` ARMException - - be e - - -
` AIXException - - e - - - -
` WinException - e be e - be -
` WasmException - e be - - - -
` DebugHandlerBase - b be - be - be
` BTFDebug - e - - - - b
` CodeViewDebug - be - - - - b
` DWARFDebug yes be - - - - b

Doing virtual function calls per instruction is costly and useless when
the called function does nothing.

This commit performs the following clean-up/improvements:

- PseudoProbeHandler is no longer an AsmPrinterHandler -- it used
nothing of its functionality to hook in at the possible points. This
avoids virtual function calls when a pseudo probe printer is present.

- DebugHandlerBase is no longer an AsmPrinterHandler, but a separate
base class. DebugHandlerBase is the only remaining "hook" for begin/end
instruction and setSymbolSize (only used by DWARFDebug). begin/end for
function and basic block sections are never overriden and therefore are
no longer virtual. (Originally I intended there to be only one debug
handler, but BPF as the only target supports two at the same time: DWARF
and BTF.)

- AsmPrinterHandler no longer has begin/end instruction and
setSymbolSize hooks -- these were only used by DebugHandlerBase. This
avoid iterating over handlers in every instruction.

AsmPrinterHandler Mod Fn mFE BBS FL
` WinCFGuard e e - - -
` EHStreamer - - - - -
` DwarfCFIException e be - be -
` ARMException - be e - -
` AIXException - e - - -
` WinException e be e - be
` WasmException e be - - -

SymSz Mod Fn BBS Inst
DebugHandlerBase - b be be be
` BTFDebug - e b
` CodeViewDebug - be b
` DWARFDebug yes be b

PseudoProbeHandler (no shared methods)

To continue allowing external users (e.g., Julia) to hook in at every
instruction, a new method addDebugHandler is exposed.

This results in a performance improvement, especially in the -O0 -g0
case with unwind information (e.g., JIT baseline).

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[unittests] Add missing includes (#65681)

There are missing include and using in TextStubTests and
AsmPrinterDwarfTest and they causes build failures when using vanilla
GoogleTest v1.14.0. This pa

[unittests] Add missing includes (#65681)

There are missing include and using in TextStubTests and
AsmPrinterDwarfTest and they causes build failures when using vanilla
GoogleTest v1.14.0. This patch fixes this issue.

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[MC] De-capitalize SwitchSection. NFC

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

[MC] Lower case the first letter of EmitCOFF* EmitWin* EmitCV*. NFC

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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[unittests][CodeGen] Mark tests that cannot be executed with GTEST_SKIP()

This helps to distinguish such tests from successfully passed ones.

Differential Revision: https://reviews.llvm.org/D102754

[debug-info] refactor emitDwarfUnitLength

remove `Hi` `Lo` argument from `emitDwarfUnitLength`, so we
can make caller of emitDwarfUnitLength easier.

Reviewed By: MaskRay, dblaikie, ikudrin

Differe

[debug-info] refactor emitDwarfUnitLength

remove `Hi` `Lo` argument from `emitDwarfUnitLength`, so we
can make caller of emitDwarfUnitLength easier.

Reviewed By: MaskRay, dblaikie, ikudrin

Differential Revision: https://reviews.llvm.org/D96409

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[Debug-Info][NFC] move emitDwarfUnitLength to MCStreamer class

We may need to do some customization for DWARF unit length in DWARF
section headers for some targets for some code generation path.

Fo

[Debug-Info][NFC] move emitDwarfUnitLength to MCStreamer class

We may need to do some customization for DWARF unit length in DWARF
section headers for some targets for some code generation path.

For example, for XCOFF in assembly path, AIX assembler does not require
the debug section containing its debug unit length in the header.

Move emitDwarfUnitLength to MCStreamer class so that we can do
customization in different Streamers

Reviewed By: ikudrin

Differential Revision: https://reviews.llvm.org/D95932

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make the AsmPrinterHandler array public

This lets external consumers customize the output, similar to how
AssemblyAnnotationWriter lets the caller define callbacks when printing
IR. The array of han

make the AsmPrinterHandler array public

This lets external consumers customize the output, similar to how
AssemblyAnnotationWriter lets the caller define callbacks when printing
IR. The array of handlers already existed, this just cleans up the code
so that it can be exposed publically.

Replaces https://reviews.llvm.org/D74158

Differential Revision: https://reviews.llvm.org/D89613

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Revert "make the AsmPrinterHandler array public"

I messed up one of the tests.

make the AsmPrinterHandler array public

This lets external consumers customize the output, similar to how
AssemblyAnnotationWriter lets the caller define callbacks when printing
IR. The array of han

make the AsmPrinterHandler array public

This lets external consumers customize the output, similar to how
AssemblyAnnotationWriter lets the caller define callbacks when printing
IR. The array of handlers already existed, this just cleans up the code
so that it can be exposed publically.

Differential Revision: https://reviews.llvm.org/D74158

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[DebugInfo] Add new emitting methods for values which depend on the DWARF format (3/19).

These methods are going to be used in subsequent patches.

Differential Revision: https://reviews.llvm.org/D8

[DebugInfo] Add new emitting methods for values which depend on the DWARF format (3/19).

These methods are going to be used in subsequent patches.

Differential Revision: https://reviews.llvm.org/D87010

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[DebugInfo] Fix methods of AsmPrinter to emit values corresponding to the DWARF format (1/19).

These methods are used to emit values which are 32-bit in DWARF32 and
64-bit in DWARF64. The patch fixe

[DebugInfo] Fix methods of AsmPrinter to emit values corresponding to the DWARF format (1/19).

These methods are used to emit values which are 32-bit in DWARF32 and
64-bit in DWARF64. The patch fixes them so that they choose the length
automatically, depending on the DWARF format set in the Context.

Differential Revision: https://reviews.llvm.org/D87008

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