Commit Graph

65 Commits

Author SHA1 Message Date
Fangrui Song 57fa68897b [Driver][ARM][AArch64] Use err_drv_unsupported_option_argument for -march=/-mcpu=/-mtune= diagnostics
err_drv_clang_unsupported is for a Clang unsupported option (any value is rejected).
err_drv_unsupported_option_argument is for an unsupported value (other values may be supported).
2022-06-28 16:01:30 -07:00
Fangrui Song 068b8af796 [ARM][AArch64] Change -mharden-sls= to use err_drv_unsupported_option_argument
Update the diagnostic in D81404: the convention is to use
err_drv_unsupported_option_argument instead of adding a new diagnostic for every
option.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D126511
2022-05-27 22:03:48 -07:00
tyb0807 9a015ee1f9 [AArch64] Avoid scanning feature list for target parsing
As discussed in https://reviews.llvm.org/D120111, this patch proposes an
alternative implementation to avoid scanning feature list for
architecture version over and over again. The insertion position for
default extensions is also captured during this single scan of the
feature list.

Differential Revision: https://reviews.llvm.org/D120864
2022-04-02 14:51:23 +01:00
tyb0807 b93893e60f [AArch64] Default HBC/MOPS features in clang
This implements minimum support in clang for default HBC/MOPS features
on v8.8-a/v9.3-a or later architectures.

Differential Revision: https://reviews.llvm.org/D120111
2022-04-02 14:51:23 +01:00
Keith Smiley 955cff803e reland: [AArch64] Add support for -march=native for Apple M1 CPU
This reverts commit fc3cdd0b29.

The issue was imports being scoped to specific architectures for Apple
platforms.
2022-03-23 15:19:17 -07:00
Keith Smiley fc3cdd0b29 Revert "[AArch64] Add support for -march=native for Apple M1 CPU"
This reverts commit fcca10c69a.
2022-03-23 14:27:02 -07:00
Keith Smiley fcca10c69a [AArch64] Add support for -march=native for Apple M1 CPU
This improves the getHostCPUName check for Apple M1 CPUs, which
previously would always be considered cyclone instead. This also enables
`-march=native` support when building on M1 CPUs which would previously
fail. This isn't as sophisticated as the X86 CPU feature checking which
consults the CPU via getHostCPUFeatures, but this is still better than
before. This CPU selection could also be invalid if this was run on an
iOS device instead, ideally we can improve those cases as they come up.

Differential Revision: https://reviews.llvm.org/D119788
2022-03-23 14:06:59 -07:00
David Spickett c3b98194df Reland "[llvm][AArch64] Insert "bti j" after call to setjmp"
This reverts commit edb7ba714a.

This changes BLR_BTI to take variable_ops meaning that we can accept
a register or a label. The pattern still expects one argument so we'll
never get more than one. Then later we can check the type of the operand
to choose BL or BLR to emit.

(this is what BLR_RVMARKER does but I missed this detail of it first time around)

Also require NoSLSBLRMitigation which I missed in the first version.
2022-03-23 11:43:43 +00:00
David Spickett edb7ba714a Revert "[llvm][AArch64] Insert "bti j" after call to setjmp"
This reverts commit eb5ecbbcbb
due to failures on buildbots with expensive checks enabled.
2022-03-23 10:43:20 +00:00
David Spickett eb5ecbbcbb [llvm][AArch64] Insert "bti j" after call to setjmp
Some implementations of setjmp will end with a br instead of a ret.
This means that the next instruction after a call to setjmp must be
a "bti j" (j for jump) to make this work when branch target identification
is enabled.

The BTI extension was added in armv8.5-a but the bti instruction is in the
hint space. This means we can emit it for any architecture version as long
as branch target enforcement flags are passed.

The starting point for the hint number is 32 then call adds 2, jump adds 4.
Hence "hint #36" for a "bti j" (and "hint #34" for the "bti c" you see
at the start of functions).

The existing Arm command line option -mno-bti-at-return-twice has been
applied to AArch64 as well.

Support is added to SelectionDAG Isel and GlobalIsel. FastIsel will
defer to SelectionDAG.

Based on the change done for M profile Arm in https://reviews.llvm.org/D112427

Fixes #48888

Reviewed By: danielkiss

Differential Revision: https://reviews.llvm.org/D121707
2022-03-23 09:51:02 +00:00
tyb0807 650aec687e [ARM][AArch64] Add missing v8.x checks
Summary:
This patch adds checks that were missing in clang for Armv8.5/6/7-A. These include:
* ACLE macro defines for AArch32.
* Handling of crypto and SM4, SHA and AES feature flags on clang's driver.

Reviewers: dmgreen, SjoerdMeijer, tmatheson

Differential Revision: https://reviews.llvm.org/D116153
2022-02-22 09:07:59 +00:00
Yuanfang Chen b96106af3f [AArch64][ARM] add -Wunaligned-access only for clang
Reviewed By: lenary

Differential Revision: https://reviews.llvm.org/D119301
2022-02-10 10:26:30 -08:00
serge-sans-paille 75e164f61d [llvm] Cleanup header dependencies in ADT and Support
The cleanup was manual, but assisted by "include-what-you-use". It consists in

1. Removing unused forward declaration. No impact expected.
2. Removing unused headers in .cpp files. No impact expected.
3. Removing unused headers in .h files. This removes implicit dependencies and
   is generally considered a good thing, but this may break downstream builds.
   I've updated llvm, clang, lld, lldb and mlir deps, and included a list of the
   modification in the second part of the commit.
4. Replacing header inclusion by forward declaration. This has the same impact
   as 3.

Notable changes:

- llvm/Support/TargetParser.h no longer includes llvm/Support/AArch64TargetParser.h nor llvm/Support/ARMTargetParser.h
- llvm/Support/TypeSize.h no longer includes llvm/Support/WithColor.h
- llvm/Support/YAMLTraits.h no longer includes llvm/Support/Regex.h
- llvm/ADT/SmallVector.h no longer includes llvm/Support/MemAlloc.h nor llvm/Support/ErrorHandling.h

You may need to add some of these headers in your compilation units, if needs be.

As an hint to the impact of the cleanup, running

clang++ -E  -Iinclude -I../llvm/include ../llvm/lib/Support/*.cpp -std=c++14 -fno-rtti -fno-exceptions | wc -l

before: 8000919 lines
after:  7917500 lines

Reduced dependencies also helps incremental rebuilds and is more ccache
friendly, something not shown by the above metric :-)

Discourse thread on the topic: https://llvm.discourse.group/t/include-what-you-use-include-cleanup/5831
2022-01-21 13:54:49 +01:00
Mubashar Ahmad 35737df4dc [Clang][AArch64][ARM] Unaligned Access Warning Added
Added warning for potential cases of
unaligned access when option
-mno-unaligned-access has been specified

Differential Revision: https://reviews.llvm.org/D116221
2022-01-20 14:12:49 +00:00
Archibald Elliott 3aec4b3d34 Revert "Unaligned Access Warning Added"
This reverts commits:
- 2cd2600aba
- 11c67e5a4e

Due to test failures on Windows.
2022-01-07 13:07:30 +00:00
Archibald Elliott 11c67e5a4e [clang][driver] Don't pass -Wunaligned-access to cc1as
This is to fix some failing assembler tests.
2022-01-07 10:45:26 +00:00
Mubashar Ahmad 2cd2600aba Unaligned Access Warning Added
Added warning for potential cases of
unaligned access when option
-mno-unaligned-access has been specified
2022-01-07 09:54:20 +00:00
Tomas Matheson 4435d1819e [ARM][AArch64] clang support for Armv9.3-A
This patch introduces support for targetting the Armv9.3-A architecture,
which should map to the existing Armv8.8-A extensions.

Differential Revision: https://reviews.llvm.org/D116159
2022-01-03 16:02:36 +00:00
Simon Tatham d50072f74e [ARM] Introduce an empty "armv8.8-a" architecture.
This is the first commit in a series that implements support for
"armv8.8-a" architecture. This should contain all the necessary
boilerplate to make the 8.8-A architecture exist from LLVM and Clang's
point of view: it adds the new arch as a subtarget feature, a definition
in TargetParser, a name on the command line, an appropriate set of
predefined macros, and adds appropriate tests. The new architecture name
is supported in both AArch32 and AArch64.

However, in this commit, no actual _functionality_ is added as part of
the new architecture. If you specify -march=armv8.8a, the compiler
will accept it and set the right predefines, but generate no code any
differently.

Differential Revision: https://reviews.llvm.org/D115694
2021-12-31 16:43:53 +00:00
Archibald Elliott 52faad83c9 [AArch64] Use Feature for A53 Erratum 835769 Fix
When this pass was originally implemented, the fix pass was enabled
using a llvm command-line flag. This works fine, except in the case of
LTO, where the flag is not passed into the linker plugin in order to
enable the function pass in the LTO backend.

Now LTO exists, the expectation now is to use target features rather
than command-line arguments to control code generation, as this ensures
that different command-line arguments in different files are correctly
represented, and target-features always get to the LTO plugin as they
are encoded into LLVM IR.

The fall-out of this change is that the fix pass has to always be added
to the backend pass pipeline, so now it makes no changes if the function
does not have the right target feature to enable it. This should make a
minimal difference to compile time.

One advantage is it's now much easier to enable when compiling for a
Cortex-A53, as CPUs imply their own individual sets of target-features,
in a more fine-grained way. I haven't done this yet, but it is an
option, if the fix should be enabled in more places.

Existing tests of the user interface are unaffected, the changes are to
reflect that the argument is now turned into a target feature.

Reviewed By: tmatheson

Differential Revision: https://reviews.llvm.org/D114703
2021-12-10 15:09:59 +00:00
Dimitry Andric df08b2fe8b [AArch64] Avoid crashing on invalid -Wa,-march= values
As reported in https://bugs.freebsd.org/260078, the gnutls Makefiles
pass -Wa,-march=all to compile a number of assembly files. Clang does
not support this -march value, but because of a mistake in handling
the arguments, an unitialized Arg pointer is dereferenced, which can
cause a segfault.

Work around this by adding a check if the local WaMArch variable is
initialized, and if so, using its value in the diagnostic message.

Reviewed By: tschuett

Differential Revision: https://reviews.llvm.org/D114677
2021-11-28 22:23:42 +01:00
Bradley Smith 26f56438e3 [Clang][SVE] Properly enable/disable dependant SVE target features based upon +(no)sve.* options
Co-authored-by: Graham Hunter <graham.hunter@arm.com>

Differential Revision: https://reviews.llvm.org/D113776
2021-11-18 15:52:28 +00:00
Alexandros Lamprineas 8689f5e6e7 [AArch64] Add support for the 'R' architecture profile.
This change introduces subtarget features to predicate certain
instructions and system registers that are available only on
'A' profile targets. Those features are not present when
targeting a generic CPU, which is the default processor.

In other words the generic CPU now means the intersection of
'A' and 'R' profiles. To maintain backwards compatibility we
enable the features that correspond to -march=armv8-a when the
architecture is not explicitly specified on the command line.

References: https://developer.arm.com/documentation/ddi0600/latest

Differential Revision: https://reviews.llvm.org/D110065
2021-10-27 12:32:30 +01:00
Victor Campos 3550e242fa [Clang][ARM][AArch64] Add support for Armv9-A, Armv9.1-A and Armv9.2-A
armv9-a, armv9.1-a and armv9.2-a can be targeted using the -march option
both in ARM and AArch64.

 - Armv9-A maps to Armv8.5-A.
 - Armv9.1-A maps to Armv8.6-A.
 - Armv9.2-A maps to Armv8.7-A.
 - The SVE2 extension is enabled by default on these architectures.
 - The cryptographic extensions are disabled by default on these
 architectures.

The Armv9-A architecture is described in the Arm® Architecture Reference
Manual Supplement Armv9, for Armv9-A architecture profile
(https://developer.arm.com/documentation/ddi0608/latest).

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D109517
2021-10-11 17:44:09 +01:00
Jian Cai 0eac975b51 Reland "[AArch64] handle -Wa,-march="
This reverts commit fd11a26d36, which was
reverted by 9145a3d4ab due to a test
failure on aarch64 backend, e.g.
https://lab.llvm.org/buildbot/#/builders/43/builds/7031. This patch
fixed the test failure.

Reviewed By: DavidSpickett, nickdesaulniers

Differential Revision: https://reviews.llvm.org/D103184
2021-06-23 12:01:57 -07:00
Jian Cai 9145a3d4ab Revert "[AArch64] handle -Wa,-march="
This reverts commit fd11a26d36.
2021-06-07 14:31:07 -07:00
Jian Cai fd11a26d36 [AArch64] handle -Wa,-march=
This fixed PR#48894 for AArch64. The issue has been fixed for Arm in
https://reviews.llvm.org/D95872

The following rules apply to -Wa,-march with this change:
  - Only compiler options apply to non assembly files
  - Compiler and assembler options apply to assembly files
  - For assembly files, we prefer the assembler option(s) if we have both kinds of option
  - Of the options that apply (or are preferred), the last value wins (it's not additive)

Reviewed By: DavidSpickett, nickdesaulniers

Differential Revision: https://reviews.llvm.org/D103184
2021-06-07 10:15:53 -07:00
Daniel Kiss 801ab71032 [ARM][AArch64] SLSHardening: make non-comdat thunks possible
Linker scripts might not handle COMDAT sections. SLSHardeing adds
new section for each __llvm_slsblr_thunk_xN. This new option allows
the generation of the thunks into the normal text section to handle these
exceptional cases.
,comdat or ,noncomdat can be added to harden-sls to control the codegen.
-mharden-sls=[all|retbr|blr],nocomdat.

Reviewed By: kristof.beyls

Differential Revision: https://reviews.llvm.org/D100546
2021-05-20 17:07:05 +02:00
Ahmed Bougacha cedb5b06df [AArch64] Don't always override CPU for arm64e.
This demotes the apple-a12 CPU selection for arm64e to just be the
last-resort default.  Concretely, this means:
- an explicitly-specified -mcpu will override the arm64e default;
  a user could potentially pick an invalid CPU that doesn't have
  v8.3a support, but that's not a major problem anymore
- arm64e-apple-macos (and variants) will pick apple-m1 instead of
  being forced to apple-a12.
2021-04-20 08:41:04 -07:00
Ahmed Bougacha a8a3a43792 [AArch64] Add apple-m1 CPU, and default to it for macOS.
apple-m1 has the same level of ISA support as apple-a14,
so this is a straightforward mechanical change.  However, that
also means this inherits apple-a14's v8.5a+nobti quirkiness.

rdar://68287159
2021-04-20 08:41:04 -07:00
Tim Northover c4542005da AArch64/MacOS: switch default CPU to apple-a13.
The DevKits had A12 processors, but they're all gone now and real hardware has
an A13.
2021-03-08 15:47:05 +00:00
Lucas Prates c4d851b079 [ARM][AAarch64] Initial command-line support for v8.7-A
This introduces command-line support for the 'armv8.7-a' architecture name
(and an alias without the '-', as usual), and for the 'ls64' extension name.

Based on patches written by Simon Tatham.

Reviewed By: ostannard

Differential Revision: https://reviews.llvm.org/D91776
2020-12-17 13:47:28 +00:00
Sjoerd Meijer 99ad078b91 [AArch64] Cortex-R82: remove crypto
Remove target features crypto for Cortex-R82, because it doesn't have any, and
add LSE which was missing while we are at it.
This also removes crypto from the v8-R architecture description because that
aligns better with GCC and so far none of the R-cores have implemented crypto,
so is probably a more sensible default.

Differential Revision: https://reviews.llvm.org/D91994
2020-12-10 12:54:51 +00:00
Peter Waller 2315e9874c [AArch64][Driver][SVE] Push missing SVE feature error from driver to frontend
... and give more guidance to users.

If specifying -msve-vector-bits on a non-SVE target, clang would say:

    error: '-msve-vector-bits' is not supported without SVE enabled

1. The driver lacks logic for "implied features".
   This would result in this error being raised for -march=...+sve2,
   even though +sve2 implies +sve.

2. Feature implication is well modelled in LLVM, so push the error down
   the stack.

3. Hint to the user what flag they need to consider setting.

Now clang fails later, when the feature is used, saying:

  aarch64-sve-vector-bits.c:42:41: error: 'arm_sve_vector_bits' attribute is not supported on targets missing 'sve'; specify an appropriate -march= or -mcpu=
  typedef svint32_t noflag __attribute__((arm_sve_vector_bits(256)));

Move clang/test/Sema/{neon => arm}-vector-types-support.c and put tests for
this warning together in one place.

Reviewed By: sdesmalen

Differential Revision: https://reviews.llvm.org/D92487
2020-12-10 12:43:14 +00:00
Ahmed Bougacha f77c948d56 [Triple][MachO] Define "arm64e", an AArch64 subarch for Pointer Auth.
This also teaches MachO writers/readers about the MachO cpu subtype,
beyond the minimal subtype reader support present at the moment.

This also defines a preprocessor macro to allow users to distinguish
__arm64__ from __arm64e__.

arm64e defaults to an "apple-a12" CPU, which supports v8.3a, allowing
pointer-authentication codegen.
It also currently defaults to ios14 and macos11.

Differential Revision: https://reviews.llvm.org/D87095
2020-12-03 07:53:59 -08:00
Alex Lorenz de1016ce5c [driver][arm64] Set target CPU to A12 for compiler invocations that
target Apple Silicon macOS machines

Differential Revision: https://reviews.llvm.org/D82699
2020-10-21 23:35:27 -07:00
Sjoerd Meijer 8825fec37e [AArch64] Add CPU Cortex-R82
This adds support for -mcpu=cortex-r82. Some more information about this
core can be found here:

https://www.arm.com/products/silicon-ip-cpu/cortex-r/cortex-r82

One note about the system register: that is a bit of a refactoring because of
small differences between v8.4-A AArch64 and v8-R AArch64.

This is based on patches from Mark Murray and Mikhail Maltsev.

Differential Revision: https://reviews.llvm.org/D88660
2020-10-02 12:47:23 +01:00
Jon Roelofs c145a1ca25 AArch64::ArchKind's underlying type is uint64_t 2020-09-17 12:13:57 -07:00
Brad Smith 44613bbec8 Create strict aligned code for OpenBSD/arm64. 2020-08-16 07:14:34 -04:00
Paul Walker ab7abd8bf4 [Driver] Add support for -msve-vector-bits=scalable.
No real action is taken for a value of scalable but it provides a
route to disable an earlier specification and is effectively its
default value when omitted.

Patch also removes an "unused variable" warning.

Differential Revision: https://reviews.llvm.org/D84021
2020-07-20 10:46:22 +00:00
Cullen Rhodes bb160e769d [Sema][AArch64] Add parsing support for arm_sve_vector_bits attribute
Summary:

This patch implements parsing support for the 'arm_sve_vector_bits' type
attribute, defined by the Arm C Language Extensions (ACLE, version 00bet5,
section 3.7.3) for SVE [1].

The purpose of this attribute is to define fixed-length (VLST) versions
of existing sizeless types (VLAT). For example:

    #if __ARM_FEATURE_SVE_BITS==512
    typedef svint32_t fixed_svint32_t __attribute__((arm_sve_vector_bits(512)));
    #endif

Creates a type 'fixed_svint32_t' that is a fixed-length version of
'svint32_t' that is normal-sized (rather than sizeless) and contains
exactly 512 bits. Unlike 'svint32_t', this type can be used in places
such as structs and arrays where sizeless types can't.

Implemented in this patch is the following:

  * Defined and tested attribute taking single argument.
  * Checks the argument is an integer constant expression.
  * Attribute can only be attached to a single SVE vector or predicate
    type, excluding tuple types such as svint32x4_t.
  * Added the `-msve-vector-bits=<bits>` flag. When specified the
    `__ARM_FEATURE_SVE_BITS__EXPERIMENTAL` macro is defined.
  * Added a language option to store the vector size specified by the
    `-msve-vector-bits=<bits>` flag. This is used to validate `N ==
    __ARM_FEATURE_SVE_BITS`, where N is the number of bits passed to the
    attribute and `__ARM_FEATURE_SVE_BITS` is the feature macro defined under
    the same flag.

The `__ARM_FEATURE_SVE_BITS` macro will be made non-experimental in the final
patch of the series.

[1] https://developer.arm.com/documentation/100987/latest

This is patch 1/4 of a patch series.

Reviewers: sdesmalen, rsandifo-arm, efriedma, ctetreau, cameron.mcinally, rengolin, aaron.ballman

Reviewed By: sdesmalen, aaron.ballman

Differential Revision: https://reviews.llvm.org/D83550
2020-07-17 10:06:54 +00:00
Francesco Petrogalli 438e95e95b [clang][aarch64] Generate preprocessor macros for -march=armv8.6a+sve.
Summary:
The following preprocessor macros are implied when `-march=armv8.6a+sve`:

```
__ARM_FEATURE_SVE 1
__ARM_FEATURE_SVE_BF16 1
__ARM_FEATURE_SVE_MATMUL_FP32 1
__ARM_FEATURE_SVE_MATMUL_INT8 1
```

Reviewers: sdesmalen, efriedma, SjoerdMeijer, rengolin

Subscribers: tschuett, kristof.beyls, danielkiss, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D83079
2020-07-14 17:42:28 +00:00
Kristof Beyls c113b59ef5 [AArch64] Add clang command line support for -mharden-sls=
The accepted options to -mharden-sls= are:
* all: enable all mitigations against Straight Line Speculation that are
  implemented.
* none: disable all mitigations against Straight Line Speculation.
* retbr: enable the mitigation against Straight Line Speculation for RET
  and BR instructions.
* blr: enable the mitigation against Straight Line Speculation for BLR
  instructions.

Differential Revision: https://reviews.llvm.org/D81404
2020-06-19 07:31:48 +01:00
Francis Visoiu Mistrih e770153865 [AArch64] Add support for -ffixed-x30
Add support for reserving LR in:

* the driver through `-ffixed-x30`
* cc1 through `-target-feature +reserve-x30`
* the backend through `-mattr=+reserve-x30`
* a subtarget feature `reserve-x30`

the same way we're doing for the other registers.
2020-04-28 08:48:28 -07:00
Luke Geeson 740a1dd050 [ARM] Armv8.6-a Matrix Mul cmd line support
This patch upstreams support for the Armv8.6-a Matrix Multiplication
Extension. A summary of the features can be found here:

https://community.arm.com/developer/ip-products/processors/b/processors-ip-blog/posts/arm-architecture-developments-armv8-6-a

This patch includes:

- Command line options to enable these features with +i8mm, +f32mm, or f64mm

Note: +f32mm and +f64mm are optional and so are not enabled by default

This is part of a patch series, starting with BFloat16 support and
the other components in the armv8.6a extension (in previous patches
linked in phabricator)

Based on work by:
- Luke Geeson
- Oliver Stannard
- Luke Cheeseman

Reviewers: t.p.northover, DavidSpickett

Reviewed By: DavidSpickett

Subscribers: DavidSpickett, ostannard, kristof.beyls, danielkiss,
cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D77875
2020-04-24 15:54:06 +01:00
Benjamin Kramer e8f13f4f62 Replace std::string::find == 0 with StringRef::startswith
This is both more readable and faster. Found by clang-tidy's
abseil-string-find-startswith.
2020-03-31 21:01:09 +02:00
Benjamin Kramer adcd026838 Make llvm::StringRef to std::string conversions explicit.
This is how it should've been and brings it more in line with
std::string_view. There should be no functional change here.

This is mostly mechanical from a custom clang-tidy check, with a lot of
manual fixups. It uncovers a lot of minor inefficiencies.

This doesn't actually modify StringRef yet, I'll do that in a follow-up.
2020-01-28 23:25:25 +01:00
Tim Northover 903e5c3028 AArch64: add missing Apple CPU names and use them by default.
Apple's CPUs are called A7-A13 in official communication, occasionally with
weird suffixes which we probably don't need to care about. This adds each one
and describes its features. It also switches the default CPU to the canonical
name for Cyclone, but leaves legacy support in so that existing bitcode still
compiles.
2020-01-08 09:24:06 +00:00
Reid Kleckner 90c64a3456 Move endian constant from Host.h to SwapByteOrder.h, prune include
Works on this dependency chain:
  ArrayRef.h ->
  Hashing.h -> --CUT--
  Host.h ->
  StringMap.h / StringRef.h

ArrayRef is very popular, but Host.h is rarely needed. Move the
IsBigEndianHost constant to SwapByteOrder.h. Clients of that header are
more likely to need it.

llvm-svn: 375316
2019-10-19 00:48:11 +00:00
Oliver Stannard d83a559318 [AArch64] Support selecting TPIDR_EL[1-3] as the thread base
Add an -mtp=el[0-3] option to select which of the AArch64 thread ID registers
will be used for the TLS base pointer.

This is a followup to rL356657 which added subtarget features to enable
accesses to the privileged thread ID registers.

Patch by Philip Derrin!

Differential revision: https://reviews.llvm.org/D59631

llvm-svn: 357250
2019-03-29 13:32:41 +00:00