Commit Graph

119 Commits

Author SHA1 Message Date
Benjamin Kramer bdc4956bac Pass DebugLoc and SDLoc by const ref.
This used to be free, copying and moving DebugLocs became expensive
after the metadata rewrite. Passing by reference eliminates a ton of
track/untrack operations. No functionality change intended.

llvm-svn: 272512
2016-06-12 15:39:02 +00:00
Sanjay Patel dba8b4c04d transform obscured FP sign bit ops into a fabs/fneg using TLI hook
This is effectively a revert of:
http://reviews.llvm.org/rL249702 - [InstCombine] transform masking off of an FP sign bit into a fabs() intrinsic call (PR24886)
and:
http://reviews.llvm.org/rL249701 - [ValueTracking] teach computeKnownBits that a fabs() clears sign bits
and a reimplementation as a DAG combine for targets that have IEEE754-compliant fabs/fneg instructions.

This is intended to resolve the objections raised on the dev list:
http://lists.llvm.org/pipermail/llvm-dev/2016-April/098154.html
and:
https://llvm.org/bugs/show_bug.cgi?id=24886#c4

In the interest of patch minimalism, I've only partly enabled AArch64. PowerPC, MIPS, x86 and others can enable later.

Differential Revision: http://reviews.llvm.org/D19391

llvm-svn: 271573
2016-06-02 20:01:37 +00:00
Silviu Baranga f60be28ed8 [AArch64] Implement lowering of the X constraint on AArch64
Summary:
This implements the lowering of the X constraint on
AArch64.

The default behaviour of the X constraint lowering is to
restrict it to "f". This is a problem because the "f"
constraint is not implemented on AArch64 and would be too
restrictive anyway. Therefore, the AArch64 hook will
lower this to "w" (if the operand is a floating point or
vector) or "r" otherwise.

The implementation is similar with the one added for
ARM (r267411).

This is the AArch64 side of the fix for http://llvm.org/PR26493

Reviewers: rengolin

Subscribers: aemerson, rengolin, llvm-commits, t.p.northover

Differential Revision: http://reviews.llvm.org/D19967

llvm-svn: 268907
2016-05-09 11:10:44 +00:00
Evandro Menezes bcb95cd0ed [AArch64] Use the reciprocal estimation machinery
This patch adds support for estimating the square root, its reciprocal and
division or reciprocal using the combiner generic reciprocal machinery.

llvm-svn: 268539
2016-05-04 20:18:27 +00:00
Craig Topper 18e69f4f63 Use MVT instead of EVT to remove a bunch of unnecessary calls to getSimpleVT.
llvm-svn: 266414
2016-04-15 06:20:21 +00:00
Manman Ren 5751814eda Swift Calling Convention: swifterror target support.
Differential Revision: http://reviews.llvm.org/D18716

llvm-svn: 265997
2016-04-11 21:08:06 +00:00
Tim Shen 0012756489 [SSP] Remove llvm.stackprotectorcheck.
This is a cleanup patch for SSP support in LLVM. There is no functional change.
llvm.stackprotectorcheck is not needed, because SelectionDAG isn't
actually lowering it in SelectBasicBlock; rather, it adds check code in
FinishBasicBlock, ignoring the position where the intrinsic is inserted
(See FindSplitPointForStackProtector()).

llvm-svn: 265851
2016-04-08 21:26:31 +00:00
Evgeniy Stepanov dde29e2799 Faster stack-protector for Android/AArch64.
Bionic has a defined thread-local location for the stack protector
cookie. Emit a direct load instead of going through __stack_chk_guard.

llvm-svn: 265481
2016-04-05 22:41:50 +00:00
Matthias Braun cc7fba40fe AArch64ISelLowering: Remove unused variables/arguments; NFC
llvm-svn: 265098
2016-04-01 02:49:17 +00:00
Haicheng Wu 6a6bc750d5 [AArch64] Do not lower scalar sdiv/udiv to a shifts + mul sequence when optimizing for minsize
Mimic what x86 does when optimizing sdiv/udiv for minsize.

llvm-svn: 264606
2016-03-28 18:17:07 +00:00
Quentin Colombet ba2a01645b [GlobalISel] Re-apply r260922-260923 with MSVC-friendly code.
Original message:
Get rid of the ifdefs in TargetLowering.
Introduce a new API used only by GlobalISel: CallLowering.
This API will contain target hooks dedicated to call lowering.

llvm-svn: 260998
2016-02-16 19:26:02 +00:00
Aaron Ballman fc64ef1a15 Reverting r260922-260923; they cause link failures with MSVC.
http://lab.llvm.org:8011/builders/lldb-x86-windows-msvc2015/builds/15436/steps/build/logs/stdio
http://bb.pgr.jp/builders/msbuild-llvmclang-x64-msc18-DA/builds/961/steps/build_llvm/logs/stdio

llvm-svn: 260972
2016-02-16 15:29:06 +00:00
Quentin Colombet 1ce38545fb [GlobalISel] Get rid of the ifdefs in TargetLowering.
Introduce a new API used only by GlobalISel: CallLowering.
This API will contain target hooks dedicated to call lowering.

llvm-svn: 260922
2016-02-16 00:57:44 +00:00
Quentin Colombet 1cb8fac171 [AArch64] Implements the lowering of formal arguments for GlobalISel.
This is just a trivial implementation:
- Support only arguments passed in registers.
- Support only "plain" arguments, i.e., no sext/zext attribute.

At this point, it is possible to play with the IRTranslator on AArch64:
llc -mtriple arm64-<vendor>-<os> -print-machineinstrs <input.ll> -o - -global-isel

For now, we only support the translation of program with adds and returns.

Follow-up patches are on their way to add a test case (the MIRParser is
not ready as it is).

llvm-svn: 260600
2016-02-11 21:45:08 +00:00
Quentin Colombet 5cf7b415cc [AArch64] Trivial implementation of lower return for the IRTranslator.
llvm-svn: 260574
2016-02-11 19:45:27 +00:00
Balaram Makam 92431703d7 AArch64: Implement missed conditional compare sequences.
Summary:
This is an extension to the existing implementation of r242436 which
restricts to only select inputs. This version fixes missed opportunities
in pr26084 by attempting to lower conditional compare sequences of
and/or trees with setcc leafs. This will additionaly handle the case
when a tree with select input is not a conjunction-disjunction tree
but some of the sub trees are conjunction-disjunction trees.

Reviewers: jmolloy, t.p.northover, mcrosier, MatzeB

Subscribers: mcrosier, llvm-commits, junbuml, haicheng, mssimpso, gberry

Differential Revision: http://reviews.llvm.org/D16291

llvm-svn: 259387
2016-02-01 19:13:07 +00:00
Manman Ren cbe4f9417d CXX_FAST_TLS calling convention: performance improvement for AArch64.
The access function has a short entry and a short exit, the initialization
block is only run the first time. To improve the performance, we want to
have a short frame at the entry and exit.

We explicitly handle most of the CSRs via copies. Only the CSRs that are not
handled via copies will be in CSR_SaveList.

Frame lowering and prologue/epilogue insertion will generate a short frame
in the entry and exit according to CSR_SaveList. The majority of the CSRs will
be handled by register allcoator. Register allocator will try to spill and
reload them in the initialization block.

We add CSRsViaCopy, it will be explicitly handled during lowering.

1> we first set FunctionLoweringInfo->SplitCSR if conditions are met (the target
   supports it for the given machine function and the function has only return
   exits). We also call TLI->initializeSplitCSR to perform initialization.
2> we call TLI->insertCopiesSplitCSR to insert copies from CSRsViaCopy to
   virtual registers at beginning of the entry block and copies from virtual
   registers to CSRsViaCopy at beginning of the exit blocks.
3> we also need to make sure the explicit copies will not be eliminated.

The target independent portion was committed as r255353.
rdar://problem/23557469

Differential Revision: http://reviews.llvm.org/D15341

llvm-svn: 255821
2015-12-16 21:04:19 +00:00
Geoff Berry 8f5acb1bd1 Remove dead function AArch64TargetLowering::getFunctionAlignment. NFC.
Reviewers: t.p.northover, jmolloy, mcrosier

Subscribers: aemerson, rengolin, llvm-commits

Differential Revision: http://reviews.llvm.org/D15458

llvm-svn: 255509
2015-12-14 17:01:10 +00:00
Sanjay Patel 241c31fb64 [AArch64] add overrides for isCheapToSpeculateCttz() and isCheapToSpeculateCtlz()
AArch64 has instructions for efficient count-leading/trailing-zeros, so this should be
considered a cheap operation (and therefore fair game for speculation) for any AArch64
implementation.

The net result of allowing this speculation for the regression tests in this
patch is that we get this code:

ctlz:
  clz  w0, w0
  ret

cttz:
  rbit  w8, w0
  clz  w0, w8
  ret

Instead of:

ctlz:
  cbz  w0, .LBB0_2
  clz  w0, w0
  ret
.LBB0_2:
  orr  w0, wzr, #0x20
  ret

cttz:
  cbz  w0, .LBB1_2
  rbit  w8, w0
  clz  w0, w8
  ret
.LBB1_2:
  orr  w0, wzr, #0x20
  ret

See D14469 for the larger motivation.

Differential Revision: http://reviews.llvm.org/D14505

llvm-svn: 252625
2015-11-10 18:11:37 +00:00
Sanjay Patel 776e59b0fe don't repeat function names in comments; NFC
llvm-svn: 252502
2015-11-09 19:18:26 +00:00
Joseph Tremoulet f748c8937e [WinEH] Update exception pointer registers
Summary:
The CLR's personality routine passes these in rdx/edx, not rax/eax.

Make getExceptionPointerRegister a virtual method parameterized by
personality function to allow making this distinction.

Similarly make getExceptionSelectorRegister a virtual method parameterized
by personality function, for symmetry.


Reviewers: pgavlin, majnemer, rnk

Subscribers: jyknight, dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D14344

llvm-svn: 252383
2015-11-07 01:11:31 +00:00
Evgeniy Stepanov d1aad26589 [safestack] Fast access to the unsafe stack pointer on AArch64/Android.
Android libc provides a fixed TLS slot for the unsafe stack pointer,
and this change implements direct access to that slot on AArch64 via
__builtin_thread_pointer() + offset.

This change also moves more code into TargetLowering and its
target-specific subclasses to get rid of target-specific codegen
in SafeStackPass.

This change does not touch the ARM backend because ARM lowers
builting_thread_pointer as aeabi_read_tp, which is not available
on Android.

The previous iteration of this change was reverted in r250461. This
version leaves the generic, compiler-rt based implementation in
SafeStack.cpp instead of moving it to TargetLoweringBase in order to
allow testing without a TargetMachine.

llvm-svn: 251324
2015-10-26 18:28:25 +00:00
Evgeniy Stepanov 9addbc9fc1 Revert "[safestack] Fast access to the unsafe stack pointer on AArch64/Android."
Breaks the hexagon buildbot.

llvm-svn: 250461
2015-10-15 21:26:49 +00:00
Evgeniy Stepanov 142947e9f0 [safestack] Fast access to the unsafe stack pointer on AArch64/Android.
Android libc provides a fixed TLS slot for the unsafe stack pointer,
and this change implements direct access to that slot on AArch64 via
__builtin_thread_pointer() + offset.

This change also moves more code into TargetLowering and its
target-specific subclasses to get rid of target-specific codegen
in SafeStackPass.

This change does not touch the ARM backend because ARM lowers
builting_thread_pointer as aeabi_read_tp, which is not available
on Android.

llvm-svn: 250456
2015-10-15 20:50:16 +00:00
Ahmed Bougacha 07a844d758 [AArch64] Emit clrex in the expanded cmpxchg fail block.
In the comparison failure block of a cmpxchg expansion, the initial
ldrex/ldxr will not be followed by a matching strex/stxr.
On ARM/AArch64, this unnecessarily ties up the execution monitor,
which might have a negative performance impact on some uarchs.

Instead, release the monitor in the failure block.
The clrex instruction was designed for this: use it.

Also see ARMARM v8-A B2.10.2:
"Exclusive access instructions and Shareable memory locations".

Differential Revision: http://reviews.llvm.org/D13033

llvm-svn: 248291
2015-09-22 17:21:44 +00:00
Ahmed Bougacha 5246867384 [CodeGen] Refactor TLI/AtomicExpand interface to make LLSC explicit.
We used to have this magic "hasLoadLinkedStoreConditional()" callback,
which really meant two things:
- expand cmpxchg (to ll/sc).
- expand atomic loads using ll/sc (rather than cmpxchg).

Remove it, and, instead, introduce explicit callbacks:
- bool shouldExpandAtomicCmpXchgInIR(inst)
- AtomicExpansionKind shouldExpandAtomicLoadInIR(inst)

Differential Revision: http://reviews.llvm.org/D12557

llvm-svn: 247429
2015-09-11 17:08:28 +00:00
Ahmed Bougacha 9d677131c4 [CodeGen] Rename AtomicRMWExpansionKind to AtomicExpansionKind.
This lets us generalize its usage to the other atomic instructions.

llvm-svn: 247428
2015-09-11 17:08:17 +00:00
James Molloy edf38f0cb0 [AArch64] Replace the custom AArch64ISD::FMIN/MAX nodes with ISD::FMINNAN/MAXNAN
NFCI. This just removes custom ISDNodes that are no longer needed.

llvm-svn: 244594
2015-08-11 12:06:33 +00:00
Akira Hatanaka f53b0403f8 [AArch64] Define subtarget feature strict-align.
This commit defines subtarget feature strict-align and uses it instead of
cl::opt -aarch64-strict-align to decide whether strict alignment should be
forced.

rdar://problem/21529937

llvm-svn: 243516
2015-07-29 14:17:26 +00:00
Sanjay Patel 1dd15598cf fix TLI's combineRepeatedFPDivisors interface to return the minimum user threshold
This fix was suggested as part of D11345 and is part of fixing PR24141.

With this change, we can avoid walking the uses of a divisor node if the target
doesn't want the combineRepeatedFPDivisors transform in the first place.

There is no NFC-intended other than that.

Differential Revision: http://reviews.llvm.org/D11531

llvm-svn: 243498
2015-07-28 23:05:48 +00:00
Adhemerval Zanella 7bc3319d84 Implement __builtin_thread_pointer
This path add the aarch64 lowering of __builtin_thread_pointer.  It uses
the already implemented AArch64ISD::THREAD_POINTER used in TLS generation.

llvm-svn: 243412
2015-07-28 13:03:31 +00:00
Matthias Braun af7d7709d6 AArch64: Implement conditional compare sequence matching.
This is a new iteration of the reverted r238793 /
http://reviews.llvm.org/D8232 which wrongly assumed that any and/or
trees can be represented by conditional compare sequences, however there
are some restrictions to that. This version fixes this and adds comments
that explain exactly what types of and/or trees can actually be
implemented as conditional compare sequences.

Related to http://llvm.org/PR20927, rdar://18326194

Differential Revision: http://reviews.llvm.org/D10579

llvm-svn: 242436
2015-07-16 20:02:37 +00:00
Pat Gavlin a717f255b6 Allow {e,r}bp as the target of {read,write}_register.
This patch allows the read_register and write_register intrinsics to
read/write the RBP/EBP registers on X86 iff the targeted register is
the frame pointer for the containing function.

Differential Revision: http://reviews.llvm.org/D10977

llvm-svn: 241827
2015-07-09 17:40:29 +00:00
Mehdi Amini eaabc51e78 Re-instate the EVT parameter to getScalarShiftAmountTy() for OOT user
A documentation for this function would be nice by the way.

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241807
2015-07-09 15:12:23 +00:00
Mehdi Amini 0cdec1e2ab Make isLegalAddressingMode() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, llvm-commits, rafael, yaron.keren

Differential Revision: http://reviews.llvm.org/D11040

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241778
2015-07-09 02:09:40 +00:00
Mehdi Amini 9639d650bb Make TargetLowering::getShiftAmountTy() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, llvm-commits, rafael, yaron.keren

Differential Revision: http://reviews.llvm.org/D11037

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241776
2015-07-09 02:09:20 +00:00
Mehdi Amini 44ede33a69 Make TargetLowering::getPointerTy() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, ted, yaron.keren, rafael, llvm-commits

Differential Revision: http://reviews.llvm.org/D11028

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241775
2015-07-09 02:09:04 +00:00
Benjamin Kramer 9bfb627a0e [TargetLowering] StringRefize asm constraint getters.
There is some functional change here because it changes target code from
atoi(3) to StringRef::getAsInteger which has error checking. For valid
constraints there should be no difference.

llvm-svn: 241411
2015-07-05 19:29:18 +00:00
Hao Liu 7ec8ee3119 [AArch64] Lower interleaved memory accesses to ldN/stN intrinsics. This patch also adds a function to calculate the cost of interleaved memory accesses.
E.g. Lower an interleaved load:
        %wide.vec = load <8 x i32>, <8 x i32>* %ptr
        %v0 = shuffle %wide.vec, undef, <0, 2, 4, 6>
        %v1 = shuffle %wide.vec, undef, <1, 3, 5, 7>
     into:
        %ld2 = { <4 x i32>, <4 x i32> } call llvm.aarch64.neon.ld2(%ptr)
        %vec0 = extractelement { <4 x i32>, <4 x i32> } %ld2, i32 0
        %vec1 = extractelement { <4 x i32>, <4 x i32> } %ld2, i32 1

E.g. Lower an interleaved store:
        %i.vec = shuffle <8 x i32> %v0, <8 x i32> %v1, <0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11>
        store <12 x i32> %i.vec, <12 x i32>* %ptr
     into:
        %sub.v0 = shuffle <8 x i32> %v0, <8 x i32> v1, <0, 1, 2, 3>
        %sub.v1 = shuffle <8 x i32> %v0, <8 x i32> v1, <4, 5, 6, 7>
        %sub.v2 = shuffle <8 x i32> %v0, <8 x i32> v1, <8, 9, 10, 11>
        call void llvm.aarch64.neon.st3(%sub.v0, %sub.v1, %sub.v2, %ptr)

Differential Revision: http://reviews.llvm.org/D10533

llvm-svn: 240754
2015-06-26 02:32:07 +00:00
Matthias Braun 8321006d44 Revert "AArch64: Use CMP;CCMP sequences for and/or/setcc trees."
The patch triggers a miscompile on SPEC 2006 403.gcc with the (ref)
200.i and scilab.i inputs. I opened PR23866 to track analysis of this.

This reverts commit r238793.

llvm-svn: 239880
2015-06-17 04:02:32 +00:00
Matthias Braun 72b8f74813 AArch64: Use CMP;CCMP sequences for and/or/setcc trees.
Previously CCMP/FCCMP instructions were only used by the
AArch64ConditionalCompares pass for control flow. This patch uses them
for SELECT like instructions as well by matching patterns in ISelLowering.

PR20927, rdar://18326194

Differential Revision: http://reviews.llvm.org/D8232

llvm-svn: 238793
2015-06-01 22:31:17 +00:00
Matt Arsenault bd7d80a4a6 Add address space argument to isLegalAddressingMode
This is important because of different addressing modes
depending on the address space for GPU targets.

This only adds the argument, and does not update
any of the uses to provide the correct address space.

llvm-svn: 238723
2015-06-01 05:31:59 +00:00
Matthias Braun d04893fa36 Change getTargetNodeName() to produce compiler warnings for missing cases, fix them
llvm-svn: 236775
2015-05-07 21:33:59 +00:00
Matthias Braun b6ac8fa39e AArch64: Don't lower ISD::SELECT to ISD::SELECT_CC
Instead of lowering SELECT to SELECT_CC which is further lowered later
immediately call the SELECT_CC lowering code. This is preferable
because:
- Avoids an unnecessary roundtrip through the legalization queues with
  an intermediate node.
- More importantly: Lowered operations get visited last leading to SELECT_CC
  getting visited with legalized operands and unlegalized ones for preexisting
  SELECT_CC nodes. This does not hurt the current code (hence no testcase) but
  is required for another patch I am working on.

Differential Revision: http://reviews.llvm.org/D8187

llvm-svn: 234334
2015-04-07 17:33:05 +00:00
Quentin Colombet 6843ac470b [AArch64] Enable the codegenprepare optimization that promotes operation to form
extended loads.
Implement the related target lowering hook so that the optimization has a better
estimation of the cost of an extension.

rdar://problem/19267165

llvm-svn: 233753
2015-03-31 20:52:32 +00:00
Daniel Sanders f731eee322 [aarch64] Distinguish the 'Q' and 'm' inline assembly memory constraints.
Summary:
But still handle them the same way since I don't know how they differ on
this target.

Clang also has code for 'Ump', 'Utf', 'Usa', and 'Ush' but calls
llvm_unreachable() on this code path so they are not converted to a
constraint id at the moment.

No functional change intended.

Reviewers: t.p.northover

Subscribers: aemerson, llvm-commits

Differential Revision: http://reviews.llvm.org/D8177

llvm-svn: 232941
2015-03-23 11:33:15 +00:00
Daniel Sanders bf5b80f5f9 Make each target map all inline assembly memory constraints to InlineAsm::Constraint_m. NFC.
Summary:
This is instead of doing this in target independent code and is the last
non-functional change before targets begin to distinguish between
different memory constraints when selecting code for the ISD::INLINEASM
node.

Next, each target will individually move away from the idea that all
memory constraints behave like 'm'.

Subscribers: jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D8173

llvm-svn: 232373
2015-03-16 13:13:41 +00:00
Ahmed Bougacha fab5892f8b [AArch64] Avoid going through GPRs for across-vector instructions.
This adds new node types for each intrinsic.
For instance, for addv, we have AArch64ISD::UADDV, such that:
  (v4i32 (uaddv ...))
is the same as
  (v4i32 (scalar_to_vector (i32 (int_aarch64_neon_uaddv ...))))
that is,
  (v4i32 (INSERT_SUBREG (v4i32 (IMPLICIT_DEF)),
           (i32 (int_aarch64_neon_uaddv ...)), ssub)

In a combine, we transform all such across-vector-lanes intrinsics to:

  (i32 (extract_vector_elt (uaddv ...), 0))

This has one big advantage: by making the extract_element explicit, we
enable the existing patterns for lane-aware instructions to fire.
This lets us avoid needlessly going through the GPRs.  Consider:

    uint32x4_t test_mul(uint32x4_t a, uint32x4_t b) {
        return vmulq_n_u32(a, vaddvq_u32(b));
    }

We now generate:
    addv.4s  s1, v1
    mul.4s   v0, v0, v1[0]
instead of the previous:
    addv.4s  s1, v1
    fmov     w8, s1
    dup.4s   v1, w8
    mul.4s   v0, v1, v0

rdar://20044838

llvm-svn: 231840
2015-03-10 20:45:38 +00:00
JF Bastien f14889ee34 Mutate TargetLowering::shouldExpandAtomicRMWInIR to specifically dictate how AtomicRMWInsts are expanded.
Summary:
In PNaCl, most atomic instructions have their own @llvm.nacl.atomic.* function, each one, with a few exceptions, represents a consistent behaviour across all NaCl-supported targets. Unfortunately, the atomic RMW operations nand, [u]min, and [u]max aren't directly represented by any such @llvm.nacl.atomic.* function. This patch refines shouldExpandAtomicRMWInIR in TargetLowering so that a future `Le32TargetLowering` class can selectively inform the caller how the target desires the atomic RMW instruction to be expanded (ie via load-linked/store-conditional for ARM/AArch64, via cmpxchg for X86/others?, or not at all for Mips) if at all.

This does not represent a behavioural change and as such no tests were added.

Patch by: Richard Diamond.

Reviewers: jfb

Reviewed By: jfb

Subscribers: jfb, aemerson, t.p.northover, llvm-commits

Differential Revision: http://reviews.llvm.org/D7713

llvm-svn: 231250
2015-03-04 15:47:57 +00:00
Kristof Beyls aea8461820 Fix PR22408 - LLVM producing AArch64 TLS relocations that GNU linkers cannot handle yet.
As is described at http://llvm.org/bugs/show_bug.cgi?id=22408, the GNU linkers
ld.bfd and ld.gold currently only support a subset of the whole range of AArch64
ELF TLS relocations. Furthermore, they assume that some of the code sequences to
access thread-local variables are produced in a very specific sequence.
When the sequence is not as the linker expects, it can silently mis-relaxe/mis-optimize
the instructions.
Even if that wouldn't be the case, it's good to produce the exact sequence,
as that ensures that linkers can perform optimizing relaxations.

This patch:

* implements support for 16MiB TLS area size instead of 4GiB TLS area size. Ideally clang
  would grow an -mtls-size option to allow support for both, but that's not part of this patch.
* by default doesn't produce local dynamic access patterns, as even modern ld.bfd and ld.gold
  linkers do not support the associated relocations. An option (-aarch64-elf-ldtls-generation)
  is added to enable generation of local dynamic code sequence, but is off by default.
* makes sure that the exact expected code sequence for local dynamic and general dynamic
  accesses is produced, by making use of a new pseudo instruction. The patch also removes
  two (AArch64ISD::TLSDESC_BLR, AArch64ISD::TLSDESC_CALL) pre-existing AArch64-specific pseudo
  SDNode instructions that are superseded by the new one (TLSDESC_CALLSEQ).

llvm-svn: 231227
2015-03-04 09:12:08 +00:00