Commit Graph

48120 Commits

Author SHA1 Message Date
Sjoerd Meijer 3b599d75d5 [AArch64] Armv8.4-A: Virtualization system registers
This adds the Secure EL2 extension.

Differential Revision: https://reviews.llvm.org/D48711

llvm-svn: 335962
2018-06-29 11:03:15 +00:00
Simon Pilgrim aab8660e23 [X86][SSE] Support v16i8/v32i8 vector rotations
This uses the same technique as for shifts - split the rotation into 4/2/1-bit partial rotations and select those partials based on the amount bit, making use of PBLENDVB if available. This halves the use of PBLENDVB compared to expanding to shifts, which can be a slow op.

Unfortunately I haven't found a decent way to share much of this code with the shift equivalent.

Differential Revision: https://reviews.llvm.org/D48655

llvm-svn: 335957
2018-06-29 09:36:39 +00:00
Sjoerd Meijer 195e904002 [ARM][AArch64] Armv8.4-A Enablement
Initial patch adding assembly support for Armv8.4-A.

Besides adding v8.4 as a supported architecture to the usual places, this also
adds target features for the different crypto algorithms. Armv8.4-A introduced
new crypto algorithms, made them optional, and allows different combinations:

- none of the v8.4 crypto functions are supported, which is independent of the
  implementation of the Armv8.0 SHA1 and SHA2 instructions.
- the v8.4 SHA512 and SHA3 support is implemented, in this case the Armv8.0
  SHA1 and SHA2 instructions must also be implemented.
- the v8.4 SM3 and SM4 support is implemented, which is independent of the
  implementation of the Armv8.0 SHA1 and SHA2 instructions.
- all of the v8.4 crypto functions are supported, in this case the Armv8.0 SHA1
  and SHA2 instructions must also be implemented.

The v8.4 crypto instructions are added to AArch64 only, and not AArch32,
and are made optional extensions to Armv8.2-A.

The user-facing Clang options will map on these new target features, their
naming will be compatible with GCC and added in follow-up patches.

The Armv8.4-A instruction sets can be downloaded here:
https://developer.arm.com/products/architecture/a-profile/exploration-tools

Differential Revision: https://reviews.llvm.org/D48625

llvm-svn: 335953
2018-06-29 08:43:19 +00:00
Craig Topper 875e9f8fa4 [X86] Remove masking from the avx512 packed sqrt intrinsics. Use select in IR instead.
While there improve the coverage of the intrinsic testing and add fast-isel tests.

llvm-svn: 335944
2018-06-29 05:43:26 +00:00
Tom Stellard c5a154db48 AMDGPU: Separate R600 and GCN TableGen files
Summary:
We now have two sets of generated TableGen files, one for R600 and one
for GCN, so each sub-target now has its own tables of instructions,
registers, ISel patterns, etc.  This should help reduce compile time
since each sub-target now only has to consider information that
is specific to itself.  This will also help prevent the R600
sub-target from slowing down new features for GCN, like disassembler
support, GlobalISel, etc.

Reviewers: arsenm, nhaehnle, jvesely

Reviewed By: arsenm

Subscribers: MatzeB, kzhuravl, wdng, mgorny, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D46365

llvm-svn: 335942
2018-06-28 23:47:12 +00:00
Eli Friedman 65d885e376 [ARM] Assert that ARMDAGToDAGISel creates valid UBFX/SBFX nodes.
We don't ever check these again (unless you're using
-fno-integrated-as), so make sure the extracted bits are well-defined.

I don't think it's possible to trigger any of the assertions on trunk,
but it's difficult to prove.  (The first one depends on DAGCombine to
minimize the number of set bits in AND masks; I think the others are
mathematically impossible to hit.)

llvm-svn: 335931
2018-06-28 21:49:41 +00:00
Benjamin Kramer 23d8282047 [NVPTX] Delete dead code
No functionality change.

llvm-svn: 335913
2018-06-28 20:05:35 +00:00
Eli Friedman 6613efbd4e [ARM] Add missing Thumb2 assembler diagnostics.
Mostly just adding checks for Thumb2 instructions which correspond to
ARM instructions which already had diagnostics. While I'm here, also fix
ARM-mode strd to check the input registers correctly.

Differential Revision: https://reviews.llvm.org/D48610

llvm-svn: 335909
2018-06-28 19:53:12 +00:00
Simon Pilgrim c09b5e31d7 Remove unnecessary semicolon. NFCI.
Fixes -Wpedantic warning.

llvm-svn: 335901
2018-06-28 18:37:16 +00:00
Craig Topper 90317d1d94 [X86] Suppress load folding into and/or/xor if it will prevent matching btr/bts/btc.
This is a follow up to r335753. At the time I forgot about isProfitableToFold which makes this pretty easy.

Differential Revision: https://reviews.llvm.org/D48706

llvm-svn: 335895
2018-06-28 17:58:01 +00:00
Jonas Devlieghere b757fc3878 Revert "Re-land r335297 "[X86] Implement more of x86-64 large and medium PIC code models""
Reverting because this is causing failures in the LLDB test suite on
GreenDragon.

  LLVM ERROR: unsupported relocation with subtraction expression, symbol
  '__GLOBAL_OFFSET_TABLE_' can not be undefined in a subtraction
  expression

llvm-svn: 335894
2018-06-28 17:56:43 +00:00
Jessica Paquette dafa198c96 [MachineOutliner] Define MachineOutliner support in TargetOptions
Targets should be able to define whether or not they support the outliner
without the outliner being added to the pass pipeline. Before this, the
outliner pass would be added, and ask the target whether or not it supports the
outliner.

After this, it's possible to query the target in TargetPassConfig, before the
outliner pass is created. This ensures that passing -enable-machine-outliner
will not modify the pass pipeline of any target that does not support it.

https://reviews.llvm.org/D48683

llvm-svn: 335887
2018-06-28 17:45:43 +00:00
Simon Pilgrim 99f701673d [WebAssembly] Add getSetCCResultType placeholder override to handle vector compare results.
Necessary to get the rL335821 bugfix (which was reverted at rL335871) un-reverted.

llvm-svn: 335884
2018-06-28 17:27:09 +00:00
Matthias Braun da5e7e11d1 SelectionDAGBuilder, mach-o: Skip trap after noreturn call (for Mach-O)
Add NoTrapAfterNoreturn target option which skips emission of traps
behind noreturn calls even if TrapUnreachable is enabled.

Enable the feature on Mach-O to save code size; Comments suggest it is
not possible to enable it for the other users of TrapUnreachable.

rdar://41530228

DifferentialRevision: https://reviews.llvm.org/D48674
llvm-svn: 335877
2018-06-28 17:00:45 +00:00
Stanislav Mekhanoshin 67aa18f165 [AMDGPU] Early expansion of 32 bit udiv/urem
This allows hoisting of a common code, for instance if denominator
is loop invariant. Current change is expansion only, adding licm to
the target pass list going to be a separate patch. Given this patch
changes to codegen are minor as the expansion is similar to that on
DAG. DAG expansion still must remain for R600.

Differential Revision: https://reviews.llvm.org/D48586

llvm-svn: 335868
2018-06-28 15:59:18 +00:00
Stanislav Mekhanoshin 298a61590a [AMDGPU] Overload llvm.amdgcn.fmad.ftz to support f16
Differential Revision: https://reviews.llvm.org/D48677

llvm-svn: 335866
2018-06-28 15:24:46 +00:00
Sjoerd Meijer c89ca5582a [ARM] Parallel DSP Pass
Armv6 introduced instructions to perform 32-bit SIMD operations. The purpose of
this pass is to do some straightforward IR pattern matching to create ACLE DSP
intrinsics, which map on these 32-bit SIMD operations.

Currently, only the SMLAD instruction gets recognised. This instruction
performs two multiplications with 16-bit operands, and stores the result in an
accumulator. We will follow this up with patches to recognise SMLAD in more
cases, and also to generate other DSP instructions (like e.g. SADD16).

Patch by: Sam Parker and Sjoerd Meijer

Differential Revision: https://reviews.llvm.org/D48128

llvm-svn: 335850
2018-06-28 12:55:29 +00:00
Hans Wennborg a257376003 s/TablesChecked/TableChecked/ after r335823
llvm-svn: 335831
2018-06-28 10:24:38 +00:00
Matt Arsenault 75e7192ba3 AMDGPU: Remove MFI::ABIArgOffset
We have too many mechanisms for tracking the various offsets
used for kernel arguments, so remove one. There's still a lot of
confusion with these because there are two different "implicit"
argument areas located at the beginning and end of the kernarg
segment.

Additionally, the offset was determined based on the memory
size of the split element types. This would break in a future
commit where v3i32 is decomposed into separate i32 pieces.

llvm-svn: 335830
2018-06-28 10:18:55 +00:00
Matt Arsenault 1fb9013368 AMDGPU: Error on calls from graphics shaders
In principle nothing should stop these from working, but
work is necessary to create an ABI for dealing with the stack
related registers.

llvm-svn: 335829
2018-06-28 10:18:36 +00:00
Matt Arsenault 12269dda5c AMDGPU: Fix AMDGPUCodeGenPrepare using uninitialized AMDGPUAS struct
Not sure how this wasn't noticed before.

llvm-svn: 335828
2018-06-28 10:18:23 +00:00
Matt Arsenault 513e0c0ea4 AMDGPU: Fix assert on aggregate type kernel arguments
Just fix the crash for now by not doing the optimization since
figuring out how to properly convert the bits for an arbitrary
struct is a pain.

Also fix a crash when there is only an empty struct argument.

llvm-svn: 335827
2018-06-28 10:18:11 +00:00
Benjamin Kramer f9613b2995 Unify sorted asserts to use the existing atomic pattern
These are all benign races and only visible in !NDEBUG. tsan complains
about it, but a simple atomic bool is sufficient to make it happy.

llvm-svn: 335823
2018-06-28 10:03:45 +00:00
Craig Topper ec5d568ac1 [X86] Use PatFrag with hardcoded numbers for FROUND_NO_EXC/FROUND_CURRENT instead of ImmLeafs with predicates where one of the two numbers was hardcoded.
This more efficient for the isel table generator since we can use CheckChildInteger instead of MoveChild, CheckPredicate, MoveParent. This reduced the table size by 1-2K.

I wish there was a way to share the values with X86BaseInfo.h and still use a PatFrag like this. These numbers are fixed by the X86 intrinsic spec going back many years and we should never need to change them. So we shouldn't waste table bytes to support sharing.

llvm-svn: 335806
2018-06-28 01:45:44 +00:00
Craig Topper ab70f58891 [X86] Change how we prefer shift by immediate over folding a load into a shift.
BMI2 added new shift by register instructions that have the ability to fold a load.

Normally without doing anything special isel would prefer folding a load over folding an immediate because the load folding pattern has higher "complexity". This would require an instruction to move the immediate into a register. We would rather fold the immediate instead and have a separate instruction for the load.

We used to enforce this priority by artificially lowering the complexity of the load pattern.

This patch changes this to instead reject the load fold in isProfitableToFoldLoad if there is an immediate. This is more consistent with other binops and feels less hacky.

llvm-svn: 335804
2018-06-28 00:47:41 +00:00
Benjamin Kramer e214f046af [X86] Make folding table checking threadsafe
This is a benign race, but tsan likes to complain about it. Just make it
happy.

llvm-svn: 335788
2018-06-27 21:01:53 +00:00
Craig Topper 880e34ed45 [X86] In X86DAGToDAGISel::PreprocessISelDAG, make sure we don't access N after we delete it.
If we turn X86ISD::AND into ISD::AND, we delete N. But we were continuing onto the next block of code even though N no longer existed.

Just happened to notice it. I assume asan didn't notice it because we explicitly unpoison deleted nodes and give them a DELETE_NODE opcode.

llvm-svn: 335787
2018-06-27 20:58:46 +00:00
Sameer AbuAsal 9b65ffb097 [RISCV] Add machine function pass to merge base + offset
Summary:
   In r333455 we added a peephole to fix the corner cases that result
   from separating base + offset lowering of global address.The
   peephole didn't handle some of the cases because it only has a basic
   block view instead of a function level view.

   This patch replaces that logic with a machine function pass. In
   addition to handling the original cases it handles uses of the global
   address across blocks in function and folding an offset from LW\SW
   instruction. This pass won't run for OptNone compilation, so there
   will be a negative impact overall vs the old approach at O0.

Reviewers: asb, apazos, mgrang

Reviewed By: asb

Subscribers: MartinMosbeck, brucehoult, the_o, rogfer01, mgorny, rbar, johnrusso, simoncook, niosHD, kito-cheng, shiva0217, zzheng, llvm-commits, edward-jones

Differential Revision: https://reviews.llvm.org/D47857

llvm-svn: 335786
2018-06-27 20:51:42 +00:00
Fangrui Song b0d57a535b [X86] Fix unmatched parenthesis in r335768
llvm-svn: 335769
2018-06-27 19:12:07 +00:00
Craig Topper 6bea2c7f9b [X86] Teach the disassembler to use %eiz/%riz instead of NoRegister when the SIB byte is present, but doesn't encode an index register and there was another shorter encoding that would achieve the same result.
The %eiz/%riz are dummy registers that force the encoder to emit a SIB byte when it normally wouldn't. By emitting them in the disassembly output we ensure that assembling the disassembler output would also produce a SIB byte.

This should match the behavior of objdump from binutils.

llvm-svn: 335768
2018-06-27 19:03:36 +00:00
Daniel Sanders bdeb880d14 [globalisel][legalizer] Add AtomicOrdering to LegalityQuery and use it in AArch64
Now that we have the ability to legalize based on MMO's. Add support for
legalizing based on AtomicOrdering and use it to correct the legalization
of the atomic instructions.

Also extend all() to be a variadic template as this ruleset now requires
3 and 4 argument versions.

llvm-svn: 335767
2018-06-27 19:03:21 +00:00
Jessica Paquette f472f6159a [MachineOutliner] Don't outline sequences where x16/x17/nzcv are live across
It isn't safe to outline sequences of instructions where x16/x17/nzcv live
across the sequence.

This teaches the outliner to check whether or not a specific canidate has
x16/x17/nzcv live across it and discard the candidate in the case that that is
true.

https://bugs.llvm.org/show_bug.cgi?id=37573
https://reviews.llvm.org/D47655

llvm-svn: 335758
2018-06-27 17:43:27 +00:00
Craig Topper 812fcb35e7 [X86] Use bts/btr/btc for single bit set/clear/complement of a variable bit position
If we are just modifying a single bit at a variable bit position we can use the BT* instructions to make the change instead of shifting a 1(or rotating a -1) and doing a binop. These instruction also ignore the upper bits of their index input so we can also remove an and if one is present on the index.

Fixes PR37938.

llvm-svn: 335754
2018-06-27 16:47:39 +00:00
Craig Topper 31cbe75b3b [X86] Rename the autoupgraded of packed fp compare and fpclass intrinsics that don't take a mask as input to exclude '.mask.' from their name.
I think the intrinsics named 'avx512.mask.' should refer to the previous behavior of taking a mask argument in the intrinsic instead of using a 'select' or 'and' instruction in IR to accomplish the masking. This is more consistent with the goal that eventually we will have no intrinsics that have masking builtin. When we reach that goal, we should have no intrinsics named "avx512.mask".

llvm-svn: 335744
2018-06-27 15:57:53 +00:00
Stanislav Mekhanoshin 1a1687f1bb [AMDGPU] Convert rcp to rcp_iflag
If a source of rcp instruction is a result of any conversion from
an integer convert it into rcp_iflag instruction. No FP exception
can ever happen except division by zero if a single precision rcp
argument is a representation of an integral number.

Differential Revision: https://reviews.llvm.org/D48569

llvm-svn: 335742
2018-06-27 15:33:33 +00:00
Luke Geeson 316327150b [AArch64] Reverting FP16 vcvth_n_s64_f16 to fix
llvm-svn: 335737
2018-06-27 14:34:40 +00:00
Adhemerval Zanella cadcfed7aa [AArch64] Add custom lowering for v4i8 trunc store
This patch adds a custom trunc store lowering for v4i8 vector types.
Since there is not v.4b register, the v4i8 is promoted to v4i16 (v.4h)
and default action for v4i8 is to extract each element and issue 4
byte stores.

A better strategy would be to extended the promoted v4i16 to v8i16
(with undef elements) and extract and store the word lane which
represents the v4i8 subvectores. The construction:

  define void @foo(<4 x i16> %x, i8* nocapture %p) {
    %0 = trunc <4 x i16> %x to <4 x i8>
    %1 = bitcast i8* %p to <4 x i8>*
    store <4 x i8> %0, <4 x i8>* %1, align 4, !tbaa !2
    ret void
  }

Can be optimized from:

  umov    w8, v0.h[3]
  umov    w9, v0.h[2]
  umov    w10, v0.h[1]
  umov    w11, v0.h[0]
  strb    w8, [x0, #3]
  strb    w9, [x0, #2]
  strb    w10, [x0, #1]
  strb    w11, [x0]
  ret

To:

  xtn     v0.8b, v0.8h
  str     s0, [x0]
  ret

The patch also adjust the memory cost for autovectorization, so the C
code:

  void foo (const int *src, int width, unsigned char *dst)
  {
    for (int i = 0; i < width; i++)
       *dst++ = *src++;
  }

can be vectorized to:

  .LBB0_4:                                // %vector.body
                                          // =>This Inner Loop Header: Depth=1
        ldr     q0, [x0], #16
        subs    x12, x12, #4            // =4
        xtn     v0.4h, v0.4s
        xtn     v0.8b, v0.8h
        st1     { v0.s }[0], [x2], #4
        b.ne    .LBB0_4

Instead of byte operations.

llvm-svn: 335735
2018-06-27 13:58:46 +00:00
Ivan A. Kosarev 7231598fce [NEON] Support vldNq intrinsics in AArch32 (LLVM part)
This patch adds support for the q versions of the dup
(load-to-all-lanes) NEON intrinsics, such as vld2q_dup_f16() for
example.

Currently, non-q versions of the dup intrinsics are implemented
in clang by generating IR that first loads the elements of the
structure into the first lane with the lane (to-single-lane)
intrinsics, and then propagating it other lanes. There are at
least two problems with this approach. First, there are no
double-spaced to-single-lane byte-element instructions. For
example, there is no such instruction as 'vld2.8 { d0[0], d2[0]
}, [r0]'. That means we cannot rely on the to-single-lane
intrinsics and instructions to implement the q versions of the
dup intrinsics. Note that to-all-lanes instructions do support
all sizes of data items, including bytes.

The second problem with the current approach is that we need a
separate vdup instruction to propagate the structure to each
lane. So for vld4q_dup_f16() we would need four vdup instructions
in addition to the initial vld instruction.

This patch introduces dup LLVM intrinsics and reworks handling of
the currently supported (non-q) NEON dup intrinsics to expand
them into those LLVM intrinsics, thus eliminating the need for
using to-single-lane intrinsics and instructions.

Additionally, this patch adds support for u64 and s64 dup NEON
intrinsics. These are marked as Arch64-only in the ARM NEON
Reference, but it seems there are no reasons to not support them
in AArch32 mode. Please correct, if that is wrong.

That's what we generate with this patch applied:

vld2q_dup_f16:
  vld2.16 {d0[], d2[]}, [r0]
  vld2.16 {d1[], d3[]}, [r0]

vld3q_dup_f16:
  vld3.16 {d0[], d2[], d4[]}, [r0]
  vld3.16 {d1[], d3[], d5[]}, [r0]

vld4q_dup_f16:
  vld4.16 {d0[], d2[], d4[], d6[]}, [r0]
  vld4.16 {d1[], d3[], d5[], d7[]}, [r0]

Differential Revision: https://reviews.llvm.org/D48439

llvm-svn: 335733
2018-06-27 13:57:52 +00:00
Luke Geeson 68cb233c0f [AArch64] Remove Duplicate FP16 Patterns with same encoding, match on existing patterns
llvm-svn: 335715
2018-06-27 09:20:13 +00:00
Konstantin Zhuravlyov 30f03b3bc0 AMDGPU/NFC: Fix typo in comment
llvm-svn: 335707
2018-06-27 05:36:03 +00:00
Craig Topper 33aba0eb4c [X86] Don't store register and memory FMA3 opcodes in the same X86InstrFMA3Group.
Nothing was using this relationship. By splitting them we no longer need to worry about register or memory entries being empty in a group.

The memory folding tables in X86InstrInfo.cpp can be used to access this relationship if needed.

llvm-svn: 335694
2018-06-27 00:42:24 +00:00
Konstantin Zhuravlyov 777477705a AMDGPU: Silence unused warnings in waitcnt insertion pass in release build
Differential Revision: https://reviews.llvm.org/D48607

llvm-svn: 335669
2018-06-26 21:33:38 +00:00
Jessica Paquette 67599c2e1e [X86][AsmParser] Recommit r335658
Recommit of r335658 so that it does not change the behaviour of any
existing error output.

llvm-svn: 335668
2018-06-26 21:30:34 +00:00
Jessica Paquette 0a80af0761 Revert "[X86][AsmParser] Emit an error when RIP-relative instructions are used in 32-bit mode"
This reverts commit 4850a9aae8b38c7deadc103d634ec7397e6c323b.

It caused MC/X86/x86_errors.s to fail. Will fix and recommit shortly.

llvm-svn: 335660
2018-06-26 20:57:19 +00:00
Jessica Paquette 0e40d4bfc3 [X86][AsmParser] Emit an error when RIP-relative instructions are used in 32-bit mode
Right now, when we use RIP-relative instructions in 32-bit mode, we'll just
assert and crash.

This adds an error message which tells the user that they can't do that in
32-bit mode, so that we don't crash (and also can see the issue outside of
assert builds).

llvm-svn: 335658
2018-06-26 20:33:46 +00:00
Stanislav Mekhanoshin dacda79ee6 [AMDGPU] Add llvm.amdgcn.fmad.ftz intrinsic
This intrinsic selects v_mad_f32 regardless of fp32 denorm support.

Differential Revision: https://reviews.llvm.org/D48573

llvm-svn: 335654
2018-06-26 20:04:19 +00:00
Matt Arsenault 8c4a35237a AMDGPU: Add pass to lower kernel arguments to loads
This replaces most argument uses with loads, but for
now not all.

The code in SelectionDAG for calling convention lowering
is actively harmful for amdgpu_kernel. It attempts to
split the argument types into register legal types, which
results in low quality code for arbitary types. Since
all kernel arguments are passed in memory, we just want the
raw types.

I've tried a couple of methods of mitigating this in SelectionDAG,
but it's easier to just bypass this problem alltogether. It's
possible to hack around the problem in the initial lowering,
but the real problem is the DAG then expects to be able to use
CopyToReg/CopyFromReg for uses of the arguments outside the block.

Exposing the argument loads in the IR also has the advantage
that the LoadStoreVectorizer can merge them.

I'm not sure the best approach to dealing with the IR
argument list is. The patch as-is just leaves the IR arguments
in place, so all the existing code will still compute the same
kernarg size and pointlessly lowers the arguments.

Arguably the frontend should emit kernels with an empty argument
list in the first place. Alternatively a dummy array could be
inserted as a single argument just to reserve space.

This does have some disadvantages. Local pointer kernel arguments can
no longer have AssertZext placed  on them as the equivalent !range
metadata is not valid on pointer  typed loads. This is mostly bad
for SI which needs to know about the known bits in order to use the
DS instruction offset, so in this case this is not done.

More importantly, this skips noalias arguments since this pass
does not yet convert this to the equivalent !alias.scope and !noalias
metadata. Producing this metadata correctly seems to be tricky,
although this logically is the same as inlining into a function which
doesn't exist. Additionally, exposing these loads to the vectorizer
may result in degraded aliasing information if a pointer load is
merged with another argument load.

I'm also not entirely sure this is preserving the current clover
ABI, although I would greatly prefer if it would stop widening
arguments and match the HSA ABI. As-is I think it is extending
< 4-byte arguments to 4-bytes but doesn't align them to 4-bytes.

llvm-svn: 335650
2018-06-26 19:10:00 +00:00
Brendon Cahoon b7169c435a [Hexagon] Add a "generic" cpu
Add the generic processor for Hexagon so that it can be used
with 3rd party programs that create a back-end with the
"generic" CPU. This patch also enables the JIT for Hexagon.

Differential Revision: https://reviews.llvm.org/D48571

llvm-svn: 335641
2018-06-26 18:44:05 +00:00
Simon Pilgrim aa2bf2be31 [TargetLowering] isVectorClearMaskLegal - use ArrayRef<int> instead of const SmallVectorImpl<int>&
This is more generic and matches isShuffleMaskLegal.

Differential Revision: https://reviews.llvm.org/D48591

llvm-svn: 335605
2018-06-26 14:15:31 +00:00
Than McIntosh 3190993a02 [X86,ARM] Retain split-stack prolog check for sibling calls
Summary:
If a routine with no stack frame makes a sibling call, we need to
preserve the stack space check even if the local stack frame is empty,
since the call target could be a "no-split" function (in which case
the linker needs to be able to fix up the prolog sequence in order to
switch to a larger stack).

This fixes PR37807.

Reviewers: cherry, javed.absar

Subscribers: srhines, llvm-commits

Differential Revision: https://reviews.llvm.org/D48444

llvm-svn: 335604
2018-06-26 14:11:30 +00:00