Commit Graph

2007 Commits

Author SHA1 Message Date
Reid Kleckner
b3275b9fca Fix ARM intrinsics-overflow.ll test on Windows
Windows on ARM only supports thumb mode execution, so we have to
explicitly pick some non-Windows OS to test ARM mode codegen.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208448 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-09 21:52:48 +00:00
Louis Gerbarg
7a9fbab182 Add custom lowering for add/sub with overflow intrinsics to ARM
This patch adds support to ARM for custom lowering of the
llvm.{u|s}add.with.overflow.i32 intrinsics for i32/i64. This is particularly useful
for handling idiomatic saturating math functions as generated by
InstCombineCompare.

Test cases included.

rdar://14853450

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208435 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-09 17:02:49 +00:00
James Molloy
bfaccd494f Attempt to pacify the bots - this commit requires asserts.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208424 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-09 16:20:53 +00:00
Oliver Stannard
e2948385b9 ARM: HFAs must be passed in consecutive registers
When using the ARM AAPCS, HFAs (Homogeneous Floating-point Aggregates) must
be passed in a block of consecutive floating-point registers, or on the stack.
This means that unused floating-point registers cannot be back-filled with
part of an HFA, however this can currently happen. This patch, along with the
corresponding clang patch (http://reviews.llvm.org/D3083) prevents this.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208413 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-09 14:01:47 +00:00
Saleem Abdulrasool
74d614a6fc ARM: support PIC on Windows on ARM
Handle lowering of global addresses for PIC mode compilation on Windows.  Always
use the movw/movt load to load the address as Windows on ARM requires ARMv7+ and
is a pure Thumb environment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208385 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-09 00:58:32 +00:00
Justin Bogner
73773ce844 test/CodeGen: Check that the correct register is used in a store
This tightens up r208351 to ensure that a store is fed with the
correct value.

Thanks to Quentin Colombet for spotting this!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208368 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-08 22:45:07 +00:00
Justin Bogner
8115f93cdb Make a CodeGen test more robust against vector register selection
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208351 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-08 18:53:56 +00:00
Saleem Abdulrasool
f37151a2fd test: fix test on Windows
When building on Windows, the default target is Windows.  Windows on ARM does
not support ARM mode compilation, resulting in test failures.  Simply specify a
triple to ensure that we are testing the correct behaviour.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208340 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-08 17:11:29 +00:00
Christian Pirker
c60a59cad3 ARM big endian function argument passing
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208316 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-08 14:06:24 +00:00
Joerg Sonnenberger
2ecdcdc026 Allow using normal .eh_frame based unwinding on ARM. Use the same
encodings as x86. Use this exception model for NetBSD.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208166 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-07 07:49:34 +00:00
Saleem Abdulrasool
0029e2d665 ARM: fix WoA PEI instruction selection
The ARM::BLX instruction is an ARM mode instruction.  The Windows on ARM target
is limited to Thumb instructions.  Correctly use the thumb mode tBLXr
instruction.  This would manifest as an errant write into the object file as the
instruction is 4-bytes in length rather than 2.  The result would be a corrupted
object file that would eventually result in an executable that would crash at
runtime.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208152 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-07 03:03:27 +00:00
Joerg Sonnenberger
b84f890bc3 If a function needs a frame pointer, but r11 (aka fp) has not been used,
remove it from the list of unspilled registers. Otherwise the following
attempt to keep the stack aligned by picking an extra GPR register to
spill will not work as it picks up r11.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208129 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-06 20:43:01 +00:00
Renato Golin
22f779d1fd Implememting named register intrinsics
This patch implements the infrastructure to use named register constructs in
programs that need access to specific registers (bare metal, kernels, etc).

So far, only the stack pointer is supported as a technology preview, but as it
is, the intrinsic can already support all non-allocatable registers from any
architecture.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208104 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-06 16:51:25 +00:00
Saleem Abdulrasool
8d538f1122 CodeGen: correct memset emittance for WoA
Windows on ARM does not conform to AEABI.  However, memset would be emitted
using the AEABI signature, resulting in inverted parameters.  Handle this
special case appropriately.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207943 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-04 23:13:21 +00:00
Saleem Abdulrasool
4fc5273a49 CodeGen: strengthen WoA AEABI avoidance tests
Add additional test cases for WoA AEABI avoidance checking.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207942 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-04 23:13:18 +00:00
Saleem Abdulrasool
ddbde80aae ARM: support stack probe emission for Windows on ARM
This introduces the stack lowering emission of the stack probe function for
Windows on ARM. The stack on Windows on ARM is a dynamically paged stack where
any page allocation which crosses a page boundary of the following guard page
will cause a page fault. This page fault must be handled by the kernel to
ensure that the page is faulted in. If this does not occur and a write access
any memory beyond that, the page fault will go unserviced, resulting in an
abnormal program termination.

The watermark for the stack probe appears to be at 4080 bytes (for
accommodating the stack guard canaries and stack alignment) when SSP is
enabled.  Otherwise, the stack probe is emitted on the page size boundary of
4096 bytes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207615 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 07:05:07 +00:00
Saleem Abdulrasool
745fff806d ARM: partially handle 32-bit relocations for WoA
IMAGE_REL_ARM_MOV32T relocations require that the movw/movt pair-wise
relocation is not split up and reordered. When expanding the mov32imm
pseudo-instruction, create a bundle if the machine operand is referencing an
address.  This helps ensure that the relocatable address load is not reordered
by subsequent passes.

Unfortunately, this only partially handles the case as the Constant Island Pass
occurs after the instructions are unbundled and does not properly handle
bundles.  That is a more fundamental issue with the pass itself and beyond the
scope of this change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207608 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 04:54:58 +00:00
Tim Northover
65baf804ba ARM: fix test after change to indirect symbol emission.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207519 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 10:13:10 +00:00
Tim Northover
8ea9566fee ARM: emit hidden stubs into a proper non_lazy_symbol_pointer section.
rdar://problem/16660411

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207517 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 10:06:05 +00:00
Saleem Abdulrasool
25bc383612 ARM: remove @llvm.arm.sevl
This intrinsic is no longer needed with the new @llvm.arm.hint(i32) intrinsic
which provides a generic, extensible manner for adding hint instructions.  This
functionality can now be represented as @llvm.arm.hint(i32 5).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207246 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 17:51:25 +00:00
Saleem Abdulrasool
04f826c062 ARM: provide a new generic hint intrinsic
Introduce the llvm.arm.hint(i32) intrinsic that can be used to inject hints into
the instruction stream. This is particularly useful for generating IR from a
compiler where the user may inject an intrinsic (e.g. __yield). These are then
pattern substituted into the correct instruction which already existed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207242 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 17:24:24 +00:00
Reid Kleckner
aaff72bcd8 Fix test/CodeGen/arm.ll
The 'CHECK: add' line was occasionally matching against the filename,
breaking the subsequent CHECK-NOT.  Also use CHECK-LABEL.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206936 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-23 01:09:29 +00:00
Tim Northover
74bd57b16b ARM: disable emission of __XYZvfp in soft-float environment.
The point of these calls is to allow Thumb-1 code to make use of the VFP unit
to perform its operations. This is not desirable with -msoft-float, since most
of the reasons you'd want that apply equally to the runtime library.

rdar://problem/13766161

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206874 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-22 10:10:09 +00:00
Akira Hatanaka
f3930395f5 Make FastISel::SelectInstruction return before target specific fast-isel code
handles Intrinsic::trap if TargetOptions::TrapFuncName is set.

This fixes a bug in which the trap function was not taken into consideration
when a program was compiled without optimization (at -O0).

<rdar://problem/16291933>



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206323 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-15 21:30:06 +00:00
Akira Hatanaka
268c0509a9 Fix a bug in which BranchProbabilityInfo wasn't setting branch weights of basic blocks inside loops correctly.
Previously, BranchProbabilityInfo::calcLoopBranchHeuristics would determine the weights of basic blocks inside loops even when it didn't have enough information to estimate the branch probabilities correctly. This patch fixes the function to exit early if it doesn't see any exit edges or back edges and let the later heuristics determine the weights.

This fixes PR18705 and <rdar://problem/15991090>.

Differential Revision: http://reviews.llvm.org/D3363



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206194 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-14 16:56:19 +00:00
Richard Trieu
b79d042e4e Fix 2008-03-05-SxtInRegBug.ll so that the CHECK-NOT will not match the filename.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206193 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-14 16:53:50 +00:00
Richard Trieu
6a871a361d Add extra checks to mvn.ll test to prevent the "f1" check from matching
on a directory name instead of the function name.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206104 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-12 04:47:04 +00:00
Hal Finkel
24517d023f Add the ability to use GEPs for address sinking in CGP
The current memory-instruction optimization logic in CGP, which sinks parts of
the address computation that can be adsorbed by the addressing mode, does this
by explicitly converting the relevant part of the address computation into
IR-level integer operations (making use of ptrtoint and inttoptr). For most
targets this is currently not a problem, but for targets wishing to make use of
IR-level aliasing analysis during CodeGen, the use of ptrtoint/inttoptr is a
problem for two reasons:
  1. BasicAA becomes less powerful in the face of the ptrtoint/inttoptr
  2. In cases where type-punning was used, and BasicAA was used
     to override TBAA, BasicAA may no longer do so. (this had forced us to disable
     all use of TBAA in CodeGen; something which we can now enable again)

This (use of GEPs instead of ptrtoint/inttoptr) is not currently enabled by
default (except for those targets that use AA during CodeGen), and so aside
from some PowerPC subtargets and SystemZ, there should be no change in
behavior. We may be able to switch completely away from the ptrtoint/inttoptr
sinking on all targets, but further testing is required.

I've doubled-up on a number of existing tests that are sensitive to the
address sinking behavior (including some store-merging tests that are
sensitive to the order of the resulting ADD operations at the SDAG level).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206092 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-12 00:59:48 +00:00
Reid Kleckner
bc1fd917f0 Move the segmented stack switch to a function attribute
This removes the -segmented-stacks command line flag in favor of a
per-function "split-stack" attribute.

Patch by Luqman Aden and Alex Crichton!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205997 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-10 22:58:43 +00:00
Saleem Abdulrasool
2abadea537 ARM: yet another round of ARM test clean ups
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205586 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 23:47:24 +00:00
Saleem Abdulrasool
5fe5b3dcc8 ARM: update even more tests
More updating of tests to be explicit about the target triple rather than
relying on the default target triple supporting ARM mode.

Indicate to lit that object emission is not yet available for Windows on ARM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205545 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 17:35:22 +00:00
Saleem Abdulrasool
27b1252c13 ARM: fixup more tests to specify the target more explicitly
This changes the tests that were targeting ARM EABI to explicitly specify the
environment rather than relying on the default.  This breaks with the new
Windows on ARM support when running the tests on Windows where the default
environment is no longer EABI.

Take the opportunity to avoid a pointless redirect (helps when trying to debug
with providing a command line invocation which can be copy and pasted) and
removing a few greps in favour of FileCheck.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205541 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 16:01:44 +00:00
Tim Northover
d5561bb1f0 ARM: tell LLVM about zext properties of ldrexb/ldrexh
Implementing this via ComputeMaskedBits has two advantages:
  + It actually works. DAGISel doesn't deal with the chains properly
    in the previous pattern-based solution, so they never trigger.
  + The information can be used in other DAG combines, as well as the
    trivial "get rid of truncs". For example if the trunc is in a
    different basic block.

rdar://problem/16227836

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205540 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 15:10:35 +00:00
Tim Northover
3eb87654a5 ARM: skip cmpxchg failure barrier if ordering is monotonic.
The terminal barrier of a cmpxchg expansion will be either Acquire or
SequentiallyConsistent. In either case it can be skipped if the
operation has Monotonic requirements on failure.

rdar://problem/15996804

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205535 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 13:06:54 +00:00
Tim Northover
badb137729 ARM: expand atomic ldrex/strex loops in IR
The previous situation where ATOMIC_LOAD_WHATEVER nodes were expanded
at MachineInstr emission time had grown to be extremely large and
involved, to account for the subtly different code needed for the
various flavours (8/16/32/64 bit, cmpxchg/add/minmax).

Moving this transformation into the IR clears up the code
substantially, and makes future optimisations much easier:

1. an atomicrmw followed by using the *new* value can be more
   efficient. As an IR pass, simple CSE could handle this
   efficiently.
2. Making use of cmpxchg success/failure orderings only has to be done
   in one (simpler) place.
3. The common "cmpxchg; did we store?" idiom can be exposed to
   optimisation.

I intend to gradually improve this situation within the ARM backend
and make sure there are no hidden issues before moving the code out
into CodeGen to be shared with (at least ARM64/AArch64, though I think
PPC & Mips could benefit too).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205525 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 11:44:58 +00:00
Silviu Baranga
3f11cd0d25 [ARM] When generating a vpaddl node the input lane type is not always the type of the
add operation since extract_vector_elt can perform an extend operation. Get the input lane
type from the vector on which we're performing the vpaddl operation on and extend or
truncate it to the output type of the original add node.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205523 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 10:44:27 +00:00
Saleem Abdulrasool
6d4e5ab349 ARM: fixup tests to specify the target more explicitly
This changes the tests that were targeting ARM EABI to explicitly specify the
environment rather than relying on the default.  This breaks with the new
Windows on ARM support when running the tests on Windows where the default
environment is no longer EABI.

Take the opportunity to avoid a pointless redirect (helps when trying to debug
with providing a command line invocation which can be copy and pasted) and
removing a few greps in favour of FileCheck.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205465 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-02 21:22:03 +00:00
Saleem Abdulrasool
396e5e328c ARM: update subtarget information for Windows on ARM
Update the subtarget information for Windows on ARM.  This enables using the MC
layer to target Windows on ARM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205459 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-02 20:32:05 +00:00
Oliver Stannard
af48fc4136 ARM: Add support for segmented stacks
Patch by Alex Crichton, ILyoan, Luqman Aden and Svetoslav.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205430 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-02 16:10:33 +00:00
Renato Golin
421397ac00 Remove duplicated DMB instructions
ARM specific optimiztion, finding places in ARM machine code where 2 dmbs
follow one another, and eliminating one of them.

Patch by Reinoud Elhorst.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205409 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-02 09:03:43 +00:00
Tim Northover
c077472250 ARM: add cyclone CPU with ZeroCycleZeroing feature.
The Cyclone CPU is similar to swift for most LLVM purposes, but does have two
preferred instructions for zeroing a VFP register. This teaches LLVM about
them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205309 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-01 13:22:02 +00:00
David Blaikie
a07c1ab4e6 DebugInfo: Avoid creating unnecessary/empty line tables and remove the special case of '0' in DwarfCompileUnit::initStmtList by just always using a label difference
This moves one case of raw text checking down into the MCStreamer
interfaces in the form of a virtual function, even if we ultimately end
up consolidating on the one-or-many line tables issue one day, this is
nicer in the interim. This just generally streamlines a bunch of use
cases into a common code path.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205287 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-01 08:07:52 +00:00
Tim Northover
fc4fa22846 ARM: add intrinsics for the v8 ldaex/stlex
We've already got versions without the barriers, so this just adds IR-level
support for generating the new v8 ones.

rdar://problem/16227836

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204813 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-26 14:39:31 +00:00
Renato Golin
c4b058f9e7 Add @llvm.clear_cache builtin
Implementing the LLVM part of the call to __builtin___clear_cache
which translates into an intrinsic @llvm.clear_cache and is lowered
by each target, either to a call to __clear_cache or nothing at all
incase the caches are unified.

Updating LangRef and adding some tests for the implemented architectures.
Other archs will have to implement the method in case this builtin
has to be compiled for it, since the default behaviour is to bail
unimplemented.

A Clang patch is required for the builtin to be lowered into the
llvm intrinsic. This will be done next.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204802 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-26 12:52:28 +00:00
Saleem Abdulrasool
f50e709043 test: fix CHECK lines
Thanks to gix for pointing out that the CHECK-LABEL lines were incorrect!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204700 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-25 03:39:39 +00:00
Kevin Qin
fc029f2983 Fix test command line to avoid generating output file.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204437 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-21 07:20:29 +00:00
Kevin Qin
c53b3dbc20 Fix an assertion caused by using inline asm with indirect register inputs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204425 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-21 02:14:50 +00:00
Weiming Zhao
4eb2d228e9 Fix PR19136: [ARM] Fix Folding SP Update into vpush/vpop
Sicne MBB->computeRegisterLivenes() returns Dead for sub regs like s0,
d0 is used in vpop instead of updating sp, which causes s0 dead before
its use.

This patch checks the liveness of each subreg to make sure the reg is
actually dead.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204411 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-20 23:28:16 +00:00
Hao Liu
19a3e9aabe [ARM]Fix an assertion failure in A15SDOptimizer about DPair reg class by treating DPair as QPR.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204304 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-20 05:36:59 +00:00
Rafael Espindola
1f21e0dd0d Remove the linker_private and linker_private_weak linkages.
These linkages were introduced some time ago, but it was never very
clear what exactly their semantics were or what they should be used
for. Some investigation found these uses:

* utf-16 strings in clang.
* non-unnamed_addr strings produced by the sanitizers.

It turns out they were just working around a more fundamental problem.
For some sections a MachO linker needs a symbol in order to split the
section into atoms, and llvm had no idea that was the case. I fixed
that in r201700 and it is now safe to use the private linkage. When
the object ends up in a section that requires symbols, llvm will use a
'l' prefix instead of a 'L' prefix and things just work.

With that, these linkages were already dead, but there was a potential
future user in the objc metadata information. I am still looking at
CGObjcMac.cpp, but at this point I am convinced that linker_private
and linker_private_weak are not what they need.

The objc uses are currently split in

* Regular symbols (no '\01' prefix). LLVM already directly provides
whatever semantics they need.
* Uses of a private name (start with "\01L" or "\01l") and private
linkage. We can drop the "\01L" and "\01l" prefixes as soon as llvm
agrees with clang on L being ok or not for a given section. I have two
patches in code review for this.
* Uses of private name and weak linkage.

The last case is the one that one could think would fit one of these
linkages. That is not the case. The semantics are

* the linker will merge these symbol by *name*.
* the linker will hide them in the final DSO.

Given that the merging is done by name, any of the private (or
internal) linkages would be a bad match. They allow llvm to rename the
symbols, and that is really not what we want. From the llvm point of
view, these objects should really be (linkonce|weak)(_odr)?.

For now, just keeping the "\01l" prefix is probably the best for these
symbols. If we one day want to have a more direct support in llvm,
IMHO what we should add is not a linkage, it is just a hidden_symbol
attribute. It would be applicable to multiple linkages. For example,
on weak it would produce the current behavior we have for objc
metadata. On internal, it would be equivalent to private (and we
should then remove private).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203866 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-13 23:18:37 +00:00