Commit Graph

1476 Commits

Author SHA1 Message Date
Eric Christopher
4638c99333 Remove the target independent TargetMachine::getSubtarget and
TargetMachine::getSubtargetImpl routines.

This keeps the target independent code free of bare subtarget
calls while the remainder of the backends are migrated, or not
if they don't wish to support per-function subtargets as would
be needed for function multiversioning or LTO of disparate
cpu subarchitecture types, e.g.

clang -msse4.2 -c foo.c -emit-llvm -o foo.bc
clang -c bar.c -emit-llvm -o bar.bc
llvm-link foo.bc bar.bc -o baz.bc
llc baz.bc

and get appropriate code for what the command lines requested.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232885 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-21 04:22:23 +00:00
Daniel Sanders
d30081aaa7 [sparc] Small fix to r232719 to make 2007-12-17-InvokeAsm.ll pass on the buildbot.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232720 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-19 11:27:23 +00:00
Daniel Sanders
334291cfb6 [sparc] Only support the 'm' inline assembly memory constraint. NFC.
Summary:
SPARC doesn't seem to support any additional constraints. Therefore remove
the target hook.

No functional change intended.

Reviewers: venkatra

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8214


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232719 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-19 11:26:05 +00:00
Rafael Espindola
c7c4c36694 Split the object streamer callback in one per file format.
There are two main advantages to doing this

* Targets that only need to handle one of the formats specially don't have
  to worry about the others. For example, x86 now only registers a
  constructor for the COFF streamer.

* Changes to the arguments passed to one format constructor will not impact
  the other formats.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232699 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-19 01:50:16 +00:00
Rafael Espindola
64d662ba93 two or more, use a for.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232688 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-18 23:15:49 +00:00
Rafael Espindola
7b8bb89ecd Pass in a "const Triple &T" instead of a raw StringRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232429 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 22:29:29 +00:00
Rafael Espindola
63641de2e6 Remove unused argument. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232428 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 22:06:15 +00:00
Rafael Espindola
9130d115d6 There is only one Asm streamer, there is no need for targets to register it.
Instead, have the targets register a TargetStreamer to be use with the
asm streamer (if any).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232423 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 21:43:42 +00:00
David Blaikie
7610ba7d24 Fix uses of reserved identifiers starting with an underscore followed by an uppercase letter
This covers essentially all of llvm's headers and libs. One or two weird
cases I wasn't sure were worth/appropriate to fix.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232394 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 18:06:57 +00:00
Daniel Sanders
6d9e62f432 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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232373 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-16 13:13:41 +00:00
Daniel Sanders
547ba56bd0 Recommit r232027 with PR22883 fixed: Add infrastructure for support of multiple memory constraints.
The operand flag word for ISD::INLINEASM nodes now contains a 15-bit
memory constraint ID when the operand kind is Kind_Mem. This constraint
ID is a numeric equivalent to the constraint code string and is converted
with a target specific hook in TargetLowering.

This patch maps all memory constraints to InlineAsm::Constraint_m so there
is no functional change at this point. It just proves that using these
previously unused bits in the encoding of the flag word doesn't break
anything.

The next patch will make each target preserve the current mapping of
everything to Constraint_m for itself while changing the target independent
implementation of the hook to return Constraint_Unknown appropriately. Each
target will then be adapted in separate patches to use appropriate
Constraint_* values.

PR22883 was caused the matching operands copying the whole of the operand flags
for the matched operand. This included the constraint id which needed to be
replaced with the operand number. This has been fixed with a conversion
function. Following on from this, matching operands also used the operand
number as the constraint id. This has been fixed by looking up the matched
operand and taking it from there. 



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232165 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-13 12:45:09 +00:00
Hal Finkel
8faeecead0 Revert "r232027 - Add infrastructure for support of multiple memory constraints"
This (r232027) has caused PR22883; so it seems those bits might be used by
something else after all. Reverting until we can figure out what else to do.

Original commit message:

The operand flag word for ISD::INLINEASM nodes now contains a 15-bit
memory constraint ID when the operand kind is Kind_Mem. This constraint
ID is a numeric equivalent to the constraint code string and is converted
with a target specific hook in TargetLowering.

This patch maps all memory constraints to InlineAsm::Constraint_m so there
is no functional change at this point. It just proves that using these
previously unused bits in the encoding of the flag word doesn't break anything.

The next patch will make each target preserve the current mapping of
everything to Constraint_m for itself while changing the target independent
implementation of the hook to return Constraint_Unknown appropriately. Each
target will then be adapted in separate patches to use appropriate Constraint_*
values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232093 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 20:09:39 +00:00
Daniel Sanders
67f6425792 Add infrastructure for support of multiple memory constraints.
Summary:
The operand flag word for ISD::INLINEASM nodes now contains a 15-bit
memory constraint ID when the operand kind is Kind_Mem. This constraint
ID is a numeric equivalent to the constraint code string and is converted
with a target specific hook in TargetLowering.

This patch maps all memory constraints to InlineAsm::Constraint_m so there
is no functional change at this point. It just proves that using these
previously unused bits in the encoding of the flag word doesn't break anything.

The next patch will make each target preserve the current mapping of
everything to Constraint_m for itself while changing the target independent
implementation of the hook to return Constraint_Unknown appropriately. Each
target will then be adapted in separate patches to use appropriate Constraint_*
values.

Reviewers: hfinkel

Reviewed By: hfinkel

Subscribers: hfinkel, jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D8171


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232027 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 11:00:48 +00:00
Eric Christopher
257ea92cdf Remove some unnecessary forward declarations and put a couple more
where they're supposed to reside.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232014 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 06:07:16 +00:00
Eric Christopher
013ed4aa69 Remove the need to cache the subtarget in the Sparc TargetRegisterInfo
classes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232013 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 05:55:26 +00:00
Mehdi Amini
ceb9150268 Move the DataLayout to the generic TargetMachine, making it mandatory.
Summary:
I don't know why every singled backend had to redeclare its own DataLayout.
There was a virtual getDataLayout() on the common base TargetMachine, the
default implementation returned nullptr. It was not clear from this that
we could assume at call site that a DataLayout will be available with
each Target.

Now getDataLayout() is no longer virtual and return a pointer to the
DataLayout member of the common base TargetMachine. I plan to turn it into
a reference in a future patch.

The only backend that didn't have a DataLayout previsouly was the CPPBackend.
It now initializes the default DataLayout. This commit is NFC for all the
other backends.

Test Plan: clang+llvm ninja check-all

Reviewers: echristo

Subscribers: jfb, jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D8243

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231987 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-12 00:07:24 +00:00
Eric Christopher
85aa6fd741 Have getCallPreservedMask and getThisCallPreservedMask take a
MachineFunction argument so that we can grab subtarget specific
features off of it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231979 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-11 22:42:13 +00:00
Eric Christopher
5233c26b6b Have getCalleeSavedRegs take a non-null MachineFunction all the
time. The target independent code was passing in one all the
time and targets weren't checking validity before using. Update
a few calls to pass in a MachineFunction where necessary.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231970 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-11 21:41:28 +00:00
Eric Christopher
57849e3bb4 Remove the use of the subtarget in MCCodeEmitter creation and
update all ports accordingly. Required a couple of small rewrites
in handling subtarget features during creation in PPC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231861 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-10 22:03:14 +00:00
Eric Christopher
acdd4442cb getRegForInlineAsmConstraint wants to use TargetRegisterInfo for
a lookup, pass that in rather than use a naked call to getSubtargetImpl.
This involved passing down and around either a TargetMachine or
TargetRegisterInfo. Update all callers/definitions around the targets
and SelectionDAG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230699 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-26 22:38:43 +00:00
Eric Christopher
a01bc6a59f Remove an argument-less call to getSubtargetImpl from TargetLoweringBase.
This required plumbing a TargetRegisterInfo through computeRegisterProperties
and into findRepresentativeClass which uses it for register class
iteration. This required passing a subtarget into a few target specific
initializations of TargetLowering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230583 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-26 00:00:24 +00:00
Tim Northover
ca7e0787f0 CodeGen: convert CCState interface to using ArrayRefs
Everyone except R600 was manually passing the length of a static array
at each callsite, calculated in a variety of interesting ways. Far
easier to let ArrayRef handle that.

There should be no functional change, but out of tree targets may have
to tweak their calls as with these examples.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230118 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-21 02:11:17 +00:00
Michael Kuperstein
2b5910a767 Reverting r229831 due to multiple ARM/PPC/MIPS build-bot failures.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229841 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-19 11:38:11 +00:00
Michael Kuperstein
23dd089d8f Use std::bitset for SubtargetFeatures
Previously, subtarget features were a bitfield with the underlying type being uint64_t. 
Since several targets (X86 and ARM, in particular) have hit or were very close to hitting this bound, switching the features to use a bitset.

No functional change.

Differential Revision: http://reviews.llvm.org/D7065

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229831 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-19 09:01:04 +00:00
Aaron Ballman
66981fe208 Removing LLVM_DELETED_FUNCTION, as MSVC 2012 was the last reason for requiring the macro. NFC; LLVM edition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229340 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-15 22:54:22 +00:00
Chandler Carruth
417c5c172c [PM] Remove the old 'PassManager.h' header file at the top level of
LLVM's include tree and the use of using declarations to hide the
'legacy' namespace for the old pass manager.

This undoes the primary modules-hostile change I made to keep
out-of-tree targets building. I sent an email inquiring about whether
this would be reasonable to do at this phase and people seemed fine with
it, so making it a reality. This should allow us to start bootstrapping
with modules to a certain extent along with making it easier to mix and
match headers in general.

The updates to any code for users of LLVM are very mechanical. Switch
from including "llvm/PassManager.h" to "llvm/IR/LegacyPassManager.h".
Qualify the types which now produce compile errors with "legacy::". The
most common ones are "PassManager", "PassManagerBase", and
"FunctionPassManager".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229094 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-13 10:01:29 +00:00
Eric Christopher
bcc0fa6a64 Reuse a bunch of cached subtargets and remove getSubtarget calls
without a Function argument.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227644 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-30 23:46:43 +00:00
Eric Christopher
04bcc11905 Move DataLayout back to the TargetMachine from TargetSubtargetInfo
derived classes.

Since global data alignment, layout, and mangling is often based on the
DataLayout, move it to the TargetMachine. This ensures that global
data is going to be layed out and mangled consistently if the subtarget
changes on a per function basis. Prior to this all targets(*) have
had subtarget dependent code moved out and onto the TargetMachine.

*One target hasn't been migrated as part of this change: R600. The
R600 port has, as a subtarget feature, the size of pointers and
this affects global data layout. I've currently hacked in a FIXME
to enable progress, but the port needs to be updated to either pass
the 64-bitness to the TargetMachine, or fix the DataLayout to
avoid subtarget dependent features.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227113 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-26 19:03:15 +00:00
David Blaikie
341a7e245e std::unique_ptrify the MCStreamer argument to createAsmPrinter
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@226414 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-18 20:29:04 +00:00
Brad Smith
f449c53c89 Use the integrated assembler by default on SPARC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225957 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-14 07:53:39 +00:00
Ahmed Bougacha
7fac1d945f [SelectionDAG] Allow targets to specify legality of extloads' result
type (in addition to the memory type).

The *LoadExt* legalization handling used to only have one type, the
memory type.  This forced users to assume that as long as the extload
for the memory type was declared legal, and the result type was legal,
the whole extload was legal.

However, this isn't always the case.  For instance, on X86, with AVX,
this is legal:
    v4i32 load, zext from v4i8
but this isn't:
    v4i64 load, zext from v4i8
Whereas v4i64 is (arguably) legal, even without AVX2.

Note that the same thing was done a while ago for truncstores (r46140),
but I assume no one needed it yet for extloads, so here we go.

Calls to getLoadExtAction were changed to add the value type, found
manually in the surrounding code.

Calls to setLoadExtAction were mechanically changed, by wrapping the
call in a loop, to match previous behavior.  The loop iterates over
the MVT subrange corresponding to the memory type (FP vectors, etc...).
I also pulled neighboring setTruncStoreActions into some of the loops;
those shouldn't make a difference, as the additional types are illegal.
(e.g., i128->i1 truncstores on PPC.)

No functional change intended.

Differential Revision: http://reviews.llvm.org/D6532


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225421 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-08 00:51:32 +00:00
Duncan P. N. Exon Smith
2f7982026d Revert "Use the integrated assembler by default on 32-bit PowerPC and SPARC"
This reverts commit r225213.  It's failing on multiple buildbots [1][2].

[1]: http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/22032
[2]: http://lab.llvm.org:8080/green/view/Clang/job/clang-stage1-cmake-RA-incremental_check/2357/

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225222 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-05 23:31:51 +00:00
Brad Smith
a45b58174f Use the integrated assembler by default on 32-bit PowerPC and SPARC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225213 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-05 21:48:16 +00:00
Craig Topper
00d70e98f0 Minor cleanup to all the switches after MatchInstructionImpl in all the AsmParsers.
Make sure they all have llvm_unreachable on the default path out of the switch. Remove unnecessary "default: break". Remove a 'return' after unreachable. Fix some indentation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225114 91177308-0d34-0410-b5e6-96231b3b80d8
2015-01-03 08:16:34 +00:00
Matthias Braun
5b17297b3d [CodeGen] Add print and verify pass after each MachineFunctionPass by default
Previously print+verify passes were added in a very unsystematic way, which is
annoying when debugging as you miss intermediate steps and allows bugs to stay
unnotice when no verification is performed.

To make this change practical I added the possibility to explicitely disable
verification. I used this option on all places where no verification was
performed previously (because alot of places actually don't pass the
MachineVerifier).
In the long term these problems should be fixed properly and verification
enabled after each pass. I'll enable some more verification in subsequent
commits.

This is the 2nd attempt at this after realizing that PassManager::add() may
actually delete the pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224059 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-11 21:26:47 +00:00
Rafael Espindola
428923cfe2 This reverts commit r224043 and r224042.
check-llvm was failing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224045 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-11 20:03:57 +00:00
Matthias Braun
71f56c4aac [CodeGen] Add print and verify pass after each MachineFunctionPass by default
Previously print+verify passes were added in a very unsystematic way, which is
annoying when debugging as you miss intermediate steps and allows bugs to stay
unnotice when no verification is performed.

To make this change practical I added the possibility to explicitely disable
verification. I used this option on all places where no verification was
performed previously (because alot of places actually don't pass the
MachineVerifier).
In the long term these problems should be fixed properly and verification
enabled after each pass. I'll enable some more verification in subsequent
commits.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224042 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-11 19:42:05 +00:00
Simon Pilgrim
1c86b63b9b Target triple OS detection tidyup. NFC
Use Triple::isOS*() helpers where possible.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222960 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-29 19:18:21 +00:00
Reid Kleckner
d12434058d Add out of line virtual destructors to all LLVMTargetMachine subclasses
These recently all grew a unique_ptr<TargetLoweringObjectFile> member in
r221878.  When anyone calls a virtual method of a class, clang-cl
requires all virtual methods to be semantically valid. This includes the
implicit virtual destructor, which triggers instantiation of the
unique_ptr destructor, which fails because the type being deleted is
incomplete.

This is just part of the ongoing saga of PR20337, which is affecting
Blink as well. Because the MSVC ABI doesn't have key functions, we end
up referencing the vtable and implicit destructor on any virtual call
through a class. We don't actually end up emitting the dtor, so it'd be
good if we could avoid this unneeded type completion work.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222480 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-20 23:37:18 +00:00
Aditya Nandakumar
365df40768 We can get the TLOF from the TargetMachine - so constructor no longer requires TargetLoweringObjectFile to be passed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221926 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-13 21:29:21 +00:00
Aditya Nandakumar
847729d19a This patch changes the ownership of TLOF from TargetLoweringBase to TargetMachine so that different subtargets could share the TLOF effectively
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221878 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-13 09:26:31 +00:00
Rafael Espindola
6a222ec893 Pass an ArrayRef to MCDisassembler::getInstruction.
With this patch MCDisassembler::getInstruction takes an ArrayRef<uint8_t>
instead of a MemoryObject.

Even on X86 there is a maximum size an instruction can have. Given
that, it seems way simpler and more efficient to just pass an ArrayRef
to the disassembler instead of a MemoryObject and have it do a virtual
call every time it wants some extra bytes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221751 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-12 02:04:27 +00:00
Rafael Espindola
d342c4c748 Misc style fixes. NFC.
This fixes a few cases of:

* Wrong variable name style.
* Lines longer than 80 columns.
* Repeated names in comments.
* clang-format of the above.

This make the next patch a lot easier to read.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221615 91177308-0d34-0410-b5e6-96231b3b80d8
2014-11-10 18:11:10 +00:00
Robin Morisset
d310963833 Erase fence insertion from SelectionDAGBuilder.cpp (NFC)
Summary:
Backends can use setInsertFencesForAtomic to signal to the middle-end that
montonic is the only memory ordering they can accept for
stores/loads/rmws/cmpxchg. The code lowering those accesses with a stronger
ordering to fences + monotonic accesses is currently living in
SelectionDAGBuilder.cpp. In this patch I propose moving this logic out of it
for several reasons:
- There is lots of redundancy to avoid: extremely similar logic already
  exists in AtomicExpand.
- The current code in SelectionDAGBuilder does not use any target-hooks, it
  does the same transformation for every backend that requires it
- As a result it is plain *unsound*, as it was apparently designed for ARM.
  It happens to mostly work for the other targets because they are extremely
  conservative, but Power for example had to switch to AtomicExpand to be
  able to use lwsync safely (see r218331).
- Because it produces IR-level fences, it cannot be made sound ! This is noted
  in the C++11 standard (section 29.3, page 1140):
```
Fences cannot, in general, be used to restore sequential consistency for atomic
operations with weaker ordering semantics.
```
It can also be seen by the following example (called IRIW in the litterature):
```
atomic<int> x = y = 0;
int r1, r2, r3, r4;
Thread 0:
  x.store(1);
Thread 1:
  y.store(1);
Thread 2:
  r1 = x.load();
  r2 = y.load();
Thread 3:
  r3 = y.load();
  r4 = x.load();
```
r1 = r3 = 1 and r2 = r4 = 0 is impossible as long as the accesses are all seq_cst.
But if they are lowered to monotonic accesses, no amount of fences can prevent it..

This patch does three things (I could cut it into parts, but then some of them
would not be tested/testable, please tell me if you would prefer that):
- it provides a default implementation for emitLeadingFence/emitTrailingFence in
terms of IR-level fences, that mimic the original logic of SelectionDAGBuilder.
As we saw above, this is unsound, but the best that can be done without knowing
the targets well (and there is a comment warning about this risk).
- it then switches Mips/Sparc/XCore to use AtomicExpand, relying on this default
implementation (that exactly replicates the logic of SelectionDAGBuilder, so no
functional change)
- it finally erase this logic from SelectionDAGBuilder as it is dead-code.

Ideally, each target would define its own override for emitLeading/TrailingFence
using target-specific fences, but I do not know the Sparc/Mips/XCore memory model
well enough to do this, and they appear to be dealing fine with the ARM-inspired
default expansion for now (probably because they are overly conservative, as
Power was). If anyone wants to compile fences more agressively on these
platforms, the long comment should make it clear why he should first override
emitLeading/TrailingFence.

Test Plan: make check-all, no functional change

Reviewers: jfb, t.p.northover

Subscribers: aemerson, llvm-commits

Differential Revision: http://reviews.llvm.org/D5474

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219957 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-16 20:34:57 +00:00
Rafael Espindola
90ce9f70e2 Simplify handling of --noexecstack by using getNonexecutableStackSection.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219799 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-15 16:12:52 +00:00
Eric Christopher
b7cd35b171 Cache TargetLowering on SelectionDAGISel and update previous
calls to getTargetLowering() with the cached variable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219284 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-08 07:32:17 +00:00
Lang Hames
3025b00b7f [MCJIT] Nuke MachineRelocation and MachineCodeEmitter. Now that the old JIT is
gone they're no longer needed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218320 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-23 18:08:47 +00:00
Aaron Ballman
c21e4e197d Reverting NFC changes from r218050. Instead, the warning was disabled for GCC in r218059, so these changes are no longer required.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218062 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-18 17:34:23 +00:00
Aaron Ballman
cf5bea8e4a Fixing a bunch of -Woverloaded-virtual warnings due to hiding getSubtargetImpl from the base class. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218050 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-18 13:27:14 +00:00
Rafael Espindola
3f0ce4fa18 Fix a lot of confusion around inserting nops on empty functions.
On MachO, and MachO only, we cannot have a truly empty function since that
breaks the linker logic for atomizing the section.

When we are emitting a frame pointer, the presence of an unreachable will
create a cfi instruction pointing past the last instruction. This is perfectly
fine. The FDE information encodes the pc range it applies to. If some tool
cannot handle this, we should explicitly say which bug we are working around
and only work around it when it is actually relevant (not for ELF for example).

Given the unreachable we could omit the .cfi_def_cfa_register, but then
again, we could also omit the entire function prologue if we wanted to.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217801 91177308-0d34-0410-b5e6-96231b3b80d8
2014-09-15 18:32:58 +00:00