24929 Commits

Author SHA1 Message Date
Matthias Braun
a4e932db16 [CodeGen] Let MachineVerifierPass own its banner string
llvm-svn: 224041
2014-12-11 19:41:51 +00:00
Patrik Hagglund
cb06a36c9a Bugfix in InlineSpiller::traceSiblingValue().
Properly determine whether or not a phi was added by splitting.
Check against the current VNInfo of OrigLI instead of against the
OrigVNI argument.

Patch provided by Jonas Paulsson. Reviewed by Quentin Colombet.

llvm-svn: 224009
2014-12-11 10:40:17 +00:00
Ekaterina Romanova
75fd123967 Reverting commit 223981, because the test that I added (incorrect-variable-debugloc1.ll) failed for llvm-ppc64.
The test is failing for llvm-ppc64 because for this platform the location list is not being generated at all (most likely because of the bug in PPC code optimization or generation). I will file a bug agains PPC compiler, but meanwhile, until PPC bug is fixed, I will have to revert my change.  

llvm-svn: 224000
2014-12-11 06:22:35 +00:00
Philip Reames
1e30897497 GCStrategy should not own GCFunctionInfo
This change moves the ownership and access of GCFunctionInfo (the object which describes the safepoints associated with a safepoint under GCRoot) to GCModuleInfo. Previously, this was owned by GCStrategy which was in turned owned by GCModuleInfo. This made GCStrategy module specific which is 'surprising' given it's name and other purposes.

There's a few more changes needed, but we're getting towards the point we can reuse GCStrategy for gc.statepoint as well.

p.s. The style of this code ends up being a mess. I was trying to move code around without otherwise changing much. Once I get the ownership structure rearranged, I will go through and fixup spacing, naming, comments etc.

Differential Revision: http://reviews.llvm.org/D6587

llvm-svn: 223994
2014-12-11 01:47:23 +00:00
Matthias Braun
09afa1ea74 LiveInterval: Use range based for loops for subregister ranges.
llvm-svn: 223991
2014-12-11 00:59:06 +00:00
Ekaterina Romanova
ceeaba7932 A fix for PR21176.
DW_OP_const <const> doesn't describe a constant value, but a value at a constant address.
The proper way to describe a constant value is DW_OP_constu <const>, DW_OP_stack_value.

Added DW_OP_stack_value to the stack.

-This line, and those below, will be ignored--

M    lib/CodeGen/AsmPrinter/DwarfDebug.cpp
A    test/DebugInfo/incorrect-variable-debugloc1.ll

llvm-svn: 223981
2014-12-10 23:19:56 +00:00
Matthias Braun
96761959d4 LiveInterval: Use more range based for loops for value numbers and segments.
llvm-svn: 223978
2014-12-10 23:07:54 +00:00
Aaron Ballman
e5a2a0c9a8 Silencing a -Wsequence-point warning, and the resulting undefined behavior. NFC.
llvm-svn: 223926
2014-12-10 14:14:54 +00:00
Matthias Braun
96d7732b08 MachineVerifier: Allow physreg use if just a subreg is defined.
We can't mark partially undefined registers, so we have to allow reading
a register in the machine verifier if just parts of a register are
defined.

llvm-svn: 223896
2014-12-10 01:13:13 +00:00
Matthias Braun
21554d9b30 MachineVerifier: Allow LiveInterval segments to end at a partial write.
In the subregister liveness tracking case we do not create implicit
reads on partial register writes anymore, still we need to produce a new
SSA value for partial writes so the live segment has to end.

llvm-svn: 223895
2014-12-10 01:13:11 +00:00
Matthias Braun
279f83645c VirtRegMap: Improve block live-in info if subregister liveness is available.
llvm-svn: 223894
2014-12-10 01:13:08 +00:00
Matthias Braun
d70caaf5a5 VirtRegMap: No implicit defs/uses for super registers with subreg liveness tracking.
Adding the implicit defs/uses to the superregisters is semantically questionable
but was not dangerous before as the register allocator never assigned the same
register to two overlapping LiveIntervals even when the actually live
subregisters do not overlap. With subregister liveness tracking enabled this
does actually happen and leads to subsequent bugs if we don't stop adding
the superregister defs/uses.

llvm-svn: 223892
2014-12-10 01:13:04 +00:00
Matthias Braun
587e27415d LiveRegMatrix: Respect subregister liveness when allocating registers.
llvm-svn: 223891
2014-12-10 01:13:01 +00:00
Matthias Braun
a0f0c1f013 LiveIntervalUnion: Allow specification of liverange when unifying/extracting.
This allows it to add subregister ranges into the union.

llvm-svn: 223890
2014-12-10 01:12:59 +00:00
Matthias Braun
14f764c872 RegisterCoalescer: Preserve subregister liveranges.
llvm-svn: 223888
2014-12-10 01:12:52 +00:00
Matthias Braun
2079aa9140 LiveInterval: Add removeEmptySubRanges().
llvm-svn: 223887
2014-12-10 01:12:40 +00:00
Matthias Braun
8970d847c4 LiveIntervalAnalysis: Add subregister aware variants pruneValue().
llvm-svn: 223886
2014-12-10 01:12:36 +00:00
Matthias Braun
e3d3b88cb9 Add a flag to enable/disable subregister liveness.
llvm-svn: 223884
2014-12-10 01:12:30 +00:00
Matthias Braun
e5f861b781 LiveIntervalAnalysis: Adapt repairIntervalsInRange() to subregister liveness.
llvm-svn: 223883
2014-12-10 01:12:26 +00:00
Matthias Braun
fe896c703c LiveRangeEdit: Adapt eliminateDeadDef() to subregister liveness.
llvm-svn: 223882
2014-12-10 01:12:23 +00:00
Matthias Braun
7044d69e87 LiveIntervalAnalysis: Adapt handleMove() to subregister ranges.
llvm-svn: 223881
2014-12-10 01:12:20 +00:00
Matthias Braun
20e1f38a41 LiveIntervalAnalysis: Update SubRanges in shrinkToUses().
llvm-svn: 223880
2014-12-10 01:12:18 +00:00
Matthias Braun
2f66232bde LiveIntervalAnalysis: Compute subregister ranges.
llvm-svn: 223878
2014-12-10 01:12:12 +00:00
Matthias Braun
3f1d8fdd33 LiveInterval: Add support to track liveness of subregisters.
This code adds the required data structures. Algorithms to compute it follow.

llvm-svn: 223877
2014-12-10 01:12:10 +00:00
Matthias Braun
e62c207092 LiveInterval: Add a 'covers' operation to LiveRange.
llvm-svn: 223876
2014-12-10 01:12:06 +00:00
Philip Reames
de226055ca Remove the Module pointer from GCStrategy and GCMetadataPrinter
In the current implementation, GCStrategy is a part of the ownership structure for the gc metadata which describes a Module. It also contains a reference to the module in question. As a result, GCStrategy instances are essentially Module specific.

I plan to transition away from this design. Instead, a GCStrategy will be owned by the LLVMContext. It will be a lightweight policy object which contains no information about the Modules or Functions involved, but can be easily reached given a Function.

The first step in this transition is to remove the direct Module reference from GCStrategy. This also requires removing the single user of this reference, the GCMetadataPrinter hierarchy. In theory, this will allow the lifetime of the printers to be scoped to the LLVMContext as well, but in practice, I'm not actually changing that. (Yet?)

An alternate design would have been to move the direct Module reference into the GCMetadataPrinter and change the keying of the owning maps to explicitly key off both GCStrategy and Module. I'm open to doing it that way instead, but didn't see much value in preserving the per Module association for GCMetadataPrinters.

The next change in this sequence will be to start unwinding the intertwined ownership between GCStrategy, GCModuleInfo, and GCFunctionInfo.

Differential Revision: http://reviews.llvm.org/D6566

llvm-svn: 223859
2014-12-09 23:57:54 +00:00
Duncan P. N. Exon Smith
5bf8fef580 IR: Split Metadata from Value
Split `Metadata` away from the `Value` class hierarchy, as part of
PR21532.  Assembly and bitcode changes are in the wings, but this is the
bulk of the change for the IR C++ API.

I have a follow-up patch prepared for `clang`.  If this breaks other
sub-projects, I apologize in advance :(.  Help me compile it on Darwin
I'll try to fix it.  FWIW, the errors should be easy to fix, so it may
be simpler to just fix it yourself.

This breaks the build for all metadata-related code that's out-of-tree.
Rest assured the transition is mechanical and the compiler should catch
almost all of the problems.

Here's a quick guide for updating your code:

  - `Metadata` is the root of a class hierarchy with three main classes:
    `MDNode`, `MDString`, and `ValueAsMetadata`.  It is distinct from
    the `Value` class hierarchy.  It is typeless -- i.e., instances do
    *not* have a `Type`.

  - `MDNode`'s operands are all `Metadata *` (instead of `Value *`).

  - `TrackingVH<MDNode>` and `WeakVH` referring to metadata can be
    replaced with `TrackingMDNodeRef` and `TrackingMDRef`, respectively.

    If you're referring solely to resolved `MDNode`s -- post graph
    construction -- just use `MDNode*`.

  - `MDNode` (and the rest of `Metadata`) have only limited support for
    `replaceAllUsesWith()`.

    As long as an `MDNode` is pointing at a forward declaration -- the
    result of `MDNode::getTemporary()` -- it maintains a side map of its
    uses and can RAUW itself.  Once the forward declarations are fully
    resolved RAUW support is dropped on the ground.  This means that
    uniquing collisions on changing operands cause nodes to become
    "distinct".  (This already happened fairly commonly, whenever an
    operand went to null.)

    If you're constructing complex (non self-reference) `MDNode` cycles,
    you need to call `MDNode::resolveCycles()` on each node (or on a
    top-level node that somehow references all of the nodes).  Also,
    don't do that.  Metadata cycles (and the RAUW machinery needed to
    construct them) are expensive.

  - An `MDNode` can only refer to a `Constant` through a bridge called
    `ConstantAsMetadata` (one of the subclasses of `ValueAsMetadata`).

    As a side effect, accessing an operand of an `MDNode` that is known
    to be, e.g., `ConstantInt`, takes three steps: first, cast from
    `Metadata` to `ConstantAsMetadata`; second, extract the `Constant`;
    third, cast down to `ConstantInt`.

    The eventual goal is to introduce `MDInt`/`MDFloat`/etc. and have
    metadata schema owners transition away from using `Constant`s when
    the type isn't important (and they don't care about referring to
    `GlobalValue`s).

    In the meantime, I've added transitional API to the `mdconst`
    namespace that matches semantics with the old code, in order to
    avoid adding the error-prone three-step equivalent to every call
    site.  If your old code was:

        MDNode *N = foo();
        bar(isa             <ConstantInt>(N->getOperand(0)));
        baz(cast            <ConstantInt>(N->getOperand(1)));
        bak(cast_or_null    <ConstantInt>(N->getOperand(2)));
        bat(dyn_cast        <ConstantInt>(N->getOperand(3)));
        bay(dyn_cast_or_null<ConstantInt>(N->getOperand(4)));

    you can trivially match its semantics with:

        MDNode *N = foo();
        bar(mdconst::hasa               <ConstantInt>(N->getOperand(0)));
        baz(mdconst::extract            <ConstantInt>(N->getOperand(1)));
        bak(mdconst::extract_or_null    <ConstantInt>(N->getOperand(2)));
        bat(mdconst::dyn_extract        <ConstantInt>(N->getOperand(3)));
        bay(mdconst::dyn_extract_or_null<ConstantInt>(N->getOperand(4)));

    and when you transition your metadata schema to `MDInt`:

        MDNode *N = foo();
        bar(isa             <MDInt>(N->getOperand(0)));
        baz(cast            <MDInt>(N->getOperand(1)));
        bak(cast_or_null    <MDInt>(N->getOperand(2)));
        bat(dyn_cast        <MDInt>(N->getOperand(3)));
        bay(dyn_cast_or_null<MDInt>(N->getOperand(4)));

  - A `CallInst` -- specifically, intrinsic instructions -- can refer to
    metadata through a bridge called `MetadataAsValue`.  This is a
    subclass of `Value` where `getType()->isMetadataTy()`.

    `MetadataAsValue` is the *only* class that can legally refer to a
    `LocalAsMetadata`, which is a bridged form of non-`Constant` values
    like `Argument` and `Instruction`.  It can also refer to any other
    `Metadata` subclass.

(I'll break all your testcases in a follow-up commit, when I propagate
this change to assembly.)

llvm-svn: 223802
2014-12-09 18:38:53 +00:00
Juergen Ributzka
8bda738221 [CGP] Rewrite pattern match for splitBranchCondition to work with Values instead.
Rewrite the pattern match code to work also with Values instead with
Instructions only. Also remove the no longer need matcher (m_Instruction).

llvm-svn: 223797
2014-12-09 17:50:10 +00:00
Juergen Ributzka
194350a936 Revert "Move function to obtain branch weights into the BranchInst class. NFC."
This reverts commit r223784 and copies the 'ExtractBranchMetadata' to CodeGenPrepare.

llvm-svn: 223795
2014-12-09 17:32:12 +00:00
Juergen Ributzka
c1bbcbbd32 [CodeGenPrepare] Split branch conditions into multiple conditional branches.
This optimization transforms code like:
bb1:
  %0 = icmp ne i32 %a, 0
  %1 = icmp ne i32 %b, 0
  %or.cond = or i1 %0, %1
  br i1 %or.cond, label %TrueBB, label %FalseBB

into a multiple branch instructions like:

bb1:
  %0 = icmp ne i32 %a, 0
  br i1 %0, label %TrueBB, label %bb2
bb2:
  %1 = icmp ne i32 %b, 0
  br i1 %1, label %TrueBB, label %FalseBB

This optimization is already performed by SelectionDAG, but not by FastISel.
FastISel cannot perform this optimization, because it cannot generate new
MachineBasicBlocks.

Performing this optimization at CodeGenPrepare time makes it available to both -
SelectionDAG and FastISel - and the implementation in SelectiuonDAG could be
removed. There are currenty a few differences in codegen for X86 and PPC, so
this commmit only enables it for FastISel.

Reviewed by Jim Grosbach

This fixes rdar://problem/19034919.

llvm-svn: 223786
2014-12-09 16:36:13 +00:00
Owen Anderson
558012a3fc Fix a few instances found in SelectionDAG where we were not handling F16 at parity with F32 and F64.
llvm-svn: 223760
2014-12-09 06:50:39 +00:00
Hal Finkel
c8cf2b88bc Handle early-clobber registers in the aggressive anti-dep breaker
The aggressive anti-dep breaker, used by the PowerPC backend during post-RA
scheduling (but is available to all targets), did not handle early-clobber MI
operands (at all). When constructing the list of available registers for the
replacement of some def operand, check the using instructions, and remove
registers assigned to early-clobbered defs from the set.

Fixes PR21452.

llvm-svn: 223727
2014-12-09 01:00:59 +00:00
Tom Stellard
3e01d47d98 MISched: Fix moving stores across barriers
This fixes an issue with ScheduleDAGInstrs::buildSchedGraph
where stores without an underlying object would not be added
as a predecessor to the current BarrierChain.

llvm-svn: 223717
2014-12-08 23:36:48 +00:00
Justin Bogner
61ba2e3996 InstrProf: An intrinsic and lowering for instrumentation based profiling
Introduce the ``llvm.instrprof_increment`` intrinsic and the
``-instrprof`` pass. These provide the infrastructure for writing
counters for profiling, as in clang's ``-fprofile-instr-generate``.

The implementation of the instrprof pass is ported directly out of the
CodeGenPGO classes in clang, and with the followup in clang that rips
that code out to use these new intrinsics this ends up being NFC.

Doing the instrumentation this way opens some doors in terms of
improving the counter performance. For example, this will make it
simple to experiment with alternate lowering strategies, and allows us
to try handling profiling specially in some optimizations if we want
to.

Finally, this drastically simplifies the frontend and puts all of the
lowering logic in one place.

llvm-svn: 223672
2014-12-08 18:02:35 +00:00
Hans Wennborg
08de833c1c SelectionDAG switch lowering: Replace unreachable default with most popular case.
This can significantly reduce the size of the switch, allowing for more
efficient lowering.

I also worked with the idea of exploiting unreachable defaults by
omitting the range check for jump tables, but always ended up with a
non-neglible binary size increase. It might be worth looking into some more.

SimplifyCFG currently does this transformation, but I'm working towards changing
that so we can optimize harder based on unreachable defaults.

Differential Revision: http://reviews.llvm.org/D6510

llvm-svn: 223566
2014-12-06 01:28:50 +00:00
Eric Christopher
d1fb7e4590 These two calls were grabbing the same register info. Unify them.
llvm-svn: 223502
2014-12-05 19:23:55 +00:00
Ahmed Bougacha
55e3c2d9cf [CodeGenPrepare] Use variables for reused values. NFC.
llvm-svn: 223491
2014-12-05 18:04:40 +00:00
Hal Finkel
66d7791176 Revert "r223440 - Consider subregs when calling MI::registerDefIsDead for phys deps"
Reverting this because, while it fixes the problem in the reduced test case, it
does not fix the problem in the full test case from the bug report.

llvm-svn: 223442
2014-12-05 02:07:35 +00:00
Hal Finkel
d013d99fe0 Consider subregs when calling MI::registerDefIsDead for phys deps
The scheduling dependency graph is built bottom-up within each scheduling
region, and ScheduleDAGInstrs::addPhysRegDeps is called to add output/anti
dependencies, based on physical registers, to the SUs for instructions
based on those that come before them.

In the test case, we start before post-RA scheduling with a block that looks
like this:

...
	INLINEASM <...
andc $0,$0,$2
stdcx. $0,0,$3
bne- 1b
> [sideeffect] [mayload] [maystore] [attdialect], $0:[regdef-ec:G8RC], %X6<earlyclobber,def,dead>, $1:[mem], %X3<kill>, $2:[reguse:G8RC], %X5<kill>, $3:[reguse:G8RC], %X3, $4:[mem], %X3, $5:[clobber], %CC<earlyclobber,imp-def,dead>, <<badref>>
	...
	%X4<def,dead> = ANDIo8 %X4<kill>, 1, %CR0<imp-def,dead>, %CR0GT<imp-def>
	...
	%R29<def> = ISEL %R3<undef>, %R4<kill>, %CR0GT<kill>

where it is relevant that %CC is an alias to %CR0, and that %CR0GT is a
subregister of %CR0. However, for post-RA scheduling, no dependency was added
to prevent the INLINEASM from being scheduled in between the ANDIo8 and the
ISEL (which communicate via the %CR0GT register).

In ScheduleDAGInstrs::addPhysRegDeps, when called for the %CC operand, we'd
iterate over all of its aliases (which include %CC itself and also %CR0), and
look for previously-encountered defs of those registers. We'd find the ANDIo8,
but decide not to add a dependency between the INLINEASM and the ANDIo8 because
both the INLINEASM's def of %CC is dead, and also the ANDIo8 def of %CR0 is
dead. This ignores, however, that ANDIo8 has a non-dead def of %CR0GT, a
subregister of %CR0, and thus a dependency still must exist.

To fix this problem, when calling registerDefIsDead on the SU with the def, we
also check all subregisters for possible non-dead defs, and add the dependency
if any are found.

Fixes PR21742.

llvm-svn: 223440
2014-12-05 01:57:22 +00:00
Adrian Prantl
ab255fcd09 Cleanup: Calls to getDwarfRegNum() may actually fail, if there is
no DWARF register number mapping, or if the register was a virtual
register that was never materialized. Previously, we would just emit a
bogus location, after this patch we don't emit a location at all by
doing an early exit.

After my bugfix in r223401 today, this doesn't actually happen on any
target that I tested this with, but it's still preferable to make the
possibility of a failure explicit.

llvm-svn: 223428
2014-12-05 01:02:46 +00:00
Adrian Prantl
da7e03f1bf Simplify implementation and testcase of r223401 based on feedback from dblaikie.
llvm-svn: 223405
2014-12-04 22:58:41 +00:00
Adrian Prantl
a3ae0b3b5b Debug info: If the RegisterCoalescer::reMaterializeTrivialDef() is
eliminating all uses of a vreg, update any DBG_VALUE describing that vreg
to point to the rematerialized register instead.

llvm-svn: 223401
2014-12-04 22:29:04 +00:00
Patrik Hagglund
d06de4b954 Use DomTree in MachineSink to sink over diamonds.
According to a previous FIXME comment we now not only look at MBB
successors, but also handle code sinking past them:

  x = computation
  if () {} else {}
  use x

The instruction could be sunk over the whole diamond for the
if/then/else (or loop, etc), allowing it to be sunk into other blocks
after that.

Modified test added in r204522, due to one spill less present.

Minor fixes in comments.

Patch provided by Jonas Paulsson. Reviewed by Hal Finkel.

llvm-svn: 223350
2014-12-04 10:36:42 +00:00
Simon Pilgrim
be24ab367b [InstCombine] Minor optimization for bswap with binary ops
Added instcombine optimizations for BSWAP with AND/OR/XOR ops:

OP( BSWAP(x), BSWAP(y) ) -> BSWAP( OP(x, y) )
OP( BSWAP(x), CONSTANT ) -> BSWAP( OP(x, BSWAP(CONSTANT) ) )

Since its just a one liner, I've also added BSWAP to the DAGCombiner equivalent as well:

fold (OP (bswap x), (bswap y)) -> (bswap (OP x, y))

Refactored bswap-fold tests to use FileCheck instead of just checking that the bswaps had gone.

Differential Revision: http://reviews.llvm.org/D6407

llvm-svn: 223349
2014-12-04 09:44:01 +00:00
Elena Demikhovsky
f1de34b84d Masked Load / Store Intrinsics - the CodeGen part.
I'm recommiting the codegen part of the patch.
The vectorizer part will be send to review again.

Masked Vector Load and Store Intrinsics.
Introduced new target-independent intrinsics in order to support masked vector loads and stores. The loop vectorizer optimizes loops containing conditional memory accesses by generating these intrinsics for existing targets AVX2 and AVX-512. The vectorizer asks the target about availability of masked vector loads and stores.
Added SDNodes for masked operations and lowering patterns for X86 code generator.
Examples:
<16 x i32> @llvm.masked.load.v16i32(i8* %addr, <16 x i32> %passthru, i32 4 /* align */, <16 x i1> %mask)
declare void @llvm.masked.store.v8f64(i8* %addr, <8 x double> %value, i32 4, <8 x i1> %mask)

Scalarizer for other targets (not AVX2/AVX-512) will be done in a separate patch.

http://reviews.llvm.org/D6191

llvm-svn: 223348
2014-12-04 09:40:44 +00:00
Matt Arsenault
4e27343eec Allow target to specify prefix for labels
Use the MCAsmInfo instead of the DataLayout, and allow
specifying a custom prefix for labels specifically. HSAIL
requires that labels begin with @, but global symbols with &.

llvm-svn: 223323
2014-12-04 00:06:57 +00:00
Quentin Colombet
079aba733a [RegAllocFast] Handle implicit definitions conservatively.
Prior to this commit, physical registers defined implicitly were considered free
right after their definition, i.e.. like dead definitions. Therefore, their uses
had to immediately follow their definitions, otherwise the related register may
be reused to allocate a virtual register.

This commit fixes this assumption by keeping implicit definitions alive until
they are actually used. The downside is that if the implicit definition was dead
(and not marked at such), we block an otherwise available register. This is
however conservatively correct and makes the fast register allocator much more
robust in particular regarding the scheduling of the instructions.

Fixes PR21700.

llvm-svn: 223317
2014-12-03 23:38:08 +00:00
Peter Collingbourne
51d2de7b9e Prologue support
Patch by Ben Gamari!

This redefines the `prefix` attribute introduced previously and
introduces a `prologue` attribute.  There are a two primary usecases
that these attributes aim to serve,

  1. Function prologue sigils

  2. Function hot-patching: Enable the user to insert `nop` operations
     at the beginning of the function which can later be safely replaced
     with a call to some instrumentation facility

  3. Runtime metadata: Allow a compiler to insert data for use by the
     runtime during execution. GHC is one example of a compiler that
     needs this functionality for its tables-next-to-code functionality.

Previously `prefix` served cases (1) and (2) quite well by allowing the user
to introduce arbitrary data at the entrypoint but before the function
body. Case (3), however, was poorly handled by this approach as it
required that prefix data was valid executable code.

Here we redefine the notion of prefix data to instead be data which
occurs immediately before the function entrypoint (i.e. the symbol
address). Since prefix data now occurs before the function entrypoint,
there is no need for the data to be valid code.

The previous notion of prefix data now goes under the name "prologue
data" to emphasize its duality with the function epilogue.

The intention here is to handle cases (1) and (2) with prologue data and
case (3) with prefix data.

References
----------

This idea arose out of discussions[1] with Reid Kleckner in response to a
proposal to introduce the notion of symbol offsets to enable handling of
case (3).

[1] http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-May/073235.html

Test Plan: testsuite

Differential Revision: http://reviews.llvm.org/D6454

llvm-svn: 223189
2014-12-03 02:08:38 +00:00
Hal Finkel
bbdee93638 [PowerPC] Implement readcyclecounter for PPC32
We've long supported readcyclecounter on PPC64, but it is easier there (the
read of the 64-bit time-base register can be accomplished via a single
instruction). This now provides an implementation for PPC32 as well. On PPC32,
the time-base register is still 64 bits, but can only be read 32 bits at a time
via two separate SPRs. The ISA manual explains how to do this properly (it
involves re-reading the upper bits and looping if the counter has wrapped while
being read).

This requires PPC to implement a custom integer splitting legalization for the
READCYCLECOUNTER node, turning it into a target-specific SDAG node, which then
gets turned into a pseudo-instruction, which is then expanded to the necessary
sequence (which has three SPR reads, the comparison and the branch).

Thanks to Paul Hargrove for pointing out to me that this was still unimplemented.

llvm-svn: 223161
2014-12-02 22:01:00 +00:00
Philip Reames
72fbe7a6f0 Restructure some assertion checking based on post commit feedback by Aaron and Tom.
llvm-svn: 223150
2014-12-02 21:01:48 +00:00