6376 Commits

Author SHA1 Message Date
Benjamin Kramer
bb81d9d5fa SDAG: Legalize vector BSWAP into a shuffle if the shuffle is legal but the bswap not.
- On ARM/ARM64 we get a vrev because the shuffle matching code is really smart. We still unroll anything that's not v4i32 though.
- On X86 we get a pshufb with SSSE3. Required more cleverness in isShuffleMaskLegal.
- On PPC we get a vperm for v8i16 and v4i32. v2i64 is unrolled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209123 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-19 13:12:38 +00:00
Saleem Abdulrasool
82b1114fef Target: remove old constructors for CallLoweringInfo
This is mostly a mechanical change changing all the call sites to the newer
chained-function construction pattern.  This removes the horrible 15-parameter
constructor for the CallLoweringInfo in favour of setting properties of the call
via chained functions.  No functional change beyond the removal of the old
constructors are intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209082 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-17 21:50:17 +00:00
Saleem Abdulrasool
d825568843 Target: change member from reference to pointer
This is a preliminary step to help ease the construction of CallLoweringInfo.
Changing the construction to a chained function pattern requires that the
parameter be nullable.  However, rather than copying the vector, save a pointer
rather than the reference to permit a late binding of the arguments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209080 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-17 21:50:01 +00:00
Rafael Espindola
ad6d7f58c7 Delete getAliasedGlobal.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209040 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-16 22:37:03 +00:00
Jay Foad
b7ba5c2e2e Instead of littering asserts throughout the code after every call to
computeKnownBits, consolidate them into one assert at the end of
computeKnownBits itself.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208876 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-15 12:12:55 +00:00
Jay Foad
6b543713a2 Rename ComputeMaskedBits to computeKnownBits. "Masked" has been
inappropriate since it lost its Mask parameter in r154011.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208811 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-14 21:14:37 +00:00
Jay Foad
5fa4d1cd1a Update the comments for ComputeMaskedBits, which lost its Mask parameter
in r154011.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208757 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-14 08:00:07 +00:00
Pete Cooper
5a5a0640d8 Use a logical not when inverting SetCC. This unfortunately doesn't fire on any targets so I couldn't find a test case to trigger it.
The problem occurs when a non-i1 setcc is inverted.  For example 'i8 = setcc' will get 'xor 0xff' to invert this.   This is clearly wrong when the boolean contents are ZeroOrOne.

This patch introduces getLogicalNOT and updates SetCC legalisation to use it.

Reviewed by Hal Finkel.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208641 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-12 23:26:58 +00:00
Adam Nemet
73282018a1 [DAGCombiner] Split up an indexed load if only the base pointer value is live
Right now the load may not get DCE'd because of the side-effect of updating
the base pointer.

This can happen if we lower a read-modify-write of an illegal larger type
(e.g. i48) such that the modification only affects one of the subparts (the
lower i32 part but not the higher i16 part).  See the testcase.

In order to spot the dead load we need to revisit it when SimplifyDemandedBits
decided that the value of the load is masked off.  This is the
CommitTargetLoweringOpt piece.

I checked compile time with ARM64 by sending SPEC bitcode files through llc.
No measurable change.

Fixes <rdar://problem/16031651>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208640 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-12 23:00:03 +00:00
Matt Arsenault
621299806c Make SimplifyDemandedBits understand BUILD_PAIR
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208598 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-12 17:14:48 +00:00
Hal Finkel
24f554f052 Pass the value type to TLI::getRegisterByName
We must validate the value type in TLI::getRegisterByName, because if we
don't and the wrong type was used with the IR intrinsic, then we'll assert
(because we won't be able to find a valid register class with which to
construct the requested copy operation). For PPC64, additionally, the type
information is necessary to decide between the 64-bit register and the 32-bit
subregister.

No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208508 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-11 19:29:07 +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
Matt Arsenault
ad4e6970a1 Fix using wrong result type for setcc.
When reducing the bitwidth of a comparison against a constant, the
original setcc's result type was used, which was incorrect.

No test since I don't think any other in tree targets change the
bitwidth of the setcc type depending on the bitwidth of the compared
type.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208236 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-07 18:26:58 +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
Benjamin Kramer
71aafce117 Satisfy GCC's urgent need for parentheses around ‘&&’ within ‘||’.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207871 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-02 21:28:49 +00:00
Tim Northover
b20252764d DAGCombine: prevent formation of illegal ConstantFP nodes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207850 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-02 17:25:02 +00:00
Benjamin Kramer
bcf1501839 Allow SelectionDAG::FoldConstantArithmetic to work when it's called with a vector VT but scalar values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207835 91177308-0d34-0410-b5e6-96231b3b80d8
2014-05-02 12:35:22 +00:00
Alexey Samsonov
846781235d Convert more loops to range-based equivalents
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207714 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 22:17:38 +00:00
Weiming Zhao
fa1cf8cd68 [ARM64] Prevent bit extraction to be adjusted by following shift
For pattern like ((x >> C1) & Mask) << C2, DAG combiner may convert it
into (x >> (C1-C2)) & (Mask << C2), which makes pattern matching of ubfx
more difficult.
For example:
Given
  %shr = lshr i64 %x, 4
  %and = and i64 %shr, 15
  %arrayidx = getelementptr inbounds [8 x [64 x i64]]* @arr, i64 0, %i64 2, i64 %and
  %0 = load i64* %arrayidx
With current shift folding, it takes 3 instrs to compute base address:
  lsr x8, x0, #1
  and x8, x8, #0x78
  add x8, x9, x8

If using ubfx, it only needs 2 instrs:
  ubfx  x8, x0, #4, #4
  add x8, x9, x8, lsl #3

This fixes bug 19589


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207702 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 21:07:24 +00:00
Craig Topper
7ae9b5fc71 Use makeArrayRef insted of calling ArrayRef<T> constructor directly. I introduced most of these recently.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207616 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-30 07:17:30 +00:00
Jim Grosbach
f822dab3dd Tidy up whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207583 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 22:41:50 +00:00
Craig Topper
eda7f44b27 [C++11] Add 'override' keywords and remove 'virtual'. Additionally add 'final' and leave 'virtual' on some methods that are marked virtual without overriding anything and have no obvious overrides themselves.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207511 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-29 07:58:41 +00:00
Eric Christopher
916c24522c We already calculate WideVT above, just reuse it.
Patch by Jan Vesely <jan.vesely@rutgers.edu>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207455 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-28 22:24:57 +00:00
Craig Topper
7d811a53de Convert more SelectionDAG functions to use ArrayRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207397 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-28 05:57:50 +00:00
Craig Topper
a8e8d83e65 Convert AddNodeIDNode and SelectionDAG::getNodeIfExiists to use ArrayRef<SDValue>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207383 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 23:22:43 +00:00
Craig Topper
a440b0f2dd Convert SelectionDAGISel::MorphNode to use ArrayRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207379 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:21:20 +00:00
Craig Topper
f564ea31f0 Convert SelectionDAG::MorphNodeTo to use ArrayRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207378 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:21:16 +00:00
Craig Topper
1aa05f3844 Convert SelectionDAG::SelectNodeTo to use ArrayRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207377 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:21:11 +00:00
Craig Topper
7e1ae6d9e0 Convert one last signature of getNode to take an ArrayRef of SDUse.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207376 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:21:06 +00:00
Craig Topper
479c81774d Convert SDNode constructor to use ArrayRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207375 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:21:02 +00:00
Craig Topper
a7f892b33b Convert SelectionDAG::getMergeValues to use ArrayRef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207374 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:20:57 +00:00
Craig Topper
e046664a0e Const-correct SelectionDAG::getAtomic.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207373 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 19:20:47 +00:00
Benjamin Kramer
55e03c1992 SelectionDAG: Aggressively fold shuffles of constant splats.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207352 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-27 11:41:06 +00:00
Benjamin Kramer
eb3430cfbd DAGCombiner: Simplify code a bit, make more transforms work with vectors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207338 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 23:09:49 +00:00
Craig Topper
72c93595de Convert getMemIntrinsicNode to take ArrayRef of SDValue instead of pointer and size.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207329 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 19:29:41 +00:00
Craig Topper
80d8db7a1f Convert SelectionDAG::getNode methods to use ArrayRef<SDValue>.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207327 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 18:35:24 +00:00
Craig Topper
57d7597572 Remove an unused version of getMemIntrinsicNode and getNode. Additionally, these were calling makeVTList with the pointers passed in which would were unlikely to belong to SelectionDAG and likely would have just been stack pointers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207326 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 18:35:13 +00:00
Benjamin Kramer
75125c127d Rip out X86-specific vector SDIV lowering, make the corresponding DAGCombiner transform work on vectors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207316 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 13:00:53 +00:00
Benjamin Kramer
aab6231cd9 DAGCombiner: Turn divs of vector splats into vectorized multiplications.
Otherwise the legalizer would just scalarize everything. Support for
mulhi in the targets isn't that great yet so on most targets we get
exactly the same scalarized output. Add a test for x86 vector udiv.

I had to disable the mulhi nodes on ARM because there aren't any patterns
for it. As far as I know ARM has instructions for getting the high part of
a multiply so this should be fixed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207315 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 12:06:28 +00:00
Juergen Ributzka
d10a9fb25a [DAG] During DAG legalization keep opaque constants even after expanding.
The included test case would return the incorrect results, because the expansion
of an shift with a constant shift amount of 0 would generate undefined behavior.

This is because ExpandShiftByConstant assumes that all shifts by constants with
a value of 0 have already been optimized away. This doesn't happen for opaque
constants and usually this isn't a problem, because opaque constants won't take
this code path - they are not supposed to. In the case that the opaque constant
has to be expanded by the legalizer, the legalizer would drop the opaque flag.
In this case we hit the limitations of ExpandShiftByConstant and create incorrect
code.

This commit fixes the legalizer by not dropping the opaque flag when expanding
opaque constants and adding an assertion to ExpandShiftByConstant to catch this
not supported case in the future.

This fixes <rdar://problem/16718472>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207304 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 02:58:04 +00:00
Adrian Prantl
988b78a846 This reapplies r207235 with an additional bugfixes caught by the msan
buildbot - do not insert debug intrinsics before phi nodes.

Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207269 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 20:49:25 +00:00
Adrian Prantl
25c74de500 Revert "This reapplies r207130 with an additional testcase+and a missing check for"
This reverts commit 207235 to investigate msan buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207250 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:18:09 +00:00
Adrian Prantl
7e96d88347 This reapplies r207130 with an additional testcase+and a missing check for
AllocaInst that was missing in one location.
Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207235 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 17:01:00 +00:00
Adrian Prantl
680311d2d2 Revert "This reapplies r207130 with an additional testcase+and a missing check for"
Typo in testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207166 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 00:42:50 +00:00
Adrian Prantl
50e7ba14ca This reapplies r207130 with an additional testcase+and a missing check for
AllocaInst that was missing in one location.
Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207165 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 00:38:40 +00:00
Adrian Prantl
ab6ab3c333 Revert "Debug info for optimized code: Support variables that are on the stack and"
This reverts commit 207130 for buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207162 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 00:04:49 +00:00
Adrian Prantl
f28f471f16 Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine-intrinsics testcase and included source


rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207130 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 17:41:45 +00:00
Hao Liu
07dcdc7c90 Fix an infinite loop bug in DAG Combine about keeping transfering between ANY_EXTEND and SIGN_EXTEND.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206873 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-22 09:57:06 +00:00
Chandler Carruth
8677f2ff9a [Modules] Remove potential ODR violations by sinking the DEBUG_TYPE
define below all header includes in the lib/CodeGen/... tree. While the
current modules implementation doesn't check for this kind of ODR
violation yet, it is likely to grow support for it in the future. It
also removes one layer of macro pollution across all the included
headers.

Other sub-trees will follow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206837 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-22 02:02:50 +00:00
Chandler Carruth
283b399377 [Modules] Make Support/Debug.h modular. This requires it to not change
behavior based on other files defining DEBUG_TYPE, which means it cannot
define DEBUG_TYPE at all. This is actually better IMO as it forces folks
to define relevant DEBUG_TYPEs for their files. However, it requires all
files that currently use DEBUG(...) to define a DEBUG_TYPE if they don't
already. I've updated all such files in LLVM and will do the same for
other upstream projects.

This still leaves one important change in how LLVM uses the DEBUG_TYPE
macro going forward: we need to only define the macro *after* header
files have been #include-ed. Previously, this wasn't possible because
Debug.h required the macro to be pre-defined. This commit removes that.
By defining DEBUG_TYPE after the includes two things are fixed:

- Header files that need to provide a DEBUG_TYPE for some inline code
  can do so by defining the macro before their inline code and undef-ing
  it afterward so the macro does not escape.

- We no longer have rampant ODR violations due to including headers with
  different DEBUG_TYPE definitions. This may be mostly an academic
  violation today, but with modules these types of violations are easy
  to check for and potentially very relevant.

Where necessary to suppor headers with DEBUG_TYPE, I have moved the
definitions below the includes in this commit. I plan to move the rest
of the DEBUG_TYPE macros in LLVM in subsequent commits; this one is big
enough.

The comments in Debug.h, which were hilariously out of date already,
have been updated to reflect the recommended practice going forward.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206822 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-21 22:55:11 +00:00