Commit Graph

117 Commits

Author SHA1 Message Date
Matthias Braun
e4603f0daf MachineInstr: Change return value of getOpcode() to unsigned.
This was previously returning int. However there are no negative opcode
numbers and more importantly this was needlessly different from
MCInstrDesc::getOpcode() (which even is the value returned here) and
SDValue::getOpcode()/SDNode::getOpcode().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237611 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-18 20:27:55 +00:00
Ulrich Weigand
cf0fa9b9dd [SystemZ] Add CodeGen support for scalar f64 ops in vector registers
The z13 vector facility includes some instructions that operate only on the
high f64 in a v2f64, effectively extending the FP register set from 16
to 32 registers.  It's still better to use the old instructions if the
operands happen to fit though, since the older instructions have a shorter
encoding.

Based on a patch by Richard Sandiford.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236524 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-05 19:28:34 +00:00
Ulrich Weigand
aa5c996eda [SystemZ] Add CodeGen support for integer vector types
This the first of a series of patches to add CodeGen support exploiting
the instructions of the z13 vector facility.  This patch adds support
for the native integer vector types (v16i8, v8i16, v4i32, v2i64).

When the vector facility is present, we default to the new vector ABI.
This is characterized by two major differences:
- Vector types are passed/returned in vector registers
  (except for unnamed arguments of a variable-argument list function).
- Vector types are at most 8-byte aligned.

The reason for the choice of 8-byte vector alignment is that the hardware
is able to efficiently load vectors at 8-byte alignment, and the ABI only
guarantees 8-byte alignment of the stack pointer, so requiring any higher
alignment for vectors would require dynamic stack re-alignment code.

However, for compatibility with old code that may use vector types, when
*not* using the vector facility, the old alignment rules (vector types
are naturally aligned) remain in use.

These alignment rules are not only implemented at the C language level
(implemented in clang), but also at the LLVM IR level.  This is done
by selecting a different DataLayout string depending on whether the
vector ABI is in effect or not.

Based on a patch by Richard Sandiford.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236521 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-05 19:25:42 +00:00
Ulrich Weigand
cb1b3ad4e1 [SystemZ] Support RISBGN instruction on zEC12
So far, we do not yet support any instruction specific to zEC12.
Most of the facilities added with zEC12 are indeed not very useful
to compiler code generation, but there is one exception: the
miscellaneous-extensions facility provides the RISBGN instruction,
which is a variant of RISBG that does not set the condition code.

Add support for this facility, MC support for RISBGN, and CodeGen
support for prefering RISBGN over RISBG on zEC12, unless we can
actually make use of the condition code set by RISBG.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233690 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-31 12:58:17 +00:00
Benjamin Kramer
b22e2f9f2a ArrayRefize memory operand folding. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230846 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-28 12:04:00 +00:00
Aaron Ballman
d898d31ebc Removing LLVM_EXPLICIT, 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@229335 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-15 22:00:20 +00:00
Benjamin Kramer
3cdf75c5cf [SystemZ] Make operator bool explicit. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219069 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-04 22:44:35 +00:00
Eric Christopher
c6bf2379c1 Remove target machine caching from SystemZInstrInfo and
SystemZRegisterInfo and replace it with the subtarget as that's
all they needed in the first place. Update all uses and calls
accordingly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211877 91177308-0d34-0410-b5e6-96231b3b80d8
2014-06-27 07:01:17 +00:00
Craig Topper
c848b1bbcf [C++] Use 'nullptr'. Target edition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207197 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 05:30:21 +00:00
Chandler Carruth
58f58c97f0 [cleanup] Lift using directives, DEBUG_TYPE definitions, and even some
system headers above the includes of generated '.inc' files that
actually contain code. In a few targets this was already done pretty
consistently, but it wasn't done *really* consistently anywhere. It is
strictly cleaner IMO and necessary in a bunch of places where the
DEBUG_TYPE is referenced from the generated code. Consistency with the
necessary places trumps. Hopefully the build bots are OK with the
movement of intrin.h...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206838 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-22 02:03:14 +00:00
Alp Toker
8f5a7de1e6 Remove some empty statements
Cleanup only.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206710 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 23:56:35 +00:00
Richard Sandiford
9a1cd05a3d [SystemZ] Update namespace formatting to match current guidelines
No functional change intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203103 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-06 10:38:30 +00:00
Benjamin Kramer
d628f19f5d [C++11] Replace llvm::next and llvm::prior with std::next and std::prev.
Remove the old functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202636 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-02 12:27:27 +00:00
Alp Toker
ae43cab6ba Fix known typos
Sweep the codebase for common typos. Includes some changes to visible function
names that were misspelt.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200018 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-24 17:20:08 +00:00
Chandler Carruth
974a445bd9 Re-sort all of the includes with ./utils/sort_includes.py so that
subsequent changes are easier to review. About to fix some layering
issues, and wanted to separate out the necessary churn.

Also comment and sink the include of "Windows.h" in three .inc files to
match the usage in Memory.inc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198685 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-07 11:48:04 +00:00
Juergen Ributzka
354362524a [weak vtables] Remove a bunch of weak vtables
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file. The memory leaks in this version have been fixed. Thanks
Alexey for pointing them out.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195064 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-19 00:57:56 +00:00
Alexey Samsonov
b21ab43cfc Revert r194865 and r194874.
This change is incorrect. If you delete virtual destructor of both a base class
and a subclass, then the following code:
  Base *foo = new Child();
  delete foo;
will not cause the destructor for members of Child class. As a result, I observe
plently of memory leaks. Notable examples I investigated are:
ObjectBuffer and ObjectBufferStream, AttributeImpl and StringSAttributeImpl.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194997 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 09:31:53 +00:00
Juergen Ributzka
5a364c5561 [weak vtables] Remove a bunch of weak vtables
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194865 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 22:34:48 +00:00
Richard Sandiford
d1a4f579bf [SystemZ] Improve handling of SETCC
We previously used the default expansion to SELECT_CC, which in turn would
expand to "LHI; BRC; LHI".  In most cases it's better to use an IPM-based
sequence instead.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192784 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-16 11:10:55 +00:00
Richard Sandiford
f8f993b675 [SystemZ] Use A(G)SI when spilling the target of a constant addition
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192681 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-15 08:42:59 +00:00
Richard Sandiford
e22c56d6d8 [SystemZ] Add comparisons of high words and memory
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191777 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 15:00:44 +00:00
Richard Sandiford
185ef05ad6 [SystemZ] Add comparisons of large immediates using high words
There are no corresponding patterns for small immediates because they would
prevent the use of fused compare-and-branch instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191775 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 14:56:23 +00:00
Richard Sandiford
ad366a3f67 [SystemZ] Add immediate addition involving high words
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191774 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 14:53:46 +00:00
Richard Sandiford
bd1958d8e9 [SystemZ] Extend test-under-mask support to high GR32s
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191773 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 14:41:52 +00:00
Richard Sandiford
b9dcca8265 [SystemZ] Allow integer AND involving high words
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191762 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 14:20:41 +00:00
Richard Sandiford
1ff62e182e [SystemZ] Allow integer XOR involving high words
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191759 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 14:08:44 +00:00
Richard Sandiford
1c831f7f1f [SystemZ] Allow integer OR involving high words
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191755 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 13:22:41 +00:00
Richard Sandiford
645d250b84 [SystemZ] Allow integer insertions with a high-word destination
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191753 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 13:18:56 +00:00
Richard Sandiford
4c8feae136 [SystemZ] Add patterns to load a constant into a high word (IIHF)
Similar to low words, we can use the shorter LLIHL and LLIHH if it turns
out that the other half of the GR64 isn't live.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191750 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 13:02:28 +00:00
Richard Sandiford
79e2ed4d83 [SystemZ] Add register zero extensions involving at least one high word
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191746 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 12:49:07 +00:00
Richard Sandiford
9813dbf396 [SystemZ] Add truncating high-word stores (STCH and STHH)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191743 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 12:22:49 +00:00
Richard Sandiford
9a05f040e7 [SystemZ] Add zero-extending high-word loads (LLCH and LLHH)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191742 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 12:19:08 +00:00
Richard Sandiford
ced450f0e6 [SystemZ] Add sign-extending high-word loads (LBH and LHH)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191740 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 12:11:47 +00:00
Richard Sandiford
55d7d83b6c [SystemZ] Use upper words of GR64s for codegen
This just adds the basics necessary for allocating the upper words to
virtual registers (move, load and store).  The move support is parameterised
in a way that makes it easy to handle zero extensions, but the associated
zero-extend patterns are added by a later patch.

The easiest way of testing this seemed to be add a new "h" register
constraint for high words.  I don't expect the constraint to be useful
in real inline asms, but it should work, so I didn't try to hide it
behind an option.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191739 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-01 11:26:28 +00:00
Richard Sandiford
745ca1eed7 [SystemZ] Rename subregs and add subreg_h32
Use subreg_hNN and subreg_lNN for the high and low NN bits of a register.
List the low registers first, so that subreg_l32 also means the low 32
bits of a 128-bit register.

Floats are stored in the upper 32 bits of a 64-bit register, so they
should use subreg_h32 rather than subreg_l32.

No behavioral change intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191659 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-30 10:28:35 +00:00
Richard Sandiford
0548a5487a [SystemZ] Rein back the use of block operations
The backend tries to use block operations like MVC, NC, OC and XC for
simple scalar operations.  For correctness reasons, it rejects any case
in which the regions might partially overlap.  However, for performance
reasons, it should also reject cases where the regions might be equal,
since the instruction might then not use the fast path.

This fixes a performance regression seen in bzip2.  We may want to limit
the optimisation even more in future, or even remove it entirely, but I'll
try with this for now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191525 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-27 15:29:20 +00:00
Richard Sandiford
259a6006e8 [SystemZ] Define the GR64 low-word logic instructions as pseudo aliases.
Another patch to avoid duplication of encoding information.  Things like
NILF, NILL and NILH are used as both 32-bit and 64-bit instructions.
Here the 64-bit versions are defined as aliases of the 32-bit ones.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191369 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-25 11:11:53 +00:00
Richard Sandiford
e39a156b92 [SystemZ] Use subregs for 64-bit truncating stores
Another patch to reduce the duplication of encoding information.
Rather than define separate patterns for truncating 64-bit stores,
use the 32-bit stores with a subreg.  No behavioral changed intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191365 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-25 10:29:47 +00:00
Richard Sandiford
e2d6f91d63 [SystemZ] Add unsigned compare-and-branch instructions
For some reason I never got around to adding these at the same time as
the signed versions.  No idea why.

I'm not sure whether this SystemZII::BranchC* stuff is useful, or whether
it should just be replaced with an "is normal" flag.  I'll leave that
for later though.

There are some boundary conditions that can be tweaked, such as preferring
unsigned comparisons for equality with [128, 256), and "<= 255" over "< 256",
but again I'll leave those for a separate patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190930 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-18 09:56:40 +00:00
Richard Sandiford
6a079fef4f [SystemZ] Fix handling of 64-bit memcmp results
Generalize r188163 to cope with return types other than MVT::i32, just
as the existing visitMemCmpCall code did.  I've split this out into a
subroutine so that it can be used for other upcoming patches.

I also noticed that I'd used the wrong API to record the out chain.
It's a load that uses DAG.getRoot() rather than getRoot(), so the out
chain should go on PendingLoads.  I don't have a testcase for that because
we don't do any interesting scheduling on z yet.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188540 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-16 10:55:47 +00:00
Richard Sandiford
6c51f89498 [SystemZ] Fix sign of integer memcmp result
r188163 used CLC to implement memcmp.  Code that compares the result
directly against zero can test the CC value produced by CLC, but code
that needs an integer result must use IPM.  The sequence I'd used was:

   ipm <reg>
   sll <reg>, 2
   sra <reg>, 30

but I'd forgotten that this inverts the order, so that CC==1 ("less")
becomes an integer greater than zero, and CC==2 ("greater") becomes
an integer less than zero.  This sequence should only be used if the
CLC arguments are reversed to compensate.  The problem then is that
the branch condition must also be reversed when testing the CLC
result directly.

Rather than do that, I went for a different sequence that works with
the natural CLC order:

   ipm <reg>
   srl <reg>, 28
   rll <reg>, <reg>, 31

One advantage of this is that it doesn't clobber CC.  A disadvantage
is that any sign extension to 64 bits must be done separately,
rather than being folded into the shifts.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188538 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-16 10:22:54 +00:00
Richard Sandiford
ac168b8bc8 [SystemZ] Use CLC and IPM to implement memcmp
For now this is restricted to fixed-length comparisons with a length
in the range [1, 256], as for memcpy() and MVC.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188163 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-12 10:28:10 +00:00
Richard Sandiford
29e873ddb6 [SystemZ] Optimize floating-point comparisons with zero
This follows the same lines as the integer code.  In the end it seemed
easier to have a second 4-bit mask in TSFlags to specify the compare-like
CC values.  That eats one more TSFlags bit than adding a CCHasUnordered
would have done, but it feels more concise.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187883 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-07 11:10:06 +00:00
Richard Sandiford
9379557478 [SystemZ] Use BRCT and BRCTG to eliminate add-&-compare sequences
This patch just uses a peephole test for "add; compare; branch" sequences
within a single block.  The IR optimizers already convert loops to
decrement-and-branch-on-nonzero form in some cases, so even this
simplistic test triggers many times during a clang bootstrap and
projects/test-suite run.  It looks like there are still cases where we
need to more strongly prefer branches on nonzero though.  E.g. I saw a
case where a loop that started out with a check for 0 ended up with a
check for -1.  I'll try to look at that sometime.

I ended up adding the Reference class because MachineInstr::readsRegister()
doesn't check for subregisters (by design, as far as I could tell).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187723 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-05 11:23:46 +00:00
Richard Sandiford
9b05c709c6 [SystemZ] Use LOAD AND TEST to eliminate comparisons against zero
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187720 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-05 11:03:20 +00:00
Richard Sandiford
8f0ad5ae8f [SystemZ] Reuse CC results for integer comparisons with zero
This also fixes a bug in the predication of LR to LOCR: I'd forgotten
that with these in-place instruction builds, the implicit operands need
to be added manually.  I think this was latent until now, but is tested
by int-cmp-45.c.  It also adds a CC valid mask to STOC, again tested by
int-cmp-45.c.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187573 91177308-0d34-0410-b5e6-96231b3b80d8
2013-08-01 10:39:40 +00:00
Richard Sandiford
6824f127f9 [SystemZ] Be more careful about inverting CC masks
System z branches have a mask to select which of the 4 CC values should
cause the branch to be taken.  We can invert a branch by inverting the mask.
However, not all instructions can produce all 4 CC values, so inverting
the branch like this can lead to some oddities.  For example, integer
comparisons only produce a CC of 0 (equal), 1 (less) or 2 (greater).
If an integer EQ is reversed to NE before instruction selection,
the branch will test for 1 or 2.  If instead the branch is reversed
after instruction selection (by inverting the mask), it will test for
1, 2 or 3.  Both are correct, but the second isn't really canonical.
This patch therefore keeps track of which CC values are possible
and uses this when inverting a mask.

Although this is mostly cosmestic, it fixes undefined behavior
for the CIJNLH in branch-08.ll.  Another fix would have been
to mask out bit 0 when generating the fused compare and branch,
but the point of this patch is that we shouldn't need to do that
in the first place.

The patch also makes it easier to reuse CC results from other instructions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187495 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-31 12:30:20 +00:00
Richard Sandiford
0416e3c599 [SystemZ] Move compare-and-branch generation even later
r187116 moved compare-and-branch generation from the instruction-selection
pass to the peephole optimizer (via optimizeCompare).  It turns out that even
this is a bit too early.  Fused compare-and-branch instructions don't
interact well with predication, where a CC result is needed.  They also
make it harder to reuse the CC side-effects of earlier instructions
(not yet implemented, but the subject of a later patch).

Another problem was that the AnalyzeBranch family of routines weren't
handling compares and branches, so we weren't able to reverse the fused
form in cases where we would reverse a separate branch.  This could have
been fixed by extending AnalyzeBranch, but given the other problems,
I've instead moved the fusing to the long-branch pass, which is also
responsible for the opposite transformation: splitting out-of-range
compares and branches into separate compares and long branches.

I've added a test for the AnalyzeBranch problem.  A test for the
predication problem is included in the next patch, which fixes a bug
in the choice of CC mask.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187494 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-31 12:11:07 +00:00
Richard Sandiford
b3f912b510 [SystemZ] Postpone NI->RISBG conversion to convertToThreeAddress()
r186399 aggressively used the RISBG instruction for immediate ANDs,
both because it can handle some values that AND IMMEDIATE can't,
and because it allows the destination register to be different from
the source.  I realized later while implementing the distinct-ops
support that it would be better to leave the choice up to
convertToThreeAddress() instead.  The AND IMMEDIATE form is shorter
and is less likely to be cracked.

This is a problem for 32-bit ANDs because we assume that all 32-bit
operations will leave the high word untouched, whereas RISBG used in
this way will either clear the high word or copy it from the source
register.  The patch uses the z196 instruction RISBLG for this instead.

This means that z10 will be restricted to NILL, NILH and NILF for
32-bit ANDs, but I think that should be OK for now.  Although we're
using z10 as the base architecture, the optimization work is going
to be focused more on z196 and zEC12.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187492 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-31 11:36:35 +00:00
Richard Sandiford
ea14085be5 [SystemZ] Rework compare and branch support
Before the patch we took advantage of the fact that the compare and
branch are glued together in the selection DAG and fused them together
(where possible) while emitting them.  This seemed to work well in practice.
However, fusing the compare so early makes it harder to remove redundant
compares in cases where CC already has a suitable value.  This patch
therefore uses the peephole analyzeCompare/optimizeCompareInstr pair of
functions instead.

No behavioral change intended, but it paves the way for a later patch.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187116 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-25 09:34:38 +00:00