Commit Graph

26416 Commits

Author SHA1 Message Date
Chandler Carruth c1bb0e84bc [x86] Switch some of the new consolidated vector tests to use
a bare-metal triple and have nice BB labels, etc.

No significant change here, just tidying up to have a consistent set of
OS-agnostic vector functionality here.

llvm-svn: 218854
2014-10-02 06:52:19 +00:00
Eric Christopher 94ec17fac9 Remove test directories with no tests.
llvm-svn: 218843
2014-10-02 00:42:30 +00:00
Chandler Carruth 8a16802d46 [x86] Improve and correct how the new vector shuffle lowering was
matching and lowering 64-bit insertions.

The first problem was that we weren't looking through bitcasts to
discover that we *could* lower as insertions. Once fixed, we in turn
weren't looking through bitcasts to discover that we could fold a load
into the lowering. Once fixed, we weren't forming a SCALAR_TO_VECTOR
node around the inserted element and instead were passing a scalar to
a DAG node that expected a vector. It turns out there are some patterns
that will "lower" this into the correct asm, but the rest of the X86
backend is very unhappy with such antics.

This should fix a few more edge case regressions I've spotted going
through the regression test suite to enable the new vector shuffle
lowering.

llvm-svn: 218839
2014-10-01 23:14:28 +00:00
Sanjay Patel 9ebfbb969d Lower FNEG ( FABS (x) ) -> FNABS (x) [X86 codegen] PR20578
Negative FABS of either a scalar or vector should be handled the same way
on x86 with SSE/AVX: a single OR instruction of the FP operand with a
constant to light up the sign bit(s).

http://llvm.org/bugs/show_bug.cgi?id=20578

Differential Revision: http://reviews.llvm.org/D5201

llvm-svn: 218822
2014-10-01 21:20:06 +00:00
Chandler Carruth f795e4805e [x86] Merge the remaining test cases into vector-blend.ll and remove all
the ISA-specific test files.

llvm-svn: 218818
2014-10-01 21:07:07 +00:00
Chandler Carruth b21e033b2a [x86] Expand the ISA coverage of our blend test in preparation for
merging ISA-specific testing into this file.

llvm-svn: 218816
2014-10-01 21:03:21 +00:00
Chandler Carruth a406d6c386 [x86] Merge the interesting test cases from blend-msb.ll into
vector-blend.ll and remove the former.

llvm-svn: 218814
2014-10-01 20:56:57 +00:00
Chandler Carruth 19a5366481 [x86] Move the AVX blend test to a generic name. I'm going to fold other
blend tests into this one.

llvm-svn: 218813
2014-10-01 20:52:55 +00:00
Chandler Carruth b4b09c7a6c [x86] Remove a test that wasn't doing anything really. We have plenty of
better tests for zext of vectors at this point.

llvm-svn: 218811
2014-10-01 20:50:58 +00:00
Chandler Carruth ab5ddea2cb [x86] Add a 32-bit run to the sext test, and remove a sad vec_sext.ll
test file.

This old test had a bunch of functions that were never even checked. =/
The only thing it really did was to make sure that we did something
reasonable in 32-bit mode with SSE4.1. Adding another run line to the
main vector-sext.ll test seems a better way to do that.

llvm-svn: 218810
2014-10-01 20:49:54 +00:00
Chandler Carruth bbbdb9f0ee [x86] Teach both sext and zext vector tests to cover a nice wide range
of architectures: SSE2, SSSE3, SSE4.1, AVX, and AVX2.

Unfortunately, this exposses the absolute horror of the code we generate
for many of these patterns. Anyone wanting to familiarize themselves
with the x86 backend and improve performance could do a lot of good
sitting down and making these test cases not look so terrible. While the
new vector shuffle code I'm working on well help some, it won't fix all
of the crimes here.

llvm-svn: 218807
2014-10-01 20:41:36 +00:00
Sanjay Patel 7b2cd9ad86 Make the sqrt intrinsic return undef for a negative input.
As discussed here:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20140609/220598.html

And again here:
http://lists.cs.uiuc.edu/pipermail/llvmdev/2014-September/077168.html

The sqrt of a negative number when using the llvm intrinsic is undefined. 
We should return undef rather than 0.0 to match the definition in the LLVM IR lang ref.

This change should not affect any code that isn't using "no-nans-fp-math"; 
ie, no-nans is a requirement for generating the llvm intrinsic in place of a sqrt function call.

Unfortunately, the behavior introduced by this patch will not match current gcc, xlc, icc, and 
possibly other compilers. The current clang/llvm behavior of returning 0.0 doesn't either. 
We knowingly approve of this difference with the other compilers in an attempt to flag code 
that is invoking undefined behavior.

A front-end warning should also try to convince the user that the program will fail:
http://llvm.org/bugs/show_bug.cgi?id=21093

Differential Revision: http://reviews.llvm.org/D5527

llvm-svn: 218803
2014-10-01 20:36:33 +00:00
Chandler Carruth b5c9e04b51 [x86] Sort the ISA-specific RUN lines for vector-sext.ll to go from
oldest to newest. This makes more sense to me and is more consistent
with other tests.

llvm-svn: 218802
2014-10-01 20:32:44 +00:00
Tim Northover 6a1ef73140 ARM: yes it can (as of r218789)
llvm-svn: 218801
2014-10-01 20:31:58 +00:00
Chandler Carruth c66ea0fc12 [x86] Rename avx-{s,z}ext.ll to vector-{s,z}ext.ll.
These tests are far and away the best sext and zext tests we have for
vectors. I'm going to merge the other similar tests into them and expand
the ISA coverage.

llvm-svn: 218800
2014-10-01 20:30:30 +00:00
Chandler Carruth 011088fc46 [x86] Cleanup and re-generate the checks for avx-zext.ll using the new
script.

llvm-svn: 218799
2014-10-01 20:27:16 +00:00
Chandler Carruth fbba2fa8d9 [x86] Generate the FileCheck assertions for avx-blend.ll with my new
script to make them nice and predictable. This will ease updating them
for the new vector shuffle lowering and seeing the delta if any.

llvm-svn: 218795
2014-10-01 20:19:45 +00:00
Chandler Carruth 1f569b05b6 [x86] Clean up and generate detailed FileCheck assertions for
avx-sext.ll using my new script.

Also add an AVX2 mode to this test.

Part of cleaning up the test suite before enabling the new vector
shuffle lowering. This also highlights some of the abysmal failures of
the old shuffle lowering. Check out those 'pinsrw' and 'pextrw'
sequences!

llvm-svn: 218794
2014-10-01 20:19:32 +00:00
Tim Northover 5d72c5de02 ARM: allow copying of CPSR when all else fails.
As with x86 and AArch64, certain situations can arise where we need to spill
CPSR in the middle of a calculation. These should be avoided where possible
(MRS/MSR is rather expensive), which ARM is actually better at than the other
two since it tries to Glue defs to uses, but as a last ditch effort, copying is
better than crashing.

rdar://problem/18011155

llvm-svn: 218789
2014-10-01 19:21:03 +00:00
Adrian Prantl 87b7eb9d0f Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.
llvm-svn: 218787
2014-10-01 18:55:02 +00:00
Duncan P. N. Exon Smith 08a83be3ea LTO: Add missing target triple from r218784
llvm-svn: 218786
2014-10-01 18:49:58 +00:00
Reed Kotler b9dc248e9e Add fptrunc to mips fast-sel
Summary: Implement conversion of 64 to 32 bit floating point numbers (fptrunc) in mips fast-isel

Test Plan:
fptrunc.ll
checked also with 4 internal mips build bot flavors mip32r1/miprs32r2 and at -O0 and -O2

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: rfuhler

Differential Revision: http://reviews.llvm.org/D5553

llvm-svn: 218785
2014-10-01 18:47:02 +00:00
Duncan P. N. Exon Smith 30c9242caa LTO: Ignore disabled diagnostic remarks
r206400 and r209442 added remarks that are disabled by default.
However, if a diagnostic handler is registered, the remarks are sent
unfiltered to the handler.  This is the right behaviour for clang, since
it has its own filters.

However, the diagnostic handler exposed in the LTO API receives only the
severity and message.  It doesn't have the information to filter by pass
name.  For LTO, disabled remarks should be filtered by the producer.

I've changed `LLVMContext::setDiagnosticHandler()` to take a `bool`
argument indicating whether to respect the built-in filters.  This
defaults to `false`, so other consumers don't have a behaviour change,
but `LTOCodeGenerator::setDiagnosticHandler()` sets it to `true`.

To make this behaviour testable, I added a `-use-diagnostic-handler`
command-line option to `llvm-lto`.

This fixes PR21108.

llvm-svn: 218784
2014-10-01 18:36:03 +00:00
Adrian Prantl b458dc2eee Revert r218778 while investigating buldbot breakage.
"Move the complex address expression out of DIVariable and into an extra"

llvm-svn: 218782
2014-10-01 18:10:54 +00:00
Adrian Prantl 25a7174e7a Move the complex address expression out of DIVariable and into an extra
argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

llvm-svn: 218778
2014-10-01 17:55:39 +00:00
Tom Stellard 79243d9664 R600: Call EmitFunctionHeader() in the AsmPrinter to populate the ELF symbol table
llvm-svn: 218776
2014-10-01 17:15:17 +00:00
Jingyue Wu fd47fb9976 Revert r216862 due to a performance regression
Reported by Alexey Volkov in PR21115

llvm-svn: 218771
2014-10-01 15:22:13 +00:00
Oliver Stannard d4e0a4fd2c [ARM] Allow selecting VRINT[APMXZR] and VCVT[BT] instructions for FPv5
Currently, we only codegen the VRINT[APMXZR] and VCVT[BT] instructions
when targeting ARMv8, but they are actually present on any target with
FP-ARMv8. Note that FP-ARMv8 is called FPv5 when is is part of an
M-profile core, but they have the same instructions so we model them
both as FPARMv8 in the ARM backend.

llvm-svn: 218763
2014-10-01 13:13:18 +00:00
Chandler Carruth 6c02c031b8 [x86] Fix a few more tiny patterns with the new vector shuffle lowering
that keep cropping up in the regression test suite.

This also addresses one of the issues raised on the mailing list with
failing to form 'movsd' in as many cases as we realistically should.
There will be corresponding patches forthcoming for v4f32 at least. This
was a lot of fuss for a relatively small gain, but all the fuss was on
my end trying different ways of holding the pieces of the x86 fragment
patterns *just right*. Now that it works, the code is reasonably simple.

In the new test cases I'm adding here, v2i64 sticks out as just plain
horrible. I've not come up with any great ideas here other than that it
would be nice to recognize when we're *going* to take a domain crossing
hit and cross earlier to get the decent instructions. At least with AVX
it is slightly less silly....

llvm-svn: 218756
2014-10-01 11:14:02 +00:00
Tom Coxon e493f177ee [AArch64] Allow access to all system registers with MRS/MSR instructions.
The A64 instruction set includes a generic register syntax for accessing
implementation-defined system registers. The syntax for these registers is:
    S<op0>_<op1>_<CRn>_<CRm>_<op2>

The encoding space permitted for implementation-defined system registers
is:
    op0 op1  CRn   CRm   op2
    11  xxx  1x11  xxxx  xxx

The full encoding space can now be accessed:
    op0 op1  CRn   CRm   op2
    xx  xxx  xxxx  xxxx  xxx

This is useful to anyone needing to write assembly code supporting new
system registers before the assembler has learned the official names for
them.

llvm-svn: 218753
2014-10-01 10:13:59 +00:00
Evgeniy Stepanov 815f2869ad Revert r218721, r218735.
Failing bootstrap on Linux (arm, x86).

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/13139/steps/bootstrap%20clang/logs/stdio
http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15-selfhost/builds/470
http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/8518

llvm-svn: 218752
2014-10-01 10:07:28 +00:00
Asiri Rathnayake 530b3edab6 Add missing natual vector cast.
Summary: The natual vector cast node (similar to bitcast) AArch64ISD::NVCAST
was introduced in r217159 and r217138. This patch adds a missing cast from
v2f32 to v1i64 which is causing some compilation failures. Also added test
cases to cover various modimm types and BUILD_VECTORs with i64 elements.

llvm-svn: 218751
2014-10-01 09:59:45 +00:00
Oliver Stannard 37e4daab05 [ARM] Add support for Cortex-M7, FPv5-SP and FPv5-DP (LLVM)
The Cortex-M7 has 3 options for its FPU: none, FPv5-SP-D16 and
FPv5-DP-D16. FPv5 has the same instructions as FP-ARMv8, so it can be
modelled using the same target feature, and all double-precision
operations are already disabled by the fp-only-sp target features.

llvm-svn: 218747
2014-10-01 09:02:17 +00:00
Daniel Sanders 92db6b78f7 [mips] Fix disassembly of [ls][wd]c[23], cache, and pref
Fixes PR21015, and PR20993.                                                       
                                                                                  
Patch by Jun Koi

llvm-svn: 218745
2014-10-01 08:26:55 +00:00
Sasa Stankovic 7072a7968f [mips] For indirect calls we don't need $gp to point to .got. Mips linker
doesn't generate lazy binding stub for a function whose address is taken in
the program.

Differential Revision: http://reviews.llvm.org/D5067

llvm-svn: 218744
2014-10-01 08:22:21 +00:00
Justin Bogner 6a107bad15 test: XFAIL the non-darwin gmlt test on darwin
r218702 disabled a -gmlt optimization for darwin, but this means the
non-darwin test isn't working there anymore.

llvm-svn: 218742
2014-10-01 05:45:45 +00:00
Chandler Carruth 26cb9b8d2d [x86] Teach the new vector shuffle lowering to be even more aggressive
in exposing the scalar value to the broadcast DAG fragment so that we
can catch even reloads and fold them into the broadcast.

This is somewhat magical I'm afraid but seems to work. It is also what
the old lowering did, and I've switched an old test to run both
lowerings demonstrating that we get the same result.

Unlike the old code, I'm not lowering f32 or f64 scalars through this
path when we only have AVX1. The target patterns include pretty heinous
code to re-cast those as shuffles when the scalar happens to not be
spilled because AVX1 provides no broadcast mechanism from registers
what-so-ever. This is terribly brittle. I'd much rather go through our
generic lowering code to get this. If needed, we can add a peephole to
get even more opportunities to broadcast-from-spill-slots that are
exposed post-RA, but my suspicion is this just doesn't matter that much.

llvm-svn: 218734
2014-10-01 03:19:43 +00:00
Chandler Carruth 846baf2ca1 [x86] Hoist the zext-lowering up in the v4i32 lowering routine -- it is
the same speed as pshufd but we can fold loads into the pmovzx
instructions.

This fixes some regressions that came up in the regression test suite
for the new vector shuffle lowering.

llvm-svn: 218733
2014-10-01 02:25:54 +00:00
David Blaikie 32b0f365a2 Implement DW_TAG_subrange_type with DW_AT_count rather than DW_AT_upper_bound
This allows proper disambiguation of unbounded arrays and arrays of zero
bound ("struct foo { int x[]; };" and "struct foo { int x[0]; }"). GCC
instead produces an upper bound of -1 in the latter situation, but count
seems tidier. This way lower_bound is provided if it's not the language
default and count is provided if the count is known, otherwise it's
omitted. Simple.

If someone wants to look at rdar://problem/12566646 and see if this
change is acceptable to that bug/fix, that might be helpful (see the
empty-and-one-elem-array.ll test case which cites that radar).

llvm-svn: 218726
2014-10-01 00:56:55 +00:00
Chandler Carruth b9d3fa1e65 [x86] Teach the new vector shuffle lowering about VBROADCAST and
VPBROADCAST.

This has the somewhat expected pervasive impact. I don't know why
I forgot about this. Everything seems good with lots of significant
improvements in the tests.

llvm-svn: 218724
2014-10-01 00:41:21 +00:00
NAKAMURA Takumi 614f1001ec llvm/test/DebugInfo/X86/gmlt.test: Get rid of %llc_dwarf. It should not be used with -mtriple.
Also, remove object-emission. test/DebugInfo/X86 doesn't require it.

llvm-svn: 218722
2014-10-01 00:29:16 +00:00
Gerolf Hoflehner 08cc4b950c [InstCombine] Optimize icmp-select-icmp
In special cases select instructions can be eliminated by
replacing them with a cheaper bitwise operation even when the
select result is used outside its home block. The instances implemented
are patterns like
    %x=icmp.eq
    %y=select %x,%r, null
    %z=icmp.eq|neq %y, null
    br %z,true, false
==> %x=icmp.ne
    %y=icmp.eq %r,null
    %z=or %x,%y
    br %z,true,false
The optimization is integrated into the instruction
combiner and performed only when all uses of the select result can
be replaced by the select operand proper. For this dominator information
is used and dominance is now a required analysis pass in the combiner.
The optimization itself is iterative. The critical step is to replace the
select result with the non-constant select operand. So the select becomes
local and the combiner iteratively works out simpler code pattern and
eventually eliminates the select.

rdar://17853760

llvm-svn: 218721
2014-10-01 00:13:22 +00:00
David Blaikie 6cca8109ab Omit DW_AT_inline under -gmlt to save a little more space.
llvm-svn: 218719
2014-09-30 23:29:16 +00:00
Hal Finkel fd86317989 [BasicAA] Make better use of zext and sign information
Two related things:

 1. Fixes a bug when calculating the offset in GetLinearExpression. The code
    previously used zext to extend the offset, so negative offsets were converted
    to large positive ones.

 2. Enhance aliasGEP to deduce that, if the difference between two GEP
    allocations is positive and all the variables that govern the offset are also
    positive (i.e. the offset is strictly after the higher base pointer), then
    locations that fit in the gap between the two base pointers are NoAlias.

Patch by Nick White!

llvm-svn: 218714
2014-09-30 22:43:40 +00:00
Jingyue Wu fc0296704c [SimplifyCFG] threshold for folding branches with common destination
Summary:
This patch adds a threshold that controls the number of bonus instructions
allowed for folding branches with common destination. The original code allows
at most one bonus instruction. With this patch, users can customize the
threshold to allow multiple bonus instructions. The default threshold is still
1, so that the code behaves the same as before when users do not specify this
threshold.

The motivation of this change is that tuning this threshold significantly (up
to 25%) improves the performance of some CUDA programs in our internal code
base. In general, branch instructions are very expensive for GPU programs.
Therefore, it is sometimes worth trading more arithmetic computation for a more
straightened control flow. Here's a reduced example:

  __global__ void foo(int a, int b, int c, int d, int e, int n,
                      const int *input, int *output) {
    int sum = 0;
    for (int i = 0; i < n; ++i)
      sum += (((i ^ a) > b) && (((i | c ) ^ d) > e)) ? 0 : input[i];
    *output = sum;
  }

The select statement in the loop body translates to two branch instructions "if
((i ^ a) > b)" and "if (((i | c) ^ d) > e)" which share a common destination.
With the default threshold, SimplifyCFG is unable to fold them, because
computing the condition of the second branch "(i | c) ^ d > e" requires two
bonus instructions. With the threshold increased, SimplifyCFG can fold the two
branches so that the loop body contains only one branch, making the code
conceptually look like:

  sum += (((i ^ a) > b) & (((i | c ) ^ d) > e)) ? 0 : input[i];

Increasing the threshold significantly improves the performance of this
particular example. In the configuration where both conditions are guaranteed
to be true, increasing the threshold from 1 to 2 improves the performance by
18.24%. Even in the configuration where the first condition is false and the
second condition is true, which favors shortcuts, increasing the threshold from
1 to 2 still improves the performance by 4.35%.

We are still looking for a good threshold and maybe a better cost model than
just counting the number of bonus instructions. However, according to the above
numbers, we think it is at least worth adding a threshold to enable more
experiments and tuning. Let me know what you think. Thanks!

Test Plan: Added one test case to check the threshold is in effect

Reviewers: nadav, eliben, meheff, resistor, hfinkel

Reviewed By: hfinkel

Subscribers: hfinkel, llvm-commits

Differential Revision: http://reviews.llvm.org/D5529

llvm-svn: 218711
2014-09-30 22:23:38 +00:00
Chandler Carruth bebedbaf36 [x86] Add AVX1 and AVX2 testing to all of the 128-bit shuffle test
cases.

While clearly we don't need the AVX vector width, these ISA extensions
often cause us to select different instructions and we should cover them
even with the narrow vector width.

Also, while here, nuke the stress_test2 contents. There is no reason to
try to FileCheck this entire body when it is mostly a test for
successfully surviving the code generator.

llvm-svn: 218710
2014-09-30 22:16:23 +00:00
Chandler Carruth a41dceb39b [x86] Update the exact FileCheck syntax of the 256-bit and 512-bit
shuffle tests to match that used in the script I posted and now used
consistently in 128-bit tests.

Nothing interesting changing here, just using the label name as the
FileCheck label and a slightly more general comment marker consumption
strategy.

llvm-svn: 218709
2014-09-30 22:04:45 +00:00
David Blaikie 515387569a Adjust test case addition in r218702 so as not to fail when the X86 target isn't built.
llvm-svn: 218708
2014-09-30 22:02:27 +00:00
Chandler Carruth 6a62cd3538 [x86] Rework all of the 128-bit vector shuffle tests with my handy test
updating script so that they are more thorough and consistent.

Specific fixes here include:
- Actually test VEX-encoded AVX mnemonics.
- Actually use an SSE 4.1 run to test SSE 4.1 features!
- Correctly check instructions sequences from the start of the function.
- Elide the shuffle operands and comment designator in a consistent way.
- Test all of the architectures instead of just the ones I was motivated
  to manually author.

I've gone back through and fixed up any egregious issues I spotted. Let
me know if I missed something you really dislike.

One downside to this is that we're now not as diligently using FileCheck
variables for registers. I would be much more concerned with this if we
had larger register usage, but there just aren't that interesting of
register choices here and most of the registers are constrained by the
ABI. Ultimately, I don't think this is likely to be the maintenance
burden for these tests and updating them again should be staright
forward.

llvm-svn: 218707
2014-09-30 21:44:34 +00:00
David Blaikie e1c79749ca Disable the -gmlt optimization implemented in r218129 under Darwin due to issues with dsymutil.
r218129 omits DW_TAG_subprograms which have no inlined subroutines when
emitting -gmlt data. This makes -gmlt very low cost for -O0 builds.

Darwin's dsymutil reasonably considers a CU empty if it has no
subprograms (which occurs with the above optimization in -O0 programs
without any force_inline function calls) and drops the line table, CU,
and everything in this situation, making backtraces impossible.

Until dsymutil is modified to account for this, disable this
optimization on Darwin to preserve the desired functionality.
(see r218545, which should be reverted after this patch, for other
discussion/details)

Footnote:
In the long term, it doesn't look like this scheme (of simplified debug
info to describe inlining to enable backtracing) is tenable, it is far
too size inefficient for optimized code (the DW_TAG_inlined_subprograms,
even once compressed, are nearly twice as large as the line table
itself (also compressed)) and we'll be considering things like Cary's
two level line table proposal to encode all this information directly in
the line table.

llvm-svn: 218702
2014-09-30 21:28:32 +00:00
Juergen Ributzka c110c0b99a Recommit r218010 [FastISel][AArch64] Fold bit test and branch into TBZ and TBNZ.
Note: This version fixed an issue with the TBZ/TBNZ instructions that were
generated in FastISel. The issue was that the 64bit version of TBZ (TBZX)
automagically sets the upper bit of the immediate field that is used to specify
the bit we want to test. To test for any of the lower 32bits we have to first
extract the subregister and use the 32bit version of the TBZ instruction (TBZW).

Original commit message:
Teach selectBranch to fold bit test and branch into a single instruction (TBZ or
TBNZ).

llvm-svn: 218693
2014-09-30 19:59:35 +00:00
Matt Arsenault 9706978077 R600/SI: Fix printing of clamp and omod
No tests for omod since nothing uses it yet, but
this should get rid of the remaining annoying trailing
zeros after some instructions.

llvm-svn: 218692
2014-09-30 19:49:48 +00:00
Bradley Smith 7a77075530 Extend C disassembler API to allow specifying target features
llvm-svn: 218682
2014-09-30 16:31:40 +00:00
Reed Kotler 3ebdcc9ea7 Add numeric extend, trunctate to mips fast-isel
Summary:
 Add numeric extend, trunctate to mips fast-isel

 Reactivates D4827



Test Plan:
fpext.ll
loadstoreconv.ll

Reviewers: dsanders

Subscribers: mcrosier

Differential Revision: http://reviews.llvm.org/D5251

llvm-svn: 218681
2014-09-30 16:30:13 +00:00
Alex Lorenz 597eaf2a43 Revert r218673 'llvm-cov: add test for report's function & file association.'
Test causes buildbot failures.

llvm-svn: 218676
2014-09-30 14:48:12 +00:00
Alex Lorenz a891e6d44a llvm-cov: add test for report's function & file association.
This commit adds a test which checks that the functions defined in header files will get associated with the header files rather than the source files in the reports.

Differential Revision: http://reviews.llvm.org/D5489

llvm-svn: 218673
2014-09-30 12:52:31 +00:00
Alex Lorenz cb1702d45a llvm-cov: Use the number of executed functions for the function coverage metric.
This commit fixes llvm-cov's function coverage metric by using the number of executed functions instead of the number of fully covered functions.

Differential Revision: http://reviews.llvm.org/D5196

llvm-svn: 218672
2014-09-30 12:45:13 +00:00
Lorenzo Martignoni 40d3deeb7d Introduce support for custom wrappers for vararg functions.
Differential Revision: http://reviews.llvm.org/D5412

llvm-svn: 218671
2014-09-30 12:33:16 +00:00
Robert Khasanov 28a7df0b5f [AVX512] Added intrinsics for 128-, 256- and 512-bit versions of VCMPGT{BWDQ}.
Patch by Sergey Lisitsyn <sergey.lisitsyn@intel.com>

llvm-svn: 218670
2014-09-30 12:15:52 +00:00
Robert Khasanov 5aa4445bde [AVX512] Added intrinsics for 128- and 256-bit versions of VCMPEQ{BWDQ}
Fixed lowering of this intrinsics in case when mask is v2i1 and v4i1.
Now cmp intrinsics lower in the following way:
 (i8 (int_x86_avx512_mask_pcmpeq_q_128
             (v2i64 %a), (v2i64 %b), (i8 %mask))) ->
 (i8 (bitcast
   (v8i1 (insert_subvector undef,
           (v2i1 (and (PCMPEQM %a, %b),
                      (extract_subvector
                         (v8i1 (bitcast %mask)), 0))), 0))))

llvm-svn: 218669
2014-09-30 11:41:54 +00:00
Robert Khasanov b25e562d14 [AVX512] Added intrinsics for VPCMPEQB and VPCMPEQW.
Added new operand type for intrinsics (IIT_V64)

llvm-svn: 218668
2014-09-30 11:32:22 +00:00
Robert Khasanov a27c8e0fd9 [AVX512] Enabled intrinsics for VPCMPEQD and VPCMPEQQ.
Added CMP_MASK intrinsic type

llvm-svn: 218667
2014-09-30 11:19:50 +00:00
Chad Rosier aab5d7bd33 [IndVarSimplify] Widen loop unsigned compares.
This patch extends r217953 to handle unsigned comparison.
Phabricator revision: http://reviews.llvm.org/D5526

llvm-svn: 218659
2014-09-30 03:17:42 +00:00
Chandler Carruth aaf8e03d92 [x86] Revert r218588, r218589, and r218600. These patches were pursuing
a flawed direction and causing miscompiles. Read on for details.

Fundamentally, the premise of this patch series was to map
VECTOR_SHUFFLE DAG nodes into VSELECT DAG nodes for all blends because
we are going to *have* to lower to VSELECT nodes for some blends to
trigger the instruction selection patterns of variable blend
instructions. This doesn't actually work out so well.

In order to match performance with the existing VECTOR_SHUFFLE
lowering code, we would need to re-slice the blend in order to fit it
into either the integer or floating point blends available on the ISA.
When coming from VECTOR_SHUFFLE (or other vNi1 style VSELECT sources)
this works well because the X86 backend ensures that these types of
operands to VSELECT get sign extended into '-1' and '0' for true and
false, allowing us to re-slice the bits in whatever granularity without
changing semantics.

However, if the VSELECT condition comes from some other source, for
example code lowering vector comparisons, it will likely only have the
required bit set -- the high bit. We can't blindly slice up this style
of VSELECT. Reid found some code using Halide that triggers this and I'm
hopeful to eventually get a test case, but I don't need it to understand
why this is A Bad Idea.

There is another aspect that makes this approach flawed. When in
VECTOR_SHUFFLE form, we have very distilled information that represents
the *constant* blend mask. Converting back to a VSELECT form actually
can lose this information, and so I think now that it is better to treat
this as VECTOR_SHUFFLE until the very last moment and only use VSELECT
nodes for instruction selection purposes.

My plan is to:
1) Clean up and formalize the target pre-legalization DAG combine that
   converts a VSELECT with a constant condition operand into
   a VECTOR_SHUFFLE.
2) Remove any fancy lowering from VSELECT during *legalization* relying
   entirely on the DAG combine to catch cases where we can match to an
   immediate-controlled blend instruction.

One additional step that I'm not planning on but would be interested in
others' opinions on: we could add an X86ISD::VSELECT or X86ISD::BLENDV
which encodes a fully legalized VSELECT node. Then it would be easy to
write isel patterns only in terms of this to ensure VECTOR_SHUFFLE
legalization only ever forms the fully legalized construct and we can't
cycle between it and VSELECT combining.

llvm-svn: 218658
2014-09-30 02:52:28 +00:00
Chandler Carruth 964747adcf [x86] Add some vector-register broadcast operations to the 256-bit v4
tests which were missing them.

llvm-svn: 218657
2014-09-30 02:32:36 +00:00
Matt Arsenault 1c4571e0fd R600: Fix broken check lines, missing scalar case.
llvm-svn: 218655
2014-09-30 01:05:29 +00:00
Juergen Ributzka 6ac12439d0 [FastISel][AArch64] Fold sign-/zero-extends into the load instruction.
The sign-/zero-extension of the loaded value can be performed by the memory
instruction for free. If the result of the load has only one use and the use is
a sign-/zero-extend, then we emit the proper load instruction. The extend is
only a register copy and will be optimized away later on.

Other instructions that consume the sign-/zero-extended value are also made
aware of this fact, so they don't fold the extend too.

This fixes rdar://problem/18495928.

llvm-svn: 218653
2014-09-30 00:49:58 +00:00
Hans Wennborg f26bfc1671 WinCOFFObjectWriter: optimize the string table for common suffices
This is a follow-up from r207670 which did the same for ELF.

Differential Revision: http://reviews.llvm.org/D5530

llvm-svn: 218636
2014-09-29 22:43:20 +00:00
Eric Christopher 6a0551e43a Add soft-float to the key for the subtarget lookup in the TargetMachine
map, this makes sure that we can compile the same code for two different
ABIs (hard and soft float) in the same module.

Update one testcase accordingly (and fix some confusing naming) and
add a new testcase as well with the ordering swapped which would
highlight the problem.

llvm-svn: 218632
2014-09-29 21:57:54 +00:00
Matt Arsenault 3d4233fe48 R600/SI: Also fix fsub + fadd a, a to mad combines
llvm-svn: 218609
2014-09-29 14:59:38 +00:00
Matt Arsenault 02cb0ff7db R600/SI: Fix using mad with multiplies by 2
These turn into fadds, so combine them into the target
mad node.

fadd (fadd (a, a), b) -> mad 2.0, a, b

llvm-svn: 218608
2014-09-29 14:59:34 +00:00
Chad Rosier 70d54ac848 [AArch64] Improve cost model to handle sdiv by a pow-of-two.
This patch improves the target-specific cost model to better handle signed
division by a power of two. The immediate result is that this enables the SLP
vectorizer to do a better job.

http://reviews.llvm.org/D5469
PR20714

llvm-svn: 218607
2014-09-29 13:59:31 +00:00
Kevin Qin fc02e3c363 Use a loop to simplify the runtime unrolling prologue.
Runtime unrolling will create a prologue to execute the extra
iterations which is can't divided by the unroll factor. It
generates an if-then-else sequence to jump into a factor -1
times unrolled loop body, like

    extraiters = tripcount % loopfactor
    if (extraiters == 0) jump Loop:
    if (extraiters == loopfactor) jump L1
    if (extraiters == loopfactor-1) jump L2
    ...
    L1:  LoopBody;
    L2:  LoopBody;
    ...
    if tripcount < loopfactor jump End
    Loop:
    ...
    End:

It means if the unroll factor is 4, the loop body will be 7
times unrolled, 3 are in loop prologue, and 4 are in the loop.
This commit is to use a loop to execute the extra iterations
in prologue, like

        extraiters = tripcount % loopfactor
        if (extraiters == 0) jump Loop:
        else jump Prol
 Prol:  LoopBody;
        extraiters -= 1                 // Omitted if unroll factor is 2.
        if (extraiters != 0) jump Prol: // Omitted if unroll factor is 2.
        if (tripcount < loopfactor) jump End
 Loop:
 ...
 End:

Then when unroll factor is 4, the loop body will be copied by
only 5 times, 1 in the prologue loop, 4 in the original loop.
And if the unroll factor is 2, new loop won't be created, just
as the original solution.

llvm-svn: 218604
2014-09-29 11:15:00 +00:00
Oliver Stannard a4eba5ad70 [Thumb2] ldrexd and strexd are not defined on v7M
The Thumb2 ldrexd and strexd instructions are not defined for
M-class architectures.

llvm-svn: 218603
2014-09-29 10:57:29 +00:00
Chandler Carruth 6cbf43167b [x86] Make the new vector shuffle lowering lower blends as VSELECT
nodes, and rely exclusively on its logic. This removes a ton of
duplication from the blend lowering and centralizes it in one place.

One downside is that it requires a bunch of hacks to make this work with
the current legalization framework. We have to manually speculate one
aspect of legalizing VSELECT nodes to get everything to work nicely
because the existing legalization framework isn't *actually* bottom-up.

The other grossness is that we somewhat duplicate the analysis of
constant blends. I'm on the fence here. If reviewers thing this would
look better with VSELECT when it has constant operands dumping over tho
VECTOR_SHUFFLE, we could go that way. But it would be a substantial
change because currently all of the actual blend instructions are
matched via patterns in the TD files based around VSELECT nodes (despite
them not being perfect fits for that). Suggestions welcome, but at least
this removes the rampant duplication in the backend.

llvm-svn: 218600
2014-09-29 09:57:07 +00:00
Chandler Carruth b1cc7a8542 [x86] Delete a bunch of really bad and totally unnecessary code in the
X86 target-specific DAG combining that tried to convert VSELECT nodes
into VECTOR_SHUFFLE nodes that it "knew" would lower into
immediate-controlled blend nodes.

Turns out, we have perfectly good lowering of all these VSELECT nodes,
and indeed that lowering already knows how to handle lowering through
BLENDI to immediate-controlled blend nodes. The code just wasn't getting
used much because this thing forced the world to go through the vector
shuffle lowering. Yuck.

This also exposes that I was too aggressive in avoiding domain crossing
in v218588 with that lowering -- when the other option is to expand into
two 128-bit vectors, it is worth domain crossing. Restore that behavior
now that we have nice tests covering it.

The test updates here fall into two camps. One is where previously we
ended up with an unsigned encoding of the blend operand and now we get
a signed encoding. In most of those places there were elaborate comments
explaining exactly what these operands really mean. Rather than that,
just switch these tests to use the nicely decoded comments that make it
obvious that the final shuffle matches.

The other updates are just removing pointless domain crossing by
blending integers with PBLENDW rather than BLENDPS.

llvm-svn: 218589
2014-09-29 02:01:20 +00:00
Chandler Carruth c7129276cd [x86] Add the dispatch skeleton to the new vector shuffle lowering for
AVX-512.

There is no interesting logic yet. Everything ends up eventually
delegating to the generic code to split the vector and shuffle the
halves. Interestingly, that logic does a significantly better job of
lowering all of these types than the generic vector expansion code does.
Mostly, it lets most of the cases fall back to nice AVX2 code rather
than all the way back to SSE code paths.

Step 2 of basic AVX-512 support in the new vector shuffle lowering. Next
up will be to incrementally add direct support for the basic instruction
set to each type (adding tests first).

llvm-svn: 218585
2014-09-29 00:37:27 +00:00
Chandler Carruth 24e3b69cbd [x86] Teach the new vector shuffle lowering to fall back on AVX-512
vectors.

Someone will need to build the AVX512 lowering, which should follow
AVX1 and AVX2 *very* closely for AVX512F and AVX512BW resp. I've added
a dummy test which is a port of the v8f32 and v8i32 tests from AVX and
AVX2 to v8f64 and v8i64 tests for AVX512F and AVX512BW. Hopefully this
is enough information for someone to implement proper lowering here. If
not, I'll be happy to help, but right now the AVX-512 support isn't
a priority for me.

llvm-svn: 218583
2014-09-28 23:53:10 +00:00
Chandler Carruth abe742e8fb [x86] Fix the new vector shuffle lowering's use of VSELECT for AVX2
lowerings.

This was hopelessly broken. First, the x86 backend wants '-1' to be the
element value representing true in a boolean vector, and second the
operand order for VSELECT is backwards from the actual x86 instructions.
To make matters worse, the backend is just using '-1' as the true value
to get the high bit to be set. It doesn't actually symbolically map the
'-1' to anything. But on x86 this isn't quite how it works: there *only*
the high bit is relevant. As a consequence weird non-'-1' values like
0x80 actually "work" once you flip the operands to be backwards.

Anyways, thanks to Hal for helping me sort out what these *should* be.

llvm-svn: 218582
2014-09-28 23:23:55 +00:00
Chandler Carruth 6578f9208b [x86] Fix a really silly bug that I introduced fixing another bug in the
new vector shuffle target DAG combines -- it helps to actually test for
the value you want rather than just using an integer in a boolean
context.

Have I mentioned that I loathe implicit conversions recently? :: sigh ::

llvm-svn: 218576
2014-09-28 06:11:04 +00:00
Chandler Carruth b10c6b8e9e [x86] Fix yet another bug in the new vector shuffle lowering's handling
of widening masks.

We can't widen a zeroing mask unless both elements that would be merged
are either zeroed or undef. This is the only way to widen a mask if it
has a zeroed element.

Also clean up the code here by ordering the checks in a more logical way
and by using the symoblic values for undef and zero. I'm actually torn
on using the symbolic values because the existing code is littered with
the assumption that -1 is undef, and moreover that entries '< 0' are the
special entries. While that works with the values given to these
constants, using the symbolic constants actually makes it a bit more
opaque why this is the case.

llvm-svn: 218575
2014-09-28 03:30:25 +00:00
James Molloy 463db9a77c [AArch64] Redundant store instructions should be removed as dead code
If there is a store followed by a store with the same value to the same location, then the store is dead/noop. It can be removed.

This problem is found in spec2006-197.parser.

For example,
  stur    w10, [x11, #-4]
  stur    w10, [x11, #-4]
Then one of the two stur instructions can be removed.

Patch by David Xu!

llvm-svn: 218569
2014-09-27 17:02:54 +00:00
Craig Topper 5ed88de99b Update test case to match minor formatting change introduced in r218563.
llvm-svn: 218564
2014-09-27 05:36:53 +00:00
Chandler Carruth 4d03be1717 [x86] Fix terrible bugs everywhere in the new vector shuffle lowering
and in the target shuffle combining when trying to widen vector
elements.

Previously only one of these was correct, and we didn't correctly
propagate zeroing target shuffle masks (which have a different sentinel
value from undef in non- target shuffle masks now). This isn't just
a missed optimization, this caused us to drop zeroing shuffles on the
floor and miscompile code. The added test case is one example of that.

There are other fixes to the test suite as a consequence of this as well
as restoring the undef elements in some of the masks that were lost when
I brought sanity to the actual *value* of the undef and zero sentinels.

I've also just cleaned up some of the PSHUFD and PSHUFLW and PSHUFHW
combining code, but that code really needs to go. It was a nice initial
attempt, but it isn't very principled and the recursive shuffle combiner
is much more powerful.

llvm-svn: 218562
2014-09-27 04:42:44 +00:00
Chandler Carruth 81e6b29f03 [x86] Flip the sentinel values used in the target shuffle mask decoding
to significantly more sane sentinels. Notably, everywhere else in the
backend's representation of shuffles uses '-1' to represent undef. The
target shuffle masks really shouldn't diverge from that, especially as
in a few places they are manipulated by shared code.

This causes us to lose some undef lanes in various test masks. I want to
get these back, but technically it isn't invalid and there are a *lot*
of bugs here so I want to try to establish a saner baseline for fixing
some of the bugs by aligning the specific senitnel values used.

llvm-svn: 218561
2014-09-27 04:42:39 +00:00
Craig Topper 5996da2032 Fix TableGen -gen-disassembler output for bit fields with an offset.
This fixes bit assignments like this
Inst{7-0} = Foo{9-2}

Patch by Steve King.

llvm-svn: 218560
2014-09-27 04:38:02 +00:00
Sanjay Patel bdf1e38856 Refactor reciprocal and reciprocal square root estimate into target-independent functions (part 2).
This is purely refactoring. No functional changes intended. PowerPC is the only target
that is currently using this interface.

The ultimate goal is to allow targets other than PowerPC (certainly X86 and Aarch64) to turn this:

z = y / sqrt(x)

into:

z = y * rsqrte(x)

And:

z = y / x

into:

z = y * rcpe(x)

using whatever HW magic they can use. See http://llvm.org/bugs/show_bug.cgi?id=20900 .

There is one hook in TargetLowering to get the target-specific opcode for an estimate instruction
along with the number of refinement steps needed to make the estimate usable.

Differential Revision: http://reviews.llvm.org/D5484

llvm-svn: 218553
2014-09-26 23:01:47 +00:00
David Majnemer dac39857d6 Object: BSS/virtual sections don't have contents
Users of getSectionContents shouldn't try to pass in BSS or virtual
sections.  In all instances, this is a bug in the code calling this
routine.

N.B. Some COFF implementations (like CL) will mark their BSS sections as
taking space on disk.  This would confuse COFFObjectFile into thinking
the section is larger than the file.

llvm-svn: 218549
2014-09-26 22:32:16 +00:00
Kevin Enderby 8597488e5e Update llvm-objdump’s Mach-O symbolizer code to print the name of symbol stubs.
So in fully linked images when a call is made through a stub it now gets a
comment like the following in the disassembly:

    callq	0x100000f6c             ## symbol stub for: _printf

indicating the call is to a symbol stub and which symbol it is for.  This is
done for branch reference types and seeing if the branch target is in a stub
section and if so using the indirect symbol table entry for that stub and
using that symbol table entries symbol name.

llvm-svn: 218546
2014-09-26 22:20:44 +00:00
Chandler Carruth f572f3b2c0 [x86] Fix a moderately terrifying bug in the new 128-bit shuffle logic
that managed to elude all of my fuzz testing historically. =/

Something changed to allow this code path to actually be exercised and
it was doing bad things. It is especially heavily exercised by the
patterns that emerge when doing AVX shuffles that end up lowered through
the 128-bit code path.

llvm-svn: 218540
2014-09-26 20:41:45 +00:00
Chad Rosier 7b974b73ae [IndVar] Don't widen loop compare unless IV user is sign extended.
PR21030

llvm-svn: 218539
2014-09-26 20:05:35 +00:00
Matt Arsenault ed8a3e0a08 R600/SI: Add strict check lines to div_scale tests.
This has weird operand requirements so it's worthwhile
to have very strict checks for its operands.

Add different combinations of SGPR operands.

llvm-svn: 218535
2014-09-26 17:55:11 +00:00
Matt Arsenault 6a0919fb9b R600/SI Allow same SGPR to be used for multiple operands
Instead of moving the first SGPR that is different than the first,
legalize the operand that requires the fewest moves if one
SGPR is used for multiple operands.

This saves extra moves and is also required for some instructions
which require that the same operand be used for multiple operands.

llvm-svn: 218532
2014-09-26 17:55:03 +00:00
Matt Arsenault cb0ac3d1fb R600/SI: Partially move operand legalization to post-isel hook.
Disable the SGPR usage restriction parts of the DAG legalizeOperands.
It now should only be doing immediate folding until it can be replaced
later. The real legalization work is now done by the other
SIInstrInfo::legalizeOperands

llvm-svn: 218531
2014-09-26 17:54:59 +00:00
Matt Arsenault 5885bef6cf R600/SI: Don't move operands that are required to be SGPRs
e.g. v_cndmask_b32 requires the condition operand be an SGPR.
If one of the source operands were an SGPR, that would be considered
the one SGPR use and the condition operand would be illegally moved.

llvm-svn: 218529
2014-09-26 17:54:52 +00:00
Matt Arsenault aff65fbca5 R600/SI: Fix using wrong operand indices when commuting
No test since the current SIISelLowering::legalizeOperands
effectively hides this, and the general uses seem to only fire
on SALU instructions which don't have modifiers between
the operands.

When trying to use legalizeOperands immediately after
instruction selection, it now sees a lot more patterns
it did not see before which break on this.

llvm-svn: 218527
2014-09-26 17:54:43 +00:00
David Peixotto 472b05b36c Ignore annotation function calls in cost computation
The annotation instructions are dropped during codegen and have no
impact on size.  In some cases, the annotations were preventing the
unroller from unrolling a loop because the annotation calls were
pushing the cost over the unrolling threshold.

Differential Revision: http://reviews.llvm.org/D5335

llvm-svn: 218525
2014-09-26 17:48:40 +00:00
Chandler Carruth 0c9ee10d01 [x86] In the new vector shuffle lowering, when trying to do another
layer of tie-breaking sorting, it really helps to check that you're in
a tie first. =] Otherwise the whole thing cycles infinitely. Test case
added, another one found through fuzz testing.

llvm-svn: 218523
2014-09-26 17:24:26 +00:00
Chandler Carruth 5afd4c2603 [x86] Fix a large collection of bugs that crept in as I fleshed out the
AVX support.

New test cases included. Note that none of the existing test cases
covered these buggy code paths. =/ Also, it is clear from this that
SHUFPS and SHUFPD are the most bug prone shuffle instructions in x86. =[

These were all detected by fuzz-testing. (I <3 fuzz testing.)

llvm-svn: 218522
2014-09-26 17:11:02 +00:00
Renato Golin 36c626e33f Elide repeated register operand in Thumb1 instructions
This patch makes the ARM backend transform 3 operand instructions such as
'adds/subs' to the 2 operand version of the same instruction if the first
two register operands are the same.

Example: 'adds r0, r0, #1' will is transformed to 'adds r0, #1'.

Currently for some instructions such as 'adds' if you try to assemble
'adds r0, r0, #8' for thumb v6m the assembler would throw an error message
because the immediate cannot be encoded using 3 bits.

The backend should be smart enough to transform the instruction to
'adds r0, #8', which allows for larger immediate constants.

Patch by Ranjeet Singh.

llvm-svn: 218521
2014-09-26 16:14:29 +00:00