Commit Graph

700 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
9a11d668f9 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206707, reapplying r206704.  The preceding commit
to CalcSpillWeights should have sorted out the failing buildbots.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206766 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-21 17:57:07 +00:00
Duncan P. N. Exon Smith
f44eda4764 Revert "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206704, as expected.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206707 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 22:46:00 +00:00
Duncan P. N. Exon Smith
f465370a49 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206677, reapplying my BlockFrequencyInfo rewrite.

I've done a careful audit, added some asserts, and fixed a couple of
bugs (unfortunately, they were in unlikely code paths).  There's a small
chance that this will appease the failing bots [1][2].  (If so, great!)

If not, I have a follow-up commit ready that will temporarily add
-debug-only=block-freq to the two failing tests, allowing me to compare
the code path between what the failing bots and what my machines (and
the rest of the bots) are doing.  Once I've triggered those builds, I'll
revert both commits so the bots go green again.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816
[2]: http://llvm-amd64.freebsd.your.org/b/builders/clang-i386-freebsd/builds/18445

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206704 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 22:34:26 +00:00
Duncan P. N. Exon Smith
2033057de8 Revert "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)
This reverts commit r206666, as planned.

Still stumped on why the bots are failing.  Sanitizer bots haven't
turned anything up.  If anyone can help me debug either of the failures
(referenced in r206666) I'll owe them a beer.  (In the meantime, I'll be
auditing my patch for undefined behaviour.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206677 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 00:42:46 +00:00
Duncan P. N. Exon Smith
036e26bc29 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)
This reverts commit r206628, reapplying r206622 (and r206626).

Two tests are failing only on buildbots [1][2]: i.e., I can't reproduce
on Darwin, and Chandler can't reproduce on Linux.  Asan and valgrind
don't tell us anything, but we're hoping the msan bot will catch it.

So, I'm applying this again to get more feedback from the bots.  I'll
leave it in long enough to trigger builds in at least the sanitizer
buildbots (it was failing for reasons unrelated to my commit last time
it was in), and hopefully a few others.... and then I expect to revert a
third time.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816
[2]: http://llvm-amd64.freebsd.your.org/b/builders/clang-i386-freebsd/builds/18445

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206666 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 22:30:03 +00:00
Duncan P. N. Exon Smith
ebb5d29473 Revert "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)
This reverts commit r206622 and the MSVC fixup in r206626.

Apparently the remotely failing tests are still failing, despite my
attempt to fix the nondeterminism in r206621.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206628 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:56:08 +00:00
Duncan P. N. Exon Smith
54850bedf2 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206556, effectively reapplying commit r206548 and
its fixups in r206549 and r206550.

In an intervening commit I've added target triples to the tests that
were failing remotely [1] (but passing locally).  I'm hoping the mystery
is solved?  I'll revert this again if the tests are still failing
remotely.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206622 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:22:25 +00:00
Chandler Carruth
4c7edb1240 [LCG] Add support for building persistent and connected SCCs to the
LazyCallGraph. This is the start of the whole point of this different
abstraction, but it is just the initial bits. Here is a run-down of
what's going on here. I'm planning to incorporate some (or all) of this
into comments going forward, hopefully with better editing and wording.
=]

The crux of the problem with the traditional way of building SCCs is
that they are ephemeral. The new pass manager however really needs the
ability to associate analysis passes and results of analysis passes with
SCCs in order to expose these analysis passes to the SCC passes. Making
this work is kind-of the whole point of the new pass manager. =]

So, when we're building SCCs for the call graph, we actually want to
build persistent nodes that stick around and can be reasoned about
later. We'd also like the ability to walk the SCC graph in more complex
ways than just the traditional postorder traversal of the current CGSCC
walk. That means that in addition to being persistent, the SCCs need to
be connected into a useful graph structure.

However, we still want the SCCs to be formed lazily where possible.

These constraints are quite hard to satisfy with the SCC iterator. Also,
using that would bypass our ability to actually add data to the nodes of
the call graph to facilite implementing the Tarjan walk. So I've
re-implemented things in a more direct and embedded way. This
immediately makes it easy to get the persistence and connectivity
correct, and it also allows leveraging the existing nodes to simplify
the algorithm. I've worked somewhat to make this implementation more
closely follow the traditional paper's nomenclature and strategy,
although it is still a bit obtuse because it isn't recursive, using
an explicit stack and a tail call instead, and it is interruptable,
resuming each time we need another SCC.

The other tricky bit here, and what actually took almost all the time
and trials and errors I spent building this, is exactly *what* graph
structure to build for the SCCs. The naive thing to build is the call
graph in its newly acyclic form. I wrote about 4 versions of this which
did precisely this. Inevitably, when I experimented with them across
various use cases, they became incredibly awkward. It was all
implementable, but it felt like a complete wrong fit. Square peg, round
hole. There were two overriding aspects that pushed me in a different
direction:

1) We want to discover the SCC graph in a postorder fashion. That means
   the root node will be the *last* node we find. Using the call-SCC DAG
   as the graph structure of the SCCs results in an orphaned graph until
   we discover a root.

2) We will eventually want to walk the SCC graph in parallel, exploring
   distinct sub-graphs independently, and synchronizing at merge points.
   This again is not helped by the call-SCC DAG structure.

The structure which, quite surprisingly, ended up being completely
natural to use is the *inverse* of the call-SCC DAG. We add the leaf
SCCs to the graph as "roots", and have edges to the caller SCCs. Once
I switched to building this structure, everything just fell into place
elegantly.

Aside from general cleanups (there are FIXMEs and too few comments
overall) that are still needed, the other missing piece of this is
support for iterating across levels of the SCC graph. These will become
useful for implementing #2, but they aren't an immediate priority.

Once SCCs are in good shape, I'll be working on adding mutation support
for incremental updates and adding the pass manager that this analysis
enables.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206581 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 10:50:32 +00:00
Duncan P. N. Exon Smith
c7a3b95c0f Revert "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commits r206548, r206549 and r206549.

There are some unit tests failing that aren't failing locally [1], so
reverting until I have time to investigate.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206556 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 02:17:43 +00:00
Duncan P. N. Exon Smith
cc1e1707b8 blockfreq: Rewrite BlockFrequencyInfoImpl
Rewrite the shared implementation of BlockFrequencyInfo and
MachineBlockFrequencyInfo entirely.

The old implementation had a fundamental flaw:  precision losses from
nested loops (or very wide branches) compounded past loop exits (and
convergence points).

The @nested_loops testcase at the end of
test/Analysis/BlockFrequencyAnalysis/basic.ll is motivating.  This
function has three nested loops, with branch weights in the loop headers
of 1:4000 (exit:continue).  The old analysis gives non-sensical results:

    Printing analysis 'Block Frequency Analysis' for function 'nested_loops':
    ---- Block Freqs ----
     entry = 1.0
     for.cond1.preheader = 1.00103
     for.cond4.preheader = 5.5222
     for.body6 = 18095.19995
     for.inc8 = 4.52264
     for.inc11 = 0.00109
     for.end13 = 0.0

The new analysis gives correct results:

    Printing analysis 'Block Frequency Analysis' for function 'nested_loops':
    block-frequency-info: nested_loops
     - entry: float = 1.0, int = 8
     - for.cond1.preheader: float = 4001.0, int = 32007
     - for.cond4.preheader: float = 16008001.0, int = 128064007
     - for.body6: float = 64048012001.0, int = 512384096007
     - for.inc8: float = 16008001.0, int = 128064007
     - for.inc11: float = 4001.0, int = 32007
     - for.end13: float = 1.0, int = 8

Most importantly, the frequency leaving each loop matches the frequency
entering it.

The new algorithm leverages BlockMass and PositiveFloat to maintain
precision, separates "probability mass distribution" from "loop
scaling", and uses dithering to eliminate probability mass loss.  I have
unit tests for these types out of tree, but it was decided in the review
to make the classes private to BlockFrequencyInfoImpl, and try to shrink
them (or remove them entirely) in follow-up commits.

The new algorithm should generally have a complexity advantage over the
old.  The previous algorithm was quadratic in the worst case.  The new
algorithm is still worst-case quadratic in the presence of irreducible
control flow, but it's linear without it.

The key difference between the old algorithm and the new is that control
flow within a loop is evaluated separately from control flow outside,
limiting propagation of precision problems and allowing loop scale to be
calculated independently of mass distribution.  Loops are visited
bottom-up, their loop scales are calculated, and they are replaced by
pseudo-nodes.  Mass is then distributed through the function, which is
now a DAG.  Finally, loops are revisited top-down to multiply through
the loop scales and the masses distributed to pseudo nodes.

There are some remaining flaws.

  - Irreducible control flow isn't modelled correctly.  LoopInfo and
    MachineLoopInfo ignore irreducible edges, so this algorithm will
    fail to scale accordingly.  There's a note in the class
    documentation about how to get closer.  See also the comments in
    test/Analysis/BlockFrequencyInfo/irreducible.ll.

  - Loop scale is limited to 4096 per loop (2^12) to avoid exhausting
    the 64-bit integer precision used downstream.

  - The "bias" calculation proposed on llvmdev is *not* incorporated
    here.  This will be added in a follow-up commit, once comments from
    this review have been handled.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206548 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 01:57:45 +00:00
Akira Hatanaka
268c0509a9 Fix a bug in which BranchProbabilityInfo wasn't setting branch weights of basic blocks inside loops correctly.
Previously, BranchProbabilityInfo::calcLoopBranchHeuristics would determine the weights of basic blocks inside loops even when it didn't have enough information to estimate the branch probabilities correctly. This patch fixes the function to exit early if it doesn't see any exit edges or back edges and let the later heuristics determine the weights.

This fixes PR18705 and <rdar://problem/15991090>.

Differential Revision: http://reviews.llvm.org/D3363



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206194 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-14 16:56:19 +00:00
Hal Finkel
1aee811d71 Don't assert in BasicTTI::getMemoryOpCost for non-simple types
BasicTTI::getMemoryOpCost must explicitly check for non-simple types; setting
AllowUnknown=true with TLI->getSimpleValueType is not sufficient because, for
example, non-power-of-two vector types return non-simple EVTs (not MVT::Other).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206150 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-14 05:59:09 +00:00
Sebastian Pop
d541e6e6ea in findGCD of multiply expr return the gcd
we used to return 1 instead of the gcd

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205800 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-08 21:21:05 +00:00
Hal Finkel
e6a5b33e6e [PowerPC] Adjust load/store costs in PPCTTI
This provides more realistic costs for the insert/extractelement instructions
(which are load/store pairs), accounts for the cheap unaligned Altivec load
sequence, and for unaligned VSX load/stores.

Bad news:
MultiSource/Applications/sgefa/sgefa - 35% slowdown (this will require more investigation)
SingleSource/Benchmarks/McGill/queens - 20% slowdown (we no longer vectorize this, but it was a constant store that was scalarized)
MultiSource/Benchmarks/FreeBench/pcompress2/pcompress2 - 2% slowdown

Good news:
SingleSource/Benchmarks/Shootout/ary3 - 54% speedup
SingleSource/Benchmarks/Shootout-C++/ary - 40% speedup
MultiSource/Benchmarks/Ptrdist/ks/ks - 35% speedup
MultiSource/Benchmarks/FreeBench/neural/neural - 30% speedup
MultiSource/Benchmarks/TSVC/Symbolics-flt/Symbolics-flt - 20% speedup

Unfortunately, estimating the costs of the stack-based scalarization sequences
is hard, and adjusting these costs is like a game of whac-a-mole :( I'll
revisit this again after we have better codegen for vector extloads and
truncstores and unaligned load/stores.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205658 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-04 23:51:18 +00:00
Hal Finkel
d68b03bcd2 Account for scalarization costs in BasicTTI::getMemoryOpCost for extending vector loads
When a vector type legalizes to a larger vector type, and the target does not
support the associated extending load (or truncating store), then legalization
will scalarize the load (or store) resulting in an associated scalarization
cost.  BasicTTI::getMemoryOpCost needs to account for this.

Between this, and r205487, PowerPC on the P7 with VSX enabled shows:

MultiSource/Benchmarks/PAQ8p/paq8p: 43% speedup
SingleSource/Benchmarks/BenchmarkGame/puzzle: 51% speedup
SingleSource/UnitTests/Vectorizer/gcc-loops 28% speedup

(some of these are new; some of these, such as PAQ8p, just reverse regressions
that VSX support would trigger)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205495 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-03 00:53:59 +00:00
Hal Finkel
9263e6f08d Fix multi-register costs in BasicTTI::getCastInstrCost
For an cast (extension, etc.), the currently logic predicts a low cost if the
associated operation (keyed on the destination type) is legal (or promoted).
This is not true when the number of values required to legalize the type is
changing. For example, <8 x i16> being sign extended by <8 x i32> is not
generically cheap on PPC with VSX, even though sign extension to v4i32 is
legal, because two output v4i32 values are required compared to the single
v8i16 input value, and without custom logic in the target, this conversion will
scalarize.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205487 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-02 23:18:54 +00:00
Tim Northover
7b837d8c75 ARM64: initial backend import
This adds a second implementation of the AArch64 architecture to LLVM,
accessible in parallel via the "arm64" triple. The plan over the
coming weeks & months is to merge the two into a single backend,
during which time thorough code review should naturally occur.

Everything will be easier with the target in-tree though, hence this
commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@205090 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-29 10:18:08 +00:00
Arnold Schwaighofer
23463c9261 PR15967 Fix in basicaa for faulty returning no alias.
This commit consist of two parts.
The first part fix the PR15967. The wrong conclusion was made when the MaxLookup
limit was reached. The fix introduce a out parameter (MaxLookupReached) to
DecomposeGEPExpression that the function aliasGEP can act upon.
The second part is introducing the constant MaxLookupSearchDepth to make sure
that DecomposeGEPExpression and GetUnderlyingObject use the same search depth.
This is a small cleanup to clarify the original algorithm.

Patch by Karl-Johan Karlsson!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204859 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-26 21:30:19 +00:00
Benjamin Kramer
c1c74fb2b4 ScalarEvolution: Compute exit counts for loops with a power-of-2 step.
If we have a loop of the form
for (unsigned n = 0; n != (k & -32); n += 32) {}
then we know that n is always divisible by 32 and the loop must
terminate. Even if we have a condition where the loop counter will
overflow it'll always hold this invariant.

PR19183. Our loop vectorizer creates this pattern and it's also
occasionally formed by loop counters derived from pointers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204728 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-25 16:25:12 +00:00
Rafael Espindola
38048cdb1c Reject alias to undefined symbols in the verifier.
On ELF and COFF an alias is just another name for a position in the file.
There is no way to refer to a position in another file, so an alias to
undefined is meaningless.

MachO currently doesn't support aliases. The spec has a N_INDR, which when
implemented will have a different set of restrictions. Adding support for
it shouldn't be harder than any other IR extension.

For now, having the IR represent what is actually possible with current
tools makes it easier to fix the design of GlobalAlias.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203705 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-12 20:15:49 +00:00
Raul E. Silvera
6df2b69098 When analyzing vectors of element type that require legalization,
the legalization cost must be included to get an accurate
estimation of the total cost of the scalarized vector.
The inaccurate cost triggered unprofitable SLP vectorization on
32-bit X86.

Summary:
Include legalization overhead when computing scalarization cost

Reviewers: hfinkel, nadav

CC: chandlerc, rnk, llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2992

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203509 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-10 22:59:13 +00:00
Matt Arsenault
38c18efe41 Teach lint about address spaces
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203132 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-06 17:33:55 +00:00
Sebastian Pop
4449ed2a70 add -da-delinearize runs and checks to MIV testcases
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201869 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-21 18:15:18 +00:00
Nico Rieck
c15d3a82ae Add extra CHECK prefix to tests with explicit prefix
These tests mistakenly assume that CHECK is still available even if an
explicit prefix is specified.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201492 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-16 13:28:15 +00:00
Nico Rieck
da39cf486a Actually call FileCheck in tests
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201491 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-16 13:27:39 +00:00
Nico Rieck
268e96a8a6 Fix broken CHECK lines
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201479 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-16 07:31:05 +00:00
Andrea Di Biagio
029a76b0a2 [Vectorizer] Add a new 'OperandValueKind' in TargetTransformInfo called
'OK_NonUniformConstValue' to identify operands which are constants but
not constant splats.

The cost model now allows returning 'OK_NonUniformConstValue'
for non splat operands that are instances of ConstantVector or
ConstantDataVector.

With this change, targets are now able to compute different costs
for instructions with non-uniform constant operands.
For example, On X86 the cost of a vector shift may vary depending on whether
the second operand is a uniform or non-uniform constant.

This patch applies the following changes:
 - The cost model computation now takes into account non-uniform constants;
 - The cost of vector shift instructions has been improved in
   X86TargetTransformInfo analysis pass;
 - BBVectorize, SLPVectorizer and LoopVectorize now know how to distinguish
   between non-uniform and uniform constant operands.

Added a new test to verify that the output of opt
'-cost-model -analyze' is valid in the following configurations: SSE2,
SSE4.1, AVX, AVX2.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201272 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-12 23:43:47 +00:00
Craig Topper
c7709a43ee Test case I forgot to 'add' for r201126.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201207 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-12 03:58:47 +00:00
Benjamin Kramer
cb27441554 ScalarEvolution: Analyze trip count of loops with a switch guarding the exit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201159 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-11 15:44:32 +00:00
Tim Northover
0c245b69f7 X86: add costs for 64-bit vector ext/trunc & rebalance
The most important part of this is probably adding any cost at all for
operations like zext <8 x i8> to <8 x i32>. Before they were being
recorded as extremely costly (24, I believe) which made LLVM fall back
on a 4-wide vectorisation of a loop.

It also rebalances the values for sext, zext and trunc. Lacking any
other sane metric that might work across CPU microarchitectures I went
for instructions. This seems to be in reasonable accord with the rest
of the table (sitofp, ...) though no doubt at least one value is
sub-optimal for some bizarre reason.

Finally, separate AVX and AVX2 values are provided where appropriate.
The CodeGen is quite different in many cases.

rdar://problem/15981990

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200928 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-06 18:18:36 +00:00
Chandler Carruth
57732bff1e [PM] Add a new "lazy" call graph analysis pass for the new pass manager.
The primary motivation for this pass is to separate the call graph
analysis used by the new pass manager's CGSCC pass management from the
existing call graph analysis pass. That analysis pass is (somewhat
unfortunately) over-constrained by the existing CallGraphSCCPassManager
requirements. Those requirements make it *really* hard to cleanly layer
the needed functionality for the new pass manager on top of the existing
analysis.

However, there are also a bunch of things that the pass manager would
specifically benefit from doing differently from the existing call graph
analysis, and this new implementation tries to address several of them:

- Be lazy about scanning function definitions. The existing pass eagerly
  scans the entire module to build the initial graph. This new pass is
  significantly more lazy, and I plan to push this even further to
  maximize locality during CGSCC walks.
- Don't use a single synthetic node to partition functions with an
  indirect call from functions whose address is taken. This node creates
  a huge choke-point which would preclude good parallelization across
  the fanout of the SCC graph when we got to the point of looking at
  such changes to LLVM.
- Use a memory dense and lightweight representation of the call graph
  rather than value handles and tracking call instructions. This will
  require explicit update calls instead of some updates working
  transparently, but should end up being significantly more efficient.
  The explicit update calls ended up being needed in many cases for the
  existing call graph so we don't really lose anything.
- Doesn't explicitly model SCCs and thus doesn't provide an "identity"
  for an SCC which is stable across updates. This is essential for the
  new pass manager to work correctly.
- Only form the graph necessary for traversing all of the functions in
  an SCC friendly order. This is a much simpler graph structure and
  should be more memory dense. It does limit the ways in which it is
  appropriate to use this analysis. I wish I had a better name than
  "call graph". I've commented extensively this aspect.

This is still very much a WIP, in fact it is really just the initial
bits. But it is about the fourth version of the initial bits that I've
implemented with each of the others running into really frustrating
problms. This looks like it will actually work and I'd like to split the
actual complexity across commits for the sake of my reviewers. =] The
rest of the implementation along with lots of wiring will follow
somewhat more rapidly now that there is a good path forward.

Naturally, this doesn't impact any of the existing optimizer. This code
is specific to the new pass manager.

A bunch of thanks are deserved for the various folks that have helped
with the design of this, especially Nick Lewycky who actually sat with
me to go through the fundamentals of the final version here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200903 91177308-0d34-0410-b5e6-96231b3b80d8
2014-02-06 04:37:03 +00:00
Nick Lewycky
4bfa6fecc1 Fix crasher introduced in r200203 and caught by a libc++ buildbot. Don't assume that getMulExpr returns a SCEVMulExpr, it may have simplified it to something else!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200210 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-27 10:47:44 +00:00
Nick Lewycky
f2282cac95 Teach SCEV to handle more cases of 'and X, CST', specifically where CST is any number of contiguous 1 bits in a row, with any number of leading and trailing 0 bits.
Unfortunately, this in turn led to some lower quality SCEVs due to some different paths through expression simplification, so add getUDivExactExpr and use it. This fixes all instances of the problems that I found, but we can make that function smarter as necessary.

Merge test "xor-and.ll" into "and-xor.ll" since I needed to update it anyways. Test 'nsw-offset.ll' analyzes a little deeper, %n now gets a scev in terms of %no instead of a SCEVUnknown.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200203 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-27 10:04:03 +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
Arnold Schwaighofer
8963071a14 BasicAA: We need to check both access sizes when comparing a gep and an
underlying object of unknown size.

Fixes PR18460.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199351 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-16 04:53:18 +00:00
Benjamin Kramer
ccdb9c9483 Fix broken CHECK lines.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199016 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-11 21:06:00 +00:00
Stepan Dyatkovskiy
3539d6d40c Fixed old typo in ScalarEvolution, that caused wrong SCEVs zext operation.
Detailed description is here:
http://llvm.org/bugs/show_bug.cgi?id=18000#c16

For participation in bugfix process special thanks to David Wiberg.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198863 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-09 12:26:12 +00:00
Arnold Schwaighofer
3036182e99 BasicAA: Use reachabilty instead of dominance for checking value equality in phi
cycles

This allows the value equality check to work even if we don't have a dominator
tree. Also add some more comments.

I was worried about compile time impacts and did not implement reachability but
used the dominance check in the initial patch. The trade-off was that the
dominator tree was required.
The llvm utility function isPotentiallyReachable cuts off the recursive search
after 32 visits. Testing did not show any compile time regressions showing my
worries unjustfied.

No compile time or performance regressions at O3 -flto -mavx on test-suite +
externals.

Addresses review comments from r198290.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198400 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-03 05:47:03 +00:00
Arnold Schwaighofer
1bdb320dae BasicAA: Fix value equality and phi cycles
When there are cycles in the value graph we have to be careful interpreting
"Value*" identity as "value" equivalence. We interpret the value of a phi node
as the value of its operands.
When we check for value equivalence now we make sure that the "Value*" dominates
all cycles (phis).

%0 = phi [%noaliasval, %addr2]
%l = load %ptr
%addr1 = gep @a, 0, %l
%addr2 = gep @a, 0, (%l + 1)
store %ptr ...

Before this patch we would return NoAlias for (%0, %addr1) which is wrong
because the value of the load is from different iterations of the loop.

Tested on x86_64 -mavx at O3 and O3 -flto with no performance or compile time
regressions.

PR18068
radar://15653794

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198290 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-02 03:31:36 +00:00
Matt Arsenault
74c996cbd1 Use correct size for address space in BasicAA.
The tests just hit this with a different sized
address space since I haven't figured out how
to use this to break it.

I thought I committed this a long time ago,
and I'm not sure why missing this hasn't caused
any problems.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194903 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-16 00:36:43 +00:00
Sebastian Pop
430b6eb419 improve dependence analysis testcases
print the name of the function on which the dependence analysis is performed
such that changes to the testcase are easier to review.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194528 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-12 22:47:30 +00:00
Sebastian Pop
5230ad61fd delinearization of arrays
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194527 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-12 22:47:20 +00:00
Andrew Trick
10bb82e54f Rewrite SCEV's backedge taken count computation.
Patch by Michele Scandale!

Rewrite of the functions used to compute the backedge taken count of a
loop on LT and GT comparisons.

I decided to split the handling of LT and GT cases becasue the trick
"a > b == -a < -b" in some cases prevents the trip count computation
due to the multiplication by -1 on the two operands of the
comparison. This issue comes from the conservative computation of
value range of SCEVs: taking the negative SCEV of an expression that
have a small positive range (e.g. [0,31]), we would have a SCEV with a
fullset as value range.

Indeed, in the new rewritten function I tried to better handle the
maximum backedge taken count computation when MAX/MIN expression are
used to handle the cases where no entry guard is found.

Some test have been modified in order to check the new value correctly
(I manually check them and reasoning on possible overflow the new
values seem correct).

I finally added a new test case related to the multiplication by -1
issue on GT comparisons.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194116 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-06 02:08:26 +00:00
Hal Finkel
e14fb07357 Consider (x == -1) unlikely in BranchProbabilityInfo
This adds another heuristic to BPI, similar to the existing heuristic that
considers (x == 0) unlikely to be true. As suggested in the PACT'98 paper by
Deitrich, Cheng, and Hwu, -1 is often used to indicate an invalid index, and
equality comparisons with -1 are also unlikely to succeed. Local
experimentation supports this hypothesis: This yields a 1-2% speedup in the
test-suite sqlite benchmark on the PPC A2 core, with no significant
regressions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193855 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-01 10:58:22 +00:00
Benjamin Kramer
19ea37059a SCEV: Make the final add of an inbounds GEP nuw if we know that the index is positive.
We can't do this for the general case as saying a GEP with a negative index
doesn't have unsigned wrap isn't valid for negative indices.
  %gep = getelementptr inbounds i32* %p, i64 -1

But an inbounds GEP cannot run past the end of address space. So we check for
the very common case of a positive index and make GEPs derived from that NUW.
Together with Andy's recent non-unit stride work this lets us analyze loops
like

  void foo3(int *a, int *b) {
    for (; a < b; a++) {}
  }

PR12375, PR12376.

Differential Revision: http://llvm-reviews.chandlerc.com/D2033

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193514 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-28 07:30:06 +00:00
Shuxin Yang
69bd41dfe3 Revert r193251 : Use address-taken to disambiguate global variable and indirect memops.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193489 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-27 03:08:44 +00:00
Benjamin Kramer
bb41c75ab5 X86: Custom lower sext v16i8 to v16i16, and the corresponding truncate.
Also update the cost model.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193270 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-23 21:06:07 +00:00
Shuxin Yang
8e3851a6eb Use address-taken to disambiguate global variable and indirect memops.
Major steps include:
 1). introduces a not-addr-taken bit-field in GlobalVariable
 2). GlobalOpt pass sets "not-address-taken" if it proves a global varirable 
    dosen't have its address taken.
 3). AA use this info for disambiguation. 


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193251 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-23 17:28:19 +00:00
Manman Ren
b62e1033a4 Simplify testing case (Thanks Rafael for the testing case).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193177 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-22 18:15:50 +00:00
Manman Ren
11d78777d5 TBAA: fix PR17620.
We can have a struct type with a single field and the field does not start
with 0. In that case, we should correctly update the offset.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193137 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-22 01:40:25 +00:00