Commit Graph

12482 Commits

Author SHA1 Message Date
Tim Northover
7f75841a73 DeadArgElim: aggregate Return assessment properly.
I mistakenly thought the liveness of each "RetVal(F, i)" depended only on F. It
actually depends on the index too, which means we need to be careful about how
the results are combined before return. In particular if a single Use returns
Live, that counts for the entire object, at the granularity we're considering.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228885 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 23:13:11 +00:00
Mehdi Amini
23af697ae6 Reassociate: cannot negate a INT_MIN value
Summary:
When trying to canonicalize negative constants out of
multiplication expressions, we need to check that the
constant is not INT_MIN which cannot be negated.

Reviewers: mcrosier

Reviewed By: mcrosier

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7286

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228872 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 19:54:44 +00:00
James Molloy
4de471dd0a [SimplifyCFG] Swap to using TargetTransformInfo for cost
analysis.

We're already using TTI in SimplifyCFG, so remove the hard-baked "cheapness"
heuristic and use TTI directly. Generally NFC intended, but we're using a slightly
different heuristic now so there is a slight test churn.

Test changes:
  * combine-comparisons-by-cse.ll: Removed unneeded branch check.
  * 2014-08-04-muls-it.ll: Test now doesn't branch but emits muleq.
  * coalesce-subregs.ll: Superfluous block check.
  * 2008-01-02-hoist-fp-add.ll: fadd is safe to speculate. Change to udiv.
  * PhiBlockMerge.ll: Superfluous CFG checking code. Main checks still present.
  * select-gep.ll: A variable GEP is not expensive, just TCC_Basic, according to the TTI.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228826 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 12:15:41 +00:00
James Molloy
caba7561ae [LoopReroll] Introduce the concept of DAGRootSets.
A DAGRootSet models an induction variable being used in a rerollable
loop. For example:

   x[i*3+0] = y1
   x[i*3+1] = y2
   x[i*3+2] = y3

   Base instruction -> i*3
                    +---+----+
                   /    |     \
               ST[y1]  +1     +2  <-- Roots
                        |      |
                      ST[y2] ST[y3]

There may be multiple DAGRootSets, for example:

   x[i*2+0] = ...   (1)
   x[i*2+1] = ...   (1)
   x[i*2+4] = ...   (2)
   x[i*2+5] = ...   (2)
   x[(i+1234)*2+5678] = ... (3)
   x[(i+1234)*2+5679] = ... (3)

This concept is similar to the "Scale" member used previously, but allows
multiple independent sets of roots based off the same induction variable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228821 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 09:19:47 +00:00
Zachary Turner
c371307e60 Use ADDITIONAL_HEADER_DIRS in all LLVM CMake projects.
This allows IDEs to recognize the entire set of header files for
each of the core LLVM projects.

Differential Revision: http://reviews.llvm.org/D7526
Reviewed By: Chris Bieneman

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228798 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 03:28:02 +00:00
Justin Bogner
167ce4489c InstrProf: Lower coverage mappings by setting their sections appropriately
Add handling for __llvm_coverage_mapping to the InstrProfiling
pass. We need to make sure the constant and any profile names it
refers to are in the correct sections, which is easier and cleaner to
do here where we have to know about profiling sections anyway.

This is really tricky to test without a frontend, so I'm committing
the test for the fix in clang. If anyone knows a good way to test this
within LLVM, please let me know.

Fixes PR22531.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228793 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 02:52:44 +00:00
Reid Kleckner
690248bf52 Don't promote asynch EH invokes of nounwind functions to calls
If the landingpad of the invoke is using a personality function that
catches asynch exceptions, then it can catch a trap.

Also add some landingpads to invalid LLVM IR test cases that lack them.

Over-the-shoulder reviewed by David Majnemer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228782 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-11 01:23:16 +00:00
David Majnemer
0f8bd667a1 EarlyCSE: It isn't safe to CSE across synchronization boundaries
This fixes PR22514.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228760 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-10 23:09:43 +00:00
Tim Northover
b613f8842e DeadArgElim: arguments affect all returned sub-values by default.
Unless we meet an insertvalue on a path from some value to a return, that value
will be live if *any* of the return's components are live, so all of those
components must be added to the MaybeLiveUses.

Previously we were deleting arguments if sub-value 0 turned out to be dead.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228731 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-10 19:49:18 +00:00
Chandler Carruth
3e77df419d Revert r228556: InstCombine: propagate nonNull through assume
This commit isn't using the correct context, and is transfoming calls
that are operands to loads rather than calls that are operands to an
icmp feeding into an assume. I've replied on the original review thread
with a very reduced test case and some thoughts on how to rework this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228677 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-10 08:07:32 +00:00
Philip Reames
2fc495a300 Adjust how we avoid poll insertion inside the poll function (NFC)
I realized that my early fix for this was overly complicated.  Rather than scatter checks around in a bunch of places, just exit early when we visit the poll function itself.

Thinking about it a bit, the whole inlining mechanism used with gc.safepoint_poll could probably be cleaned up a bit.  Originally, poll insertion was fused with gc relocation rewriting.  It might be worth going back to see if we can simplify the chain of events now that these two are seperated.  As one thought, maybe it makes sense to rewrite calls inside the helper function before inlining it to the many callers.  This would require us to visit the poll function before any other functions though..



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228634 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-10 00:04:53 +00:00
Adrian Prantl
8abe95ce83 Debug info: When updating debug info during SROA, do not emit debug info
for any padding introduced by SROA. In particular, do not emit debug info
for an alloca that represents only the padding introduced by a previous
iteration.

Fixes PR22495.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228632 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 23:57:22 +00:00
Adrian Prantl
4f1b7f3100 Debug info: Use DW_OP_bit_piece instead of DW_OP_piece in the
intermediate representation. This
- increases consistency by using the same granularity everywhere
- allows for pieces < 1 byte
- DW_OP_piece didn't actually allow storing an offset.

Part of PR22495.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228631 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 23:57:15 +00:00
Ramkumar Ramachandra
4ee0217aee [Statepoint] Improve two asserts, fix some style (NFC)
Summary:
It's important that our users immediately know what gc.safepoint_poll
is. Also fix the style of the declaration of CreateGCStatepoint, in
preparation for another change that will wrap it.

Reviewers: reames

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7517

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228626 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 23:02:10 +00:00
Ramkumar Ramachandra
69a5c89128 PlaceSafepoints: modernize gc.result.* -> gc.result
Differential Revision: http://reviews.llvm.org/D7516

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228625 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 23:00:40 +00:00
Philip Reames
9a61a8236f Update file comment to clarify points highlighted in review (NFC)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228621 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 22:44:03 +00:00
Philip Reames
2b9d3c4186 Use range for loops in PlaceSafepoints (NFC)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228620 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 22:26:11 +00:00
Duncan P. N. Exon Smith
a30b342b77 IR: Take uint64_t in DIBuilder::createExpression()
`DIExpression` deals with `uint64_t`, so it doesn't make sense that
`createExpression()` is created from `int64_t`.  Switch to `uint64_t` to
unify them.

I've temporarily left in the `int64_t` version, which forwards to the
`uint64_t` version.  I'll delete it once I've updated the callers.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228619 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 22:13:27 +00:00
Philip Reames
c016fa420f Add basic tests for PlaceSafepoints
This is just adding really simple tests which should have been part of the original submission.  When doing so, I discovered that I'd mistakenly removed required pieces when preparing the patch for upstream submission.  I fixed two such bugs in this submission.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228610 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 21:48:05 +00:00
Akira Hatanaka
522cf235e9 Fix a bug in DemoteRegToStack where a reload instruction was inserted into the
wrong basic block.

This would happen when the result of an invoke was used by a phi instruction
in the invoke's normal destination block. An instruction to reload the invoke's
value would get inserted before the critical edge was split and a new basic
block (which is the correct insertion point for the reload) was created. This
commit fixes the bug by splitting the critical edge before all the reload
instructions are inserted.

Also, hoist up the code which computes the insertion point to the only place
that need that computation.

rdar://problem/15978721


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228566 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 06:38:23 +00:00
Tim Northover
968ed6a5f0 DeadArgElim: fix mismatch in accounting of array return types.
Some parts of DeadArgElim were only considering the individual fields
of StructTypes separately, but others (where insertvalue &
extractvalue instructions occur) also looked into ArrayTypes.

This one is an actual bug; the mismatch can lead to an argument being
considered used by a return sub-value that isn't being tracked (and
hence is dead by default). It then gets incorrectly eliminated.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228559 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 01:21:00 +00:00
Tim Northover
c4af8c9467 DeadArgElim: assess uses of entire return value aggregate.
Previously, a non-extractvalue use of an aggregate return value meant
the entire return was considered live (the algorithm gave up
entirely). This was correct, but conservative. It's better to actually
look at that Use, making the analysis results apply to all sub-values
under consideration.

E.g.

  %val = call { i32, i32 } @whatever()
  [...]
  ret { i32, i32 } %val

The return is using the entire aggregate (sub-values 0 and 1). We can
still simplify @whatever if we can prove that this return is itself
unused.

Also unifies the logic slightly between aggregate and non-aggregate
cases..

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228558 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 01:20:53 +00:00
Ramkumar Ramachandra
5439a80dca InstCombine: propagate nonNull through assume
Make assume (load (call|invoke) != null) set nonNull return attribute
for the call and invoke. Also include tests.

Differential Revision: http://reviews.llvm.org/D7107

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228556 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-09 01:13:13 +00:00
Bjorn Steinbrink
61a16d2a16 Correctly combine alias.scope metadata by a union instead of intersecting
Summary:
The alias.scope metadata represents sets of things an instruction might
alias with. When generically combining the metadata from two
instructions the result must be the union of the original sets, because
the new instruction might alias with anything any of the original
instructions aliased with.

Reviewers: hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7490

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228525 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-08 17:07:14 +00:00
Benjamin Kramer
fd3cd51a3a LoopIdiom: Use utility functions.
The only difference between deleteIfDeadInstruction and
RecursivelyDeleteTriviallyDeadInstructions is that the former also
manually invalidates SCEV. That's unnecessary because SCEV automatically
gets informed when an instruction is deleted via a ValueHandle. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228508 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-07 21:37:08 +00:00
Bjorn Steinbrink
2dd5f23a1d Properly update AA metadata when performing call slot optimization
Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7482

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228500 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-07 17:54:36 +00:00
Evgeniy Stepanov
e9f5367fed [msan] Fix "missing origin" in atomic store.
An atomic store always make the target location fully initialized (in the
current implementation). It should not store origin. Initialized memory can't
have meaningful origin, and, due to origin granularity (4 bytes) there is a
chance that this extra store would overwrite meaningfull origin for an adjacent
location.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228444 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 21:47:39 +00:00
Michael Zolotukhin
c9da41492f Use estimated number of optimized insns in unroll-threshold computation.
If complete-unroll could help us to optimize away N% of instructions, we
might want to do this even if the final size would exceed loop-unroll
threshold. However, we don't want to unroll huge loop, and we are add
AbsoluteThreshold to avoid that - this threshold will never be crossed,
even if we expect to optimize 99% instructions after that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228434 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 20:20:40 +00:00
Michael Zolotukhin
3da8e45675 [InstSimplify] Add SimplifyFPBinOp function.
It is a variation of SimplifyBinOp, but it takes into account
FastMathFlags.

It is needed in inliner and loop-unroller to accurately predict the
transformation's outcome (previously we dropped the flags and were too
conservative in some cases).

Example:
float foo(float *a, float b) {
 float r;
 if (a[1] * b)
   r = /* a lot of expensive computations */;
 else
   r = 1;
 return r;
}
float boo(float *a) {
 return foo(a, 0.0);
}

Without this patch, we don't inline 'foo' into 'boo'.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228432 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 20:02:51 +00:00
Adam Nemet
b3189eac3f [LV] Move addRuntimeCheck to LoopAccessAnalysis
This will allow it to be shared with the new Loop Distribution pass.

getFirstInst is currently duplicated across LoopVectorize.cpp and
LoopAccessAnalysis.cpp.  This is a short-term work-around until we figure out
a better solution.

NFC.  (The code moved is adjusted a bit for the name of the Loop member and
that PtrRtCheck is now a reference rather than a pointer.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228418 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 18:31:04 +00:00
Benjamin Kramer
e003f1ac8c Make helper functions/classes/globals static. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228410 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 17:51:54 +00:00
Matthias Braun
2f2dec87fb InstCombine: Combine select sequences into a single select
Normalize
select(C0, select(C1, a, b), b) -> select((C0 & C1), a, b)
select(C0, a, select(C1, a, b)) -> select((C0 | C1), a, b)

This normal form may enable further combines on the And/Or and shortens
paths for the values. Many targets prefer the other but can go back
easily in CodeGen.

Differential Revision: http://reviews.llvm.org/D7399

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228409 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 17:49:36 +00:00
Benjamin Kramer
33988ee4ca IRCE: Demote template to ArrayRef and SmallVector to array.
NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228398 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-06 14:43:49 +00:00
Alexey Samsonov
639e3cd880 [ASan] Enable -asan-stack-dynamic-alloca by default.
By default, store all local variables in dynamic alloca instead of
static one. It reduces the stack space usage in use-after-return mode
(dynamic alloca will not be called if the local variables are stored
in a fake stack), and improves the debug info quality for local
variables (they will not be described relatively to %rbp/%rsp, which
are assumed to be clobbered by function calls).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228336 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 19:39:20 +00:00
Hans Wennborg
2cdfb4b5da LowerSwitch: Use ConstantInt for CaseRange::{Low,High}
Case values are always ConstantInt. This allows us to remove
a bunch of casts. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228312 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 16:58:10 +00:00
Hans Wennborg
5243154a6a LowerSwitch: remove default args from CaseRange ctor; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228311 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 16:50:27 +00:00
Aaron Ballman
04688c792c Removing an unused variable warning I accidentally introduced with my last warning fix; NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228295 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 13:52:42 +00:00
Aaron Ballman
ac7a1d5994 Silencing an MSVC warning about a switch statement with no cases; NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228294 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 13:40:04 +00:00
Michael Zolotukhin
710ce5d36b Implement new heuristic for complete loop unrolling.
Complete loop unrolling can make some loads constant, thus enabling a
lot of other optimizations. To catch such cases, we look for loads that
might become constants and estimate number of instructions that would be
simplified or become dead after substitution.

Example:
Suppose we have:
int a[] = {0, 1, 0};
v = 0;
for (i = 0; i < 3; i ++)
  v += b[i]*a[i];

If we completely unroll the loop, we would get:
v = b[0]*a[0] + b[1]*a[1] + b[2]*a[2]

Which then will be simplified to:
v = b[0]* 0 + b[1]* 1 + b[2]* 0

And finally:
v = b[1]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228265 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-05 02:34:00 +00:00
Tom Stellard
f22ee14444 StructurizeCFG: Remove obsolete fix for loop backedge detection
This is no longer needed now that we are using a reverse post-order
traversal.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228187 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 20:49:47 +00:00
Tom Stellard
7c038bc15f StructurizeCFG: Use a reverse post-order traversal
We were previously doing a post-order traversal and operating on the
list in reverse, however this would occasionaly cause backedges for
loops to be visited before some of the other blocks in the loop.

We know use a reverse post-order traversal, which avoids this issue.

The reverse post-order traversal is not completely ideal, so we need
to manually fixup the list to ensure that inner loop backedges are
visited before outer loop backedges.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228186 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 20:49:44 +00:00
Duncan P. N. Exon Smith
a7a6be22eb Utils: Resolve cycles under distinct MDNodes
Track unresolved nodes under distinct `MDNode`s during `MapMetadata()`,
and resolve them at the end.  Previously, these cycles wouldn't get
resolved.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228180 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 19:44:34 +00:00
Reid Kleckner
7724d08fc6 Add range adapters predecessors() and successors() for BBs
Use them in two isolated transforms so we know they work and aren't dead
code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228173 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 19:14:57 +00:00
Alexey Samsonov
282314741d SpecialCaseList: Add support for parsing multiple input files.
Summary:
This change allows users to create SpecialCaseList objects from
multiple local files. This is needed to implement a proper support
for -fsanitize-blacklist flag (allow users to specify multiple blacklists,
in addition to default blacklist, see PR22431).

DFSan can also benefit from this change, as DFSan instrumentation pass now
accepts ABI-lists both from -fsanitize-blacklist= and -mllvm -dfsan-abilist flags.

Go bindings are fixed accordingly.

Test Plan: regression test suite

Reviewers: pcc

Subscribers: llvm-commits, axw, kcc

Differential Revision: http://reviews.llvm.org/D7367

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228155 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 17:39:48 +00:00
Aaron Ballman
e818df583c Fixing a -Wsign-compare warning; NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228142 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 14:01:08 +00:00
Philip Reames
c27a1d9ccb Fix a warning in non-asserts builds
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228114 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 05:11:20 +00:00
Kostya Serebryany
0013784dd3 [sanitizer] add another workaround for PR 17409: when over a threshold emit coverage instrumentation as calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228102 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 01:21:45 +00:00
Philip Reames
1efb1ce986 Clang format of a file introduced in 228090 (NFC)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228091 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 00:39:57 +00:00
Philip Reames
2e38beb32f Add a pass for inserting safepoints into (nearly) arbitrary IR
This pass is responsible for figuring out where to place call safepoints and safepoint polls. It doesn't actually make the relocations explicit; that's the job of the RewriteStatepointsForGC pass (http://reviews.llvm.org/D6975).

Note that this code is not yet finalized.  Its moving in tree for incremental development, but further cleanup is needed and will happen over the next few days.  It is not yet part of the standard pass order.  

Planned changes in the near future:
 - I plan on restructuring the statepoint rewrite to use the functions add to the IRBuilder a while back. 
 - In the current pass, the function "gc.safepoint_poll" is treated specially but is not an intrinsic. I plan to make identifying the poll function a property of the GCStrategy at some point in the near future.
 - As follow on patches, I will be separating a collection of test cases we have out of tree and submitting them upstream. 
 - It's not explicit in the code, but these two patches are introducing a new state for a statepoint which looks a lot like a patchpoint. There's no a transient form which doesn't yet have the relocations explicitly represented, but does prevent reordering of memory operations. Once this is in, I need to update actually make this explicit by reserving the 'unused' argument of the statepoint as a flag, updating the docs, and making the code explicitly check for such a thing. This wasn't really planned, but once I split the two passes - which was done for other reasons - the intermediate state fell out. Just reminds us once again that we need to merge statepoints and patchpoints at some point in the not that distant future.

Future directions planned:
 - Identifying more cases where a backedge safepoint isn't required to ensure timely execution of a safepoint poll.
 - Tweaking the insertion process to generate easier to optimize IR. (For example, investigating making SplitBackedge) the default.
 - Adding opt-in flags for a GCStrategy to use this pass. Once done, add this pass to the actual pass ordering.

Differential Revision: http://reviews.llvm.org/D6981



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228090 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-04 00:37:33 +00:00
Adam Nemet
6daac09e80 [LV] Split off memcheck block really at the first check
I've noticed this while trying to move addRuntimeCheck to LoopAccessAnalysis.

I think that the intention was to early exit from the overflow checking before
the code for the memchecks.  This is the entire reason why we compute
FirstCheckInst but then we don't use that as the splitting instruction but the
final check.  Looks like an oversight.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228056 91177308-0d34-0410-b5e6-96231b3b80d8
2015-02-03 22:45:39 +00:00