Commit Graph

4028 Commits

Author SHA1 Message Date
David Green 7c35de124a [Dominators] Remove verifyDomTree and add some verifying for Post Dom Trees
Removes verifyDomTree, using assert(verify()) everywhere instead, and
changes verify a little to always run IsSameAsFreshTree first in order
to print good output when we find errors. Also adds verifyAnalysis for
PostDomTrees, which will allow checking of PostDomTrees it the same way
we check DomTrees and MachineDomTrees.

Differential Revision: https://reviews.llvm.org/D41298

llvm-svn: 326315
2018-02-28 11:00:08 +00:00
Matt Davis 523c656e25 [Debug] Add dbg.value intrinsics for PHIs created during LCSSA.
Summary:
This patch is an enhancement to propagate dbg.value information when Phis are created on behalf of LCSSA.
I noticed a case where a value carried across a loop was reported as <optimized out>.

Specifically this case:
```
int bar(int x, int y) {
  return x + y;
}

int foo(int size) {
  int val = 0;
  for (int i = 0; i < size; ++i) {
    val = bar(val, i);  // Both val and i are correct
  }
  return val; // <optimized out>
}
```

In the above case, after all of the interesting computation completes our value
is reported as "optimized out." This change will add a dbg.value to correct this.

This patch also moves the dbg.value insertion routine from LoopRotation.cpp 
into Local.cpp, so that we can share it in both places (LoopRotation and LCSSA).

Reviewers: mzolotukhin, aprantl, vsk, davide

Reviewed By: aprantl, vsk

Subscribers: dberlin, llvm-commits

Differential Revision: https://reviews.llvm.org/D42551

llvm-svn: 325926
2018-02-23 17:38:27 +00:00
Vedant Kumar 1ceabcf080 [Utils] Avoid a hash table lookup in salvageDI, NFC
According to the current coverage report salvageDebugInfo() is called
5.12 million times during testing and almost always returns early.

The early return depends on LocalAsMetadata::getIfExists returning null,
which involves a DenseMap lookup in an LLVMContextImpl. We can probably
speed this up by simply checking the IsUsedByMD bit in Value.

llvm-svn: 325738
2018-02-22 01:29:41 +00:00
Brian Gesiak d1eabb1810 Revert "[mem2reg] Use range loops (NFCI)"
This reverts commit r325532.

llvm-svn: 325539
2018-02-19 22:48:51 +00:00
Brian Gesiak 49a9d1a4e6 [mem2reg] Use range loops (NFCI)
Summary:
Several for loops in PromoteMemoryToRegister.cpp leave their increment
expression empty, instead incrementing the iterator within the for loop
body. I believe this is because these loops were previously implemented
as while loops; see https://reviews.llvm.org/rL188327.

Incrementing the iterator within the body of the for loop instead of
in its increment expression makes it seem like the iterator will be
modified or conditionally incremented within the loop, but that is not
the case in these loops.

Instead, use range loops.

Test Plan: `check-llvm`

Reviewers: davide, bkramer

Reviewed By: davide, bkramer

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D43473

llvm-svn: 325532
2018-02-19 21:44:52 +00:00
Vedant Kumar 044b588929 [Utils] salvageDI: Add a comment and move a call earlier, NFC
llvm-svn: 325280
2018-02-15 19:13:03 +00:00
Rafael Espindola 7186753218 Pass a module reference to CloneModule.
It can never be null and most callers were already using references or
std::unique_ptr.

llvm-svn: 325160
2018-02-14 19:50:40 +00:00
David Green 0d5f9651f2 Move llvm::computeLoopSafetyInfo from LICM.cpp to LoopUtils.cpp. NFC
Move computeLoopSafetyInfo, defined in Transforms/Utils/LoopUtils.h,
into the corresponding LoopUtils.cpp, as opposed to LICM where it resides
at the moment. This will allow other functions from Transforms/Utils
to reference it.

llvm-svn: 325151
2018-02-14 18:34:53 +00:00
Petar Jovanovic 1768957c82 [Utils] Salvage the debug info of DCE'ed 'and' instructions
Preserve debug info from a dead 'and' instruction with a constant.

Patch by Djordje Todorovic.

Differential Revision: https://reviews.llvm.org/D43163

llvm-svn: 325119
2018-02-14 13:10:35 +00:00
Elena Demikhovsky 945b7e5aa6 Adding a width of the GEP index to the Data Layout.
Making a width of GEP Index, which is used for address calculation, to be one of the pointer properties in the Data Layout.
p[address space]:size:memory_size:alignment:pref_alignment:index_size_in_bits.
The index size parameter is optional, if not specified, it is equal to the pointer size.

Till now, the InstCombiner normalized GEPs and extended the Index operand to the pointer width.
It works fine if you can convert pointer to integer for address calculation and all registered targets do this.
But some ISAs have very restricted instruction set for the pointer calculation. During discussions were desided to retrieve information for GEP index from the Data Layout.
http://lists.llvm.org/pipermail/llvm-dev/2018-January/120416.html

I added an interface to the Data Layout and I changed the InstCombiner and some other passes to take the Index width into account.
This change does not affect any in-tree target. I added tests to cover data layouts with explicitly specified index size.

Differential Revision: https://reviews.llvm.org/D42123

llvm-svn: 325102
2018-02-14 06:58:08 +00:00
Vedant Kumar 388fac5de6 [Utils] Salvage debug info from all no-op casts
We already try to salvage debug values from no-op bitcasts and inttoptr
instructions: we should handle ptrtoint instructions as well.

This saves an additional 24,444 debug values in a stage2 build of clang,
and (according to llvm-dwarfdump --statistics) provides an additional
289 unique source variables.

llvm-svn: 324982
2018-02-13 03:34:23 +00:00
Vedant Kumar 4011c26cc7 [Utils] Salvage debug info of DCE'ed mul/sdiv/srem instructions
Here are the number of additional debug values salvaged in a stage2
build of clang:

  63 SALVAGE: MUL
  1250 SALVAGE: SDIV

(No values were salvaged from `srem` instructions in this experiment,
but it's a simple case to handle so we might as well.)

llvm-svn: 324976
2018-02-13 01:09:52 +00:00
Vedant Kumar 31ec356a48 [Utils] Salvage debug info of DCE'ed shl/lhsr/ashr instructions
Here are the number of additional debug values salvaged in a stage2
build of clang:

  1912 SALVAGE: ASHR
   405 SALVAGE: LSHR
   249 SALVAGE: SHL

llvm-svn: 324975
2018-02-13 01:09:49 +00:00
Vedant Kumar 47b16c45d7 [Utils] Salvage the debug info of DCE'ed 'sub' instructions
This salvages 14 debug values in a stage2 build of clang.

llvm-svn: 324974
2018-02-13 01:09:47 +00:00
Vedant Kumar 96b7dc041b [Utils] Salvage the debug info of DCE'ed 'xor' instructions
This salvages 259 debug values in a stage2 build of clang.

Differential Revision: https://reviews.llvm.org/D43207

llvm-svn: 324973
2018-02-13 01:09:46 +00:00
Vedant Kumar 04386d8e3d [Utils] Salvage debug info from dead 'or' instructions
Extend salvageDebugInfo to preserve the debug info from a dead 'or'
with a constant.

Patch by Ismail Badawi!

Differential Revision: https://reviews.llvm.org/D43129

llvm-svn: 324764
2018-02-09 19:19:55 +00:00
Serguei Katkov 66182d6c38 [SimplifyCFG] Re-apply Relax restriction for folding unconditional branches
The commit rL308422 introduces a restriction for folding unconditional
branches. Specifically if empty block with unconditional branch leads to
header of the loop then elimination of this basic block is prohibited.
However it seems this condition is redundantly strict.
If elimination of this basic block does not introduce more back edges
then we can eliminate this block.

The patch implements this relax of restriction.

The test profile/Linux/counter_promo_nest.c in compiler-rt project
is updated to meet this change.

Reviewers: efriedma, mcrosier, pacxx, hsung, davidxl	
Reviewed By: pacxx
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42691

llvm-svn: 324572
2018-02-08 07:16:29 +00:00
Daniel Neilson a894201313 [InlineFunction] Update deprecated use of IRBuilder CreateMemCpy (NFC)
Summary:
This change is part of step five in the series of changes to remove alignment argument from
memcpy/memmove/memset in favour of alignment attributes. In particular, this changes the
InlineFunction pass to ceause using the old IRBuilder CreateMemCpy single-alignment API
in favour of the new API that allows setting source and destination alignments independently.

Steps:
Step 1) Remove alignment parameter and create alignment parameter attributes for
memcpy/memmove/memset. ( rL322965, rC322964, rL322963 )
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments. ( rL323597 )
Step 3) Update Clang to use the new IRBuilder API. ( rC323617 )
Step 4) Update Polly to use the new IRBuilder API. ( rL323618 )
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use [get|set]DestAlignment()
and [get|set]SourceAlignment() instead. ( rL323886, rL323891, rL324148, rL324273, rL324278 )
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.

Reference
   http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
   http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

llvm-svn: 324384
2018-02-06 19:14:31 +00:00
Daniel Neilson 3c23f6668b [LowerMemIntrinsics] Update uses of deprecated MemIntrinsic::getAlignment API (NFC)
Summary:
This change is part of step five in the series of changes to remove alignment argument from
memcpy/memmove/memset in favour of alignment attributes. In particular, this changes the
LowerMemIntrinsics pass to cease using the old getAlignment() API of MemoryIntrinsic in
favour of getting source & dest specific alignments through the new API.

Steps:
Step 1) Remove alignment parameter and create alignment parameter attributes for
memcpy/memmove/memset. ( rL322965, rC322964, rL322963 )
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments. ( rL323597 )
Step 3) Update Clang to use the new IRBuilder API. ( rC323617 )
Step 4) Update Polly to use the new IRBuilder API. ( rL323618 )
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use [get|set]DestAlignment()
and [get|set]SourceAlignment() instead. ( rL323886, rL323891, rL324148, rL324273 )
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.

Reference
   http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
   http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

llvm-svn: 324278
2018-02-05 22:23:58 +00:00
Daniel Neilson 8acd8b036c [SimplifyLibCalls] Update from deprecated IRBuilder API for creating memory intrinsics (NFC)
Summary:
This change is part of step five in the series of changes to remove alignment argument from
memcpy/memmove/memset in favour of alignment attributes. In particular, this changes the
SimplifyLibCalls pass to cease using the old IRBuilder createMemCpy/createMemMove
single-alignment APIs in favour of the new API that allows setting source and destination
alignments independently.

Steps:
Step 1) Remove alignment parameter and create alignment parameter attributes for
memcpy/memmove/memset. ( rL322965, rC322964, rL322963 )
Step 2) Expand the IRBuilder API to allow creation of memcpy/memmove with differing
source and dest alignments. ( rL323597 )
Step 3) Update Clang to use the new IRBuilder API. ( rC323617 )
Step 4) Update Polly to use the new IRBuilder API. ( rL323618 )
Step 5) Update LLVM passes that create memcpy/memmove calls to use the new IRBuilder API,
and those that use use MemIntrinsicInst::[get|set]Alignment() to use [get|set]DestAlignment()
and [get|set]SourceAlignment() instead. ( rL323886, rL323891, r3L24148 )
Step 6) Remove the single-alignment IRBuilder API for memcpy/memmove, and the
MemIntrinsicInst::[get|set]Alignment() methods.

Reference
   http://lists.llvm.org/pipermail/llvm-dev/2015-August/089384.html
   http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20151109/312083.html

llvm-svn: 324273
2018-02-05 21:23:22 +00:00
Peter Collingbourne b4edfb9af9 LTO: Include dso-local bit in ThinLTO cache key.
Differential Revision: https://reviews.llvm.org/D42713

llvm-svn: 324253
2018-02-05 17:17:51 +00:00
Hans Wennborg 22db17cf43 Revert r323472 "[Debug] Add dbg.value intrinsics for PHIs created during LCSSA."
This broke the Chromium build; see PR36238.

> This patch is an enhancement to propagate dbg.value information when
> Phis are created on behalf of LCSSA.  I noticed a case where a value
> carried across a loop was reported as <optimized out>.
>
> Specifically this case:
>
>   int bar(int x, int y) {
>     return x + y;
>   }
>
>   int foo(int size) {
>     int val = 0;
>     for (int i = 0; i < size; ++i) {
>       val = bar(val, i);  // Both val and i are correct
>     }
>     return val; // <optimized out>
>   }
>
> In the above case, after all of the interesting computation completes
> our value is reported as "optimized out." This change will add a
> dbg.value to correct this.
>
> This patch also moves the dbg.value insertion routine from
> LoopRotation.cpp into Local.cpp, so that we can share it in both places
> (LoopRotation and LCSSA).
>
> Patch by Matt Davis!
>
> Differential Revision: https://reviews.llvm.org/D42551

llvm-svn: 324247
2018-02-05 16:10:42 +00:00
Serguei Katkov 276b32bb14 Revert [SimplifyCFG] Relax restriction for folding unconditional branches
The patch causes the failure of the test
compiler-rt/test/profile/Linux/counter_promo_nest.c

To unblock buildbot, revert the patch while investigation is in progress.

Differential Revision: https://reviews.llvm.org/D42691

llvm-svn: 324214
2018-02-05 09:05:43 +00:00
Serguei Katkov 6e93980e82 [SimplifyCFG] Relax restriction for folding unconditional branches
The commit rL308422 introduces a restriction for folding unconditional
branches. Specifically if empty block with unconditional branch leads to
header of the loop then elimination of this basic block is prohibited.
However it seems this condition is redundantly strict.
If elimination of this basic block does not introduce more back edges
then we can eliminate this block.

The patch implements this relax of restriction.

Reviewers: efriedma, mcrosier, pacxx, hsung, davidxl	
Reviewed By: pacxx
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D42691

llvm-svn: 324208
2018-02-05 07:56:43 +00:00
Florian Hahn 8f804fc07d [InlineFunction] Set arg attrs even if there only are VarArg attrs.
When using the partial inliner, we might have attributes for forwarded
varargs, but the CodeExtractor does not create an empty argument
attribute set for regular arguments in that case, because it does not know
of the additional arguments. So in case we have attributes for VarArgs, we
also have to make sure we create (empty) attributes for all regular arguments.

This fixes PR36210.

llvm-svn: 324197
2018-02-04 18:27:47 +00:00
Chad Rosier a097bc69df [LV] Use Demanded Bits and ValueTracking for reduction type-shrinking
The type-shrinking logic in reduction detection, although narrow in scope, is
also rather ad-hoc, which has led to bugs (e.g., PR35734). This patch modifies
the approach to rely on the demanded bits and value tracking analyses, if
available. We currently perform type-shrinking separately for reductions and
other instructions in the loop. Long-term, we should probably think about
computing minimal bit widths in a more complete way for the loops we want to
vectorize.

PR35734
Differential Revision: https://reviews.llvm.org/D42309

llvm-svn: 324195
2018-02-04 15:42:24 +00:00
Matt Arsenault 06dfbb50d7 Utils: Fix DomTree update for entry block
If SplitBlockPredecessors was used on a function entry block,
it wouldn't update the dominator tree.

llvm-svn: 323928
2018-01-31 22:54:37 +00:00
Eli Friedman 79d297abe4 [GlobalOpt] Fix exponential compile-time with selects.
If you have a long chain of select instructions created from something
like `int* p = &g; if (foo()) p += 4; if (foo2()) p += 4;` etc., a naive
recursive visitor will recursively visit each select twice, which is
O(2^N) in the number of select instructions. Use the visited set to cut
off recursion in this case.

(No testcase because this doesn't actually change the behavior, just the
time.)

Differential Revision: https://reviews.llvm.org/D42451

llvm-svn: 323910
2018-01-31 20:42:25 +00:00
Teresa Johnson df763188c9 Teach ValueMapper to use ODR uniqued types when available
Summary:
This is exposed during ThinLTO compilation, when we import an alias by
creating a clone of the aliasee. Without this fix the debug type is
unnecessarily cloned and we get a duplicate, undoing the uniquing.

Fixes PR36089.

Reviewers: mehdi_amini, pcc

Subscribers: eraman, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D41669

llvm-svn: 323813
2018-01-30 20:16:32 +00:00
Vedant Kumar 6394df9fc4 [Debug] LCSSA: Insert dbg.value at the first available insertion point
Inserting a dbg.value instruction at the start of a basic block with a
landingpad instruction triggers a verifier failure. We should be OK if
we insert the instruction a bit later.

Speculative fix for the bot failure described here:
https://reviews.llvm.org/D42551

llvm-svn: 323482
2018-01-25 23:48:29 +00:00
Vedant Kumar 60f54084bf [Debug] Add dbg.value intrinsics for PHIs created during LCSSA.
This patch is an enhancement to propagate dbg.value information when
Phis are created on behalf of LCSSA.  I noticed a case where a value
carried across a loop was reported as <optimized out>.

Specifically this case:

  int bar(int x, int y) {
    return x + y;
  }

  int foo(int size) {
    int val = 0;
    for (int i = 0; i < size; ++i) {
      val = bar(val, i);  // Both val and i are correct
    }
    return val; // <optimized out>
  }

In the above case, after all of the interesting computation completes
our value is reported as "optimized out." This change will add a
dbg.value to correct this.

This patch also moves the dbg.value insertion routine from
LoopRotation.cpp into Local.cpp, so that we can share it in both places
(LoopRotation and LCSSA).

Patch by Matt Davis!

Differential Revision: https://reviews.llvm.org/D42551

llvm-svn: 323472
2018-01-25 21:37:07 +00:00
Vedant Kumar 6bfc869cf7 [Debug] Add a utility to propagate dbg.value to new PHIs, NFC
This simply moves an existing utility to Utils for reuse.

Split out of: https://reviews.llvm.org/D42551

Patch by Matt Davis!

llvm-svn: 323471
2018-01-25 21:37:05 +00:00
Hiroshi Inoue d24ddcd6c4 [NFC] fix trivial typos in comments
"the the" -> "the"

llvm-svn: 322934
2018-01-19 10:55:29 +00:00
Easwaran Raman e5b8de2f1f Add a ProfileCount class to represent entry counts.
Summary:
The class wraps a uint64_t and an enum to represent the type of profile
count (real and synthetic) with some helper methods.

Reviewers: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D41883

llvm-svn: 322771
2018-01-17 22:24:23 +00:00
Brian M. Rzycki 9b7ae23256 [JumpThreading] Preservation of DT and LVI across the pass
Summary:
See D37528 for a previous (non-deferred) version of this
patch and its description.

Preserves dominance in a deferred manner using a new class
DeferredDominance. This reduces the performance impact of
updating the DominatorTree at every edge insertion and
deletion. A user may call DDT->flush() within JumpThreading
for an up-to-date DT. This patch currently has one flush()
at the end of runImpl() to ensure DT is preserved across
the pass.

LVI is also preserved to help subsequent passes such as
CorrelatedValuePropagation. LVI is simpler to maintain and
is done immediately (not deferred). The code to perform the
preversation was minimally altered and simply marked as
preserved for the PassManager to be informed.

This extends the analysis available to JumpThreading for
future enhancements such as threading across loop headers.

Reviewers: dberlin, kuhar, sebpop

Reviewed By: kuhar, sebpop

Subscribers: mgorny, dmgreen, kuba, rnk, rsmith, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D40146

llvm-svn: 322401
2018-01-12 21:06:48 +00:00
Serguei Katkov a757d65cec [LoopDeletion] Handle users in unreachable block
This is a fix for PR35884.

When we want to delete dead loop we must clean uses in unreachable blocks
otherwise we'll get an assert during deletion of instructions from the loop.

Reviewers: anna, davide
Reviewed By: anna
Subscribers: llvm-commits, lebedev.ri
Differential Revision: https://reviews.llvm.org/D41943

llvm-svn: 322357
2018-01-12 07:24:43 +00:00
Dmitry Venikov e5fbf591a7 [InstCombine] Missed optimization in math expression: sin(x) / cos(x) => tan(x)
Summary: This patch enables folding sin(x) / cos(x) -> tan(x), cos(x) / sin(x) -> 1 / tan(x) under -ffast-math flag

Reviewers: hfinkel, spatel

Reviewed By: spatel

Subscribers: andrew.w.kaylor, efriedma, scanon, llvm-commits

Differential Revision: https://reviews.llvm.org/D41286

llvm-svn: 322255
2018-01-11 06:33:00 +00:00
Marcello Maggioni ddccd50313 [NFC] Commit to mention that r322248 is actually made by AndrewScheidecker
llvm-svn: 322249
2018-01-11 02:06:28 +00:00
Marcello Maggioni 7083423f22 [SimplifyCFG] Add cut-off for InitializeUniqueCases.
The function can take a significant amount of time on some
complicated test cases, but for the currently only use of
the function we can stop the initialization much earlier
when we find out we are going to discard the result anyway
in the caller of the function.

Adding configurable cut-off points so that we avoid wasting time.
NFCI.

llvm-svn: 322248
2018-01-11 02:01:16 +00:00
Florian Hahn 55be37e7d4 [CodeExtractor] Use subset of function attributes for extracted function.
In addition to target-dependent attributes, we can also preserve a
white-listed subset of target independent function attributes. The white-list
excludes problematic attributes, most prominently:

* attributes related to memory accesses, as alloca instructions
  could be moved in/out of the extracted block

* control-flow dependent attributes, like no_return or thunk, as the
  relerelevant instructions might or might not get extracted.

Thanks @efriedma and @aemerson for providing a set of attributes that cannot be
propagated.


Reviewers: efriedma, davidxl, davide, silvas

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D41334

llvm-svn: 321961
2018-01-07 11:22:25 +00:00
Florian Hahn a82eef2363 [InlineFunction] Preserve calling convention when forwarding VarArgs.
Reviewers: efriedma, rnk, davide

Reviewed By: rnk, davide

Differential Revision: https://reviews.llvm.org/D41556

llvm-svn: 321943
2018-01-06 20:56:27 +00:00
Florian Hahn de10e6e064 [InlineFunction] Preserve attributes when forwarding VarArgs.
Reviewers: rnk, efriedma

Reviewed By: rnk

Differential Revision: https://reviews.llvm.org/D41555

llvm-svn: 321942
2018-01-06 20:46:00 +00:00
Florian Hahn 80788d8088 [InlineFunction] Inline vararg functions that do not access varargs.
If the varargs are not accessed by a function, we can inline the
function.

Reviewers: dblaikie, chandlerc, davide, efriedma, rnk, hfinkel

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D41335

llvm-svn: 321940
2018-01-06 19:45:40 +00:00
Vedant Kumar b2ec02ba0b [Utils] Simplify salvageDebugInfo, NFCI
Having a single call to findDbgUsers() allows salvageDebugInfo() to
return earlier.

Differential Revision: https://reviews.llvm.org/D41787

llvm-svn: 321915
2018-01-05 23:27:02 +00:00
Reid Kleckner cd78ddc119 Revert "[JumpThreading] Preservation of DT and LVI across the pass"
This reverts r321825, it causes crashes in Chromium. Reproducer
forthcoming.

llvm-svn: 321832
2018-01-04 23:23:46 +00:00
Brian M. Rzycki cdad6c0b60 [JumpThreading] Preservation of DT and LVI across the pass
Summary:
See D37528 for a previous (non-deferred) version of this
patch and its description.

Preserves dominance in a deferred manner using a new class
DeferredDominance. This reduces the performance impact of
updating the DominatorTree at every edge insertion and
deletion. A user may call DDT->flush() within JumpThreading
for an up-to-date DT. This patch currently has one flush()
at the end of runImpl() to ensure DT is preserved across
the pass.

LVI is also preserved to help subsequent passes such as
CorrelatedValuePropagation. LVI is simpler to maintain and
is done immediately (not deferred). The code to perfom the
preversation was minimally altered and was simply marked
as preserved for the PassManager to be informed.

This extends the analysis available to JumpThreading for
future enhancements. One example is loop boundary threading.

Reviewers: dberlin, kuhar, sebpop

Reviewed By: kuhar, sebpop

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D40146

llvm-svn: 321825
2018-01-04 21:57:32 +00:00
Anna Thomas 9fca583757 Add assertion on DT availability during LI update in UpdateAnalysisInformation
This came up during discussions in llvm-commits for
rL321653: Check for unreachable preds before updating LI in
UpdateAnalysisInformation

The assert provides hints to passes to require both DT and LI if we plan on
updating LI through this function.

Tests run: make check

llvm-svn: 321805
2018-01-04 17:21:15 +00:00
Anna Thomas bdb9430917 [BasicBlockUtils] Check for unreachable preds before updating LI in UpdateAnalysisInformation
Summary:
We are incorrectly updating the LI when loop-simplify generates
dedicated exit blocks for a loop. The issue is that there's an implicit
assumption that the Preds passed into UpdateAnalysisInformation are
reachable. However, this is not true and breaks LI by incorrectly
updating the header of a loop.

One such case is when we generate dedicated exits when the exit block is
a landing pad (through SplitLandingPadPredecessors). There maybe other
cases as well, since we do not guarantee that Preds passed in are
reachable basic blocks.

The added test case shows how loop-simplify breaks LI for the outer loop (and DT in turn)
after we try to generate the LoopSimplifyForm.

Reviewers: davide, chandlerc, sanjoy

Reviewed By: davide

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D41519

llvm-svn: 321653
2018-01-02 16:25:50 +00:00
Davide Italiano 86b7949f62 [SimplifyCFG] Return to the pass manager the correct value.
I wanted to commit this with r321603, but I failed to squash
the two commits.

llvm-svn: 321606
2017-12-31 16:54:03 +00:00
Davide Italiano 0512bf5af2 [Utils/Local] Use `auto` when the type is obvious. NFCI.
llvm-svn: 321605
2017-12-31 16:51:50 +00:00