Commit Graph

20004 Commits

Author SHA1 Message Date
Evgeny Stupachenko bff9302c3d Fix LSR compile time hang.
Summary:
Limit number of reassociations in GenerateReassociationsImpl.

Reviewers: qcolombet, mkazantsev

Differential Revision: https://reviews.llvm.org/D46039

From: Evgeny Stupachenko <evstupac@gmail.com>
                         <evgeny.v.stupachenko@intel.com>
llvm-svn: 332426
2018-05-16 02:48:50 +00:00
Sanjay Patel 919882638e [InstCombine] fix binop (shuffle X), C --> shuffle (binop X, C') to check uses
llvm-svn: 332407
2018-05-15 22:00:37 +00:00
Marek Olsak 3c5fd145c5 StructurizeCFG: fix inverting conditions
Author: Samuel Pitoiset

Without this patch, it appears to me that we are selecting
the wrong operand when inverting conditions. In the attached
test, it will select %tmp3 instead of %tmp4. To fix it, just
use 'A' as everywhere.

This fixes a regression introduced by
"[PatternMatch] define m_Not using m_Xor and cst_pred_ty"

https://reviews.llvm.org/D46351

llvm-svn: 332403
2018-05-15 21:41:55 +00:00
Evgeniy Stepanov 091fed94ae [msan] Instrument masked.store, masked.load intrinsics.
Summary: Instrument masked store/load intrinsics.

Reviewers: kcc

Subscribers: hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D46785

llvm-svn: 332402
2018-05-15 21:28:25 +00:00
Sanjay Patel 3c569f0de0 [InstCombine] clean up code for binop-shuffle transforms; NFCI
llvm-svn: 332399
2018-05-15 21:23:58 +00:00
Sanjay Patel 3c35290c58 [InstCombine] fix binop-of-shuffles to check uses
llvm-svn: 332375
2018-05-15 17:14:23 +00:00
whitequark 8f0ab258bd [MergeFunctions] Fix merging of small weak functions
When two interposable functions are merged, we cannot replace
uses and have to emit calls to a common internal function. However,
writeThunk() will not actually emit a thunk if the function is too
small. This leaves us in a broken state where mergeTwoFunctions
already rewired the functions, but writeThunk doesn't do anything.

This patch changes the implementation so that:

 * writeThunk() does just that.
 * The direct replacement of calls is moved into mergeTwoFunctions()
   into the non-interposable case only.
 * isThunkProfitable() is extracted and will be called for
   the non-iterposable case always, and in the interposable case
   only if uses are still left after replacement.

This issue has been introduced in https://reviews.llvm.org/D34806,
where the code for checking thunk profitability has been moved.

Differential Revision: https://reviews.llvm.org/D46804

Reviewed By: whitequark

llvm-svn: 332342
2018-05-15 11:31:07 +00:00
Max Kazantsev 9b90373c8b [NFC] Add const to method signature
llvm-svn: 332317
2018-05-15 01:21:56 +00:00
Keno Fischer de577af8c0 [InstCombine] fix crash due to ignored addrspacecast
Summary:
Part of the InstCombine code for simplifying GEPs looks through
addrspacecasts. However, this was done by updating a variable
also used by the next transformation, for marking GEPs as
inbounds. This led to replacing a GEP with a similar instruction
in a different addrspace, which caused an assertion failure in RAUW.

This caused julia issue https://github.com/JuliaLang/julia/issues/27055

Patch by Jeff Bezanson <jeff@juliacomputing.com>

Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D46722

llvm-svn: 332302
2018-05-14 22:05:01 +00:00
Sanjay Patel bf55e6dee1 [AggressiveInstCombine] avoid crashing on unsimplified code (PR37446)
This bug:
https://bugs.llvm.org/show_bug.cgi?id=37446
...raises another question: why do we run aggressive-instcombine before 
regular instcombine?

llvm-svn: 332243
2018-05-14 13:43:32 +00:00
Nicola Zaghen d34e60ca85 Rename DEBUG macro to LLVM_DEBUG.
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.

In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.

Differential Revision: https://reviews.llvm.org/D43624

llvm-svn: 332240
2018-05-14 12:53:11 +00:00
Nicola Zaghen 617d4a8199 Test commit access.
Remove trailing whitespace.

llvm-svn: 332220
2018-05-14 08:24:29 +00:00
Craig Topper 0e71c6d5ca [X86] Remove and autoupgrade the cvtusi2sd intrinsic. Use uitofp+insertelement instead.
llvm-svn: 332206
2018-05-14 00:06:49 +00:00
Craig Topper 911025b1cd [X86] Extend instcombine folds for pclmuldq intrinsics to the 256 and 512 bit version.
llvm-svn: 332202
2018-05-13 21:56:32 +00:00
Craig Topper 85906cf041 [X86] Remove and autoupgrade masked vpermd/vpermps intrinsics.
llvm-svn: 332198
2018-05-13 18:03:59 +00:00
Craig Topper df3a9cedff [X86] Remove an autoupgrade legacy cvtss2sd intrinsics.
llvm-svn: 332187
2018-05-13 00:29:40 +00:00
Craig Topper 38ad7ddabc [X86] Remove and autoupgrade cvtsi2ss/cvtsi2sd intrinsics to match what clang has used for a very long time.
llvm-svn: 332186
2018-05-12 23:14:39 +00:00
Michael Zolotukhin a41660df7e Reapply "[PR16756] Use SSAUpdaterBulk in JumpThreading."
Stage3/stage4 bootstrap miscompares should be fixed by a non-determinism
fix in IDF (r332167).

This reverts commit r330446.

llvm-svn: 332168
2018-05-12 01:52:36 +00:00
Sergey Dmitriev 69c9cd277d [CodeExtractor] Allow extracting blocks with exception handling
This is a CodeExtractor improvement which adds support for extracting blocks
which have exception handling constructs if that is legal to do. CodeExtractor
performs validation checks to ensure that extraction is legal when it finds
invoke instructions or EH pads (landingpad, catchswitch, or cleanuppad) in
blocks to be extracted.

I have also added an option to allow extraction of blocks with alloca
instructions, but no validation is done for allocas. CodeExtractor caller has
to validate it himself before allowing alloca instructions to be extracted.
By default allocas are still not allowed in extraction blocks.

Differential Revision: https://reviews.llvm.org/D45904

llvm-svn: 332151
2018-05-11 22:49:49 +00:00
Craig Topper a17d627abb [X86] Remove and autoupgrade a bunch of FMA instrinsics that are no longer used by clang.
llvm-svn: 332146
2018-05-11 21:59:34 +00:00
Artem Belevich c2cd5d5ce0 [Split GEP] handle trunc() in separate-const-offset-from-gep pass.
Let separate-const-offset-from-gep pass handle trunc() when it calculates
constant offset relative to base. The pass itself may insert trunc()
instructions when it canonicalises array indices to pointer-size integers
and needs to handle trunc() in order to evaluate the offset.

Differential Revision: https://reviews.llvm.org/D46732

llvm-svn: 332142
2018-05-11 21:13:19 +00:00
Daniel Neilson f6651d4d94 [InstCombine] Handle atomic memset in the same way as regular memset
Summary:
This change adds handling of the atomic memset intrinsic to the
code path that simplifies the regular memset. In practice this means
that we will now also expand a small constant-length atomic memset
into a single unordered atomic store.

Reviewers: apilipenko, skatkov, mkazantsev, anna, reames

Reviewed By: reames

Subscribers: reames, llvm-commits

Differential Revision: https://reviews.llvm.org/D46660

llvm-svn: 332132
2018-05-11 20:04:50 +00:00
David Bolvansky cd93c4ef1a [InstCombine] snprintf optimizations
Reviewers: spatel, efriedma, majnemer, rja, bkramer

Reviewed By: rja, bkramer

Subscribers: mstorsjo, rja, llvm-commits

Differential Revision: https://reviews.llvm.org/D46285

llvm-svn: 332110
2018-05-11 17:50:49 +00:00
Davide Italiano 6e1f7bf316 [Reassociate] Prevent infinite loops when processing PHIs.
Phi nodes can reside in live blocks but one of their incoming
arguments can come from a dead block. Dead blocks and reassociate
don't play nice together. In fact, reassociate performs an RPO
as a first step to avoid processing dead blocks.

The reason why Reassociate might not fixpoint when examining
dead blocks is that the following:

  %xor0 = xor i16 %xor1, undef
  %xor1 = xor i16 %xor0, undef

is perfectly valid LLVM IR (if it appears in a dead block),
so the worklist algorithm keeps pushing the two instructions for
reexamination. Note that this is not Reassociate fault, at least
not entirely. It's llvm that has a weird definition of dominance.

Fixes PR37390.

llvm-svn: 332100
2018-05-11 15:45:36 +00:00
Daniel Neilson 8f30ec65b0 [InstCombine] Unify handling of atomic memtransfer with non-atomic memtransfer
Summary:
This change reworks the handling of atomic memcpy within the instcombine pass.
Previously, a constant length atomic memcpy would be lowered into loads & stores
as long as no more than 16 load/store pairs are created. This is quite different
from the lowering done for a non-atomic memcpy; which only ever lowers into a single
load/store pair of no more than 8 bytes. Larger constant-sized memcpy calls are
expanded to load/stores in later passes, such as SelectionDAG lowering.

In this change the behaviour for atomic memcpy is unified with non-atomic memcpy;
atomic memcpy is now treated in the same was as non-atomic memcpy has always been.
We leave it to later passes to lower longer-length atomic memcpy calls.

Due to the structure of the pass's handling of memtransfer intrinsics, this change
also gives us handling of atomic memmove that we did not previously have.

Reviewers: apilipenko, skatkov, mkazantsev, anna, reames

Reviewed By: reames

Subscribers: reames, llvm-commits

Differential Revision: https://reviews.llvm.org/D46658

llvm-svn: 332093
2018-05-11 14:30:02 +00:00
Brian Gesiak c651113439 [Coroutines] PR34897: Fix incorrect elisions
Summary:
https://bugs.llvm.org/show_bug.cgi?id=34897 demonstrates an incorrect
coroutine frame allocation elision in the coro-elide pass. The elision
is performed on the basis that the SSA variables from all llvm.coro.begin
are directly referenced in subsequent llvm.coro.destroy instructions.

However, this ignores the fact that the function may exit through paths
that do not run these destroy instructions. In the sample program from
PR34897, for example, the llvm.coro.destroy instruction is only
executed in exception handling code. When the coroutine function exits
normally, llvm.coro.destroy is not called. Eliding the allocation in
this case causes a subsequent reference to the coroutine handle from
outside of the function to access freed memory.

To fix the issue, when finding an llvm.coro.destroy for each llvm.coro.begin,
only consider llvm.coro.destroy that are executed along non-exceptional paths.

Test Plan:
1. Download the sample program from
   https://bugs.llvm.org/show_bug.cgi?id=34897, compile it with
   `clang++ -fcoroutines-ts -stdlib=libc++ -std=c++1z -O2`, and run it.
   It should print `"run1\ncheck1\nrun2\ncheck2"` and then exit
   successfully.
2. Compile https://godbolt.org/g/mCKfnr and confirm it is still
   optimized to a single instruction, 'return 1190'.
3. `check-llvm`

Reviewers: rsmith, GorNishanov, eric_niebler

Reviewed By: GorNishanov

Subscribers: andrewrk, lewissbaker, EricWF, llvm-commits

Differential Revision: https://reviews.llvm.org/D43242

llvm-svn: 332077
2018-05-11 03:12:28 +00:00
Kostya Serebryany a2759327fd [sanitizer-coverage] don't instrument a function if it's entry block ends with 'unreachable'
llvm-svn: 332072
2018-05-11 01:09:39 +00:00
Kamil Rytarowski 02c432a72b Register NetBSD/i386 in AddressSanitizer.cpp
Summary:
Ship kNetBSD_ShadowOffset32 set to 1ULL << 30.

This is prepared for the amd64 kernel runtime.

Sponsored by <The NetBSD Foundation>

Reviewers: vitalybuka, joerg, kcc

Reviewed By: vitalybuka

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46724

llvm-svn: 332069
2018-05-11 00:58:01 +00:00
Wei Mi 0c2f6be662 [SampleFDO] Don't treat warm callsite with inline instance in the profile as cold
We found current sampleFDO had a performance issue when triaging a regression.
For a callsite with inline instance in the profile, even if hot callsite inliner
cannot inline it, it may still execute enough times and should not be treated as
cold in regular inliner later. However, currently if such callsite is not inlined
by hot callsite inliner, and the BB where the callsite locates doesn't get
samples from other instructions inside of it, the callsite will have no profile
metadata annotated. In regular inliner cost analysis, if the callsite has no
profile annotated and its caller has profile information, it will be treated as
cold.

The fix changes the isCallsiteHot check and chooses to compare
CallsiteTotalSamples with hot cutoff value computed by ProfileSummaryInfo.

Differential Revision: https://reviews.llvm.org/D45377

llvm-svn: 332058
2018-05-10 23:02:27 +00:00
Vedant Kumar e0b5f86b30 [STLExtras] Add distance() for ranges, pred_size(), and succ_size()
This commit adds a wrapper for std::distance() which works with ranges.
As it would be a common case to write `distance(predecessors(BB))`, this
also introduces `pred_size()` and `succ_size()` helpers to make that
easier to write.

Differential Revision: https://reviews.llvm.org/D46668

llvm-svn: 332057
2018-05-10 23:01:54 +00:00
Craig Topper ea78a261de [InstCombine] Replace an 'if' that should always be true with an assert.
The bitwidth of the operation should always be wider than the result width of the truncate since we don't recurse through any width changing operations.

llvm-svn: 332055
2018-05-10 22:45:28 +00:00
Martin Storsjo 86e6742c17 Revert "[InstCombine] snprintf optimizations"
This reverts commit SVN r331889, which could trigger failed
assertions for cases where the snprintf function is declared
with a vaguely differing signature (e.g. being defined as
static inline), see PR37408.

llvm-svn: 332043
2018-05-10 21:23:36 +00:00
Sanjay Patel c7bb14301a [InstCombine] add folds for minnum(-a, -b) --> -maxnum(a, b)
This is similar to what we do for integer min/max with 'not'
ops (rL321882).

This should fix:
https://bugs.llvm.org/show_bug.cgi?id=37404
https://bugs.llvm.org/show_bug.cgi?id=37405

llvm-svn: 332031
2018-05-10 20:03:13 +00:00
Omer Paparo Bivas fbb83deef7 [InstCombine] Moving overflow computation logic from InstCombine to ValueTracking; NFC
Differential Revision: https://reviews.llvm.org/D46704

Change-Id: Ifabcbe431a2169743b3cc310f2a34fd706f13f02
llvm-svn: 332026
2018-05-10 19:46:19 +00:00
Chandler Carruth baf045fb28 [PM/LoopUnswitch] Avoid pointlessly creating an exit block set.
This code can just test whether blocks are *in* the loop, which we
already have a dedicated set tracking in the loop itself.

llvm-svn: 332004
2018-05-10 17:33:20 +00:00
Daniel Neilson 71fa1b904a [DSE] Teach the pass about partial overwrite of atomic memory intrinsics
Summary:
This change teaches DSE that the atomic memory intrinsics can be overwriten
partially in the same way as the non-atomic forms. Specifically, that the
atomic memcpy & memset can be shortened at the end and that the atomic memset
can be shortened at the beginning, if they partially overwritten
by later stores.

Reviewers: mkazantsev, skatkov, apilipenko, efriedma, rsmith, spatel, filcab, sanjoy

Reviewed By: efriedma

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45584

llvm-svn: 331991
2018-05-10 15:12:49 +00:00
whitequark 68403564df [PR37339] Fix assertion in FunctionComparator::cmpInlineAsm
Fixes bug https://bugs.llvm.org/show_bug.cgi?id=37339.

InlineAsm is only uniqued if the FunctionTypes are exactly the
same, while cmpTypes() for example considers all pointer types
in the default address space to be the same. For this reason
the end of cmpInlineAsm() can be reached.

This patch replaces the unreachable assertion with a check that
the function types are not identical.

Differential Revision: https://reviews.llvm.org/D46495

Reviewers: jfb
llvm-svn: 331990
2018-05-10 15:05:47 +00:00
Benjamin Kramer 456f473ea8 [InstCombine] Only propagate known leading zeros from udiv input to output.
Put in a conservatively correct estimate for now. Avoids miscompiling
clang in FDO mode. This is really tricky to trigger in reality as
basically all interesting cases will be folded away by computeKnownBits
earlier, I was unable to find a reasonably small test case.

llvm-svn: 331975
2018-05-10 11:45:18 +00:00
Craig Topper 553d451e95 [InstCombine] Reorder an if condition to put a cheap check in front of a computeKnownBits call. NFC
llvm-svn: 331948
2018-05-10 00:53:25 +00:00
Craig Topper 333efc951a [InstCombine] Use APInt::getBitsSetFrom to shortern a line and fix an 80 columns violation. NFC
Fix a similar line in the same function.

llvm-svn: 331947
2018-05-10 00:53:22 +00:00
Philip Reames 913a779df2 [Inscombine] fix a signedness warning which broke -Werror builds
llvm-svn: 331944
2018-05-10 00:05:29 +00:00
Sanjay Patel ac3951a735 [AggressiveInstCombine] convert a chain of 'and-shift' bits into masked compare
This is a follow-up to D45986. As suggested there, we should match the "all-bits-set" 
pattern in addition to "any-bits-set".

This was a little more complicated than I thought it would be initially because the 
"and 1" instruction can be anywhere in the chain. Hopefully, the code comments make 
that logic understandable, but if you see a way to simplify or improve that, it's 
most appreciated.

This transforms patterns that emerge from bitfield tests as seen in PR37098:
https://bugs.llvm.org/show_bug.cgi?id=37098

I think it would also help reduce the large test from:
D46336
D46595 
but we need something to reassociate that case to the forms we're expecting here first.

Differential Revision: https://reviews.llvm.org/D46649

llvm-svn: 331937
2018-05-09 23:08:15 +00:00
Philip Reames 79e917d117 [InstCombine] Widen guards with conditions between
The previous handling for guard widening in InstCombine was extremely restrictive. In particular, it didn't handle the common case where we had two guards separated by a single icmp. Handle this by scanning through a small fixed window of instructions to find the next guard if needed.

Differential Revision: https://reviews.llvm.org/D46203

llvm-svn: 331935
2018-05-09 22:56:32 +00:00
Benjamin Kramer 0d2fc1a501 [InstCombine] Teach SimplifyDemandedBits that udiv doesn't demand low dividend bits that are zero in the divisor
This is safe as long as the udiv is not exact. The pattern is not common in
C++ code, but comes up all the time in code generated by XLA's GPU backend.

Differential Revision: https://reviews.llvm.org/D46647

llvm-svn: 331933
2018-05-09 22:27:34 +00:00
David Bolvansky 9b5e6e8288 [InstCombine] snprintf optimizations
Reviewers: spatel, efriedma, majnemer, rja, bkramer

Reviewed By: rja, bkramer

Subscribers: rja, llvm-commits

Differential Revision: https://reviews.llvm.org/D46285

llvm-svn: 331889
2018-05-09 16:09:31 +00:00
Krzysztof Parzyszek ea4c1bb772 [LV] Change MaxVectorSize bound to 256 in assertion, NFC otherwise
It's possible to have a vector of 256 bytes in HVX code on Hexagon
(vector pair in 128-byte mode).

llvm-svn: 331885
2018-05-09 15:18:12 +00:00
Benjamin Kramer ccb0fbe9a0 Revert "[InstCombine] snprintf optimizations"
This reverts commit r331849. It miscompiles
snprintf(buf, sizeof(buf), "%s", "any constant string); into
memcpy(buf, "%s", sizeof("any constant string"));

llvm-svn: 331866
2018-05-09 11:38:57 +00:00
Bjorn Pettersson 9f953cdd7c [MergedLoadStoreMotion] Fix a debug invariant bug in mergeStores
Summary:
MergedLoadStoreMotion::mergeStores is using some heuristics
to limit the amount of stores that it tries to sink (see
MagicCompileTimeControl in MergedLoadStoreMotion.cpp). The
heuristic involves counting the number of instructions in
one of the basic blocks that is part of the transformation.

We now ignore dbg intrinsics when counting instruction for
the MagicCompileTimeControl heuristic. This to make sure that
the amount of stores that are sunk doesn't depend on the amount
of debug information (if -g is used or not).

Reviewers: Gerolf, davide, majnemer

Reviewed By: davide

Subscribers: dberlin, bjope, aprantl, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D46600

llvm-svn: 331852
2018-05-09 06:52:12 +00:00
David Bolvansky 44a37f04b2 [InstCombine] snprintf optimizations
Reviewers: spatel, efriedma, majnemer, rja

Reviewed By: rja

Subscribers: rja, llvm-commits

Differential Revision: https://reviews.llvm.org/D46285

llvm-svn: 331849
2018-05-09 06:34:20 +00:00
Shiva Chen 2c864551df [DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label.
In order to set breakpoints on labels and list source code around
labels, we need collect debug information for labels, i.e., label
name, the function label belong, line number in the file, and the
address label located. In order to keep these information in LLVM
IR and to allow backend to generate debug information correctly.
We create a new kind of metadata for labels, DILabel. The format
of DILabel is

!DILabel(scope: !1, name: "foo", file: !2, line: 3)

We hope to keep debug information as much as possible even the
code is optimized. So, we create a new kind of intrinsic for label
metadata to avoid the metadata is eliminated with basic block.
The intrinsic will keep existing if we keep it from optimized out.
The format of the intrinsic is

llvm.dbg.label(metadata !1)

It has only one argument, that is the DILabel metadata. The
intrinsic will follow the label immediately. Backend could get the
label metadata through the intrinsic's parameter.

We also create DIBuilder API for labels to be used by Frontend.
Frontend could use createLabel() to allocate DILabel objects, and use
insertLabel() to insert llvm.dbg.label intrinsic in LLVM IR.

Differential Revision: https://reviews.llvm.org/D45024

Patch by Hsiangkai Wang.

llvm-svn: 331841
2018-05-09 02:40:45 +00:00
Heejin Ahn bf7716952a Support a funclet operand bundle in LowerInvoke
Summary:
The current LowerInvoke pass cannot handle invoke instructions with a
funclet bundle operand. The order of operands for an invoke instruction
is {call arguments, callee, funclet operand (if any), normal dest,
unwind dest}. The current code assumes there is no funclet operand and
incorrectly includes a funclet operand into call arguments.

Reviewers: rnk

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D46242

llvm-svn: 331832
2018-05-09 00:53:50 +00:00
Davide Italiano 48283ba3a1 [SimplifyCFG] Fix a crash when folding PHIs.
We enter MergeBlockIntoPredecessor with a block looking like this:

for.inc.us-lcssa:                                 ; preds = %cond.end
  %k.1.lcssa.ph = phi i32 [ %conv15, %cond.end ]
  %t.3.lcssa.ph = phi i32 [ %k.1.lcssa.ph, %cond.end ]
  br label %for.inc, !dbg !66

[note the first arg of the PHI being a PHI].
FoldSingleEntryPHINodes gets rid of both PHIs (calling, eraseFromParent).
But right before we call the function, we push into IncomingValues the
only argument of the PHIs, and shortly after we try to iterate over
something which has been invalidated before :(

The fix its not trying to remove PHIs which have an incoming value
coming from the same BB we're looking at.

Fixes PR37300 and rdar://problem/39910460

Differential Revision:  https://reviews.llvm.org/D46568

llvm-svn: 331824
2018-05-08 23:28:15 +00:00
Hideki Saito d722d61402 [LV] Fix for PR37248, Broadcast codegen incorrectly assumed vector loop body is single basic block
Summary:
Broadcast code generation emitted instructions in pre-header, while the instruction they are dependent on in the vector loop body.
This resulted in an IL verification error ---- value used before defined.


Reviewers: rengolin, fhahn, hfinkel

Reviewed By: rengolin, fhahn

Subscribers: dcaballe, Ka-Ka, llvm-commits

Differential Revision: https://reviews.llvm.org/D46302

llvm-svn: 331799
2018-05-08 18:57:34 +00:00
Bjorn Pettersson 51cebc98f3 [LCSSA] Do not remove used PHI nodes in formLCSSAForInstructions
Summary:
In formLCSSAForInstructions we speculatively add new PHI
nodes, that sometimes ends up without having any uses. It
has been discovered that sometimes an added PHI node can
appear as being unused in one iteration of the Worklist,
although it can end up being used by a PHI node added in
a later iteration. We now check, a second time, that the
PHI node still is unused before we remove it. This avoids
an assert about "Trying to remove a phi with uses." for the
added test case.

Reviewers: davide, mzolotukhin, mattd, dberlin

Reviewed By: mzolotukhin, dberlin

Subscribers: dberlin, mzolotukhin, davide, bjope, uabelho, llvm-commits

Differential Revision: https://reviews.llvm.org/D46422

llvm-svn: 331741
2018-05-08 06:59:47 +00:00
Teresa Johnson 59da890c96 [NewPM] Emit inliner NoDefinition missed optimization remark
Summary: Makes this consistent with the old PM.

Reviewers: eraman

Subscribers: mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D46526

llvm-svn: 331709
2018-05-08 01:45:46 +00:00
Dmitry Mikulin 738bac77c1 Remove explicit setting of the CFI jumptable section name, it does not appear
to be needed: jump table sections are created with .cfi.jumptable suffix. With
this change each jump table is placed in a separate section, which allows the
linker to re-order them.

Differential Revision: https://reviews.llvm.org/D46537

llvm-svn: 331680
2018-05-07 21:30:15 +00:00
Fangrui Song 862eebb6d6 Simplify LLVM_ATTRIBUTE_USED call sites.
llvm-svn: 331599
2018-05-05 20:14:38 +00:00
George Burgess IV f9d26af4ea Range-ify for loop; NFC
llvm-svn: 331582
2018-05-05 04:52:26 +00:00
Craig Topper 781aa181ab Fix a bunch of places where operator-> was used directly on the return from dyn_cast.
Inspired by r331508, I did a grep and found these.

Mostly just change from dyn_cast to cast. Some cases also showed a dyn_cast result being converted to bool, so those I changed to isa.

llvm-svn: 331577
2018-05-05 01:57:00 +00:00
Peter Collingbourne e04ecc88de LowerTypeTests: Fix non-determinism in code that handles icall branch funnels.
This was exposed by enabling expensive checks, which causes llvm::sort
to sort randomly.

Differential Revision: https://reviews.llvm.org/D45901

llvm-svn: 331573
2018-05-05 00:51:55 +00:00
Philip Reames 5b39acd111 [LICM] Compute a must execute property for the prefix of the header as we go
Computing this property within the existing walk ensures that the cost is linear with the size of the block. If we did this from within isGuaranteedToExecute, it would be quadratic without some very fancy caching.

This allows us to reliably catch a hoistable instruction within a header which may throw at some point *after* our hoistable instruction. It doesn't do anything for non-header cases, but given how common single block loops are, this seems very worthwhile.

llvm-svn: 331557
2018-05-04 21:35:00 +00:00
Shoaib Meenai 57fadab1cb [ObjCARC] Account for catchswitch in bitcast insertion
A catchswitch is both a pad and a terminator, meaning it must be the
only non-phi instruction in its basic block. When we're inserting a
bitcast in the incoming basic block for a phi, if that incoming block is
a catchswitch, we should go up the dominator tree to find a valid
insertion point rather than attempting to insert before the catchswitch
(which would result in invalid IR).

Differential Revision: https://reviews.llvm.org/D46412

llvm-svn: 331548
2018-05-04 19:03:11 +00:00
Craig Topper ded8ee07e9 [LoopIdiomRecognize] Don't create an IRBuilder just to call getTrue/getFalse.
We can call the methods in ConstantInt directly. We just need a context.

llvm-svn: 331542
2018-05-04 17:39:08 +00:00
Max Kazantsev 786032c1b7 [IRCE] Fix misuse of dyn_cast which leads to UB
llvm-svn: 331508
2018-05-04 07:34:35 +00:00
Craig Topper 9510f70636 [LoopIdiomRecognize] Replace more unchecked dyn_casts with cast.
Two of these are immediately dereferenced on the next line. The other two are passed immediately to the IRBuilder constructor which can't handle a nullptr.

llvm-svn: 331500
2018-05-04 01:04:28 +00:00
Craig Topper cafae62ec9 [LoopIdiomRecognize] Use a regular array instead of a SmallVector and explicit ArrayRef.
llvm-svn: 331499
2018-05-04 01:04:26 +00:00
Craig Topper 8304231508 [LoopIdiomRecognize] Turn two uncheck dyn_casts into regular casts.
These are casts on users of a PHINode to Instruction. I think since PHINode is an Instruction any users would also be Instructions. At least a cast will give us an assertion if its wrong.

llvm-svn: 331498
2018-05-04 01:04:24 +00:00
Sanjay Patel e7b6654711 [InstCombine] refine select-of-constants to bitwise ops
Add logic for the special case when a cmp+select can clearly be
reduced to just a bitwise logic instruction, and remove an 
over-reaching chunk of general purpose bit magic. The primary goal 
is to remove cases where we are not improving the IR instruction 
count when doing these select transforms, and in all cases here that 
is true.

In the motivating 3-way compare tests, there are further improvements
because we can combine/propagate select values (not sure if that
belongs in instcombine, but it's there for now).

DAGCombiner has folds to turn some of these selects into bit magic,
so there should be no difference in the end result in those cases.
Not all constant combinations are handled there yet, however, so it
is possible that some targets will see more cmov/csel codegen with
this change in IR canonicalization. 

Ideally, we'll go further to *not* turn selects into multiple 
logic/math ops in instcombine, and we'll canonicalize to selects.
But we should make sure that this step does not result in regressions
first (and if it does, we should fix those in the backend).

The general direction for this change was discussed here:
http://lists.llvm.org/pipermail/llvm-dev/2016-September/105373.html
http://lists.llvm.org/pipermail/llvm-dev/2017-July/114885.html

Alive proofs for the new bit magic:
https://rise4fun.com/Alive/XG7

Differential Revision: https://reviews.llvm.org/D46086

llvm-svn: 331486
2018-05-03 21:58:44 +00:00
Piotr Padlewski c77ab8ef2f perform DSE through launder.invariant.group
Summary:
Alias Analysis knows that llvm.launder.invariant.group
returns pointer that mustalias argument, but this information
wasn't used, therefor we didn't DSE through launder.invariant.group

Reviewers: chandlerc, dberlin, bogner, hfinkel, efriedma

Reviewed By: dberlin

Subscribers: amharc, llvm-commits, nlewycky, rsmith

Differential Revision: https://reviews.llvm.org/D31581

llvm-svn: 331449
2018-05-03 11:03:53 +00:00
Craig Topper 856fd68690 [LoopIdiomRecognize] When looking for 'x & (x -1)' for popcnt, make sure the left hand side of the 'and' matches the left hand side of the 'subtract'
llvm-svn: 331437
2018-05-03 05:48:49 +00:00
Craig Topper 8ef2abdbc4 [LoopIdiomRecognize] Remove unnecessary cast from BinaryOperator to Instruction. NFC
BinaryOperator is a sub class of Instruction. We don't need an explicit cast back to Instruction.

llvm-svn: 331432
2018-05-03 05:00:18 +00:00
Shoaib Meenai a07295f977 [ObjCARC] Convert an if to an early continue. NFC
This reduces nesting and makes the logic slightly easier to follow.

Differential Revision: https://reviews.llvm.org/D46371

llvm-svn: 331422
2018-05-03 01:20:36 +00:00
Chandler Carruth e74c354d12 [gcov] Switch to an explicit if clunky array to satisfy some compilers
on various build bots that are unhappy with using makeArrayRef with an
initializer list.

llvm-svn: 331418
2018-05-03 00:11:03 +00:00
Chandler Carruth 71c3a3fac5 [GCOV] Emit the writeout function as nested loops of global data.
Summary:
Prior to this change, LLVM would in some cases emit *massive* writeout
functions with many 10s of 1000s of function calls in straight-line
code. This is a very wasteful way to represent what are fundamentally
loops and creates a number of scalability issues. Among other things,
register allocating these calls is extremely expensive. While D46127 makes this
less severe, we'll still run into scaling issues with this eventually. If not
in the compile time, just from the code size.

Now the pass builds up global data structures modeling the inputs to
these functions, and simply loops over the data structures calling the
relevant functions with those values. This ensures that the code size is
a fixed and only data size grows with larger amounts of coverage data.

A trivial change to IRBuilder is included to make it easier to build
the constants that make up the global data.

Reviewers: wmi, echristo

Subscribers: sanjoy, mcrosier, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D46357

llvm-svn: 331407
2018-05-02 22:24:39 +00:00
Daniel Sanders 8d0d1aa229 [reassociate] Fix excessive revisits when processing long chains of reassociatable instructions.
Summary:
Some of our internal testing detected a major compile time regression which I've
tracked down to:
    r278938 - Revert "Reassociate: Reprocess RedoInsts after each inst".
It appears that processing long chains of reassociatable instructions causes
non-linear (potentially exponential) growth in the number of times an
instruction is revisited. For example, the included test revisits instructions
220 times in a 20-instruction test.

It appears that r278938 reversed the order instructions were visited and that
this is preventing scheduled revisits from being cancelled as a result of
visiting the instructions naturally during normal processing. However, simply
reversing the order also harmed the generated code. Upon closer inspection, it
was discovered that revisits occurred in the opposite order to the first pass
(Thanks to escha for spotting that).

This patch makes the revisit order consistent with the first pass which allows
more revisits to be cancelled. This does appear to have a small impact on the
generated code in few cases but it significantly reduces compile-time.

After this patch, our internal test that was most affected by the regression
dropped from ~2 million revisits to ~4k resulting in Reassociate having 0.46%
of the runtime it had before (99.54% improvement).

Here's the summaries reported by lnt for the LLVM test-suite with --benchmarking-only:
| metric         | geomean before patch | geomean after patch | delta   |
| -----          | -----                | -----               | -----   |
| compile time   | 0.1956               | 0.1261              | -35.54% |
| execution time | 0.3240               | 0.3237              | -       |
| code size      | 7365.4459            | 7365.6079           | -       |

The results have a few wins and losses on compile-time, mostly in the +/- 2.5% range. There was one outlier though:
| Performance Regressions - compile_time | Δ | Previous | Current |
| MultiSource/Benchmarks/ASC_Sequoia/CrystalMk/CrystalMk | 9.82% | 2.0473 | 2.2483 |

Reviewers: javed.absar, dberlin

Reviewed By: dberlin

Subscribers: kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D45734

llvm-svn: 331381
2018-05-02 17:59:16 +00:00
Simon Pilgrim f53ee8e640 Fix '32-bit shift implicitly converted to 64 bits' warning by using APInt::setBit instead.
llvm-svn: 331359
2018-05-02 14:22:30 +00:00
Florian Hahn 5912c667b0 [LoopInterchange] Update some loops to use range base for loops (NFC).
llvm-svn: 331342
2018-05-02 10:53:04 +00:00
Sanjay Patel d2025a2e31 [AggressiveInstCombine] convert a chain of 'or-shift' bits into masked compare
and (or (lshr X, C), ...), 1 --> (X & C') != 0

I initially thought about implementing the minimal pattern in instcombine as mentioned here:
https://bugs.llvm.org/show_bug.cgi?id=37098#c6

...but we need to do better to catch the more general sequence from the motivating test 
(more than 2 bits in the compare). And a test-suite run with statistics showed that this 
pattern only happened 2 times currently. It would potentially happen more often if 
reassociation worked better (D45842), but it's probably still not too frequent?

This is small enough that I didn't see a need to create a whole new class/file within 
AggressiveInstCombine. There are likely other relatively small matchers like what was 
discussed in D44266 that would slide under foldUnusualPatterns() (name suggestions welcome). 
We could potentially also consolidate matchers for ctpop, bswap, etc under here.

Differential Revision: https://reviews.llvm.org/D45986

llvm-svn: 331311
2018-05-01 21:02:09 +00:00
Adrian Prantl 4dfcc4a788 Remove @brief commands from doxygen comments, too.
This is a follow-up to r331272.

We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by
  for i in $(git grep -l '\@brief'); do perl -pi -e 's/\@brief //g' $i & done

https://reviews.llvm.org/D46290

llvm-svn: 331275
2018-05-01 16:10:38 +00:00
Adrian Prantl 5f8f34e459 Remove \brief commands from doxygen comments.
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by

  for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done

Differential Revision: https://reviews.llvm.org/D46290

llvm-svn: 331272
2018-05-01 15:54:18 +00:00
Daniel Neilson 9e4bbe801a [LV] Preserve inbounds on created GEPs
Summary:
This is a fix for PR23997.

The loop vectorizer is not preserving the inbounds property of GEPs that it creates.
This is inhibiting some optimizations. This patch preserves the inbounds property in
the case where a load/store is being fed by an inbounds GEP.

Reviewers: mkuper, javed.absar, hsaito

Reviewed By: hsaito

Subscribers: dcaballe, hsaito, llvm-commits

Differential Revision: https://reviews.llvm.org/D46191

llvm-svn: 331269
2018-05-01 15:35:08 +00:00
Wei Mi eec5ba9fae Fix the issue that ComputeValueKnownInPredecessors only handles the case when
phi is on lhs of a comparison op.

For the following testcase,
L1:

  %t0 = add i32 %m, 7
  %t3 = icmp eq i32* %t2, null
  br i1 %t3, label %L3, label %L2

L2:

  %t4 = load i32, i32* %t2, align 4
  br label %L3

L3:

  %t5 = phi i32 [ %t0, %L1 ], [ %t4, %L2 ]
  %t6 = icmp eq i32 %t0, %t5
  br i1 %t6, label %L4, label %L5

We know if we go through the path L1 --> L3, %t6 should always be true. However
currently, if the rhs of the eq comparison is phi, JumpThreading fails to
evaluate %t6 to true. And we know that Instcombine cannot guarantee always
canonicalizing phi to the left hand side of the comparison operation according
to the operand priority comparison mechanism in instcombine. The patch handles
the case when rhs of the comparison op is a phi.

Differential Revision: https://reviews.llvm.org/D46275

llvm-svn: 331266
2018-05-01 14:47:24 +00:00
Omer Paparo Bivas 82ef8e19ef [InstCombine] Adjusting bswap pattern matching to hold for And/Shift mixed case
Differential Revision: https://reviews.llvm.org/D45731

Change-Id: I85d4226504e954933c41598327c91b2d08192a9d
llvm-svn: 331257
2018-05-01 12:25:46 +00:00
Chandler Carruth 2c85a23123 [PM/LoopUnswitch] Remove the last manual domtree update code from loop
unswitch and replace it with the amazingly simple update API code.

This addresses piles of FIXMEs around the update logic here and makes
everything substantially simpler.

llvm-svn: 331247
2018-05-01 09:54:39 +00:00
Chandler Carruth 44aab925fd [PM/LoopUnswitch] Add back a successor set that was removed based on
code review.

It turns out this *is* necessary, and I read the comment on the API
correctly the first time. ;]

The `applyUpdates` routine requires that updates are "balanced". This is
in order to cleanly handle cycles like inserting, removing, nad then
re-inserting the same edge. This precludes inserting the same edge
multiple times in a row as handling that would cause the insertion logic
to become *ordered* instead of *unordered* (which is what the API
provides).

It happens that in this specific case nothing (other than an assert and
contract violation) goes wrong because we're never inserting and
removing the same edge. The implementation *happens* to do the right
thing to eliminate redundant insertions in that case.

But the requirement is there and there is an assert to catch it.
Somehow, after the code review I never did another asserts-clang build
testing loop-unswich for a long time. As a consequence, I didn't notice
this despite a bunch of testing going on, but it shows up immediately
with an asserts build of clang itself.

llvm-svn: 331246
2018-05-01 09:42:09 +00:00
Florian Hahn 3df8844b92 [SimplifyCFG] Use BB::instructionsWithoutDebug to skip DbgInfo (NFC).
This patch updates some code responsible the skip debug info to use
BasicBlock::instructionsWithoutDebug. I think this makes things slightly
simpler and more direct.

Reviewers: aprantl, vsk, hans, danielcdh

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D46252

llvm-svn: 331221
2018-04-30 20:10:53 +00:00
Florian Hahn 8fe04ad3f7 [LoopSimplify] Use BB::instructionsWithoutDebug to skip DbgInfo (NFC).
This patch updates some code responsible the skip debug info to use
BasicBlock::instructionsWithoutDebug. I think this makes things slightly
simpler and more direct.

Reviewers: aprantl, vsk, chandlerc

Reviewed By: aprantl

Differential Revision: https://reviews.llvm.org/D46253

llvm-svn: 331217
2018-04-30 19:19:36 +00:00
Roman Lebedev aa4faec114 [InstCombine] Unfold masked merge with constant mask
Summary:
As discussed in D45733, we want to do this in InstCombine.

https://rise4fun.com/Alive/LGk

Reviewers: spatel, craig.topper

Reviewed By: spatel

Subscribers: chandlerc, xbolva00, llvm-commits

Differential Revision: https://reviews.llvm.org/D45867

llvm-svn: 331205
2018-04-30 17:59:33 +00:00
Davide Italiano bd3bf1660b [SLPVectorizer] Debug info shouldn't impact spill cost computation.
<rdar://problem/39794738>

(Also, PR32761).

Differential Revision:  https://reviews.llvm.org/D46199

llvm-svn: 331199
2018-04-30 16:57:33 +00:00
Nico Weber 432a38838d IWYU for llvm-config.h in llvm, additions.
See r331124 for how I made a list of files missing the include.
I then ran this Python script:

    for f in open('filelist.txt'):
        f = f.strip()
        fl = open(f).readlines()

        found = False
        for i in xrange(len(fl)):
            p = '#include "llvm/'
            if not fl[i].startswith(p):
                continue
            if fl[i][len(p):] > 'Config':
                fl.insert(i, '#include "llvm/Config/llvm-config.h"\n')
                found = True
                break
        if not found:
            print 'not found', f
        else:
            open(f, 'w').write(''.join(fl))

and then looked through everything with `svn diff | diffstat -l | xargs -n 1000 gvim -p`
and tried to fix include ordering and whatnot.

No intended behavior change.

llvm-svn: 331184
2018-04-30 14:59:11 +00:00
Florian Hahn deb01ea126 [LV] Use BB::instructionsWithoutDebug to skip DbgInfo (NFC).
This patch updates some code responsible the skip debug info to use
BasicBlock::instructionsWithoutDebug. I think this makes things
slightly simpler and more direct.

Reviewers: mkuper, rengolin, dcaballe, aprantl, vsk

Reviewed By: rengolin

Differential Revision: https://reviews.llvm.org/D46254

llvm-svn: 331174
2018-04-30 13:28:08 +00:00
Hideki Saito f2ec16ccc2 [NFC][LV][LoopUtil] Move LoopVectorizationLegality to its own file
Summary:
This is a follow up to D45420 (included here since it is still under review and this change is dependent on that) and D45072 (committed).
Actual change for this patch is LoopVectorize* and cmakefile. All others are all from D45420.

LoopVectorizationLegality is an analysis and thus really belongs to Analysis tree. It is modular enough and it is reusable enough ---- we can further improve those aspects once uses outside of LV picks up.

Hopefully, this will make it easier for people familiar with vectorization theory, but not necessarily LV itself to contribute, by lowering the volume of code they should deal with. We probably should start adding some code in LV to check its own capability (i.e., vectorization is legal but LV is not ready to handle it) and then bail out.


Reviewers: rengolin, fhahn, hfinkel, mkuper, aemerson, mssimpso, dcaballe, sguggill

Reviewed By: rengolin, dcaballe

Subscribers: egarcia, rogfer01, mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D45552

llvm-svn: 331139
2018-04-29 07:26:18 +00:00
Roman Lebedev 136867931a [InstCombine] Canonicalize variable mask in masked merge
Summary:
Masked merge has a pattern of: `((x ^ y) & M) ^ y`.
But, there is no difference between `((x ^ y) & M) ^ y` and `((x ^ y) & ~M) ^ x`,
We should canonicalize the pattern to non-inverted mask.

https://rise4fun.com/Alive/Yol

Reviewers: spatel, craig.topper

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45664

llvm-svn: 331112
2018-04-28 15:45:07 +00:00
Philip Reames 502d4481d4 [LoopGuardWidening] Make PostDomTree optional
The effect of doing so is not disrupting the LoopPassManager when mixing this pass with other loop passes.  This should help locality of access substaintially and avoids the cost of computing PostDom.

The assumption here is that the full GuardWidening (which does use PostDom) is run as a canonicalization before loop opts and that this version is just catching cases exposed by other loop passes.  (i.e. LoopPredication, IndVarSimplify, LoopUnswitch, etc..)

llvm-svn: 331094
2018-04-27 23:15:56 +00:00
Adrian Prantl 210a29de7b Fix a bug in GlobalOpt's handling of DIExpressions.
This patch adds support for fragment expressions
TryToShrinkGlobalToBoolean() which were previously just dropped.

Thanks to Reid Kleckner for providing me a reproducer!

llvm-svn: 331086
2018-04-27 21:41:36 +00:00
Roman Lebedev 6959b8e76f [PatternMatch] Stabilize the matching order of commutative matchers
Summary:
Currently, we
1. match `LHS` matcher to the `first` operand of binary operator,
2. and then match `RHS` matcher to the `second` operand of binary operator.
If that does not match, we swap the `LHS` and `RHS` matchers:
1. match `RHS` matcher to the `first` operand of binary operator,
2. and then match `LHS` matcher to the `second` operand of binary operator.

This works ok.
But it complicates writing of commutative matchers, where one would like to match
(`m_Value()`) the value on one side, and use (`m_Specific()`) it on the other side.

This is additionally complicated by the fact that `m_Specific()` stores the `Value *`,
not `Value **`, so it won't work at all out of the box.

The last problem is trivially solved by adding a new `m_c_Specific()` that stores the
`Value **`, not `Value *`. I'm choosing to add a new matcher, not change the existing
one because i guess all the current users are ok with existing behavior,
and this additional pointer indirection may have performance drawbacks.
Also, i'm storing pointer, not reference, because for some mysterious-to-me reason
it did not work with the reference.

The first one appears trivial, too.
Currently, we
1. match `LHS` matcher to the `first` operand of binary operator,
2. and then match `RHS` matcher to the `second` operand of binary operator.
If that does not match, we swap the ~~`LHS` and `RHS` matchers~~ **operands**:
1. match ~~`RHS`~~ **`LHS`** matcher to the ~~`first`~~ **`second`** operand of binary operator,
2. and then match ~~`LHS`~~ **`RHS`** matcher to the ~~`second`~ **`first`** operand of binary operator.

Surprisingly, `$ ninja check-llvm` still passes with this.
But i expect the bots will disagree..

The motivational unittest is included.
I'd like to use this in D45664.

Reviewers: spatel, craig.topper, arsenm, RKSimon

Reviewed By: craig.topper

Subscribers: xbolva00, wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D45828

llvm-svn: 331085
2018-04-27 21:23:20 +00:00
Philip Reames 5a6482450a [LICM] Reduce nesting with an early return [NFC]
llvm-svn: 331080
2018-04-27 20:58:30 +00:00
Daniel Neilson a19ee7d7b6 [LV] Common duplicate vector load/store address calculation (NFC)
Summary:
Commoning some obviously copy/paste code in
InnerLoopVectorizer::vectorizeMemoryInstruction

llvm-svn: 331076
2018-04-27 20:29:18 +00:00
Philip Reames de5a1da2d2 [GuardWidening] Add some clarifying comments about heuristics [NFC]
llvm-svn: 331061
2018-04-27 17:41:37 +00:00
Philip Reames 9258e9d190 [LoopGuardWidening] Split out a loop pass version of GuardWidening
The idea is to have a pass which performs the same transformation as GuardWidening, but can be run within a loop pass manager without disrupting the pass manager structure.  As demonstrated by the test case, this doesn't quite get there because of issues with post dom, but it gives a good step in the right direction.  the motivation is purely to reduce compile time since we can now preserve locality during the loop walk.

This patch only includes a legacy pass.  A follow up will add a new style pass as well.

llvm-svn: 331060
2018-04-27 17:29:10 +00:00