Commit Graph

793 Commits

Author SHA1 Message Date
Max Kazantsev 275f3a2540 [GVN][NFC] Factor out load elimination logic via PRE for reuse 2021-04-09 16:12:25 +07:00
Arthur Eubanks c5d1ccbcdf [GVN] Properly invalidate ICF cache when we simplify a value
This fixes a "Cached first special instruction is wrong!" assert.

The assert fires because replacing a value with another can cause an
instruction to no longer be "special" to ICF. In this case,
devirtualization happened, turning an indirect call to a
call to a willreturn function which is no longer special.

Reviewed By: nikic, rnk

Differential Revision: https://reviews.llvm.org/D99977
2021-04-08 14:01:57 -07:00
Philip Reames 9ef6aa020b Plumb AssumeInst through operand bundle apis [nfc]
Follow up to a6d2a8d6f5.  This covers all the public interfaces of the bundle related code.  I tried to cleanup the internals where the changes were obvious, but there's definitely more room for improvement.
2021-04-06 12:53:53 -07:00
Arthur Eubanks 4e83e59eb8 [GVN] Add missing ICF update
performScalarPREInsertion() inserts instructions into blocks that we
need to tell ImplicitControlFlowTracking about, otherwise the ICF cache
may be invalid.

Fixes PR49193.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D99909
2021-04-06 10:13:42 -07:00
Philip Reames 21d4839948 Move GCRelocateInst and GCResultInst to IntrinsicInst.h [nfc]
These two are part of the IntrinsicInst class hierarchy and it helps to cut down on some redundant includes.
2021-04-06 08:33:15 -07:00
Philip Reames 52ecd94cfb Remove last remnants of PR49607 migration [NFC]
The key change (4f5e92c) to switch gc.result and gc.relocate to being readnone landed nearly two weeks ago, and we haven't seen any fallout.  Time to remove the code added to make reverting easy.
2021-04-06 07:56:55 -07:00
Max Kazantsev a1d83776bf [NFC] Undo some erroneous renamings
Some vars renamed by mistake during auto-replacements. Undoing them.
2021-04-01 13:10:10 +07:00
Max Kazantsev 630818a850 [NFC] Disambiguate LI in GVN
Name GVN uses name 'LI' for two different unrelated things:
LoadInst and LoopInfo. This patch relates the variables with
former meaning into 'Load' to disambiguate the code.
2021-04-01 12:40:35 +07:00
KAWASHIMA Takahiro 5fac7c6046 [GVN] Propagate llvm.access.group metadata of loads
Before this change, the `llvm.access.group` metadata was dropped
when moving a load instruction in GVN. This prevents vectorizing
a C/C++ loop with `#pragma clang loop vectorize(assume_safety)`.
This change propagates the metadata as well as other metadata if
it is safe (the move-destination basic block and source basic
block belong to the same loop).

Differential Revision: https://reviews.llvm.org/D93503
2021-04-01 10:00:48 +09:00
Philip Reames 6972e39d47 [gvn] CSE gc.relocates based on meaning, not spelling (try 2)
This was (partially) reverted in cfe8f8e0 because the conversion from readonly to readnone in Intrinsics.td exposed a couple of problems.  This change has been reworked to not need that change (via some explicit checks in client code).  This is being done to address the original optimization issue and simplify the testing of the readonly changes.  I'm working on that piece under 49607.

Original commit message follows:

The last two operands to a gc.relocate represent indices into the associated gc.statepoint's gc bundle list. (Effectively, gc.relocates are projections from the gc.statepoints multiple return values.)

We can use this to recognize when two gc.relocates are equivalent (and can be CSEd), even when the indices are non-equal. This is particular useful when considering a chain of multiple statepoints as it lets us eliminate all duplicate gc.relocates in a single pass.

Differential Revision: https://reviews.llvm.org/D97974
2021-03-16 10:59:31 -07:00
Nikita Popov 3fedaf2a52 [GVN] Don't explicitly materialize undefs from dead blocks
When materializing an available load value, do not explicitly
materialize the undef values from dead blocks. Doing so will
will force creation of a phi with an undef operand, even if there
is a dominating definition. The phi will be folded away on
subsequent GVN iterations, but by then we may have already
poisoned MDA cache slots.

Simply don't register these values in the first place, and let
SSAUpdater do its thing.
2021-03-06 23:46:24 +01:00
Philip Reames 5db2735af9 [gvn] Handle simply phi equivalence cases
GVN basically doesn't handle phi nodes at all. This is for a reason - we can't value number their inputs since the predecessor blocks have probably not been visited yet.

However, it also creates a significant pass ordering problem. As it stands, instcombine and simplifycfg ends up implementing CSE of phi nodes. This means that for any series of CSE opportunities intermixed with phi nodes, we end up having to alternate instcombine/simplifycfg and gvn to make progress.

This patch handles the simplest case by simply preprocessing the phi instructions in a block, and CSEing them if they are syntactically identical. This turns out to be powerful enough to handle many cases in a single invocation of GVN since blocks which use the cse'd phi results are visited after the block containing the phi. If there's a CSE opportunity in one the phi predecessors required to recognize the phi CSE opportunity, that will require a second iteration on the function. (Still within a single run of gvn though.)

Compile time wise, this could go either way. On one hand, we're potentially causing GVN to iterate over the function more. On the other, we're cutting down on iterations between two passes and potentially shrinking the IR aggressively. So, a bit unclear what to expect.

Note that this does still rely on instcombine to canonicalize block order of the phis, but that's a one time transformation independent of the values incoming to the phi.

Differential Revision: https://reviews.llvm.org/D98080
2021-03-06 09:31:12 -08:00
Philip Reames 51b13a7ea0 [gvn] CSE gc.relocates based on meaning, not spelling
The last two operands to a gc.relocate represent indices into the associated gc.statepoint's gc bundle list. (Effectively, gc.relocates are projections from the gc.statepoints multiple return values.)

We can use this to recognize when two gc.relocates are equivalent (and can be CSEd), even when the indices are non-equal. This is particular useful when considering a chain of multiple statepoints as it lets us eliminate all duplicate gc.relocates in a single pass.

Differential Revision: https://reviews.llvm.org/D97974

(Note: Part of the reviewed change was split and landed as f352463a)
2021-03-05 10:16:12 -08:00
Kazu Hirata 5fc9e30985 [Scalar] Use range-based for loops (NFC) 2021-02-25 19:54:38 -08:00
ksyx 4125cabce1 [GVN] Fix a typo in comment
NFC.

Differential Revision: https://reviews.llvm.org/D97200

Reviewed By: fhahn
2021-02-23 10:39:34 +08:00
Kazu Hirata 302313a264 [Transforms] Use range-based for loops (NFC) 2021-02-08 22:33:53 -08:00
Kazu Hirata fb74e1e78a [Transforms/Scalar] Use range-based for loops (NFC) 2021-02-04 21:18:05 -08:00
Nick Desaulniers d36812892c [GVN] do not repeat PRE on failure to split critical edge
Fixes an infinite loop encountered in GVN.

GVN will delay PRE if it encounters critical edges, attempt to split
them later via calls to SplitCriticalEdge(), then restart.

The caller of GVN::splitCriticalEdges() assumed a return value of true
meant that critical edges were split, that the IR had changed, and that
PRE should be re-attempted, upon which we loop infinitely.

This was exposed after D88438, by compiling the Linux kernel for s390,
but the test case is reproducible on x86.

Fixes: https://github.com/ClangBuiltLinux/linux/issues/1261

Reviewed By: void

Differential Revision: https://reviews.llvm.org/D94996
2021-01-25 11:23:44 -08:00
Kazu Hirata e53472de68 [Transforms] Use llvm::append_range (NFC) 2021-01-20 21:35:54 -08:00
Kazu Hirata ba82c0b315 [llvm] Call *(Set|Map)::erase directly (NFC)
We can erase an item in a set or map without checking its membership
first.
2021-01-03 09:57:47 -08:00
Kazu Hirata 5d2529f28f [Scalar] Construct SmallVector with iterator ranges (NFC) 2020-12-28 19:55:18 -08:00
Florian Hahn 4ad41902e8
[GVN] Correctly set modified status when doing PRE on indices.
This patch updates GVN to correctly return the modified status, if PRE
is performed on indices. It fixes a crash when building the test-suite
with EXPENSIVE_CHECKS and LTO.
2020-12-27 21:58:31 +00:00
Juneyoung Lee f1d648b973 [GVN] Use m_LogicalAnd/Or to propagate equality from branch conditions
This patch makes GVN recognize `select c1, c2, false` as well as `select c1, true, c2`
branch condition and propagate equality from these.

See llvm.org/pr48353, D93065

Differential Revision: https://reviews.llvm.org/D93841
2020-12-28 05:28:38 +09:00
Kazu Hirata 43c0e4f665 [Transforms] Use llvm::is_contained (NFC) 2020-11-18 20:42:22 -08:00
Florian Hahn be0578f0b4 [GVN] Fix MemorySSA update when replacing assume(false) with stores.
When replacing an assume(false) with a store, we have to be more careful
with the order we insert the new access. This patch updates the code to
look at the accesses in the block to find a suitable insertion point.

Alterantively we could check the defining access of the assume, but IIRC
there has been some discussion about making assume() readnone, so
looking at the access list might be more future proof.

Fixes PR48072.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D90784
2020-11-05 12:09:32 +00:00
Jameson Nash 59a6ab28c4 [GVN] small improvements to comments 2020-11-03 13:21:48 -05:00
Michael Liao c82403d025 [gvn] PRE needs to skip convergent intrinsics/calls.
- As convergent intrinsics/calls could only be moved to
  control-equivalent blocks, or more precisely the same divergent
  branch, PRE needs to skip them.

Differential Revision: https://reviews.llvm.org/D90391
2020-10-30 11:24:40 -04:00
Serguei Katkov b69919b537 [GVN LoadPRE] Add an option to disable splitting backedge
GVN Load PRE can split the backedge causing breaking the loop structure where the latch
contains the conditional branch with for example induction variable.

Different optimizations expect this form of the loop, so it is better to preserve it for some time.
This CL adds an option to control an ability to split backedge.

Default value is true so technically it is NFC and current behavior is not changed.

Reviewers: fedor.sergeev, mkazantsev, nikic, reames, fhahn
Reviewed By: mkazasntsev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D89854
2020-10-27 11:59:52 +07:00
Serguei Katkov b988898013 [GVN LoadPRE] Extend the scope of optimization by using context to prove safety of speculation
Use context to prove that load can be safely executed at a point where load is being hoisted.

Postpone the decision about safety of speculative load execution till the moment we know
where we hoist load and check safety at that context.

Reviewers: nikic, fhahn, mkazantsev, lebedev.ri, efriedma, reames
Reviewed By: reames, mkazantsev
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D88725
2020-10-06 09:25:16 +07:00
Vedant Kumar dfc5a9eb57 [Instruction] Add dropLocation and updateLocationAfterHoist helpers
Introduce a helper which can be used to update the debug location of an
Instruction after the instruction is hoisted. This can be used to safely
drop a source location as recommended by the docs.

For more context, see the discussion in https://reviews.llvm.org/D60913.

Differential Revision: https://reviews.llvm.org/D85670
2020-09-24 15:00:04 -07:00
Nikita Popov 91ce8e121b [GVN] Use that assume(!X) implies X==false (PR47496)
We already use that assume(X) implies X==true, do the same for
assume(!X) implying X==false. This fixes PR47496.
2020-09-17 21:34:44 +02:00
Krzysztof Parzyszek 8a08740db6 [GVN] Account for masked loads/stores depending on load/store instructions
This is a case where an intrinsic depends on a non-call instruction.

Differential Revision: https://reviews.llvm.org/D87423
2020-09-10 10:57:33 -05:00
Florian Hahn 2bcc4db761 [EarlyCSE] Explicitly require AAResultsWrapperPass.
The MemorySSAWrapperPass depends on AAResultsWrapperPass and if
MemorySSA is preserved but AAResultsWrapperPass is not, this could lead
to a crash when updating the last user of the MemorySSAWrapperPass.

Alternatively AAResultsWrapperPass could be marked preserved by GVN, but
I am not sure if that would be safe. I am not sure what is required in
order to preserve AAResultsWrapperPass. At the moment, it seems like a
couple of passes that do similar transforms to GVN are preserving it.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D87137
2020-09-09 09:14:50 +01:00
Sanjay Patel bdd5bfd0e4 [IR][GVN] add/allow commutative intrinsics with >2 args
Follow-up to D86798 and rGe25449f.
2020-09-03 10:14:53 -04:00
Florian Hahn a344b382a0 [GVN] Preserve MemorySSA if it is available.
Preserve MemorySSA if it is available before running GVN.

DSE with MemorySSA will run closely after GVN. If GVN and 2 other
passes preserve MemorySSA, DSE can re-use MemorySSA used by LICM
when doing LTO.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D86534
2020-09-03 12:28:13 +01:00
Sanjay Patel e25449ff57 [IR][GVN] allow intrinsics in Instruction's isCommutative query (2nd try)
The 1st try was reverted because I missed an assert that
needed softening.

As discussed in D86798 / rG09652721 , we were potentially
returning a different result for whether an Instruction
is commutable depending on if we call the base class or
derived class method.

This requires relaxing asserts in GVN, but that pass
seems to be working otherwise.

NewGVN requires more work because it uses different
code paths for numbering binops and calls.
2020-08-31 16:01:19 -04:00
Sanjay Patel badd7264e1 Revert "[IR][GVN] allow intrinsics in Instruction's isCommutative query"
This reverts commit 25597f7783.
It is causing crashing on bots such as:
http://lab.llvm.org:8011/builders/fuchsia-x86_64-linux/builds/10523/steps/ninja-build/logs/stdio
2020-08-30 17:02:51 -04:00
Sanjay Patel 25597f7783 [IR][GVN] allow intrinsics in Instruction's isCommutative query
As discussed in D86798 / rG09652721 , we were potentially
returning a different result for whether an Instruction
is commutable depending on if we call the base class or
derived class method.

This requires relaxing an assert in GVN, but that pass
seems to be working otherwise.

NewGVN requires more work because it uses different
code paths for numbering binops and calls.
2020-08-30 16:49:22 -04:00
Vedant Kumar 30c1633386 Revert "[Instruction] Add updateLocationAfterHoist helper"
This reverts commit 4a646ca9e2.

This is causing some bots to fail with "!dbg attachment points at wrong
subprogram for function", like:

http://lab.llvm.org:8011/builders/sanitizer-windows/builds/67958/steps/stage%201%20check/logs/stdio
2020-08-11 14:54:09 -07:00
Vedant Kumar 4a646ca9e2 [Instruction] Add updateLocationAfterHoist helper
Introduce a helper on Instruction which can be used to update the debug
location after hoisting.

Use this in GVN and LICM, where we were mistakenly introducing new line
0 locations after hoisting (the docs recommend dropping the location in
this case).

For more context, see the discussion in https://reviews.llvm.org/D60913.

Differential Revision: https://reviews.llvm.org/D85670
2020-08-11 14:05:20 -07:00
Jay Foad ffe1edfc53 [NFC][GVN] Fix "avaliable" typos
Differential Revision: https://reviews.llvm.org/D85520
2020-08-07 14:22:24 +01:00
Roman Lebedev e40315d2b4
[GVN] Rewrite IsValueFullyAvailableInBlock(): no recursion, less false-negatives
While this doesn't appear to help with the perf issue being exposed by
D84108, the function as-is is very weird, convoluted, and what's worse,
recursive.

There was no need for `SpeculativelyAvaliableAndUsedForSpeculation`,
tri-state choice is enough. We don't even ever check for that state.

The basic idea here is that we need to perform a depth-first traversal
of the predecessors of the basic block in question, either finding a
preexisting state for the block in a map, or inserting a "placeholder"
`SpeculativelyAvaliable`,

If we encounter an `Unavaliable` block, then we need to give up search,
and back-propagate the `Unavaliable` state to the each successor of
said block, more specifically to the each `SpeculativelyAvaliable`
we've just created.

However, if we have traversed entirety of the predecessors and have not
encountered an `Unavaliable` block, then it must mean the value is fully
available. We could update each inserted `SpeculativelyAvaliable` into
a `Avaliable`, but we don't need to, as assertion excersizes,
because we can assume that if we see an `SpeculativelyAvaliable` entry,
it is actually `Avaliable`, because during the time we've produced it,
if we would have found that it has an `Unavaliable` predecessor,
we would have updated it's successors, including this block,
into `Unavaliable`

Reviewed By: fhahn

Differential Revision: https://reviews.llvm.org/D84181
2020-07-28 10:19:28 +03:00
Roman Lebedev fb5577d4f8
[NFCI][GVN] Make IsValueFullyAvailableInBlock() readable - use enum class instead of magic numbers
This does not change any logic, it only wraps the magic 0/1/2/3 constants
into an enum class.
2020-07-19 16:33:56 +03:00
Florian Hahn 4495a6b141 [BreakCritEdges] Add option to opt-out of perserving loop-simplify.
This patch adds a new option to CriticalEdgeSplittingOptions to control
whether loop-simplify form must be preserved. It is them used by GVN to
indicate that loop-simplify form does not have to be preserved.

This fixes a crash exposed by 189efe295b.

If the critical edge we are splitting goes from a block inside a loop to
a block outside the loop, splitting the edge will create a new exit
block. As a result, the new block will branch to the original exit
block, which will add a non-loop predecessor, breaking loop-simplify
form. To preserve loop-simplify form, the predecessor blocks of the
original exit are split, but that does not work for blocks with
indirectbr terminators. If preserving loop-simplify form is requested,
bail out , before making any changes.

Reviewers: reames, hfinkel, davide, efriedma

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D81582
2020-06-12 11:47:13 +01:00
Nikita Popov 164845cd92 [GVN] Reduce expression size (NFC)
Reduce size of GVN::Expression by reordering fields to reduce padding.
2020-04-26 09:43:35 +02:00
Craig Topper 05a11974ae [CallSite removal] Remove unneeded includes of CallSite.h. NFC 2020-04-22 00:07:13 -07:00
Nikita Popov 54d01cbc15 [IPT] Don't use OrderedInstructions (NFC)
Use Instruction::comesBefore() instead of OrderedInstructions
inside InstructionPrecedenceTracking. This also removes the
dominator tree dependency.

Differential Revision: https://reviews.llvm.org/D78461
2020-04-20 18:25:31 +02:00
Tyker 1d2b76a8fc [AssumeBundles] adapte GVN to assume bundles
Summary:
prevent GVN from removing assume bundles
make GVN preserve information from removed instructions

Reviewers: jdoerfert

Reviewed By: jdoerfert

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77405
2020-04-14 12:48:14 +02:00
Eli Friedman 3f13ee8a00 [NFC] Modernize misc. uses of Align/MaybeAlign APIs.
Use the current getAlign() APIs where it makes sense, and use Align
instead of MaybeAlign when we know the value is non-zero.
2020-04-06 17:53:04 -07:00
Uday Bondhugula 4cf70af94f [GVN] Make GVN aware of aligned_alloc
Make the GVN pass aware of aligned_alloc.

Depends on D76974.

Differential Revision: https://reviews.llvm.org/D76975
2020-04-01 23:26:50 +05:30
Eli Friedman 1ee6ec2bf3 Remove "mask" operand from shufflevector.
Instead, represent the mask as out-of-line data in the instruction. This
should be more efficient in the places that currently use
getShuffleVector(), and paves the way for further changes to add new
shuffles for scalable vectors.

This doesn't change the syntax in textual IR. And I don't currently plan
to change the bitcode encoding in this patch, although we'll probably
need to do something once we extend shufflevector for scalable types.

I expect that once this is finished, we can then replace the raw "mask"
with something more appropriate for scalable vectors.  Not sure exactly
what this looks like at the moment, but there are a few different ways
we could handle it.  Maybe we could try to describe specific shuffles.
Or maybe we could define it in terms of a function to convert a fixed-length
array into an appropriate scalable vector, using a "step", or something
like that.

Differential Revision: https://reviews.llvm.org/D72467
2020-03-31 13:08:59 -07:00
Juneyoung Lee 5cbb265694 [GVN] Fold equivalent freeze instructions
Summary:
This patch defines two freeze instructions to have the same value number if they are equivalent.

This is allowed because GVN replaces all uses of a duplicated instruction with another.

If it partially rewrites use, it is not allowed. e.g)

```
a = freeze(x)
b = freeze(x)
use(a)
use(a)
use(b)
=>
use(a)
use(b) // This is not allowed!
use(b)
```

Reviewers: fhahn, reames, spatel, efriedma

Reviewed By: fhahn

Subscribers: lebedev.ri, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75398
2020-03-01 07:32:05 +09:00
Thomas Raoux e53bbf1213 [GVN] Add GVNOption to control load-pre more fine-grained.
Adds the global (cl::opt) GVNOption enable-load-in-loop-pre in order
to control whether the optimization will be performed if the load
is part of a loop.

Patch by Hendrik Greving!

Differential Revision: https://reviews.llvm.org/D73804
2020-02-03 23:00:58 -08:00
Fedor Sergeev 3478551bf3 [GVN] introduce GVNOptions to control GVN pass behavior
There are a few global (cl::opt) controls that enable optional
behavior in GVN. Introduce GVNOptions that provide corresponding
per-pass instance controls.

That will allow to use GVN multiple times in pipeline each time
with different settings.

Reviewers: asbirlea, rnk, reames, skatkov, fhahn
Reviewed By: fhahn

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D72732
2020-01-16 20:21:08 +03:00
Philip Reames 312a532dc0 [GVN/FP] Considate logic for reasoning about equality vs equivalance for floats
Factor out common logic into some reasonable commented helper functions. In the process, ensure that the in-block vs cross-block cases are handled the same. They previously weren't.

Differential Revision: https://reviews.llvm.org/D67126
2020-01-07 16:05:04 -08:00
Reid Kleckner 05da2fe521 Sink all InitializePasses.h includes
This file lists every pass in LLVM, and is included by Pass.h, which is
very popular. Every time we add, remove, or rename a pass in LLVM, it
caused lots of recompilation.

I found this fact by looking at this table, which is sorted by the
number of times a file was changed over the last 100,000 git commits
multiplied by the number of object files that depend on it in the
current checkout:
  recompiles    touches affected_files  header
  342380        95      3604    llvm/include/llvm/ADT/STLExtras.h
  314730        234     1345    llvm/include/llvm/InitializePasses.h
  307036        118     2602    llvm/include/llvm/ADT/APInt.h
  213049        59      3611    llvm/include/llvm/Support/MathExtras.h
  170422        47      3626    llvm/include/llvm/Support/Compiler.h
  162225        45      3605    llvm/include/llvm/ADT/Optional.h
  158319        63      2513    llvm/include/llvm/ADT/Triple.h
  140322        39      3598    llvm/include/llvm/ADT/StringRef.h
  137647        59      2333    llvm/include/llvm/Support/Error.h
  131619        73      1803    llvm/include/llvm/Support/FileSystem.h

Before this change, touching InitializePasses.h would cause 1345 files
to recompile. After this change, touching it only causes 550 compiles in
an incremental rebuild.

Reviewers: bkramer, asbirlea, bollu, jdoerfert

Differential Revision: https://reviews.llvm.org/D70211
2019-11-13 16:34:37 -08:00
Simon Pilgrim 77debf51ab [GVN] Fix uninitialized variable warnings. NFCI. 2019-11-05 14:10:32 +00:00
Simon Pilgrim 1842fe6be3 Add missing GVN =operator. NFCI.
Fixes PVS Studio warning that the 'ValueTable' class implements a copy constructor, but lacks the '=' operator.
2019-11-05 13:41:50 +00:00
Guillaume Chatelet 734c74ba14 [Alignment][NFC] Convert LoadInst to MaybeAlign
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: hiraditya, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69302

llvm-svn: 375498
2019-10-22 12:35:55 +00:00
Teresa Johnson 9c27b59cec Change TargetLibraryInfo analysis passes to always require Function
Summary:
This is the first change to enable the TLI to be built per-function so
that -fno-builtin* handling can be migrated to use function attributes.
See discussion on D61634 for background. This is an enabler for fixing
handling of these options for LTO, for example.

This change should not affect behavior, as the provided function is not
yet used to build a specifically per-function TLI, but rather enables
that migration.

Most of the changes were very mechanical, e.g. passing a Function to the
legacy analysis pass's getTLI interface, or in Module level cases,
adding a callback. This is similar to the way the per-function TTI
analysis works.

There was one place where we were looking for builtins but not in the
context of a specific function. See FindCXAAtExit in
lib/Transforms/IPO/GlobalOpt.cpp. I'm somewhat concerned my workaround
could provide the wrong behavior in some corner cases. Suggestions
welcome.

Reviewers: chandlerc, hfinkel

Subscribers: arsenm, dschuff, jvesely, nhaehnle, mehdi_amini, javed.absar, sbc100, jgravelle-google, eraman, aheejin, steven_wu, george.burgess.iv, dexonsmith, jfb, asbirlea, gchatelet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D66428

llvm-svn: 371284
2019-09-07 03:09:36 +00:00
Philip Reames 30dc2da827 [GVN] Remove a todo introduced w/rL370791
When I dug into this, it turns out to be *much* more involved than I'd realized and doesn't actually simplify anything.  

The general purpose of the leader table is that we want to find the most-dominating definition quickly.  The problem for equivalance folding is slightly different; we want to find the most dominating *value* whose definition block dominates our use quickly.

To make this change, we'd end up having to restructure the leader table (either the sorting thereof, or maybe even introducing multiple leader tables per value) and that complexity is just not worth it.

llvm-svn: 370824
2019-09-03 21:56:17 +00:00
Philip Reames 37e2f5f125 [GVN] Propagate simple equalities from assumes within the tail of the block
This extends the existing logic for propagating constant expressions in an analogous manner for what we do across basic blocks. The core point is that we chose some order of operands, and canonicalize uses towards that one.

The heuristic used is inspired by the one used across blocks; in a follow up change, I'd plan to common them so that the cross block version uses the slightly stronger ordering herein. 

As noted by the TODOs in the code, there's a good amount of room for improving the existing code and making it more powerful.  Some follow up work planned.

Differential Revision: https://reviews.llvm.org/D66977

llvm-svn: 370791
2019-09-03 17:31:19 +00:00
Wei Mi 5ef5829fb0 [GVN] Verify value equality before doing phi translation for call instruction
This is an updated version of https://reviews.llvm.org/D66909 to fix PR42605.

Basically, current phi translatation translates an old value number to an new
value number for a call instruction based on the literal equality of call
expression, without verifying there is no clobber in between. This is incorrect.

To get a finegrain check, use MachineDependence analysis to do the job. However,
this is still not ideal. Although given a call instruction,
`MemoryDependenceResults::getCallDependencyFrom` returns identical call
instructions without clobber in between using MemDepResult with its DepType to
be `Def`. However, identical is too strict here and we want it to be relaxed a
little to consider phi-translation -- callee is the same, param operands can be
different. That means changing the semantic of `MemDepResult::Def` and I don't
know the potential impact.

So currently the patch is still conservative to only handle
MemDepResult::NonFuncLocal, which means the current call has no function local
clobber. If there is clobber, even if the clobber doesn't stand in between the
current call and the call with the new value, we won't do phi-translate.

Differential Revision: https://reviews.llvm.org/D67013

llvm-svn: 370547
2019-08-30 23:01:22 +00:00
Florian Hahn b5e52bfd83 [GVN] Do PHI translations across all edges between the load and the unavailable pred.
Currently we do not properly translate addresses with PHIs if LoadBB !=
LI->getParent(), because PHITranslateAddr expects a direct predecessor as argument,
because it considers all instructions outside of the current block to
not requiring translation.

The amount of cases that trigger this should be very low, as most single
predecessor blocks should be folded into their predecessor by GVN before
we actually start with value numbering. It is still not guaranteed to
happen, so we should do PHI translation along all edges between the
loads' block and the predecessor where we have to place a load.

There are a few test cases showing current limits of the PHI translation, which
could be improved later.

Reviewers: spatel, reames, efriedma, john.brawn

Reviewed By: efriedma

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65020

llvm-svn: 369570
2019-08-21 20:06:50 +00:00
Florian Hahn 189efe295b Recommit "[GVN] Preserve loop related analysis/canonical forms."
This fixes some pipeline tests.
This reverts commit d0b6f42936.

llvm-svn: 367401
2019-07-31 09:27:54 +00:00
Florian Hahn d0b6f42936 Revert [GVN] Preserve loop related analysis/canonical forms.
This reverts r367332 (git commit 2d7227ec3a)

llvm-svn: 367335
2019-07-30 17:04:58 +00:00
Florian Hahn 2d7227ec3a [GVN] Preserve loop related analysis/canonical forms.
LoopInfo can be easily preserved by passing it to the functions that
modify the CFG (SplitCriticalEdge and MergeBlockIntoPredecessor.
SplitCriticalEdge also preserves LoopSimplify and LCSSA form when when passing in
LoopInfo. The test case shows that we preserve LoopSimplify and
LoopInfo. Adding addPreservedID(LCSSAID) did not preserve LCSSA for some
reason.

Also I am not sure if it is possible to preserve those in the new pass
manager, as they aren't analysis passes.

Reviewers: reames, hfinkel, davide, jdoerfert

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D65137

llvm-svn: 367332
2019-07-30 16:43:39 +00:00
Cameron McInally 6e62a796d5 [GVN] Add support for unary FNeg to GVN pass
Differential Revision: https://reviews.llvm.org/D63896

llvm-svn: 364592
2019-06-27 21:05:02 +00:00
Whitney Tsang 15b7f5b72d PHINode: introduce setIncomingValueForBlock() function, and use it.
Summary:
There is PHINode::getBasicBlockIndex() and PHINode::setIncomingValue()
but no function to replace incoming value for a specified BasicBlock*
predecessor.
Clearly, there are a lot of places that could use that functionality.

Reviewer: craig.topper, lebedev.ri, Meinersbur, kbarton, fhahn
Reviewed By: Meinersbur, fhahn
Subscribers: fhahn, hiraditya, zzheng, jsji, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D63338

llvm-svn: 363566
2019-06-17 14:38:56 +00:00
Keno Fischer eb4a561fa3 [GVN] non-functional code movement
Summary: Move some code around, in preparation for later fixes
to the non-integral addrspace handling (D59661)

Patch By Jameson Nash <jameson@juliacomputing.com>

Reviewed By: reames, loladiro
Differential Revision: https://reviews.llvm.org/D59729

llvm-svn: 362853
2019-06-07 23:08:38 +00:00
Matt Arsenault b04f3258dd GVN: Handle addrspacecast
llvm-svn: 361103
2019-05-18 14:36:06 +00:00
Vedant Kumar 282b26ec4d [GVN+LICM] Use line 0 locations for better crash attribution
This is a follow-up to r291037+r291258, which used null debug locations
to prevent jumpy line tables.

Using line 0 locations achieves the same effect, but works better for
crash attribution because it preserves the right inline scope.

Differential Revision: https://reviews.llvm.org/D60913

llvm-svn: 358791
2019-04-19 22:36:40 +00:00
Nikita Popov 79dffc67b5 [IR] Add WithOverflowInst class
This adds a WithOverflowInst class with a few helper methods to get
the underlying binop, signedness and nowrap type and makes use of it
where sensible. There will be two more uses in D60650/D60656.

The refactorings are all NFC, though I left some TODOs where things
could be improved. In particular we have two places where add/sub are
handled but mul isn't.

Differential Revision: https://reviews.llvm.org/D60668

llvm-svn: 358512
2019-04-16 18:55:16 +00:00
Craig Topper 784929d045 Implementation of asm-goto support in LLVM
This patch accompanies the RFC posted here:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html

This patch adds a new CallBr IR instruction to support asm-goto
inline assembly like gcc as used by the linux kernel. This
instruction is both a call instruction and a terminator
instruction with multiple successors. Only inline assembly
usage is supported today.

This also adds a new INLINEASM_BR opcode to SelectionDAG and
MachineIR to represent an INLINEASM block that is also
considered a terminator instruction.

There will likely be more bug fixes and optimizations to follow
this, but we felt it had reached a point where we would like to
switch to an incremental development model.

Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii

Differential Revision: https://reviews.llvm.org/D53765

llvm-svn: 353563
2019-02-08 20:48:56 +00:00
Richard Trieu 5f436fc57a Move DomTreeUpdater from IR to Analysis
DomTreeUpdater depends on headers from Analysis, but is in IR.  This is a
layering violation since Analysis depends on IR.  Relocate this code from IR
to Analysis to fix the layering violation.

llvm-svn: 353265
2019-02-06 02:52:52 +00:00
James Y Knight 14359ef1b6 [opaque pointer types] Pass value type to LoadInst creation.
This cleans up all LoadInst creation in LLVM to explicitly pass the
value type rather than deriving it from the pointer's element-type.

Differential Revision: https://reviews.llvm.org/D57172

llvm-svn: 352911
2019-02-01 20:44:24 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Matt Davis 9cd9f41f0e [GVN] Update BlockRPONumber prior to use.
Summary:
The original patch addressed the use of BlockRPONumber by forcing a sequence point when accessing that map in a conditional.  In short we found cases where that map was being accessed with blocks that had not yet been added to that structure.  For context, I've kept the wall of text below,  to what we are trying to fix, by always ensuring a updated BlockRPONumber.

== Backstory ==

I was investigating an ICE (segfault accessing a DenseMap item).  This failure happened non-deterministically, with no apparent reason and only on a Windows build of LLVM (from October 2018).

After looking into the crashes (multiple core files) and running DynamoRio, the cores and DynamoRio (DR) log pointed to the same code in `GVN::performScalarPRE()`. The values in the map are unsigned integers, the keys are `llvm::BasicBlock*`.  Our test case that triggered this warning and periodic crash is rather involved.  But the problematic line looks to be:

GVN.cpp: Line 2197

```
     if (BlockRPONumber[P] >= BlockRPONumber[CurrentBlock] &&
```

To test things out, I cooked up a patch that accessed the items in the map outside of the condition, by forcing a sequence point between accesses. DynamoRio stopped warning of the issue, and the test didn't seem to crash after 1000+ runs.

My investigation was on an older version of LLVM, (source from October this year). What it looks like was occurring is the following, and the assembly from the latest pull of llvm in December seems to confirm this might still be an issue; however, I have not witnessed the crash on more recent builds. Of course the asm in question is generated from the host compiler on that Windows box (not clang), but it hints that we might want to consider how we access the BlockRPONumber map in this conditional (line 2197, listed above).  In any case, I don't think the host compiler is wrong, rather I think it is pointing out a possibly latent bug in llvm.

1) There is no sequence point for the `>=` operation.

2) A call to a `DenseMapBase::operator[]` can have the side effect of the map reallocating a larger store (more Buckets, via a call to `DenseMap::grow`).

3) It seems perfectly legal for a host compiler to generate assembly that stores the result of a call to `operator[]` on the stack (that's what my host compile of GVN.cpp is doing) .  A second call to `operator[]` //might// encourage the map to 'grow' thus making any pointers to the map's store invalid.  The `>=` compares the first and second values. If the first happens to be a pointer produced from operator[], it could be invalid when dereferenced at the time of comparison.

The assembly generated from the Window's host compiler does show the result of the first access to the map via `operator[]` produces a pointer to an unsigned int.  And that pointer is being stored on  the stack.  If a second call to the map (which does occur) causes the map to grow, that address (on the stack) is now invalid. 

Reviewers: t.p.northover, efriedma

Reviewed By: efriedma

Subscribers: efriedma, llvm-commits

Differential Revision: https://reviews.llvm.org/D55974

llvm-svn: 350880
2019-01-10 19:56:03 +00:00
Max Kazantsev 4615a505f8 [IPT] Drop cache less eagerly in GVN and LoopSafetyInfo
Current strategy of dropping `InstructionPrecedenceTracking` cache is to
invalidate the entire basic block whenever we change its contents. In fact,
`InstructionPrecedenceTracking` has 2 internal strictures: `OrderedInstructions`
that is needed to be invalidated whenever the contents changes, and the map
with first special instructions in block. This second map does not need an
update if we add/remove a non-special instuction because it cannot
affect the contents of this map.

This patch changes API of `InstructionPrecedenceTracking` so that it now
accounts for reasons under which we invalidate blocks. This should lead
to much less recalculations of the map and should save us some compile time
because in practice we don't typically add/remove special instructions.

Differential Revision: https://reviews.llvm.org/D54462
Reviewed By: efriedma

llvm-svn: 350694
2019-01-09 07:28:13 +00:00
Chandler Carruth 363ac68374 [CallSite removal] Migrate all Alias Analysis APIs to use the newly
minted `CallBase` class instead of the `CallSite` wrapper.

This moves the largest interwoven collection of APIs that traffic in
`CallSite`s. While a handful of these could have been migrated with
a minorly more shallow migration by converting from a `CallSite` to
a `CallBase`, it hardly seemed worth it. Most of the APIs needed to
migrate together because of the complex interplay of AA APIs and the
fact that converting from a `CallBase` to a `CallSite` isn't free in its
current implementation.

Out of tree users of these APIs can fairly reliably migrate with some
combination of `.getInstruction()` on the `CallSite` instance and
casting the resulting pointer. The most generic form will look like `CS`
-> `cast_or_null<CallBase>(CS.getInstruction())` but in most cases there
is a more elegant migration. Hopefully, this migrates enough APIs for
users to fully move from `CallSite` to the base class. All of the
in-tree users were easily migrated in that fashion.

Thanks for the review from Saleem!

Differential Revision: https://reviews.llvm.org/D55641

llvm-svn: 350503
2019-01-07 05:42:51 +00:00
Alexandros Lamprineas e4c91f5c4c [GVN] Don't perform scalar PRE on GEPs
Partial Redundancy Elimination of GEPs prevents CodeGenPrepare from
sinking the addressing mode computation of memory instructions back
to its uses. The problem comes from the insertion of PHIs, which
confuse CGP and make it bail.

I've autogenerated the check lines of an existing test and added a
store instruction to demonstrate the motivation behind this change.
The store is now using the gep instead of a phi.

Differential Revision: https://reviews.llvm.org/D55009

llvm-svn: 348496
2018-12-06 16:11:58 +00:00
Chandler Carruth ae98759ec5 [TI removal] Remove `TerminatorInst` from GVN.h and GVN.cpp.
This is the last interesting usage in all of LLVM's headers. The
remaining usages in headers are the core typesystem bits (Core.h,
instruction types, and InstVisitor) and as the return of
`BasicBlock::getTerminator`. The latter is the big remaining API point
that I'll remove after mass updates to user code.

llvm-svn: 344501
2018-10-15 10:00:15 +00:00
Max Kazantsev e9765ac275 [NFC] Remove meaningless code from GVN
llvm-svn: 342202
2018-09-14 04:50:38 +00:00
Sebastian Pop 6284b54ccd add flag instead of using a constant [NFC]
llvm-svn: 341837
2018-09-10 15:07:59 +00:00
Sebastian Pop ea0a91298d make flag name more specific to gvn [NFC]
llvm-svn: 341836
2018-09-10 15:07:56 +00:00
John Brawn 8967e18c4a [GVN] Invalidate cached info for values replaced by equality propagation
When GVN propagates an equality by replacing one value with another it also
needs to invalidate the cached information for the value being replaced.

Differential Revision: https://reviews.llvm.org/D51218

llvm-svn: 341820
2018-09-10 12:23:05 +00:00
Chandler Carruth 9ae926b973 [IR] Replace `isa<TerminatorInst>` with `isTerminator()`.
This is a bit awkward in a handful of places where we didn't even have
an instruction and now we have to see if we can build one. But on the
whole, this seems like a win and at worst a reasonable cost for removing
`TerminatorInst`.

All of this is part of the removal of `TerminatorInst` from the
`Instruction` type hierarchy.

llvm-svn: 340701
2018-08-26 09:51:22 +00:00
John Brawn 23cbf09fad [GVN] Invalidate cached info for phis when setting dead predecessors to undef
When GVN sets the incoming value for a phi to undef because the incoming block
is unreachable it needs to also invalidate the cached info for that phi in
MemoryDependenceAnalysis, otherwise later queries will return stale information.

Differential Revision: https://reviews.llvm.org/D51099

llvm-svn: 340529
2018-08-23 12:48:17 +00:00
Alina Sbirlea ab6f84f763 Update MemorySSA in BasicBlockUtils.
Summary:
Extend BasicBlocksUtils to update MemorySSA.

Subscribers: sanjoy, arsenm, nhaehnle, jlebar, Prazek, llvm-commits

Differential Revision: https://reviews.llvm.org/D45300

llvm-svn: 340365
2018-08-21 23:32:03 +00:00
Florian Hahn 9583d4fa03 [GVN] Assign new value number to calls reading memory, if there is no MemDep info.
Currently we assign the same value number to two calls reading the same
memory location if we do not have MemoryDependence info. Without MemDep
Info we cannot guarantee that there is no store between the two calls, so we
have to assign a new number to the second call.

It also adds a new option EnableMemDep to enable/disable running
MemoryDependenceAnalysis and also renamed NoLoads to NoMemDepAnalysis to
be more explicit what it does. As it also impacts calls that read memory,
NoLoads is a bit confusing.

Reviewers: efriedma, sebpop, john.brawn, wmi

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D50893

llvm-svn: 340319
2018-08-21 19:11:27 +00:00
Marcello Maggioni e98aaf1d91 [GVN] Fix typo in IsValueFullyAvailableInBlock. NFC.
DenseMap insert() method return a pair<iterator, bool>
not pair<iterator, char>
Noticed it and thought I might just fix it ...

llvm-svn: 339777
2018-08-15 15:06:53 +00:00
Florian Hahn 39bbe179aa [GVN,NewGVN] Move patchReplacementInstruction to Utils/Local.h
This function is shared between both implementations. I am not sure if
Utils/Local.h is the best place though.

Reviewers: davide, dberlin, efriedma, xbolva00

Reviewed By: efriedma, xbolva00

Differential Revision: https://reviews.llvm.org/D47337

llvm-svn: 339138
2018-08-07 13:27:33 +00:00
Max Kazantsev 640cb00365 [NFC] Factor out implicit control flow logic from GVN
Logic for tracking implicit control flow instructions was added to GVN to
perform PRE optimizations correctly. It appears that GVN is not the only
optimization that sometimes does PRE, so this logic is required in other
places (such as Jump Threading).

This is an NFC patch that encapsulates all ICF-related logic in a dedicated
utility class separated from GVN.

Differential Revision: https://reviews.llvm.org/D40293

llvm-svn: 339086
2018-08-07 01:47:20 +00:00
Chijun Sima 21a8b605a1 [Dominators] Convert existing passes and utils to use the DomTreeUpdater class
Summary:
This patch is the second in a series of patches related to the [[ http://lists.llvm.org/pipermail/llvm-dev/2018-June/123883.html | RFC - A new dominator tree updater for LLVM ]].

It converts passes (e.g. adce/jump-threading) and various functions which currently accept DDT in local.cpp and BasicBlockUtils.cpp to use the new DomTreeUpdater class.
These converted functions in utils can accept DomTreeUpdater with either UpdateStrategy and can deal with both DT and PDT held by the DomTreeUpdater.

Reviewers: brzycki, kuhar, dmgreen, grosser, davide

Reviewed By: brzycki

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D48967

llvm-svn: 338814
2018-08-03 05:08:17 +00:00
John Brawn fc18a6ad7d [GVN] Don't use the eliminated load as an available value in phi construction
In ConstructSSAForLoadSet if an available value is actually the load that we're
doing SSA construction to eliminate, then we can omit it as SSAUpdate will add
in the value for the phi that will be replacing it anyway. This can result in
simpler IR which can allow further optimisation.

Differential Revision: https://reviews.llvm.org/D44160

llvm-svn: 337686
2018-07-23 12:14:45 +00:00
Hiroshi Inoue f209649dfc [NFC] fix trivial typos in comments
llvm-svn: 334687
2018-06-14 05:41:49 +00:00
David Blaikie 31b98d2e99 Move Analysis/Utils/Local.h back to Transforms
Review feedback from r328165. Split out just the one function from the
file that's used by Analysis. (As chandlerc pointed out, the original
change only moved the header and not the implementation anyway - which
was fine for the one function that was used (since it's a
template/inlined in the header) but not in general)

llvm-svn: 333954
2018-06-04 21:23:21 +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
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
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