Commit Graph

1526 Commits

Author SHA1 Message Date
Max Kazantsev f10500e220 [IndVars] Use isLoopBackedgeGuardedByCond for last iteration check
Use more context to prove contextual facts about the last iteration. It is
only executed when the backedge is taken, so we can use `isLoopBackedgeGuardedByCond`
to make this check.

Differential Revision: https://reviews.llvm.org/D91535
Reviewed By: skatkov
2020-11-26 12:37:21 +07:00
Joe Ellis 06654a5348 [SVE] Fix TypeSize warning in RuntimePointerChecking::insert
The TypeSize warning would occur because RuntimePointerChecking::insert
was not scalable vector aware. The fix is to use
ScalarEvolution::getSizeOfExpr to grab the size of types.

Differential Revision: https://reviews.llvm.org/D90171
2020-11-25 16:59:03 +00:00
Max Kazantsev 9130651126 Revert "[SCEV] Generalize no-self-wrap check in isLoopInvariantExitCondDuringFirstIterations"
This reverts commit 7dcc889917.

This patch introduced a logical error that breaks whole logic of this analysis.
All checks we are making are supposed to be loop-independent, so that we could
safely remove the range check. The 'nw' fact is loop-dependent, so we can remove
the check basing on facts from this very check.

Motivating examples will follow-up.
2020-11-25 13:26:17 +07:00
Max Kazantsev 02fdbc3567 Revert "[NFC][SCEV] Generalize monotonicity check for full and limited iteration space"
This reverts commit 2734a9ebf4.

This patch appeared to not be a NFC. It introduced an execution path where
monotonicity check on limited space started relying in existing nsw/nuw
flags, which is illegal. The motivating test will follow-up.
2020-11-24 17:56:59 +07:00
Max Kazantsev 48d7cc6ae2 [SCEV] Fix incorrect treatment of max taken count. PR48225
SCEV makes a logical mistake when handling EitherMayExit in
case when both conditions must be met to exit the loop. The
mistake looks like follows: "if condition `A` fails within at most `X` first
iterations, and `B` fails within at most `Y` first iterations, then `A & B`
fails at most within `min (X, Y)` first iterations". This is wrong, because
both of them must fail at the same time.

Simple example illustrating this is following: we have an IV with step 1,
condition `A` = "IV is even", condition `B` = "IV is odd". Both `A` and `B`
will fail within first two iterations. But it doesn't mean that both of them
will fail within first two first iterations at the same time, which would mean
that IV is neither even nor odd at the same time within first 2 iterations.

We can only do so for known exact BE counts, but not for max.

Differential Revision: https://reviews.llvm.org/D91942
Reviewed By: nikic
2020-11-23 16:52:39 +07:00
Max Kazantsev 47e31d1b5e [NFC] Reduce code duplication in binop processing in computeExitLimitFromCondCached
Handling of `and` and `or` vastly uses copy-paste. Factored out into
a helper function as preparation step for further fix (see PR48225).

Differential Revision: https://reviews.llvm.org/D91864
Reviewed By: nikic
2020-11-23 13:18:12 +07:00
Philip Reames 0f41a2fe83 test commit for new client 2020-11-16 17:26:52 -08:00
Philip Reames 257d33c815 [SCEV] Factor out part of wrap flag detection logic [NFC](try 2)
This is a cut down version of 1ec6e1 which was reverted due to a compile time issue.  The key changes made from that patch: 1) only infer the flags needed along each path, 2) be careful to preserve order of checks, and 3) avoid computing NW flags at all since we need to prove the stronger property (does not cross 0) in the caller anyways.

Assuming this doesn't trip regressions, I'm going to try weakening (1).  My end objective is to move flag inference into addrec construction.  If I can't weaken (1) without compile time impact, I'll have a problem.
2020-11-16 12:07:21 -08:00
Nikita Popov 9ace4b337f Revert "[SCEV] Factor out part of wrap flag detection logic [NFC-ish]"
This reverts commit 1ec6e1eb8a.

This change causes a significant compile-time regression:
https://llvm-compile-time-tracker.com/compare.php?from=dd0b8b94d0796bd895cc998dd163b4fbebceb0b8&to=1ec6e1eb8a084bffae8a40236eb9925d8026dd07&stat=instructions

I assume that this is due to the non-NFC part of the change, which
now performs expensive nowrap inference even for nowrap flags that
are not used by the particular code.
2020-11-15 10:19:44 +01:00
Philip Reames 1ec6e1eb8a [SCEV] Factor out part of wrap flag detection logic [NFC-ish]
In an effort to make code around flag determination more readable, and (possibly) prepare for a follow up change, factor out some of the flag detection logic.  In the process, reduce the number of locations we mutate wrap flags by a couple.

Note that this isn't NFC.  The old code tried for NSW xor (NUW || NW).  This is, two different paths computed different sets of wrap flags.  The new code will try for all three.  The result is that some expressions end up with a few extra flags set.
2020-11-14 19:21:05 -08:00
Nikita Popov f3124a46c1 [SCEV] Fix nsw flags for GEP expressions
The SCEV code for constructing GEP expressions currently assumes
that the addition of the base and all the offsets is nsw if the GEP
is inbounds. While the addition of the offsets is indeed nsw, the
addition to the base address is not, as the base address is
interpreted as an unsigned value.

Fix the GEP expression code to not assume nsw for the base+offset
calculation. However, do assume nuw if we know that the offset is
non-negative. With this, we use the same behavior as the
construction of GEP addrecs does. (Modulo the fact that we
disregard SCEV unification, as the pre-existing FIXME points out).

Differential Revision: https://reviews.llvm.org/D90648
2020-11-13 18:19:32 +01:00
Max Kazantsev 0a1d394bf3 [NFC] Refactor loop-invariant getters to return Optional 2020-11-13 15:03:10 +07:00
Max Kazantsev 2734a9ebf4 [NFC][SCEV] Generalize monotonicity check for full and limited iteration space
A piece of logic of `isLoopInvariantExitCondDuringFirstIterations` is actually
a generalized predicate monotonicity check. This patch moves it into the
corresponding method and generalizes it a bit.

Differential Revision: https://reviews.llvm.org/D90395
Reviewed By: apilipenko
2020-11-12 12:37:07 +07:00
Max Kazantsev 7dcc889917 [SCEV] Generalize no-self-wrap check in isLoopInvariantExitCondDuringFirstIterations
Lift limitation on step being `+/- 1`. In fact, the only thing it is needed for
is proving no-self-wrap. We can instead check this flag directly.

Theoretically it can increase the scope of the transform, but I could not
construct such test easily.

Differential Revision: https://reviews.llvm.org/D91126
Reviewed By: apilipenko
2020-11-11 11:17:13 +07:00
David Green b2ac9681a7 [ARM] Alter t2DoLoopStart to define lr
This changes the definition of t2DoLoopStart from
t2DoLoopStart rGPR
to
GPRlr = t2DoLoopStart rGPR

This will hopefully mean that low overhead loops are more tied together,
and we can more reliably generate loops without reverting or being at
the whims of the register allocator.

This is a fairly simple change in itself, but leads to a number of other
required alterations.

 - The hardware loop pass, if UsePhi is set, now generates loops of the
   form:
       %start = llvm.start.loop.iterations(%N)
     loop:
       %p = phi [%start], [%dec]
       %dec = llvm.loop.decrement.reg(%p, 1)
       %c = icmp ne %dec, 0
       br %c, loop, exit
 - For this a new llvm.start.loop.iterations intrinsic was added, identical
   to llvm.set.loop.iterations but produces a value as seen above, gluing
   the loop together more through def-use chains.
 - This new instrinsic conceptually produces the same output as input,
   which is taught to SCEV so that the checks in MVETailPredication are not
   affected.
 - Some minor changes are needed to the ARMLowOverheadLoop pass, but it has
   been left mostly as before. We should now more reliably be able to tell
   that the t2DoLoopStart is correct without having to prove it, but
   t2WhileLoopStart and tail-predicated loops will remain the same.
 - And all the tests have been updated. There are a lot of them!

This patch on it's own might cause more trouble that it helps, with more
tail-predicated loops being reverted, but some additional patches can
hopefully improve upon that to get to something that is better overall.

Differential Revision: https://reviews.llvm.org/D89881
2020-11-10 15:57:58 +00:00
Max Kazantsev 3ec69c16c3 [NFC] Different way of getting step 2020-11-10 13:48:02 +07:00
Max Kazantsev 6022a8b7e8 [SCEV] Drop cached ranges of AddRecs after flag update
Our range computation methods benefit from no-wrap flags. But if the ranges
were first computed before the flags were set, the cached range will be too
pessimistic.

We need to drop cached ranges whenever we sharpen AddRec's no wrap flags.

Differential Revision: https://reviews.llvm.org/D89847
Reviewed By: fhahn
2020-11-10 12:37:12 +07:00
Max Kazantsev ab7ef35d34 Revert "[SCEV] Handle non-positive case in isImpliedViaOperations"
This reverts commit 8dc98897c4.

Commited by mistake.
2020-11-05 11:27:55 +07:00
Max Kazantsev 8dc98897c4 [SCEV] Handle non-positive case in isImpliedViaOperations
We already handle non-negative case there. Add support for non-positive.
2020-11-05 11:07:37 +07:00
Nikita Popov cc91554ebb [SCEV] Delay strengthening of nowrap flags
Strengthening nowrap flags is relatively expensive. Make sure we
only do it if we're actually going to use the flags -- we don't
use them for many recursive invocations. Additionally, if we're
reusing an existing SCEV node, there's no point in trying to
strengthen the flags if we don't have any new baseline facts.

This change falls slightly short of being NFC, because the way
flags during add+addrec / mul+addrec folding are handled may be
more precise (as less operands are included in the calculation).
2020-11-01 22:18:07 +01:00
Nikita Popov 6ec56467cb [SCEV] Construct GEP expression more efficiently (NFCI)
Instead of performing a sequence of pairwise additions, directly
construct a multi-operand add expression.

This should be NFC modulo any SCEV canonicalization deficiencies.
2020-11-01 19:00:57 +01:00
Roman Lebedev ef22d500f7
[NFCI][SCEV] getPtrToIntExpr(): use SCEVRewriteVisitor<> for ptrtoint cast sinking
This is functionally-identical to the previous implementation,
just using a generic interface to do that instead of hand-rolled one,
with caching as a bonus. Thought the sinking is still recursive..

Note that SCEVRewriteVisitor<>'s default implementations
don't preserve NoWrap flags on Add/Mul (but does on AddRec!),
but here we know we can preserve them,
so `visitAddExpr()`/`visitMulExpr()` are specialized.
2020-10-30 17:05:14 +03:00
Roman Lebedev b4916918e5
[SCEV] SCEVPtrToIntExpr simplifications
If we've got an SCEVPtrToIntExpr(op), where op is not an SCEVUnknown,
we want to sink the SCEVPtrToIntExpr into an operand,
so that the operation is performed on integers,
and eventually we end up with just an `SCEVPtrToIntExpr(SCEVUnknown)`.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D89692
2020-10-30 11:13:35 +03:00
Roman Lebedev 81fc53a36a
[SCEV] Introduce SCEVPtrToIntExpr (PR46786)
And use it to model LLVM IR's `ptrtoint` cast.

This is essentially an alternative to D88806, but with no chance for
all the problems it caused due to having the cast as implicit there.
(see rG7ee6c402474a2f5fd21c403e7529f97f6362fdb3)

As we've established by now, there are at least two reasons why we want this:
* It will allow SCEV to actually model the `ptrtoint` casts
  and their operands, instead of treating them as `SCEVUnknown`
* It should help with initial problem of PR46786 - this should eventually allow us
  to not loose pointer-ness of an expression in more cases

As discussed in [[ https://bugs.llvm.org/show_bug.cgi?id=46786 | PR46786 ]], in principle,
we could just extend `SCEVUnknown` with a `is ptrtoint` cast, because `ScalarEvolution::getPtrToIntExpr()`
should sink the cast as far down into the expression as possible,
so in the end we should always end up with `SCEVPtrToIntExpr` of `SCEVUnknown`.

But i think that it isn't the best solution, because it doesn't really matter
from memory consumption side - there probably won't be *that* many `SCEVPtrToIntExpr`s
for it to matter, and it allows for much better discoverability.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D89456
2020-10-30 11:13:35 +03:00
Max Kazantsev 3fc601b641 [NFC][SCEV] Use generic predicate checkers to simplify code 2020-10-29 18:12:28 +07:00
Florian Hahn 88d6421e4c [SCEV] Match 'zext (trunc A to iB) to iY' as URem.
URem operations with constant power-of-2 second operands are modeled as
such. This patch on its own has very little impact (e.g. no changes in
CodeGen for MultiSource/SPEC2000/SPEC2006 on X86 -O3 -flto), but I'll
soon post follow-up patches that make use of it to more accurately
determine the trip multiple.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D89821
2020-10-29 10:46:52 +00:00
Max Kazantsev ef129f01e9 [SCEV][NFC] Use general predicate checkers in monotonicity check
This makes the code more compact and readable.
2020-10-29 16:45:52 +07:00
Max Kazantsev a5b2e795c3 [NFC][SCEV] Refactor monotonic predicate checks to return enums instead of bools
This patch gets rid of output parameter which is not needed for most users
and prepares this API for further refactoring.
2020-10-29 16:01:25 +07:00
Max Kazantsev 160a453138 Return "[IndVars] Remove monotonic checks with unknown exit count"
This reverts commit e038b60d91.
This reverts commit a0d84d8031.

This revert was a mistake. The reason of the failures was
"Use uint64_t for branch weights instead of uint32_t"

Differential Revision: https://reviews.llvm.org/D87832
2020-10-28 18:51:40 +07:00
Max Kazantsev 5ef84688fb Re-enable "[SCEV] Prove implications of different type via truncation"
When we need to prove implication of expressions of different type width,
the default strategy is to widen everything to wider type and prove in this
type. This does not interact well with AddRecs with negative steps and
unsigned predicates: such AddRec will likely not have a `nuw` flag, and its
`zext` to wider type will not be an AddRec. In contraty, `trunc` of an AddRec
in some cases can easily be proved to be an `AddRec` too.

This patch introduces an alternative way to handling implications of different
type widths. If we can prove that wider type values actually fit in the narrow type,
we truncate them and prove the implication in narrow type.

The return was due to revert of underlying patch that this one depends on.

Unit test temporarily disabled because the required logic in SCEV is switched
off due to compile time reasons.

Differential Revision: https://reviews.llvm.org/D89548
2020-10-28 16:02:14 +07:00
Max Kazantsev 624fc63a05 [SCEV] Re-enable "Use nw flag and symbolic iteration count to sharpen ranges of AddRecs", attempt 3
We can sharpen the range of a AddRec if we know that it does not
self-wrap and know the symbolic iteration count in the loop. If we can
evaluate the value of AddRec on the last iteration and prove that at least
one its intermediate value lies between start and end, then no-wrap flag
allows us to conclude that all of them also lie between start and end. So
the estimate of range can be improved to union of ranges of start and end.

Switched off by default, can be turned on by flag.

Differential Revision: https://reviews.llvm.org/D89381
Reviewed By: lebedev.ri, nikic
2020-10-28 12:39:41 +07:00
Raphael Isemann e038b60d91 Revert "[IndVars] Remove monotonic checks with unknown exit count"
This reverts commit c6ca26c0bf.
This breaks stage2 builds due to hitting this assert:
```
   Assertion failed: (WeightSum <= UINT32_MAX && "Expected weights to scale down to 32 bits"), function calcMetadataWeights
```
when compiling AArch64RegisterBankInfo.cpp in LLVM.
2020-10-27 15:31:37 +01:00
Max Kazantsev c6ca26c0bf [IndVars] Remove monotonic checks with unknown exit count
Even if the exact exit count is unknown, we can still prove that this
exit will not be taken. If we can prove that the predicate is monotonic,
fulfilled on first & last iteration, and no overflow happened in between,
then the check can be removed.

Differential Revision: https://reviews.llvm.org/D87832
Reviewed By: apilipenko
2020-10-27 11:35:16 +07:00
Nikita Popov ebeef022aa [SCEV] Strenthen nowrap flags after constant folding for mul exprs
Same change as 0dda633317, but for
mul expressions. We want to first fold any constant operans and
then strengthen the nowrap flags, as we can compute more precise
flags at that point.
2020-10-25 19:43:58 +01:00
Nikita Popov 1ff313f098 [SCEV] Always constant fold mul expression operands
Establish parity with the handling of add expressions, by always
constant folding mul expression operands before checking the depth
limit (this is a non-recursive simplification). The code was already
unconditionally constant folding the case where all operands were
constants, but was not folding multiple constant operands together
if there were also non-constant operands.

This requires picking out a different demonstration for depth-based
folding differences in the limit-depth.ll test.
2020-10-25 18:50:06 +01:00
Nikita Popov 22a5cde541 [SCEV] Separate out constant folding in mul expr creation
Separate out the code handling constant folding into a separate
block, that is independent of other folds that need a constant
first operand. Also make some minor adjustments to make the
constant folding look nearly identical to the same code in
getAddExpr().

The only reason this change is not strictly NFC is that the
C1*(C2+V) fold is moved below the constant folding, which means
that it now also applies to C1*C2*(C3+V), as it should.
2020-10-25 18:46:50 +01:00
Nikita Popov 0dda633317 [SCEV] Strength nowrap flags after constant folding
We should first try to constant fold the add expression and only
strengthen nowrap flags afterwards. This allows us to determine
stronger flags if e.g. only two operands are left after constant
folding (and thus "guaranteed no wrap region" code applies) or the
resulting operands are non-negative and thus nsw->nuw strengthening
applies.
2020-10-25 18:00:22 +01:00
Max Kazantsev 6e574abf61 [SCEV][NFC] Cache symbolic max exit count
We want to have a caching version of symbolic BE exit count
rather than recompute it every time we need it.

Differential Revision: https://reviews.llvm.org/D89954
Reviewed By: nikic, efriedma
2020-10-23 12:29:37 +07:00
Max Kazantsev cc2eb3b5e2 [SCEV][NFC] Simplify internals of BackedgeTakenInfo 2020-10-22 17:39:56 +07:00
Max Kazantsev e2858bf633 [SCEV][NFC] Rename MaxAndComplete -> ConstantMaxAndComplete
This better reflects what this variable is about.
2020-10-22 16:37:06 +07:00
Max Kazantsev 6379090ea7 [SCEV][NFC] Rename getMax -> getConstantMax
This better reflects what this logic actually does.
2020-10-22 15:12:54 +07:00
Max Kazantsev bed02fa8b0 Revert "[SCEV] Prove implications of different type via truncation"
This reverts commit 80852a4f2f.

Test is now broken because underlying required patch was also reverted SUDDENLY.
2020-10-21 13:03:46 +07:00
Max Kazantsev 80852a4f2f [SCEV] Prove implications of different type via truncation
When we need to prove implication of expressions of different type width,
the default strategy is to widen everything to wider type and prove in this
type. This does not interact well with AddRecs with negative steps and
unsigned predicates: such AddRec will likely not have a `nuw` flag, and its
`zext` to wider type will not be an AddRec. In contraty, `trunc` of an AddRec
in some cases can easily be proved to be an `AddRec` too.

This patch introduces an alternative way to handling implications of different
type widths. If we can prove that wider type values actually fit in the narrow type,
we truncate them and prove the implication in narrow type.

Differential Revision: https://reviews.llvm.org/D89548
Reviewed By: fhahn
2020-10-21 12:53:22 +07:00
Fangrui Song d9f91a3d14 Revert D89381 "[SCEV] Recommit "Use nw flag and symbolic iteration count to sharpen ranges of AddRecs", attempt 2"
This reverts commit a10a64e7e3.

It broke polly/test/ScopInfo/NonAffine/non-affine-loop-condition-dependent-access_3.ll
The difference suggests that this may be a serious issue.
2020-10-20 21:03:58 -07:00
Max Kazantsev a10a64e7e3 [SCEV] Recommit "Use nw flag and symbolic iteration count to sharpen ranges of AddRecs", attempt 2
Fixed wrapping range case & proof methods reduced to constant range
checks to save compile time.

Differential Revision: https://reviews.llvm.org/D89381
2020-10-20 11:32:36 +07:00
Roman Lebedev e0567582b8
[NFCI][SCEV] Always refer to enum SCEVTypes as enum, not integer
The main tricky thing here is forward-declaring the enum:
we have to specify it's underlying data type.

In particular, this avoids the danger of switching over the SCEVTypes,
but actually switching over an integer, and not being notified
when some case is not handled.

I have updated most of such switches to be exaustive and not have
a default case, where it's pretty obvious to be the intent,
however not all of them.
2020-10-20 00:10:22 +03:00
Roman Lebedev d4b0aa9773
[NFC][SCEV] BuildConstantFromSCEV(): reformat, NFC
Makes diff in next commit more readable
2020-10-20 00:10:22 +03:00
Roman Lebedev d083d55c2c
[NFC][SCEV] Rename SCEVCastExpr into SCEVIntegralCastExpr
All existing SCEV cast types operate on integers.
D89456 will add SCEVPtrToIntExpr cast expression type.
I believe this is best for consistency.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D89455
2020-10-19 10:59:53 +03:00
Max Kazantsev 199826baa8 [NFC][SCEV] Use getMinusOne where possible 2020-10-19 12:56:09 +07:00
Roman Lebedev ec54867df5
[SCEV] Model `ashr exact x, C` as `(abs(x) EXACT/u (1<<C)) * signum(x)`
It's not pretty, but probably better than modelling it
as an opaque SCEVUnknown, i guess.

It is relevant e.g. for the loop that was brought up in
https://bugs.llvm.org/show_bug.cgi?id=46786#c26
as an example of what we'd be able to better analyze
once SCEV handles `ptrtoint` (D89456).

But as it is evident, even if we deal with `ptrtoint` there,
we also fail to model such an `ashr`.
Also, modeling of mul-of-exact-shr/div could use improvement.

As per alive2:
https://alive2.llvm.org/ce/z/tnfZKd
```
define i8 @src(i8 %0) {
  %2 = ashr exact i8 %0, 4
  ret i8 %2
}

declare i8 @llvm.abs(i8, i1)
declare i8 @llvm.smin(i8, i8)
declare i8 @llvm.smax(i8, i8)

define i8 @tgt(i8 %x) {
  %abs_x = call i8 @llvm.abs(i8 %x, i1 false)
  %div = udiv exact i8 %abs_x, 16
  %t0 = call i8 @llvm.smax(i8 %x, i8 -1)
  %t1 = call i8 @llvm.smin(i8 %t0, i8 1)
  %r = mul nsw i8 %div, %t1
  ret i8 %r
}
```
Transformation seems to be correct!
2020-10-17 21:22:24 +03:00
Roman Lebedev 130cc662b5
[NFC][SCEV] Refactor getAbsExpr() out of createSCEV() 2020-10-17 21:21:02 +03:00
Roman Lebedev be1678bdb9
[NFC][SCEV] Add 'getMinusOne()' method 2020-10-17 21:20:58 +03:00
Nikita Popov 74c8c2d903 Revert "Recommit "[SCEV] Use nw flag and symbolic iteration count to sharpen ranges of AddRecs""
This reverts commit 32b72c3165.

While better than before, this change still introduces a large
compile-time regression (>3% on mafft):
https://llvm-compile-time-tracker.com/compare.php?from=fbd62fe60fb2281ca33da35dc25ca3c87ec0bb51&to=32b72c3165bf65cca2e8e6197b59eb4c4b60392a&stat=instructions

Additionally, the logic here doesn't look quite right to me,
I will comment in more detail on the differential revision.
2020-10-16 21:36:33 +02:00
Max Kazantsev 32b72c3165 Recommit "[SCEV] Use nw flag and symbolic iteration count to sharpen ranges of AddRecs"
It was reverted because of negative compile time impact. In this version,
less powerful proof methods are used (non-recursive reasoning only), and
scope limited to constant End values to avoid explision of complex proofs.

Differential Revision: https://reviews.llvm.org/D89381
2020-10-16 17:35:13 +07:00
Nikita Popov 7d3b475810 Revert "[SCEV] Use nw flag and symbolic iteration count to sharpen ranges of AddRecs"
This reverts commit 905101c360.

This causes a large compile-time regression:
https://llvm-compile-time-tracker.com/compare.php?from=cc175c2cc8e638462bab74e0781e06f9b6eb5017&to=905101c36025fe1c8ecdf9a20cd59db036676073&stat=instructions
2020-10-16 09:47:38 +02:00
Max Kazantsev 1eb2c6d23f [SCEV][NFC] Split out type balancing in implication engine
We plan to introduce more advanced ways of dealing with different types.
2020-10-16 13:40:24 +07:00
Max Kazantsev 905101c360 [SCEV] Use nw flag and symbolic iteration count to sharpen ranges of AddRecs
We can sharpen the range of a AddRec if we know that it does not
self-wrap and know the symbolic iteration count in the loop. If we can
evaluate the value of AddRec on the last iteration and prove that at least
one its intermediate value lies between start and end, then no-wrap flag
allows us to conclude that all of them also lie between start and end. So
the estimate of range can be improved to union of ranges of start and end.

Differential Revision: https://reviews.llvm.org/D89381
Reviewed By: efriedma
2020-10-16 12:00:39 +07:00
Roman Lebedev 7ee6c40247
Revert "Reland "[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but as zext/trunc/self of SCEVUnknown"" and it's follow-ups
While we haven't encountered an earth-shattering problem with this yet,
by now it is pretty evident that trying to model the ptr->int cast
implicitly leads to having to update every single place that assumed
no such cast could be needed. That is of course the wrong approach.

Let's back this out, and re-attempt with some another approach,
possibly one originally suggested by Eli Friedman in
https://bugs.llvm.org/show_bug.cgi?id=46786#c20
which should hopefully spare us this pain and more.

This reverts commits 1fb6104293,
7324616660,
aaafe350bb,
e92a8e0c74.

I've kept&improved the tests though.
2020-10-14 16:09:18 +03:00
Roman Lebedev e92a8e0c74
[SCEV] BuildConstantFromSCEV(): actually properly handle SExt-of-pointer case
As being pointed out by @efriedma in
https://reviews.llvm.org/rGaaafe350bb65#inline-4883
of course we can't just call ptrtoint in sign-extending case
and be done with it, because it will zero-extend.

I'm not sure what i was thinking there.

This is very much not an NFC, however looking at the user of
BuildConstantFromSCEV() i'm not sure how to actually show that
it results in a different constant expression.
2020-10-13 22:22:30 +03:00
Roman Lebedev aaafe350bb
[SCEV] BuildConstantFromSCEV(): properly handle SCEVSignExtend from ptr
Much similar to the ZExt/Trunc handling.
Thanks goes to Alexander Richardson for nudging towards noticing this one proactively.

The appropriate (currently crashing) test coverage added.
2020-10-13 12:19:59 +03:00
Roman Lebedev 7324616660
[SCEV] BuildConstantFromSCEV(): properly handle SCEVZeroExtend from ptr
As being reported in https://reviews.llvm.org/D88806#2326944,
this is pretty much the sibling problem of https://reviews.llvm.org/D88806#2325340,
with root cause being that SCEV now models `ptrtoint` as trunc/zext/self of unknown.

The appropriate (currently crashing) test coverage added.
2020-10-13 11:47:44 +03:00
Roman Lebedev 1fb6104293
Reland "[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but as zext/trunc/self of SCEVUnknown"
This relands commit 1c021c64ca which was
reverted in commit 17cec6a11a because
an assertion was being triggered, since `BuildConstantFromSCEV()`
wasn't updated to handle the case where the constant we want to truncate
is actually a pointer. I was unsuccessful in coming up with a test case
where we'd end there with constant zext/sext of a pointer,
so i didn't handle those cases there until there is a test case.

Original commit message:

While we indeed can't treat them as no-ops, i believe we can/should
do better than just modelling them as `unknown`. `inttoptr` story
is complicated, but for `ptrtoint`, it seems straight-forward
to model it just as a zext-or-trunc of unknown.

This may be important now that we track towards
making inttoptr/ptrtoint casts not no-op,
and towards preventing folding them into loads/etc
(see D88979/D88789/D88788)

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D88806
2020-10-12 23:02:55 +03:00
Hans Wennborg 17cec6a11a Revert 1c021c64c "[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but as zext/trunc/self of SCEVUnknown"
> While we indeed can't treat them as no-ops, i believe we can/should
> do better than just modelling them as `unknown`. `inttoptr` story
> is complicated, but for `ptrtoint`, it seems straight-forward
> to model it just as a zext-or-trunc of unknown.
>
> This may be important now that we track towards
> making inttoptr/ptrtoint casts not no-op,
> and towards preventing folding them into loads/etc
> (see D88979/D88789/D88788)
>
> Reviewed By: mkazantsev
>
> Differential Revision: https://reviews.llvm.org/D88806

It caused the following assert during Chromium builds:

  llvm/lib/IR/Constants.cpp:1868:
  static llvm::Constant *llvm::ConstantExpr::getTrunc(llvm::Constant *, llvm::Type *, bool):
  Assertion `C->getType()->isIntOrIntVectorTy() && "Trunc operand must be integer"' failed.

See code review for a link to a reproducer.

This reverts commit 1c021c64ca.
2020-10-12 18:39:35 +02:00
Max Kazantsev 28237c33d9 [NFC] Remove redundant isFullSet checks
Full set case is handled inside intersection, no need to
litter the code with duplicating them outside.
2020-10-12 20:41:16 +07:00
Roman Lebedev 1c021c64ca
[SCEV] Model ptrtoint(SCEVUnknown) cast not as unknown, but as zext/trunc/self of SCEVUnknown
While we indeed can't treat them as no-ops, i believe we can/should
do better than just modelling them as `unknown`. `inttoptr` story
is complicated, but for `ptrtoint`, it seems straight-forward
to model it just as a zext-or-trunc of unknown.

This may be important now that we track towards
making inttoptr/ptrtoint casts not no-op,
and towards preventing folding them into loads/etc
(see D88979/D88789/D88788)

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D88806
2020-10-12 11:04:03 +03:00
Florian Hahn 2e9fd754b4 [SCEV] Handle ULE in applyLoopGuards.
Handle ULE predicate in similar fashion to ULT predicate in
applyLoopGuards.
2020-10-10 16:26:28 +01:00
Florian Hahn 8f56e382f7 [SCEV] Do not apply info from loop guards in AddRecs.
We cannot guarantee that the replacement expression is loop-invariant in
all AddRecs in the source expression. Use a rewriter that skips
AddRecExpr for now.

Fixes PR47776.
2020-10-09 14:47:26 +01:00
Simon Pilgrim 119a143699 [Analysis] ScalarEvolution::getUMinFromMismatchedTypes - assert we've found the max type. NFCI.
Found by clang static analyzer.
2020-10-08 19:04:29 +01:00
Max Kazantsev a5ef2e0a1e Return "[SCEV] Prove implicaitons via AddRec start"
The initial version of the patch was reverted because it missed the check that
the predicate being proved is actually guarded by this check on 1st iteration.
If it was not executed on 1st iteration (but possibly executes after that), then
it is incorrect to use reasoning about IV start to prove it.

Added the test where the miscompile was seen. Unfortunately, my attempts
to reduce it with bugpoint did not succeed; it can further be reduced when
we understand how to do it without losing the initial bug's notion.

Returning assuming the miscompiles are now gone.

Differential Revision: https://reviews.llvm.org/D88208
2020-10-08 11:15:35 +07:00
Max Kazantsev bbb0ee6e34 Revert "[SCEV] Prove implicaitons via AddRec start"
This reverts commit 69acdfe075.

Need to investigate reported miscompiles.
2020-10-06 11:40:14 +07:00
Max Kazantsev b8ac19cf1c [SCEV] Limited support for unsigned preds in isImpliedViaOperations
The logic there only considers `SLT/SGT` predicates. We can use the same logic
for proving `ULT/UGT` predicates if all involved values are non-negative.

Adding full-scale support for unsigned might be challenging because of code amount,
so we can consider this in the future.

Differential Revision: https://reviews.llvm.org/D88087
Reviewed By: reames
2020-10-02 10:20:57 +07:00
Max Kazantsev 69acdfe075 [SCEV] Prove implicaitons via AddRec start
If we know that some predicate is true for AddRec and an invariant
(w.r.t. this AddRec's loop), this fact is, in particular, true on the first
iteration. We can try to prove the facts we need using the start value.

The motivating example is proving things like
```
  isImpliedCondOperands(>=, X, 0, {X,+,-1}, 0}
```

Differential Revision: https://reviews.llvm.org/D88208
Reviewed By: reames
2020-10-01 17:09:38 +07:00
Max Kazantsev c93a39dd1f [SCEV][NFC] Introduce isKnownPredicateAt method
We can query known predicates in different points, respecting
their dominating conditions.
2020-10-01 12:11:24 +07:00
Florian Hahn 0eab9d5823 [SCEV] Verify that all mapped SCEV AddRecs refer to valid loops.
This check helps to guard against cases where expressions referring to
invalidated/deleted loops are not properly invalidated.

The additional check is motivated by the reproducer shared for 8fdac7cb7a
and I think in general make sense as a sanity check.

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D88166
2020-09-30 12:46:55 +01:00
Max Kazantsev 9100bd772d [SCEV][NFC] Introduce isBasicBlockEntryGuardedByCond
Currently, we have `isLoopEntryGuardedByCond` method in SCEV, which
checks that some fact is true if we enter the loop. In fact, this is just a
particular case of more general concept `isBasicBlockEntryGuardedByCond`
applied to given loop's header. In fact, the logic if this code is largely
independent on the given loop and only cares code above it.

This patch makes this generalization. Now we can query it for any block,
and `isBasicBlockEntryGuardedByCond` is just a particular case.

Differential Revision: https://reviews.llvm.org/D87828
Reviewed By: fhahn
2020-09-29 15:53:45 +07:00
Florian Hahn 0ad793f321 [SCEV] Also use info from assumes in applyLoopGuards.
Similar to collecting information from branches guarding a loop, we can
also collect information from assumes dominating the loop header.

Fixes PR47247.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D87854
2020-09-28 13:14:24 +01:00
Florian Hahn 7d274aa9be [SCEV] Add support for `x != 0` to CollectCondition.
Add support for NE predicates with 0 constants. Those can be translated
to UMaxExpr(x, 1).
2020-09-25 18:58:55 +01:00
Florian Hahn b5a3b901c7 [SCEV] Add support for `x == constant` to CollectCondition.
Add support for EQ predicates with constant operand. In that case, using
the constant instead of an unknown expression should always be
beneficial.
2020-09-25 16:56:49 +01:00
Florian Hahn 8858340bd3 [SCEV] Swap operands if LHS is not unknown.
Currently we only use information from guards for unknown expressions.
Swap LHS/RHS and predicate, if LHS is not unknown.
2020-09-25 15:50:01 +01:00
Florian Hahn df77ce7cad [SCEV] Extract code to collect conditions to lambda (NFC).
This makes re-using the common functionality easier in follow-up
patches.
2020-09-25 15:12:42 +01:00
Florian Hahn d4ddf63fc4 [SCEV] Use loop guard info when computing the max BE taken count in howFarToZero.
For some expressions, we can use information from loop guards when
we are looking for a maximum. This patch applies information from
loop guards to the expression used to compute the maximum backedge
taken count in howFarToZero. It currently replaces an unknown
expression X with UMin(X, Y), if the loop is guarded by
X ult Y.

This patch is minimal in what conditions it applies, and there
are a few TODOs to generalize.

This partly addresses PR40961. We will also need an update to
LV to address it completely.

Reviewed By: reames

Differential Revision: https://reviews.llvm.org/D67178
2020-09-24 11:06:55 +01:00
Max Kazantsev e2703c021d [SCEV] Handle `less` predicates for FoundPred = NE
Currently these predicates are ignored, yet their handling is
pretty simple. I could not find a single test where it would
actually change something, but it's only because isImpliedCondOperands
is not smart enough to prove it further on. Yet the situation when
we come there with `less` predicate is pretty common.

Differential Revision: https://reviews.llvm.org/D87890
Reviewed By: fhahn
2020-09-22 18:56:35 +07:00
Max Kazantsev 16fde88dbd [SCEV] Support unsigned predicates in isKnownPredicateViaNoOverflow
SCEV should be able to prove facts like `x <u x+1<nuw>`.

Differential Revision: https://reviews.llvm.org/D88015
Reviewed By: lebedev.ri
2020-09-22 17:14:05 +07:00
Fangrui Song 8fdac7cb7a Revert D71539 "Recommit "[SCEV] Look through single value PHIs.""
This reverts commit 11dccf8d3a.

A bootstrapped clang crashes (due to ArrayRef::front called on an empty
ArrayRef) when compiling some files.  Very strangely, this only reproduces with
modules.

```
13 0x0000564d3349e968 llvm::ArrayRef<llvm::BasicBlock*>::front() const /proc/self/cwd/llvm/include/llvm/ADT/ArrayRef.h:160:7
14 0x0000564d3349e896 llvm::LoopBase<llvm::BasicBlock, llvm::Loop>::getHeader() const /proc/self/cwd/llvm/include/llvm/Analysis/LoopInfo.h:104:50
15 0x0000564d3349fd9d llvm::LoopBase<llvm::BasicBlock, llvm::Loop>::getLoopLatch() const /proc/self/cwd/llvm/include/llvm/Analysis/LoopInfoImpl.h:210:11
16 0x0000564d33593c8a llvm::ScalarEvolution::computeBackedgeTakenCount(llvm::Loop const*, bool) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:6933:15
17 0x0000564d33592ebc llvm::ScalarEvolution::getBackedgeTakenInfo(llvm::Loop const*) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:0:30
18 0x0000564d33593a54 llvm::ScalarEvolution::getBackedgeTakenCount(llvm::Loop const*, llvm::ScalarEvolution::ExitCountKind) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:6487:36
19 0x0000564d32be2402 llvm::ScalarEvolution::getConstantMaxBackedgeTakenCount(llvm::Loop const*) /proc/self/cwd/llvm/include/llvm/Analysis/ScalarEvolution.h:768:5
20 0x0000564d33590807 llvm::ScalarEvolution::getRangeRef(llvm::SCEV const*, llvm::ScalarEvolution::RangeSignHint) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:5495:19
21 0x0000564d320abab7 llvm::ScalarEvolution::getSignedRange(llvm::SCEV const*) /proc/self/cwd/llvm/include/llvm/Analysis/ScalarEvolution.h:840:12
22 0x0000564d335a03aa llvm::ScalarEvolution::isKnownPredicateViaConstantRanges(llvm::CmpInst::Predicate, llvm::SCEV const*, llvm::SCEV const*) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:9239:60
23 0x0000564d33586a80 llvm::ScalarEvolution::isKnownViaNonRecursiveReasoning(llvm::CmpInst::Predicate, llvm::SCEV const*, llvm::SCEV const*) /proc/self/cwd/llvm/lib/Analysis/ScalarEvolution.cpp:10284:60
```
2020-09-21 17:21:43 -07:00
Roman Lebedev 0ab99bb314
[NFC][SCEV] Cleanup lowering of @llvm.uadd.sat, (-1 - V) is just ~V 2020-09-21 22:10:59 +03:00
Roman Lebedev 64e2cb7e96
[SCEV] Recognize @llvm.uadd.sat as `%y + umin(%x, (-1 - %y))`
----------------------------------------
define i32 @src(i32 %x, i32 %y) {
%0:
  %r = uadd_sat i32 %x, %y
  ret i32 %r
}
=>
define i32 @tgt(i32 %x, i32 %y) {
%0:
  %t0 = sub nsw nuw i32 4294967295, %y
  %t1 = umin i32 %x, %t0
  %r = add nuw i32 %t1, %y
  ret i32 %r
}
Transformation seems to be correct!

The alternative, naive, lowering could be the following,
although i don't think it's better,
thought it will likely be needed for sadd/ssub/*shl:

----------------------------------------
define i32 @src(i32 %x, i32 %y) {
%0:
  %r = uadd_sat i32 %x, %y
  ret i32 %r
}
=>
define i32 @tgt(i32 %x, i32 %y) {
%0:
  %t0 = zext i32 %x to i33
  %t1 = zext i32 %y to i33
  %t2 = add nuw i33 %t0, %t1
  %t3 = zext i32 4294967295 to i33
  %t4 = umin i33 %t2, %t3
  %r = trunc i33 %t4 to i32
  ret i32 %r
}
Transformation seems to be correct!
2020-09-21 20:25:54 +03:00
Roman Lebedev fedc9549d5
[SCEV] Recognize @llvm.usub.sat as `%x - (umin %x, %y)`
----------------------------------------
define i32 @src(i32 %x, i32 %y) {
%0:
  %r = usub_sat i32 %x, %y
  ret i32 %r
}
=>
define i32 @tgt(i32 %x, i32 %y) {
%0:
  %t0 = umin i32 %x, %y
  %r = sub nuw i32 %x, %t0
  ret i32 %r
}
Transformation seems to be correct!
2020-09-21 20:25:54 +03:00
Roman Lebedev 1bb7ab8c4a
[SCEV] Recognize @llvm.abs as smax(x, -x)
As per alive2 (ignoring undef):

----------------------------------------
define i32 @src(i32 %x, i1 %y) {
%0:
  %r = abs i32 %x, 0
  ret i32 %r
}
=>
define i32 @tgt(i32 %x, i1 %y) {
%0:
  %neg_x = mul i32 %x, 4294967295
  %r = smax i32 %x, %neg_x
  ret i32 %r
}
Transformation seems to be correct!

----------------------------------------
define i32 @src(i32 %x, i1 %y) {
%0:
  %r = abs i32 %x, 1
  ret i32 %r
}
=>
define i32 @tgt(i32 %x, i1 %y) {
%0:
  %neg_x = mul nsw i32 %x, 4294967295
  %r = smax i32 %x, %neg_x
  ret i32 %r
}
Transformation seems to be correct!
2020-09-21 20:25:53 +03:00
Florian Hahn 11dccf8d3a Recommit "[SCEV] Look through single value PHIs."
This commit was originally because it was suspected to cause a crash,
but a reproducer did not surface.

A crash that was exposed by this change was fixed in 1d8f2e5292.

This reverts the revert commit 0581c0b0ee.
2020-09-21 11:59:50 +01:00
Max Kazantsev 412b417bfa [NFC] Add missing `const` statements in SCEV 2020-09-14 18:43:24 +07:00
Max Kazantsev 8c0bbbade1 [NFC] Refactoring in SCEV: add missing `const` qualifiers 2020-09-10 19:06:37 +07:00
Max Kazantsev cde8fc65ae [NFC] Rename variables to avoid name confusion
Name `LI` is used for loop info, loop and load inst at the same
function, which causes a lot of confusion.
2020-09-10 13:41:10 +07:00
Juneyoung Lee 25ce1e0497 [ValueTracking] Add UndefOrPoison/Poison-only version of relevant functions
This patch adds isGuaranteedNotToBePoison and programUndefinedIfUndefOrPoison.

isGuaranteedNotToBePoison will be used at D75808. The latter function is used at isGuaranteedNotToBePoison.

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D84242
2020-09-09 20:00:26 +09:00
Max Kazantsev 795e4ee9d2 [NFC] Move functon from IndVarSimplify to SCEV
This function can be reused in other places.

Differential Revision: https://reviews.llvm.org/D87274
Reviewed By: fhahn, lebedev.ri
2020-09-09 11:20:59 +07:00
Nikita Popov ac87480bd8 [SCEV] Recognize min/max intrinsics
Recognize umin/umax/smin/smax intrinsics and convert them to the
already existing SCEV nodes of the same name.

In the future we'll want SCEVExpander to also produce the intrinsics,
but we're not ready for that yet.

Differential Revision: https://reviews.llvm.org/D87160
2020-09-05 16:30:11 +02:00
Sam Parker 2e194fe73b [SCEV] Still trying to fix windows buildbots 2020-08-24 10:26:48 +01:00
Ali Tamur 0581c0b0ee Revert "[SCEV] Look through single value PHIs."
This reverts commit e441b7a7a0.

This patch causes a compile error in tensorflow opensource project. The stack trace looks like:

Point of crash:
llvm/include/llvm/Analysis/LoopInfoImpl.h : line 35

(gdb) ptype *this
type = const class llvm::LoopBase<llvm::BasicBlock, llvm::Loop> [with BlockT = llvm::BasicBlock, LoopT = llvm::Loop]

(gdb) p *this
$1 = {ParentLoop = 0x0, SubLoops = std::vector of length 0, capacity 0, Blocks = std::vector of length 0, capacity 1,
  DenseBlockSet = {<llvm::SmallPtrSetImpl<llvm::BasicBlock const*>> = {<llvm::SmallPtrSetImplBase> = {<llvm::DebugEpochBase> = {Epoch = 3}, SmallArray = 0x1b2bf6c8, CurArray = 0x1b2bf6c8,
        CurArraySize = 8, NumNonEmpty = 0, NumTombstones = 0}, <No data fields>}, SmallStorage = {0xfffffffffffffffe, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0}}, IsInvalid = true}

(gdb) p *this->DenseBlockSet->CurArray
$2 = (const void *) 0xfffffffffffffffe

I will try to get a case from tensorflow or use creduce to get a small case.
2020-08-12 23:13:24 -07:00
Florian Hahn e441b7a7a0 [SCEV] Look through single value PHIs.
Now that SCEVExpander can preserve LCSSA form,
we do not have to worry about LCSSA form when
trying to look through PHIs. SCEVExpander will take
care of inserting LCSSA PHI nodes as required.

This increases precision of the analysis in some cases.

Reviewed By: mkazantsev, bmahjour

Differential Revision: https://reviews.llvm.org/D71539
2020-08-12 10:03:42 +01:00
Florian Hahn 3483c28c5b [SCEV] ] If RHS >= Start, simplify (Start smax RHS) to RHS for trip counts.
This is the max version of D85046.

This change causes binary changes in 44 out of 237 benchmarks (out of
MultiSource/SPEC2000/SPEC2006)

Reviewed By: lebedev.ri

Differential Revision: https://reviews.llvm.org/D85189
2020-08-11 13:20:24 +01:00
Florian Hahn ee1c12708a [SCEV] If Start>=RHS, simplify (Start smin RHS) = RHS for trip counts.
In some cases, it seems like we can get rid of unnecessary s/umins by
using information from the loop guards (unless I am missing something).

One place where this seems to be helpful in practice is when computing
loop trip counts. This patch just changes howManyGreaterThans for now.
Note that this requires a loop for which we can check 'is guarded'.

On SPEC2000/SPEC2006/MultiSource, there are some notable changes for
some programs in the number of loops unrolled and trip counts computed.

```
Same hash: 179 (filtered out)
Remaining: 58
Metric: scalar-evolution.NumTripCountsComputed

Program                                        base    patch   diff
 test-suite...langs-C/compiler/compiler.test    25.00   31.00  24.0%
 test-suite.../Applications/SPASS/SPASS.test   2020.00 2323.00 15.0%
 test-suite...langs-C/allroots/allroots.test    29.00   32.00  10.3%
 test-suite.../Prolangs-C/loader/loader.test    17.00   18.00   5.9%
 test-suite...fice-ispell/office-ispell.test   253.00  265.00   4.7%
 test-suite...006/450.soplex/450.soplex.test   3552.00 3692.00  3.9%
 test-suite...chmarks/MallocBench/gs/gs.test   453.00  470.00   3.8%
 test-suite...ngs-C/assembler/assembler.test    29.00   30.00   3.4%
 test-suite.../Benchmarks/Ptrdist/bc/bc.test   263.00  270.00   2.7%
 test-suite...rks/FreeBench/pifft/pifft.test   722.00  741.00   2.6%
 test-suite...count/automotive-bitcount.test    41.00   42.00   2.4%
 test-suite...0/253.perlbmk/253.perlbmk.test   1417.00 1451.00  2.4%
 test-suite...000/197.parser/197.parser.test   387.00  396.00   2.3%
 test-suite...lications/sqlite3/sqlite3.test   1168.00 1189.00  1.8%
 test-suite...000/255.vortex/255.vortex.test   173.00  176.00   1.7%

Metric: loop-unroll.NumUnrolled

Program                                        base   patch  diff
 test-suite...langs-C/compiler/compiler.test     1.00   3.00 200.0%
 test-suite.../Applications/SPASS/SPASS.test   134.00 234.00 74.6%
 test-suite...count/automotive-bitcount.test     3.00   4.00 33.3%
 test-suite.../Prolangs-C/loader/loader.test     3.00   4.00 33.3%
 test-suite...langs-C/allroots/allroots.test     3.00   4.00 33.3%
 test-suite...Source/Benchmarks/sim/sim.test    10.00  12.00 20.0%
 test-suite...fice-ispell/office-ispell.test    21.00  25.00 19.0%
 test-suite.../Benchmarks/Ptrdist/bc/bc.test    32.00  38.00 18.8%
 test-suite...006/450.soplex/450.soplex.test   300.00 352.00 17.3%
 test-suite...rks/FreeBench/pifft/pifft.test    60.00  69.00 15.0%
 test-suite...chmarks/MallocBench/gs/gs.test    57.00  63.00 10.5%
 test-suite...ngs-C/assembler/assembler.test    10.00  11.00 10.0%
 test-suite...0/253.perlbmk/253.perlbmk.test   145.00 157.00  8.3%
 test-suite...000/197.parser/197.parser.test    43.00  46.00  7.0%
 test-suite...TimberWolfMC/timberwolfmc.test   205.00 214.00  4.4%
 Geomean difference                                           7.6%
```

Fixes https://bugs.llvm.org/show_bug.cgi?id=46939
Fixes https://bugs.llvm.org/show_bug.cgi?id=46924 on X86.

Reviewed By: mkazantsev

Differential Revision: https://reviews.llvm.org/D85046
2020-08-03 17:22:42 +01:00