| Commit message (Collapse) | Author | Age | Files | Lines |
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information for comparisons of parameters." as it's causing miscompiles.
A testcase was provided in the original review thread.
This reverts commit r336098.
llvm-svn: 336877
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This converts them to what clang is now using for codegen. Unfortunately, there seem to be a few kinks to work out still. I'll try to address with follow up patches.
llvm-svn: 336871
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This commit suppresses turning loops like this into "(bitwidth - ctlz(input))".
unsigned foo(unsigned input) {
unsigned num = 0;
do {
++num;
input >>= 1;
} while (input != 0);
return num;
}
The loop version returns a value of 1 for both an input of 0 and an input of 1. Converting to a naive ctlz does not preserve that.
Theoretically we could do better if we checked isKnownNonZero or we could insert a select to handle the divergence. But until we have motivating cases for that, this is the easiest solution.
llvm-svn: 336864
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we shouldn't.
This loop executes one iteration without checking the input value. This produces a count of 1 for an input of 0 and 1. We are turning this into 32 - ctlz(n), but that returns 0 if n is 0.
llvm-svn: 336862
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https://bugs.llvm.org/show_bug.cgi?id=38123
https://rise4fun.com/Alive/Rny
llvm-svn: 336857
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Summary:
https://bugs.llvm.org/show_bug.cgi?id=38123
This pattern will be produced by Implicit Integer Truncation sanitizer,
https://reviews.llvm.org/D48958
https://bugs.llvm.org/show_bug.cgi?id=21530
in unsigned case, therefore it is probably a good idea to improve it.
https://rise4fun.com/Alive/Rny
^ there are more opportunities for folds, i will follow up with them afterwards.
Caveat: this somehow exposes a missing opportunities
in `test/Transforms/InstCombine/icmp-logical.ll`
It seems, the problem is in `foldLogOpOfMaskedICmps()` in `InstCombineAndOrXor.cpp`.
But i'm not quite sure what is wrong, because it calls `getMaskedTypeForICmpPair()`,
which calls `decomposeBitTestICmp()` which should already work for these cases...
As @spatel notes in https://reviews.llvm.org/D49179#1158760,
that code is a rather complex mess, so we'll let it slide.
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: yamauchi, majnemer, t.p.northover, llvm-commits
Differential Revision: https://reviews.llvm.org/D49179
llvm-svn: 336834
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isKnownNegation() is currently proposed as part of D48754,
but it could be used to make InstSimplify stronger independently
of any abs() improvements.
llvm-svn: 336822
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(REAPPLIED)
We currently only support binary instructions in the alternate opcode shuffles.
This patch is an initial attempt at adding cast instructions as well, this raises several issues that we probably want to address as we continue to generalize the alternate mechanism:
1 - Duplication of cost determination - we should probably add scalar/vector costs helper functions and get BoUpSLP::getEntryCost to use them instead of determining costs directly.
2 - Support alternate instructions with the same opcode (e.g. casts with different src types) - alternate vectorization of calls with different IntrinsicIDs will require this.
3 - Allow alternates to be a different instruction type - mixing binary/cast/call etc.
4 - Allow passthrough of unsupported alternate instructions - related to PR30787/D28907 'copyable' elements.
Reapplied with fix to only accept 2 different casts if they come from the same source type.
Differential Revision: https://reviews.llvm.org/D49135
llvm-svn: 336812
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undef elts
llvm-svn: 336809
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Initial attempt at D49135 failed as we weren't correctly handling casts with different source types.
llvm-svn: 336808
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cast instructions.
Reverting due to buildbot failures
llvm-svn: 336806
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We currently only support binary instructions in the alternate opcode shuffles.
This patch is an initial attempt at adding cast instructions as well, this raises several issues that we probably want to address as we continue to generalize the alternate mechanism:
1 - Duplication of cost determination - we should probably add scalar/vector costs helper functions and get BoUpSLP::getEntryCost to use them instead of determining costs directly.
2 - Support alternate instructions with the same opcode (e.g. casts with different src types) - alternate vectorization of calls with different IntrinsicIDs will require this.
3 - Allow alternates to be a different instruction type - mixing binary/cast/call etc.
4 - Allow passthrough of unsupported alternate instructions - related to PR30787/D28907 'copyable' elements.
Differential Revision: https://reviews.llvm.org/D49135
llvm-svn: 336804
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https://bugs.llvm.org/show_bug.cgi?id=38123
This pattern will be produced by Implicit Integer Truncation sanitizer,
https://reviews.llvm.org/D48958
https://bugs.llvm.org/show_bug.cgi?id=21530
in unsigned case, therefore it is probably a good idea to improve it.
https://rise4fun.com/Alive/Rny
llvm-svn: 336796
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The @masked_and_notA_slightly_optimized and @masked_or_A
will break when PR38123 will be fixed:
https://rise4fun.com/Alive/Rny
Clearly, they aren't optimized currently.
https://rise4fun.com/Alive/ERo
llvm-svn: 336784
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update_test_checks will drop it anyway, creating noise..
llvm-svn: 336781
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llvm-svn: 336780
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Differential Revision: https://reviews.llvm.org/D49123
llvm-svn: 336752
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This fixes PR38120
llvm-svn: 336702
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This corresponds with the code for the single binop pattern
added in rL336684.
llvm-svn: 336696
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This was originally intended with D48893, but as discussed there, we
have to make the folds safe from producing extra poison. This should
give the single binop folds the same capabilities as the existing
folds for 2-binops+shuffle.
LLVM binary opcode review: there are a total of 18 binops. There are 7
commutative binops (add, mul, and, or, xor, fadd, fmul) which we already
fold. We're able to fold 6 more opcodes with this patch (shl, lshr, ashr,
fdiv, udiv, sdiv). There are no folds for srem/urem/frem AFAIK. We don't
bother with sub/fsub with constant operand 1 because those are
canonicalized to add/fadd. 7 + 6 + 3 + 2 = 18.
llvm-svn: 336684
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llvm-svn: 336679
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The case with 2 variables is more complicated than the case where
we eliminate the shuffle entirely because a shuffle with an undef
mask element creates an undef result.
I'm not aware of any current analysis/transform that recognizes that
undef propagating to a div/rem/shift, but we have to guard against
the possibility.
llvm-svn: 336668
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Differential Revision: https://reviews.llvm.org/D48968
llvm-svn: 336667
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Summary:
Fixed two cases of where PHI nodes need to be updated by lowerswitch.
When lowerswitch find out that the switch default branch is not
reachable it remove the old default and replace it with the most
popular block from the cases, but it forget to update the PHI
nodes in the default block.
The PHI nodes also need to be updated when the switch is replaced
with a single branch.
Reviewers: hans, reames, arsenm
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D47203
llvm-svn: 336659
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switch unswitching.
The core problem was that the way we handled unswitching trivial exit
edges through the default successor of a switch. For some reason
I thought the right way to do this was to add a block containing
unreachable and point the default successor at this block. In
retrospect, this has an amazing number of problems.
The first issue is the one that this pass has always worked around -- we
have to *detect* such edges and avoid unswitching them again. This
seemed pretty easy really. You juts look for an edge to a block
containing unreachable. However, this pattern is woefully unsound. So
many things can break it. The amazing thing is that I found a test case
where *simple-loop-unswitch itself* breaks this! When we do
a *non-trivial* unswitch of a switch we will end up splitting this exit
edge. The result will be a default successor that is an exit and
terminates in ... a perfectly normal branch. So the first test case that
I started trying to fix is added to the nontrivial test cases. This is
a ridiculous example that did just amazing things previously. With just
unswitch, it would create 10+ copies of this stuff stamped out. But if
you combine it *just right* with a bunch of other passes (like
simplify-cfg, loop rotate, and some LICM) you can get it to do this
infinitely. Or at least, I never got it to finish. =[
This, in turn, uncovered another related issue. When we are manipulating
these switches after doing a trivial unswitch we never correctly updated
PHI nodes to reflect our edits. As soon as I started changing how these
edges were managed, it became obvious there were more issues that
I couldn't realistically leave unaddressed, so I wrote more test cases
around PHI updates here and ensured all of that works now.
And this, in turn, required some adjustment to how we collect and manage
the exit successor when it is the default successor. That showed a clear
bug where we failed to include it in our search for the outer-most loop
reached by an unswitched exit edge. This was actually already tested and
the test case didn't work. I (wrongly) thought that was due to SCEV
failing to analyze the switch. In fact, it was just a simple bug in the
code that skipped the default successor. While changing this, I handled
it correctly and have updated the test to reflect that we now get
precise SCEV analysis of trip counts for the outer loop in one of these
cases.
llvm-svn: 336646
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getSafeVectorConstantForBinop() was calling getBinOpIdentity() assuming
that the constant we wanted was operand 1 (RHS). That's wrong, but I
don't think we could expose a bug or even a suboptimal fold from that
because the callers have other guards for any binop that would have
been affected.
llvm-svn: 336617
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Summary:
Support for this option is needed for building Linux kernel.
This is a very frequently requested feature by kernel developers.
More details : https://lkml.org/lkml/2018/4/4/601
GCC option description for -fdelete-null-pointer-checks:
This Assume that programs cannot safely dereference null pointers,
and that no code or data element resides at address zero.
-fno-delete-null-pointer-checks is the inverse of this implying that
null pointer dereferencing is not undefined.
This feature is implemented in LLVM IR in this CL as the function attribute
"null-pointer-is-valid"="true" in IR (Under review at D47894).
The CL updates several passes that assumed null pointer dereferencing is
undefined to not optimize when the "null-pointer-is-valid"="true"
attribute is present.
Reviewers: t.p.northover, efriedma, jyknight, chandlerc, rnk, srhines, void, george.burgess.iv
Reviewed By: efriedma, george.burgess.iv
Subscribers: eraman, haicheng, george.burgess.iv, drinkcat, theraven, reames, sanjoy, xbolva00, llvm-commits
Differential Revision: https://reviews.llvm.org/D47895
llvm-svn: 336613
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In non-zero address spaces, we were reporting that an object at `null`
always occupies zero bytes. This is incorrect in many cases, so just
return `unknown` in those cases for now.
Differential Revision: https://reviews.llvm.org/D48860
llvm-svn: 336611
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llvm-svn: 336570
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As discussed in D49047 / D48987, shift-by-undef produces poison,
so we can't use undef vector elements in that case..
Note that we need to extend this for poison-generating flags,
and there's a proposal to create poison from FMF in D47963,
llvm-svn: 336562
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As noted in D48987, there are many different ways for this transform to go wrong.
In particular, the poison potential for shifts means we have to more careful with those ops.
I added tests to make that behavior visible for all of the different cases that I could find.
This is a partial fix. To make this review easier, I did not make changes for the single binop
pattern (handled in foldSelectShuffleWith1Binop()). I also left out some potential optimizations
noted with TODO comments. I'll follow-up once we're confident that things are correct here.
The goal is to correct all marked FIXME tests to either avoid the shuffle transform or do it safely.
Note that distinguishing when the shuffle mask contains undefs and using getBinOpIdentity() allows
for some improvements to div/rem patterns, so there are wins along with the missed opportunities
and fixes.
Differential Revision: https://reviews.llvm.org/D49047
llvm-svn: 336546
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r335553 with the non-trivial unswitching of switches.
The code correctly updated most aspects of the CFG and analyses, but
missed some crucial aspects:
1) When multiple cases have the same successor, we unswitch that
a single time and replace the switch with a direct branch. The CFG
here is correct, but the target of this direct branch may have had
a PHI node with multiple entries in it.
2) When we still have to clone a successor of the switch into an
unswitched copy of the loop, we'll delete potentially multiple edges
entering this successor, not just one.
3) We also have to delete multiple edges entering the successors in the
original loop when they have to be retained.
4) When the "retained successor" *also* occurs as a case successor, we
just assert failed everywhere. This doesn't happen very easily
because its always valid to simply drop the case -- the retained
successor for switches is always the default successor. However, it
is likely possible through some contrivance of different loop passes,
unrolling, and simplifying for this to occur in practice and
certainly there is nothing "invalid" about the IR so this pass needs
to handle it.
5) In the case of #4, we also will replace these multiple edges with
a direct branch much like in #1 and need to collapse the entries in
any PHI nodes to a single enrty.
All of this stems from the delightful fact that the same successor can
show up in multiple parts of the switch terminator, and each of these
are considered a distinct edge for the purpose of PHI nodes (and
iterating the successors and predecessors) but not for unswitching
itself, the dominator tree, or many other things. For the record,
I intensely dislike this "feature" of the IR in large part because of
the complexity it causes in passes like this. We already have a ton of
logic building sets and handling duplicates, and we just had to add
a bunch more.
I've added a complex test case that covers all five of the above failure
modes. I've also added a variation on it where #4 and #5 occur in loop
exit, adding fun where we have an LCSSA PHI node with "multiple entries"
despite have dedicated exits. There were no additional issues found by
this, but it seems a useful corner case to cover with testing.
One thing that working on all of this code has made painfully clear for
me as well is how amazingly inefficient our PHI node representation is
(in terms of the in-memory data structures and the APIs used to update
them). This code has truly marvelous complexity bounds because every
time we remove an entry from a PHI node we do a linear scan to find it
and then a linear update to the data structure to remove it. We could in
theory batch all of the PHI node updates into a single linear walk of
the operands making this much more efficient, but the APIs fight hard
against this and the fact that we have to handle duplicates in the
peculiar manner we do (removing all but one in some cases) makes even
implementing that very tedious and annoying. Anyways, none of this is
new here or specific to loop unswitching. All code in LLVM that updates
PHI node operands suffers from these problems.
llvm-svn: 336536
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Summary:
PGOMemOPSize only modifies CFG in a couple of places; thus we can preserve the DominatorTree with little effort.
When optimizing SQLite with -O3, this patch can decrease 3.8% of the numbers of nodes traversed by DFS and 5.7% of the times DominatorTreeBase::recalculation is called.
Reviewers: kuhar, davide, dmgreen
Reviewed By: dmgreen
Subscribers: mzolotukhin, vsk, llvm-commits
Differential Revision: https://reviews.llvm.org/D48914
llvm-svn: 336522
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In the 'detectCTLZIdiom' function support for loops that use LSHR instruction instead of ASHR has been added.
This supports creating ctlz from the following code.
int lzcnt(int x) {
int count = 0;
while (x > 0) {
count++;
x = x >> 1;
}
return count;
}
Patch by Olga Moldovanova
Differential Revision: https://reviews.llvm.org/D48354
llvm-svn: 336509
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after trivial unswitching.
This PR illustrates that a fundamental analysis update was not performed
with the new loop unswitch. This update is also somewhat fundamental to
the core idea of the new loop unswitch -- we actually *update* the CFG
based on the unswitching. In order to do that, we need to update the
loop nest in addition to the domtree.
For some reason, when writing trivial unswitching, I thought that the
loop nest structure cannot be changed by the transformation. But the PR
helps illustrate that it clearly can. I've expanded this to a number of
different test cases that try to cover the different cases of this. When
we unswitch, we move an exit edge of a loop out of the loop. If this
exit edge changes which loop reached by an exit is the innermost loop,
it changes the parent of the loop. Essentially, this transformation may
hoist the inner loop up the nest. I've added the simple logic to handle
this reliably in the trivial unswitching case. This just requires
updating LoopInfo and rebuilding LCSSA on the impacted loops. In the
trivial case, we don't even need to handle dedicated exits because we're
only hoisting the one loop and we just split its preheader.
I've also ported all of these tests to non-trivial unswitching and
verified that the logic already there correctly handles the loop nest
updates necessary.
Differential Revision: https://reviews.llvm.org/D48851
llvm-svn: 336477
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This reverts commit r336140. Our tests shows that LSR assert fails with it.
llvm-svn: 336473
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llvm-svn: 336454
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The replaceAllDbgUsesWith utility helps passes preserve debug info when
replacing one value with another.
This improves upon the existing insertReplacementDbgValues API by:
- Updating debug intrinsics in-place, while preventing use-before-def of
the replacement value.
- Falling back to salvageDebugInfo when a replacement can't be made.
- Moving the responsibiliy for rewriting llvm.dbg.* DIExpressions into
common utility code.
Along with the API change, this teaches replaceAllDbgUsesWith how to
create DIExpressions for three basic integer and pointer conversions:
- The no-op conversion. Applies when the values have the same width, or
have bit-for-bit compatible pointer representations.
- Truncation. Applies when the new value is wider than the old one.
- Zero/sign extension. Applies when the new value is narrower than the
old one.
Testing:
- check-llvm, check-clang, a stage2 `-g -O3` build of clang,
regression/unit testing.
- This resolves a number of mis-sized dbg.value diagnostics from
Debugify.
Differential Revision: https://reviews.llvm.org/D48676
llvm-svn: 336451
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As discussed in D48987 and D48893, there are many different
ways to go wrong depending on the binop (and as shown here
we already do go wrong in some cases).
llvm-svn: 336450
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Previously we only iterated over functions reachable from the set of
external functions in the module. But since some of the passes under
this (notably the always-inliner and coroutine lowerer) are required for
correctness, they need to run over everything.
This just adds an extra layer of iteration over the CallGraph to keep
track of which functions we've already visited and get the next batch of
SCCs.
Should fix PR38029.
llvm-svn: 336419
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are done"
llvm-svn: 336410
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Better NaN handling for AMDGCN fmed3.
All operands are checked for NaN now. The checks
were moved before the canonicalization to provide
a better mapping from fclamp. Changed the behaviour
of fmed3(x,y,NaN) to return max(x,y) instead of
min(x,y) in light of this. Updated tests as a result
and added some new cases to cover the fix.
Patch by Alan Baker
llvm-svn: 336375
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independent FMA and extractelement/insertelement.
llvm-svn: 336315
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We have bailout hacks based on min/max in various places in instcombine
that shouldn't be necessary. The affected test was added for:
D48930
...which is a consequence of the improvement in:
D48584 (https://reviews.llvm.org/rL336172)
I'm assuming the visitTrunc bailout in this patch was added specifically
to avoid a change from SimplifyDemandedBits, so I'm just moving that
below the EvaluateInDifferentType optimization. A narrow min/max is still
a min/max.
llvm-svn: 336293
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That makes it easier to mix and match lines into other tests.
llvm-svn: 336289
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llvm-svn: 336268
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llvm-svn: 336258
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When creating `phi` instructions to resume at the scalar part of the loop,
copy the DebugLoc from the original phi over to the new one.
Differential Revision: https://reviews.llvm.org/D48769
llvm-svn: 336256
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When zext is EvaluatedInDifferentType, InstCombine
drops the dbg.value intrinsic. This patch tries to
preserve said DI, by inserting the zext's old DI in the
resulting instruction. (Only for integer type for now)
Differential Revision: https://reviews.llvm.org/D48331
llvm-svn: 336254
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This adds coverage for a planned enhancement for ConstantExpr::getBinOpIdentity() noted in D48830.
llvm-svn: 336220
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