Extract method to compute overflow based on binop and signedness,
and then make the result handling code generic. This extends the
always-overflow handling to signed muls, but has currently no effect,
as we don't compute always overflow for them (thus NFC).
llvm-svn: 361721
Just a minor refactoring to use the new helper method
DataLayout::typeSizeEqualsStoreSize(). This is done when
checking if getTypeSizeInBits is equal/non-equal to
getTypeStoreSizeInBits.
llvm-svn: 361613
This was part of InstCombine, but it's better placed in
InstSimplify. InstCombine also had an unreachable but weaker
fold for insertelement with undef index, so that is deleted.
llvm-svn: 361559
This is reduced from a fuzzer test:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14890
Usually, demanded elements should be able to simplify shuffle
mask elements that are pointing to undef elements of its source
operands, but that doesn't happen in the test case.
llvm-svn: 361533
We were turning roundss/sd/ps/pd intrinsics with immediates of 1 or 2 into
llvm.floor/ceil. The llvm.ceil/floor intrinsics are supposed to correspond
to the libm functions. For the libm functions we need to disable the
precision exception so the llvm.floor/ceil functions should always map to
encodings 0x9 and 0xA.
We had a mix of isel patterns where some used 0x9 and 0xA and others used
0x1 and 0x2. We need to be consistent and always use 0x9 and 0xA.
Since we have no way in isel of knowing where the llvm.ceil/floor came
from, we can't map X86 specific intrinsics with encodings 1 or 2 to it.
We could map 0x9 and 0xA to llvm.ceil/floor instead, but I'd really like
to see a use case and optimization advantage first.
I've left the backend test cases to show the blend we now emit without
the extra isel patterns. But I've removed the InstCombine tests completely.
llvm-svn: 361425
This should be a valid exception to the general rule of not creating new shuffle masks in IR...
because we already do it. :)
Also, DAG combining/legalization will undo this by widening the shuffle back out if needed.
Explanation for how we already do this: SLP or vector source can create chains of insert/extract
as shown in 1 of the examples from PR16739:
https://godbolt.org/z/NlK7rAhttps://bugs.llvm.org/show_bug.cgi?id=16739
And we expect instcombine or DAGCombine to clean that up by creating relatively simple shuffles.
Differential Revision: https://reviews.llvm.org/D62024
llvm-svn: 361338
Also, break out a helper function, namely foldFNegIntoConstant(...), which performs transforms common between visitFNeg(...) and visitFSub(...).
Differential Revision: https://reviews.llvm.org/D61693
llvm-svn: 361188
Summary:
In D61918 i was looking at dropping it in DAGCombiner `visitShiftByConstant()`,
but as @craig.topper pointed out, it was copied from here.
That check claims that the transform is illegal otherwise.
That isn't true:
1. For `ISD::ADD`, we only process `ISD::SHL` outer shift => sign bit does not matter
https://rise4fun.com/Alive/K4A
2. For `ISD::AND`, there is no restriction on constants:
https://rise4fun.com/Alive/Wy3
3. For `ISD::OR`, there is no restriction on constants:
https://rise4fun.com/Alive/GOH
3. For `ISD::XOR`, there is no restriction on constants:
https://rise4fun.com/Alive/ml6
So, why is it there then?
As far as i can tell, it dates all the way back to original check-in rL7793.
I think we should just drop it.
Reviewers: spatel, craig.topper, efriedma, majnemer
Reviewed By: spatel
Subscribers: llvm-commits, craig.topper
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D61938
llvm-svn: 361043
We have a similar match for patterns ending in a truncate. This
should be ok for all targets because the default expansion would
still likely be better from replacing 2 'and' ops with 1.
Attempt to show the logic equivalence in Alive (which doesn't
currently have funnel-shift in its vocabulary AFAICT):
%shamt = zext i8 %i to i32
%m = and i32 %shamt, 31
%neg = sub i32 0, %shamt
%and4 = and i32 %neg, 31
%shl = shl i32 %v, %m
%shr = lshr i32 %v, %and4
%or = or i32 %shr, %shl
=>
%a = and i8 %i, 31
%shamt2 = zext i8 %a to i32
%neg2 = sub i32 0, %shamt2
%and4 = and i32 %neg2, 31
%shl = shl i32 %v, %shamt2
%shr = lshr i32 %v, %and4
%or = or i32 %shr, %shl
https://rise4fun.com/Alive/V9r
llvm-svn: 360605
The worklist loop that we're returning back to should be able to do the repacement itself. This is how we normally do replacements.
My main motivation was that I observed that we weren't preserving the name of the result when we do this transform. The replacement code in the worklist loop will call takeName as part of the replacement.
Differential Revision: https://reviews.llvm.org/D61695
llvm-svn: 360284
(X | C1) + C2 --> (X | C1) ^ C1 iff (C1 == -C2)
I verified the correctness using Alive:
https://rise4fun.com/Alive/YNV
This transform enables the following transform that already exists in
instcombine:
(X | Y) ^ Y --> X & ~Y
As a result, the full expected transform is:
(X | C1) + C2 --> X & ~C1 iff (C1 == -C2)
There already exists the transform in the sub case:
(X | Y) - Y --> X & ~Y
However this does not trigger in the case where Y is constant due to an earlier
transform:
X - (-C) --> X + C
With this new add fold, both the add and sub constant cases are handled.
Patch by Chris Dawson.
Differential Revision: https://reviews.llvm.org/D61517
llvm-svn: 360185
Fundamentally/generally, we should not have to rely on bailouts/crippling of
folds. In this particular case, I think we always recognize the inverted
predicate min/max pattern, so there should not be any loss of optimization.
Codegen looks better because we are eliminating an fneg.
llvm-svn: 360180
We don't always get this:
Cond ? -X : -Y --> -(Cond ? X : Y)
...even with the legacy IR form of fneg in the case with extra uses,
and we miss matching with the newer 'fneg' instruction because we
are expecting binops through the rest of the path.
Differential Revision: https://reviews.llvm.org/D61604
llvm-svn: 360075
The demanded elts rules introduced for GEPs in https://reviews.llvm.org/rL356293 replaced vector constants with undefs (by design). It turns out that the LangRef disallows such cases when indexing structs. The right fix is probably to relax the langref requirement, and update other passes to expect the result, but for the moment, limit the transform to avoid compiler crashes.
This should fix https://bugs.llvm.org/show_bug.cgi?id=41624.
llvm-svn: 359633
Follow-up to:
rL359482
Avoid this potential problem throughout by giving the type a name
and verifying the assumption that both operands are the same type.
llvm-svn: 359485
PVS Studio's copy+paste recognizer was seeing this as a typo, technically Op0/Op1 in a fcmp should always be the same type, but we might as well avoid the issue.
Reported in https://www.viva64.com/en/b/0629/
llvm-svn: 359482
This patch rewrites the existing PACKSS/PACKUS constant folding code to expand as a generic expansion.
This is a first NFCI step toward expanding PACKSS/PACKUS intrinsics which are acting as non-saturating truncations (although technically the expansion could be used in all cases - but we'll probably want to be conservative).
llvm-svn: 359111
If we have a masked.load from a location we know to be dereferenceable, we can simply issue a speculative unconditional load against that address. The key advantage is that it produces IR which is well understood by the optimizer. The select (cnd, load, passthrough) form produced should be pattern matchable back to hardware predication if profitable.
Differential Revision: https://reviews.llvm.org/D59703
llvm-svn: 359000
If we have a store to a piece of memory which is known constant, then we know the store must be storing back the same value. As a result, the store (or memset, or memmove) must either be down a dead path, or a noop. In either case, it is valid to simply remove the store.
The motivating case for this involves a memmove to a buffer which is constant down a path which is dynamically dead.
Note that I'm choosing to implement the less aggressive of two possible semantics here. We could simply say that the store *is undefined*, and prune the path. Consensus in the review was that the more aggressive form might be a good follow on change at a later date.
Differential Revision: https://reviews.llvm.org/D60659
llvm-svn: 358919
In the process, use the existing masked.load combine which is slightly stronger, and handles a mix of zero and undef elements in the mask.
llvm-svn: 358913
In InstCombine, we use an idiom of "store i1 true, i1 undef" to indicate we've found a path which we've proven unreachable. We can't actually insert the unreachable instruction since that would require changing the CFG. We leave that to simplifycfg later.
This just factors out that idiom creation so we don't duplicate the same mostly undocument idiom creation in multiple places.
llvm-svn: 358600
If a constant shift amount is used, then only some of the LHS/RHS
operand bits are demanded and we may be able to simplify based on
that. InstCombineSimplifyDemanded already had the necessary support
for that, we just weren't calling it with fshl/fshr as root.
In particular, this allows us to relax some masked funnel shifts
into simple shifts, as shown in the tests.
Patch by Shawn Landden.
Differential Revision: https://reviews.llvm.org/D60660
llvm-svn: 358515
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
Summary:
Enable some of the existing size optimizations for cold code under PGO.
A ~5% code size saving in big internal app under PGO.
The way it gets BFI/PSI is discussed in the RFC thread
http://lists.llvm.org/pipermail/llvm-dev/2019-March/130894.html
Note it doesn't currently touch loop passes.
Reviewers: davidxl, eraman
Reviewed By: eraman
Subscribers: mgorny, javed.absar, smeenai, mehdi_amini, eraman, zzheng, steven_wu, dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D59514
llvm-svn: 358422
As pointed out in D60518 folding mulo(%x, undef) to {undef, undef}
isn't correct. As a correct version of this already exists in
InstructionSimplify (bd8056ef32/lib/Analysis/InstructionSimplify.cpp (L4750-L4757)) this is just
dead code though. Drop it together with the mul(%x, 0) -> {0, false}
fold that is also already handled by InstSimplify.
Differential Revision: https://reviews.llvm.org/D60649
llvm-svn: 358339
This fixes a miscompile which was introduced in r356510 (https://reviews.llvm.org/D57372).
The problem is that the original patch removed pointer operands where the load results we're demanded, but without considering the legality of the load itself. If the masked.gather had active, but undemanded, lanes, then we could end up creating a load which loaded from an undef address. The result could be a segfault, or, in theory, an arbitrary read from a random memory location into an used register.
llvm-svn: 358299
Following D60483 and D60497, this adds support for AlwaysOverflows
handling for ssubo. This is the last case we can handle right now.
Differential Revision: https://reviews.llvm.org/D60518
llvm-svn: 358100
ssubo X, C is equivalent to saddo X, -C. Make the transformation in
InstCombine and allow the logic implemented for saddo to fold prior
usages of add nsw or sub nsw with constants.
Patch by Dan Robertson.
Differential Revision: https://reviews.llvm.org/D60061
llvm-svn: 358099
Check AlwaysOverflow condition for usubo. The implementation is the
same as the existing handling for uaddo and umulo. Handling for saddo
and ssubo will follow (smulo doesn't have the necessary ValueTracking
support).
Differential Revision: https://reviews.llvm.org/D60483
llvm-svn: 358052
This reverts commit 1383a91689.
sdiv-canonicalize.ll fails after this revision. The fold needs to be
moved outside the branch handling constant operands. However when this
is done there are further test changes, so I'm reverting this in the
meantime.
llvm-svn: 358026
Change the code to always handle the unsigned+signed cases together
with the same basic structure for add/sub/mul. The simple folds are
always handled first and then the ValueTracking overflow checks are
used.
llvm-svn: 358025
Nikita Popov