We already special-cased a few interesting patterns,
but that is strictly less powerful than using KnownBits.
So instead get the known bits for the operand of `and`,
and iff all the unset bits of the `and`-mask are known to be zeros
in the operand, we can omit said `and`.
Stepping through callstacks in the example from D99759 reveals
this potential compile-time improvement.
The savings come from avoiding ValueTracking's computing known
bits if we have already dealt with special-case patterns.
Further improvements in this direction seem possible.
This makes a degenerate test based on PR49785 about 40x faster
(25 sec -> 0.6 sec), but it does not address the larger question
of how to limit computeKnownBitsFromAssume(). Ie, the original
test there is still infinite-time for all practical purposes.
Differential Revision: https://reviews.llvm.org/D100408
"Does the predicate hold between two ranges?"
Not very surprisingly, some places were already doing this check,
without explicitly naming the algorithm, cleanup them all.
"Does the predicate hold between two ranges?"
Not very surprisingly, some places were already doing this check,
without explicitly naming the algorithm, cleanup them all.
The current code does not properly handle vector indices unless they are
the first index.
At the moment LangRef gives the impression that the vector index must be
the one and only index (https://llvm.org/docs/LangRef.html#getelementptr-instruction).
But vector indices can appear at any position and according to the
verifier there may be multiple vector indices. If that's the case, the
number of elements must match.
This patch updates SimplifyGEPInst to properly handle those additional
cases.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D99961
This is the sibling fix to c590a9880d -
as there, we can't subsitute a vector value the equality
compare replacement that we are trying requires that the
comparison is true for the entire value. Vector select
can be partly true/false.
In order to bring up scalable vector support in LLVM incrementally,
we introduced behaviour to emit a warning, instead of an error, when
asking the wrong question of a scalable vector, like asking for the
fixed number of elements.
This patch puts that behaviour under a flag. The default behaviour is
that the compiler will always error, which means that all LLVM unit
tests and regression tests will now fail when a code-path is taken that
still uses the wrong interface.
The behaviour to demote an error to a warning can be individually enabled
for tools that want to support experimental use of scalable vectors.
This patch enables that behaviour when driving compilation from Clang.
This means that for users who want to try out scalable-vector support,
fixed-width codegen support, or build user-code with scalable vector
intrinsics, Clang will not crash and burn when the compiler encounters
such a case.
This allows us to do away with the following pattern in many of the SVE tests:
RUN: .... 2>%t
RUN: cat %t | FileCheck --check-prefix=WARN
WARN-NOT: warning: ...
The behaviour to emit warnings is only temporary and we expect this flag
to be removed in the future when scalable vector support is more stable.
This patch also has fixes the following tests:
unittests:
ScalableVectorMVTsTest.SizeQueries
SelectionDAGAddressAnalysisTest.unknownSizeFrameObjects
AArch64SelectionDAGTest.computeKnownBitsSVE_ZERO_EXTEND_VECTOR_INREG
regression tests:
Transforms/InstCombine/vscale_gep.ll
Reviewed By: paulwalker-arm, ctetreau
Differential Revision: https://reviews.llvm.org/D98856
This is an alternative to D98391/D98585, playing things more
conservatively. If AllowRefinement == false, then we don't use
InstSimplify methods at all, and instead explicitly implement a
small number of non-refining folds. Most cases are handled by
constant folding, and I only had to add three folds to cover
our unit tests / test-suite. While this may lose some optimization
power, I think it is safer to approach from this direction, given
how many issues this code has already caused.
Differential Revision: https://reviews.llvm.org/D99027
This is a follow-up to D98588, and fixes the inline `FIXME` about a GEP-related simplification not
preserving the provenance.
https://alive2.llvm.org/ce/z/qbQoAY
Additional tests were added in {rGf125f28afdb59eba29d2491dac0dfc0a7bf1b60b}
Depends on D98672
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D98611
In preparation for D98611, the upcoming change will need to apply additional checks to `P` and `V`,
and so this refactor paves the way for adding additional checks in a less awkward way.
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D98672
The motivating pattern was handled in 0a2d69480d ,
but we should have this for symmetry.
But this really highlights that we could generalize for
any shifted constant if we match this in instcombine.
https://alive2.llvm.org/ce/z/MrmVNt
Add simplification of smul.fix and smul.fix.sat according to
X * 0 -> 0
X * undef -> 0
X * (1 << scale) -> X
This includes the commuted patterns and splatted vectors.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D98299
This is a patch that adds folding of two logical and/ors that share one variable:
a && (a && b) -> a && b
a && (a & b) -> a && b
...
This is towards removing the poison-unsafe select optimization (D93065 has more context).
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D96945
Pulled out from D90479 - this recognises invalid nsw shl patterns with signbit changes that result in poison.
Differential Revision: https://reviews.llvm.org/D97305
This patch adds a new intrinsic experimental.vector.reduce that takes a single
vector and returns a vector of matching type but with the original lane order
reversed. For example:
```
vector.reverse(<A,B,C,D>) ==> <D,C,B,A>
```
The new intrinsic supports fixed and scalable vectors types.
The fixed-width vector relies on shufflevector to maintain existing behaviour.
Scalable vector uses the new ISD node - VECTOR_REVERSE.
This new intrinsic is one of the named shufflevector intrinsics proposed on the
mailing-list in the RFC at [1].
Patch by Paul Walker (@paulwalker-arm).
[1] https://lists.llvm.org/pipermail/llvm-dev/2020-November/146864.html
Differential Revision: https://reviews.llvm.org/D94883
We can fold x*C1/C2 <= x to true if C1 <= C2. This is valid even
if the multiplication is not nuw: https://alive2.llvm.org/ce/z/vULors
The multiplication or division can be replaced by shifts. We don't
handle the case where both are shifts, as that should get folded
away by InstCombine.
This is a partial fix for https://bugs.llvm.org/show_bug.cgi?id=44403.
Folding gep p, q-p to q is only legal if p and q have the same
provenance. This fold should probably be guarded by something like
getUnderlyingObject(p) == getUnderlyingObject(q).
This patch is a partial fix that removes the special handling for
gep p, 0-p, which will fold to a null pointer, which would certainly
not pass an underlying object check (unless p is also null, in which
case this would fold trivially anyway). Folding to a null pointer
is particularly problematic due to the special handling it receives
in many places, making end-to-end miscompiles more likely.
Differential Revision: https://reviews.llvm.org/D93820
I don't believe this has an observable effect, because the only
thing we care about here is replacing the operand with a constant
so following folds can apply. This change is just to make the
representation follow canonical unary shuffle form.
Calling null or undef results in immediate undefined behavior.
Return poison instead of undef in this case, similar to what
we do for immediate UB due to division by zero.
Make InstSimplify return poison rather than undef for out-of-bounds
shifts, as specified by LandRef:
> If op2 is (statically or dynamically) equal to or larger than the
> number of bits in op1, this instruction returns a poison value.
Differential Revision: https://reviews.llvm.org/D93998
As the comment already indicates, performing an operation with
nnan/ninf flags on a nan/inf or undef results in poison. Now that
we have a proper poison value, we no longer need to relax it to
undef.
Div/rem by zero is immediate undefined behavior and anything goes.
Currently we fold it to undef, this patch changes it to fold to
poison instead, which is slightly stronger.
Differential Revision: https://reviews.llvm.org/D93995
This is the same change as D93990, but for extractelement rather
than insertelement.
> If idx exceeds the length of val for a fixed-length vector, the
> result is a poison value. For a scalable vector, if the value of
> idx exceeds the runtime length of the vector, the result is a
> poison value.
This is a simple patch that updates InstSimplify to return poison if the index is/can be out-of-bounds
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D93990
The last use of the function, located in RemovePredecessorAndSimplify,
was removed on Dec 25, 2020 in commit
46bea9b297.
The last use of RemovePredecessorAndSimplify was removed on Sep 29,
2010 in commit 99c985c37d.
The transform wasn't checking that the LHS of the comparison
*is* the `X` in question...
This is the miscompile that was holding up D87188.
Thanks to Dave Green for producing an actionable reproducer!
Folding a select of vector constants that include undef elements only
applies to fixed vectors, but there's no earlier check the type is not
scalable so it crashes for scalable vectors. This adds a check so this
optimization is only attempted for fixed vectors.
Reviewed By: sdesmalen
Differential Revision: https://reviews.llvm.org/D92046
This extends D78430 to solve cases like:
https://llvm.org/PR47858
There are still missed opportunities shown in the tests,
and as noted in the earlier patches, we have related
functionality in InstCombine, so we may want to extend
other folds in a similar way.
A semi-random sampling of test diff proofs in this patch:
https://rise4fun.com/Alive/sS4C
This improves simplifications for pattern `icmp (X+Y), (X+Z)` -> `icmp Y,Z`
if only one of the operands has NSW set, e.g.:
icmp slt (x + 0), (x +nsw 1)
We can still safely rewrite this to:
icmp slt 0, 1
because we know that the LHS can't overflow if the RHS has NSW set and
C1 < C2 && C1 >= 0, or C2 < C1 && C1 <= 0
This simplification is useful because ScalarEvolutionExpander which is used to
generate code for SCEVs in different loop optimisers is not always able to put
back NSW flags across control-flow, thus inhibiting CFG simplifications.
Differential Revision: https://reviews.llvm.org/D89317
If SimplifyWithOpReplaced() cannot simplify the value, null should
be returned. Make sure this really does happen in all cases,
including those where SimplifyBinOp() returns the original value.
This does not matter for existing users, but does mattter for
D87480, which would go into an infinite loop otherwise.
If the constant operand is the opposite of the min/max value,
then the result must be the other value.
This is based on the similar codegen transform proposed in:
D87571
As discussed in the sibling codegen functionality patch D87571,
this transform was created with D52766, but it is not correct.
The incorrect test diffs were missed during review, but the
'TODO' comment about this functionality was still in the code -
we need 'nnan' to enable this fold.
This is a followup to D86834, which partially fixed this issue in
InstSimplify. However, InstCombine repeats the same transform while
dropping poison flags -- which does not cover cases where poison is
introduced in some other way.
The fix here is a bit more comprehensive, because things are quite
entangled, and it's hard to only partially address it without
regressing optimization. There are really two changes here:
* Export the SimplifyWithOpReplaced API from InstSimplify, with an
added AllowRefinement flag. For replacements inside the TrueVal
we don't actually care whether refinement occurs or not, the
replacement is always legal. This part of the transform is now
done in InstSimplify only. (It should be noted that the current
AllowRefinement check is not sufficient -- that's an issue we
need to address separately.)
* Change the InstCombine fold to work by temporarily dropping
poison generating flags, running the fold and then restoring the
flags if it didn't work out. This will ensure that the InstCombine
fold is correct as long as the InstSimplify fold is correct.
Differential Revision: https://reviews.llvm.org/D87445
If we know that the abs operand is known negative, we can replace
it with a neg.
To avoid computing known bits twice, I've removed the fold for the
non-negative case from InstSimplify. Both the non-negative and the
negative case are handled by InstCombine now, with one known bits call.
Differential Revision: https://reviews.llvm.org/D87196
This addresses the remaining issue from D87188. Due to a series of
folds, we may end up with abs-of-abs represented as
x == 0 ? -abs(x) : abs(x). Rather than recognizing this as a special
abs pattern and doing an abs-of-abs fold on it afterwards,
I'm directly folding this to one of the select operands in InstSimplify.
The general pattern falls into the "select with operand replaced"
category, but that fold is not powerful enough to recognize that
both hands of the select are the same for value zero.
Differential Revision: https://reviews.llvm.org/D87197
If we have a dominating condition that x >= y, then umax(x, y) is x,
etc. I'm doing this in InstSimplify as the corresponding transform
for the select form is also done there.
Differential Revision: https://reviews.llvm.org/D87168
Replace the check for poison-producing instructions in
SimplifyWithOpReplaced() with the generic helper canCreatePoison()
that properly handles poisonous shifts and thus avoids the problem
from PR47322.
This additionally fixes a bug in IIQ.UseInstrInfo=false mode, which
previously could have caused this code to ignore poison flags.
Setting UseInstrInfo=false should reduce the possible optimizations,
not increase them.
This is not a full solution to the problem, as poison could be
introduced more indirectly. This is just a minimal, easy to backport
fix.
Differential Revision: https://reviews.llvm.org/D86834
This patch changes ElementCount so that the Min and Scalable
members are now private and can only be accessed via the get
functions getKnownMinValue() and isScalable(). In addition I've
added some other member functions for more commonly used operations.
Hopefully this makes the class more useful and will reduce the
need for calling getKnownMinValue().
Differential Revision: https://reviews.llvm.org/D86065
As pointed out in post-commit review, this can legally be called
on instructions that are not inserted into basic blocks,
so don't blindly assume that there is basic block.
Apparently, we don't do this, neither in EarlyCSE, nor in InstSimplify,
nor in (old) GVN, but do in NewGVN and SimplifyCFG of all places..
While i could teach EarlyCSE how to hash PHI nodes,
we can't really do much (anything?) even if we find two identical
PHI nodes in different basic blocks, same-BB case is the interesting one,
and if we teach InstSimplify about it (which is what i wanted originally,
https://reviews.llvm.org/D86530), we get EarlyCSE support for free.
So i would think this is pretty uncontroversial.
On vanilla llvm test-suite + RawSpeed, this has the following effects:
```
| statistic name | baseline | proposed | Δ | % | \|%\| |
|----------------------------------------------------|-----------|-----------|-------:|---------:|---------:|
| instsimplify.NumPHICSE | 0 | 23779 | 23779 | 0.00% | 0.00% |
| asm-printer.EmittedInsts | 7942328 | 7942392 | 64 | 0.00% | 0.00% |
| assembler.ObjectBytes | 273069192 | 273084704 | 15512 | 0.01% | 0.01% |
| correlated-value-propagation.NumPhis | 18412 | 18539 | 127 | 0.69% | 0.69% |
| early-cse.NumCSE | 2183283 | 2183227 | -56 | 0.00% | 0.00% |
| early-cse.NumSimplify | 550105 | 542090 | -8015 | -1.46% | 1.46% |
| instcombine.NumAggregateReconstructionsSimplified | 73 | 4506 | 4433 | 6072.60% | 6072.60% |
| instcombine.NumCombined | 3640264 | 3664769 | 24505 | 0.67% | 0.67% |
| instcombine.NumDeadInst | 1778193 | 1783183 | 4990 | 0.28% | 0.28% |
| instcount.NumCallInst | 1758401 | 1758799 | 398 | 0.02% | 0.02% |
| instcount.NumInvokeInst | 59478 | 59502 | 24 | 0.04% | 0.04% |
| instcount.NumPHIInst | 330557 | 330533 | -24 | -0.01% | 0.01% |
| instcount.TotalInsts | 8831952 | 8832286 | 334 | 0.00% | 0.00% |
| simplifycfg.NumInvokes | 4300 | 4410 | 110 | 2.56% | 2.56% |
| simplifycfg.NumSimpl | 1019808 | 999607 | -20201 | -1.98% | 1.98% |
```
I.e. it fires ~24k times, causes +110 (+2.56%) more `invoke` -> `call`
transforms, and counter-intuitively results in *more* instructions total.
That being said, the PHI count doesn't decrease that much,
and looking at some examples, it seems at least some of them
were previously getting PHI CSE'd in SimplifyCFG of all places..
I'm adjusting `Instruction::isIdenticalToWhenDefined()` at the same time.
As a comment in `InstCombinerImpl::visitPHINode()` already stated,
there are no guarantees on the ordering of the operands of a PHI node,
so if we just naively compare them, we may false-negatively say that
the nodes are not equal when the only difference is operand order,
which is especially important since the fold is in InstSimplify,
so we can't rely on InstCombine sorting them beforehand.
Fixing this for the general case is costly (geomean +0.02%),
and does not appear to catch anything in test-suite, but for
the same-BB case, it's trivial, so let's fix at least that.
As per http://llvm-compile-time-tracker.com/compare.php?from=04879086b44348cad600a0a1ccbe1f7776cc3cf9&to=82bdedb888b945df1e9f130dd3ac4dd3c96e2925&stat=instructions
this appears to cause geomean +0.03% compile time increase (regression),
but geomean -0.01%..-0.04% code size decrease (improvement).
This is a reboot of D84655, now performing the inner icmp
simplification query without undef folds.
It should be possible to handle the current foldMinMaxSharedOp()
fold based on this, by moving the logic into icmp of min/max instead,
making it more general. We can't drop the folds for constant operands,
because those also allow undef, which we exclude here.
The tests use assumes for exhaustive coverage, and have a few
more examples of misc folds we get based on icmp simplification.
Differential Revision: https://reviews.llvm.org/D85929
InstSimplify should do all transformations that ConstProp does, but
one thing that ConstProp does that InstSimplify wouldn't is inline
vector instructions that are constants, e.g. into a ret.
Previously vector instructions wouldn't be inlined in InstSimplify
because llvm::Simplify*Instruction() would return nullptr for specific
instructions, such as vector instructions that were actually constants,
if it couldn't simplify them.
This changes SimplifyInsertElementInst, SimplifyExtractElementInst, and
SimplifyShuffleVectorInst to return a vector constant when possible.
Reviewed By: efriedma
Differential Revision: https://reviews.llvm.org/D85946
This recommits the following patches now that D85684 has landed
1cf6f210a2 [IR] Disable select ? C : undef -> C fold in ConstantFoldSelectInstruction unless we know C isn't poison.
469da663f2 [InstSimplify] Re-enable select ?, undef, X -> X transform when X is provably not poison
122b0640fc [InstSimplify] Don't fold vectors of partial undef in SimplifySelectInst if the non-undef element value might produce poison
ac0af12ed2 [InstSimplify] Add test cases for opportunities to fold select ?, X, undef -> X when we can prove X isn't poison
9b1e95329a [InstSimplify] Remove select ?, undef, X -> X and select ?, X, undef -> X transforms
Similar to what we do in IIQ, add an isUndefValue() helper that
checks for undef values while respective CanUseUndef. This makes
it much easier to search for places that don't respect the flag
yet.
This is the replacement for D84250 based on D84792. As we recursively
fold with the same value twice, we need to disable undef folds,
to prevent an undef from being folded to two different values.
Reverting rG00f3579aea6e3d4a4b7464c3db47294f71cef9e4 and using the
test case from https://reviews.llvm.org/D83360#2145793, it no longer
performs the incorrect fold.
Differential Revision: https://reviews.llvm.org/D85684
I think this is the last remaining translation of an existing
instcombine transform for the corresponding cmp+sel idiom.
This interpretation is more general though - we can remove
mismatched signed/unsigned combinations in addition to the
more obvious cases.
min/max(X, Y) must produce X or Y as the result, so this is
just another clause in the existing transform that was already
matching a min/max of min/max.
Making use of undef is not safe if the simplification result is not used
to replace all uses of the result. This leads to problems in NewGVN,
which does not replace all uses in the IR directly. See PR33165 for more
details.
This patch adds an option to SimplifyQuery to disable the use of undef.
Note that I've only guarded uses if isa<UndefValue>/m_Undef where
SimplifyQuery is currently available. If we agree on the general
direction, I'll update the remaining uses.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D84792
https://rise4fun.com/Alive/pZEr
Name: mul nuw with icmp eq
Pre: (C2 %u C1) != 0
%a = mul nuw i8 %x, C1
%r = icmp eq i8 %a, C2
=>
%r = false
Name: mul nuw with icmp ne
Pre: (C2 %u C1) != 0
%a = mul nuw i8 %x, C1
%r = icmp ne i8 %a, C2
=>
%r = true
There are potentially several other transforms we need to add based on:
D51625
...but it doesn't look like there was follow-up to that patch.
This revision adds the following peephole optimization
and it's negation:
%a = urem i64 %x, %y
%b = icmp ule i64 %a, %x
====>
%b = true
With John Regehr's help this optimization was checked with Alive2
which suggests it should be valid.
This pattern occurs in the bound checks of Rust code, the program
const N: usize = 3;
const T = u8;
pub fn split_mutiple(slice: &[T]) -> (&[T], &[T]) {
let len = slice.len() / N;
slice.split_at(len * N)
}
the method call slice.split_at will check that len * N is within
the bounds of slice, this bounds check is after some transformations
turned into the urem seen above and then LLVM fails to optimize it
any further. Adding this optimization would cause this bounds check
to be fully optimized away.
ref: https://github.com/rust-lang/rust/issues/74938
Differential Revision: https://reviews.llvm.org/D85092
This is based on the existing code for the non-intrinsic idioms
in InstCombine.
The vector constant constraint is non-obvious: undefs should be
ok in the outer call, but they can't propagate safely from the
inner call in all cases. Example:
https://alive2.llvm.org/ce/z/-2bVbM
define <2 x i8> @src(<2 x i8> %x) {
%0:
%m = umin <2 x i8> %x, { 7, undef }
%m2 = umin <2 x i8> { 9, 9 }, %m
ret <2 x i8> %m2
}
=>
define <2 x i8> @tgt(<2 x i8> %x) {
%0:
%m = umin <2 x i8> %x, { 7, undef }
ret <2 x i8> %m
}
Transformation doesn't verify!
ERROR: Value mismatch
Example:
<2 x i8> %x = < undef, undef >
Source:
<2 x i8> %m = < #x00 (0) [based on undef value], #x00 (0) >
<2 x i8> %m2 = < #x00 (0), #x00 (0) >
Target:
<2 x i8> %m = < #x07 (7), #x10 (16) >
Source value: < #x00 (0), #x00 (0) >
Target value: < #x07 (7), #x10 (16) >
It's always safe to pick the earlier abs regardless of the nsw flag. We'll just lose it if it is on the outer abs but not the inner abs.
Differential Revision: https://reviews.llvm.org/D85053
abs() should be rare enough that using value tracking is not going
to be a compile-time cost burden, so use it to reduce a variety of
potential patterns. We do this in DAGCombiner too.
Differential Revision: https://reviews.llvm.org/D85043
This matches the behavior of simplify calls for regular opcodes -
rely on ConstantFolding before spending time on folds with variables.
I am not aware of any diffs from this re-ordering currently, but there was
potential for unintended behavior from the min/max intrinsics because that
code is implicitly assuming that only 1 of the input operands is constant.
This is the main icmp simplification shortcoming seen in D84655.
Alive2 agrees that the basic examples are correct at least:
define <2 x i1> @src(<2 x i8> %x) {
%0:
%r = icmp sle <2 x i8> { undef, 128 }, %x
ret <2 x i1> %r
}
=>
define <2 x i1> @tgt(<2 x i8> %x) {
%0:
ret <2 x i1> { 1, 1 }
}
Transformation seems to be correct!
define <2 x i1> @src(<2 x i32> %X) {
%0:
%A = or <2 x i32> %X, { 63, 63 }
%B = icmp ult <2 x i32> %A, { undef, 50 }
ret <2 x i1> %B
}
=>
define <2 x i1> @tgt(<2 x i32> %X) {
%0:
ret <2 x i1> { 0, 0 }
}
Transformation seems to be correct!
https://alive2.llvm.org/ce/z/omt2eehttps://alive2.llvm.org/ce/z/GW4nP_
Differential Revision: https://reviews.llvm.org/D84762
This is a step towards trying to remove unnecessary FP compares
with infinity when compiling with -ffinite-math-only or similar.
I'm intentionally not checking FMF on the fcmp itself because
I'm assuming that will go away eventually.
The analysis part of this was added with rGcd481136 for use with
isKnownNeverNaN. Similarly, that could be an enhancement here to
get predicates like 'one' and 'ueq'.
Differential Revision: https://reviews.llvm.org/D84035
This reverts most of the following patches due to reports of miscompiles.
I've left the added test cases with comments updated to be FIXMEs.
1cf6f210a2 [IR] Disable select ? C : undef -> C fold in ConstantFoldSelectInstruction unless we know C isn't poison.
469da663f2 [InstSimplify] Re-enable select ?, undef, X -> X transform when X is provably not poison
122b0640fc [InstSimplify] Don't fold vectors of partial undef in SimplifySelectInst if the non-undef element value might produce poison
ac0af12ed2 [InstSimplify] Add test cases for opportunities to fold select ?, X, undef -> X when we can prove X isn't poison
9b1e95329a [InstSimplify] Remove select ?, undef, X -> X and select ?, X, undef -> X transforms
Follow up from the transform being removed in D83360. If X is probably not poison, then the transform is safe.
Still plan to remove or adjust the code from ConstantFolding after this.
Differential Revision: https://reviews.llvm.org/D83440
We can't fold to the non-undef value unless we know it isn't poison. So check each element with isGuaranteedNotToBeUndefOrPoison. This currently rules out all constant expressions.
Differential Revision: https://reviews.llvm.org/D83442
These represent the same thing but 64BIT only showed up from
getHostCPUFeatures providing a list of featuers to clang. While
EM64T showed up from getting the features for a named CPU.
EM64T didn't have a string specifically so it would not be passed
up to clang when getting features for a named CPU. While 64bit
needed a name since that's how it is index.
Merge them by filtering 64bit out before sending features to clang
for named CPUs.
This is picking up a loose thread from D69006: We can simplify
(zext x) ule (sext x) and (zext x) sge (sext x) to true, with
various permutations. Oddly, SCEV knows about this identity,
but nothing on the IR level does.
Differential Revision: https://reviews.llvm.org/D83081
If we assume(x > y), then we should be able to fold the basic
implications of that, like x >= y. This already happens if either
one of the operands is constant (LVI) or if the conditions are
exactly the same (GVN), but not if we have an implication with
non-constant operands. Support this by querying AssumptionCache.
Fixes https://bugs.llvm.org/show_bug.cgi?id=40149.
Differential Revision: https://reviews.llvm.org/D82717
Summary:
simplifyDivRem attempts to walk a VectorType elementwise. Ensure that it
only does so for FixedVectorType
Reviewers: efriedma, spatel, lebedev.ri, david-arm, kmclaughlin
Reviewed By: spatel, david-arm
Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D81856
This intrinsic implements IEEE-754 operation roundToIntegralTiesToEven,
and performs rounding to the nearest integer value, rounding halfway
cases to even. The intrinsic represents the missed case of IEEE-754
rounding operations and now llvm provides full support of the rounding
operations defined by the standard.
Differential Revision: https://reviews.llvm.org/D75670
No changes relative to last time, but after a mitigation for
an AMDGPU regression landed.
---
If SimplifyInstruction() does not succeed in simplifying the
instruction, it will compute the known bits of the instruction
in the hope that all bits are known and the instruction can be
folded to a constant. I have removed a similar optimization
from InstCombine in D75801, and would like to drop this one as well.
On average, we spend ~1% of total compile-time performing this
known bits calculation. However, if we introduce some additional
statistics for known bits computations and how many of them succeed
in simplifying the instruction we get (on test-suite):
instsimplify.NumKnownBits: 216
instsimplify.NumKnownBitsComputed: 13828375
valuetracking.NumKnownBitsComputed: 45860806
Out of ~14M known bits calculations (accounting for approximately
one third of all known bits calculations), only 0.0015% succeed in
producing a constant. Those cases where we do succeed to compute
all known bits will get folded by other passes like InstCombine
later. On test-suite, only lencod.test and GCC-C-execute-pr44858.test
show a hash difference after this change. On lencod we see an
improvement (a loop phi is optimized away), on the GCC torture
test a regression (a function return value is determined only
after IPSCCP, preventing propagation from a noinline function.)
There are various regressions in InstSimplify tests. However, all
of these cases are already handled by InstCombine, and corresponding
tests have already been added there.
Differential Revision: https://reviews.llvm.org/D79294
If SimplifyInstruction() does not succeed in simplifying the
instruction, it will compute the known bits of the instruction
in the hope that all bits are known and the instruction can be
folded to a constant. I have removed a similar optimization
from InstCombine in D75801, and would like to drop this one as well.
On average, we spend ~1% of total compile-time performing this
known bits calculation. However, if we introduce some additional
statistics for known bits computations and how many of them succeed
in simplifying the instruction we get (on test-suite):
instsimplify.NumKnownBits: 216
instsimplify.NumKnownBitsComputed: 13828375
valuetracking.NumKnownBitsComputed: 45860806
Out of ~14M known bits calculations (accounting for approximately
one third of all known bits calculations), only 0.0015% succeed in
producing a constant. Those cases where we do succeed to compute
all known bits will get folded by other passes like InstCombine
later. On test-suite, only lencod.test and GCC-C-execute-pr44858.test
show a hash difference after this change. On lencod we see an
improvement (a loop phi is optimized away), on the GCC torture
test a regression (a function return value is determined only
after IPSCCP, preventing propagation from a noinline function.)
There are various regressions in InstSimplify tests. However, all
of these cases are already handled by InstCombine, and corresponding
tests have already been added there.
Differential Revision: https://reviews.llvm.org/D79294
The more general fold was not poison-safe, so it was removed:
rG5486e00
...but it is ok to have this transform if analysis can determine
the vector contains no poison. The test shows a simple example
of that: constant integer elements are not poison.
PR45481:
https://bugs.llvm.org/show_bug.cgi?id=45481
SDAG has an identical transform to this, so there's little
chance of any real-world impact. OTOH, that means we are
effectively sweeping the bug out of sight because poison
exists in codegen too.
This method has been commented as deprecated for a while. Remove
it and replace all uses with the equivalent getCalledOperand().
I also made a few cleanups in here. For example, to removes use
of getElementType on a pointer when we could just use getFunctionType
from the call.
Differential Revision: https://reviews.llvm.org/D78882
Summary:
Remove usages of asserting vector getters in Type in preparation for the
VectorType refactor. The existence of these functions complicates the
refactor while adding little value.
Reviewers: sunfish, sdesmalen, efriedma
Reviewed By: efriedma
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D77273
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
This change implements constant folding to constrained versions of
intrinsics, implementing rounding: floor, ceil, trunc, round, rint and
nearbyint.
Differential Revision: https://reviews.llvm.org/D72930
Summary:
Skip folds that rely on DataLayout::getTypeAllocSize(). For scalable
vector, only minimal type alloc size is known at compile-time.
Reviewers: sdesmalen, efriedma, spatel, apazos
Reviewed By: efriedma
Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75892
Summary:
Support ConstantInt::get() and Constant::getAllOnesValue() for scalable
vector type, this requires ConstantVector::getSplat() to take in 'ElementCount',
instead of 'unsigned' number of element count.
This change is needed for D73753.
Reviewers: sdesmalen, efriedma, apazos, spatel, huntergr, willlovett
Reviewed By: efriedma
Subscribers: tschuett, hiraditya, rkruppe, psnobl, cfe-commits, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D74386
This is part of the IR sibling for:
D75576
(I'm splitting part of the transform as a separate commit
to reduce risk. I don't know of any bugs that might be
exposed by this improved folding, but it's hard to see
those in advance...)
Summary:
For scalable vector, index out-of-bound can not be determined at compile-time.
The same apply for VectorUtil findScalarElement().
Add test cases to check the functionality of SimplifyInsert/ExtractElementInst for scalable vector.
Reviewers: sdesmalen, efriedma, spatel, apazos
Reviewed By: efriedma
Subscribers: cameron.mcinally, tschuett, hiraditya, rkruppe, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75782
If a call argument has the "returned" attribute, we can simplify
the call to the value of that argument. The "-inst-simplify" pass
already handled this for the constant integer argument case via
known bits, which is invoked in SimplifyInstruction. However,
non-constant (or non-int) arguments are not handled at all right now.
This addresses one of the regressions from D75801.
Differential Revision: https://reviews.llvm.org/D75815
As pointed out by jdoerfert on D75815, we must be careful when
simplifying musttail calls: We can only replace the return value
if we can eliminate the call entirely. As we can't make this
guarantee for all consumers of InstSimplify, this patch disables
simplification of musttail calls. Without this patch, musttail
simplification currently results in module verification errors.
Differential Revision: https://reviews.llvm.org/D75824
Summary:
```
br i1 c, BB1, BB2:
BB1:
use1(c)
BB2:
use2(c)
```
In BB1 and BB2, c is never undef or poison because otherwise the branch would have triggered UB.
This is a resubmission of 952ad47 with crash fix of llvm/test/Transforms/LoopRotate/freeze-crash.ll.
Checked with Alive2
Reviewers: xbolva00, spatel, lebedev.ri, reames, jdoerfert, nlopes, sanjoy
Reviewed By: reames
Subscribers: jdoerfert, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75401
InstSimplify can fold icmps of gep where the base pointers are the
same and the offsets are constant. It does so by constructing a
constant expression icmp and assumes that it gets folded -- but
this doesn't actually happen, because GEP expressions can usually
only be folded by the target-dependent constant folding layer.
As such, we need to explicitly invoke it here.
Differential Revision: https://reviews.llvm.org/D75407
Spin-off from D75407. As described there, ConstantFoldConstant()
currently returns null for non-ConstantExpr/ConstantVector inputs,
but otherwise always returns non-null, independently of whether
any folding has happened or not.
This is confusing and makes consumer code more complicated.
I would expect either that ConstantFoldConstant() returns only if
it actually folded something, or that it always returns non-null.
I'm going to the latter possibility here, which appears to be more
useful considering existing usage.
Differential Revision: https://reviews.llvm.org/D75543
Summary:
```
br i1 c, BB1, BB2:
BB1:
use1(c)
BB2:
use2(c)
```
In BB1 and BB2, c is never undef or poison because otherwise the branch would have triggered UB.
Checked with Alive2
Reviewers: xbolva00, spatel, lebedev.ri, reames, jdoerfert, nlopes, sanjoy
Reviewed By: reames
Subscribers: jdoerfert, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D75401
Summary:
* Most of the simplifications in SimplifyShuffleVectorInst depend on the
concrete value of, or the length of the mask vector. For scalable
vectors, this cannot be known at compile time.
** for these tests, detect if the vector is scalable before attempting
the transformation
* The functions ShuffleVectorInst::getMaskValue and
ShuffleVectorInst::getShuffleMask access the value of the constant mask.
However, since the length of the mask is unknown at compile time, these
function do not work for scalable vectors. Add asserts to ensure that
the input mask is not scalable
Reviewers: efriedma, sdesmalen, apazos, chrisj, huihuiz
Reviewed By: efriedma
Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D73555
This addresses https://bugs.llvm.org/show_bug.cgi?id=42801.
The m_c_ICmp() matcher is changed to provide the swapped predicate
if the operands are swapped.
Existing uses of m_c_ICmp() fall in one of two categories: Working
on equality predicates only, where swapping is irrelevant.
Or performing a manual swap, in which case this patch removes it.
The only exception is the foldICmpWithLowBitMaskedVal() fold, which
does not swap the predicate, and instead reasons about whether
a swap occurred or not for each predicate. Getting the swapped
predicate allows us to merge the logic for pairs of predicates,
instead of duplicating it.
Differential Revision: https://reviews.llvm.org/D72976
As mentioned in D72643, we'd like to be able to assert that any select
of equivalent constants has been removed before we're deep into InstCombine.
But there's a loophole in that assertion for vectors with undef elements
that don't match exactly.
This patch should close that gap. If we have undefs, we can't safely
propagate those unless both constants elements for that lane are undef.
Differential Revision: https://reviews.llvm.org/D72958
This is step 1 of damage control assuming that we need to remove several
over-reaching folds for select-of-booleans because they can cause
miscompiles as shown in D72396.
The scalar case seems obviously safe:
https://rise4fun.com/Alive/jSj
And I don't think there's any danger for vectors either - if the
condition is poisoned, then the select must be poisoned too, so undef
elements don't make any difference.
Differential Revision: https://reviews.llvm.org/D72412
shuf (inselt ?, C, IndexC), undef, <IndexC, IndexC...> --> <C, C...>
This is another missing shuffle fold pattern uncovered by the
shuffle correctness fix from D70246.
The problem was visible in the post-commit thread example, but
we managed to overcome the limitation for that particular case
with D71220.
This is something like the inverse of the previous fix - there
we didn't demand the inserted scalar, and here we are only
demanding an inserted scalar.
Differential Revision: https://reviews.llvm.org/D71488
GEP index size can be specified in the DataLayout, introduced in D42123. However, there were still places
in which getIndexSizeInBits was used interchangeably with getPointerSizeInBits. This notably caused issues
with Instcombine's visitPtrToInt; but the unit tests was incorrect, so this remained undiscovered.
This fixes the buildbot failures.
Differential Revision: https://reviews.llvm.org/D68328
Patch by Joseph Faulls!
Removed code duplication in ThreadCmpOverSelect and broke it
into several smaller functions for reusing them.
Differential Revision: https://reviews.llvm.org/D71158
GEP index size can be specified in the DataLayout, introduced in D42123. However, there were still places
in which getIndexSizeInBits was used interchangeably with getPointerSizeInBits. This notably caused issues
with Instcombine's visitPtrToInt; but the unit tests was incorrect, so this remained undiscovered.
Differential Revision: https://reviews.llvm.org/D68328
Patch by Joseph Faulls!
Summary:
Same as D60846 and D69571 but with a fix for the problem encountered
after them. Both times it was a missing context adjustment in the
handling of PHI nodes.
The reproducers created from the bugs that caused the old commits to be
reverted are included.
Reviewers: nikic, nlopes, mkazantsev, spatel, dlrobertson, uabelho, hakzsam, hans
Subscribers: hiraditya, bollu, asbirlea, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D71181
This is another transform suggested in PR44153:
https://bugs.llvm.org/show_bug.cgi?id=44153
The backend for some targets already manages to get
this if it converts copysign to bitwise logic.
This is correct for any value including NaN/inf.
We don't have this fold directly in the backend either,
but x86 manages to get it after converting things to bitops.
This caused miscompiles of Chromium (https://crbug.com/1023818). The reduced
repro is small enough to fit here:
$ cat /tmp/a.c
unsigned char f(unsigned char *p) {
unsigned char result = 0;
for (int shift = 0; shift < 1; ++shift)
result |= p[0] << (shift * 8);
return result;
}
$ bin/clang -O2 -S -o - /tmp/a.c | grep -A4 f:
f: # @f
.cfi_startproc
# %bb.0: # %entry
xorl %eax, %eax
retq
That's nicely optimized, but I don't think it's the right result :-)
> Same as D60846 but with a fix for the problem encountered there which
> was a missing context adjustment in the handling of PHI nodes.
>
> The test that caused D60846 to be reverted was added in e15ab8f277.
>
> Reviewers: nikic, nlopes, mkazantsev,spatel, dlrobertson, uabelho, hakzsam
>
> Subscribers: hiraditya, bollu, llvm-commits
>
> Tags: #llvm
>
> Differential Revision: https://reviews.llvm.org/D69571
This reverts commit 57dd4b03e4.
Same as D60846 but with a fix for the problem encountered there which
was a missing context adjustment in the handling of PHI nodes.
The test that caused D60846 to be reverted was added in e15ab8f277.
Reviewers: nikic, nlopes, mkazantsev,spatel, dlrobertson, uabelho, hakzsam
Subscribers: hiraditya, bollu, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D69571
In similar fashion to D67721, we can simplify FMA multiplications if any
of the operands is NaN or undef. In instcombine, we will simplify the
FMA to an fadd with a NaN operand, which in turn gets folded to NaN.
Note that this just changes SimplifyFMAFMul, so we still not catch the
case where only the Add part of the FMA is Nan/Undef.
Reviewers: cameron.mcinally, mcberg2017, spatel, arsenm
Reviewed By: cameron.mcinally
Differential Revision: https://reviews.llvm.org/D68265
llvm-svn: 373459
This is intended to be similar to the constant folding results from
D67446
and earlier, but not all operands are constant in these tests, so the
responsibility for folding is left to InstSimplify.
Differential Revision: https://reviews.llvm.org/D67721
llvm-svn: 373455
Because we do not constant fold multiplications in SimplifyFMAMul,
we match 1.0 and 0.0 for both operands, as multiplying by them
is guaranteed to produce an exact result (if it is allowed to do so).
Note that it is not enough to just swap the operands to ensure a
constant is on the RHS, as we want to also cover the case with
2 constants.
Reviewers: lebedev.ri, spatel, reames, scanon
Reviewed By: lebedev.ri, reames
Differential Revision: https://reviews.llvm.org/D67553
llvm-svn: 372915
As @reames pointed out post-commit, rL371518 adds additional rounding
in some cases, when doing constant folding of the multiplication.
This breaks a guarantee llvm.fma makes and must be avoided.
This patch reapplies rL371518, but splits off the simplifications not
requiring rounding from SimplifFMulInst as SimplifyFMAFMul.
Reviewers: spatel, lebedev.ri, reames, scanon
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D67434
llvm-svn: 372899
Summary:
I don't have a direct motivational case for this,
but it would be good to have this for completeness/symmetry.
This pattern is basically the motivational pattern from
https://bugs.llvm.org/show_bug.cgi?id=43251
but with different predicate that requires that the offset is non-zero.
The completeness bit comes from the fact that a similar pattern (offset != zero)
will be needed for https://bugs.llvm.org/show_bug.cgi?id=43259,
so it'd seem to be good to not overlook very similar patterns..
Proofs: https://rise4fun.com/Alive/21b
Also, there is something odd with `isKnownNonZero()`, if the non-zero
knowledge was specified as an assumption, it didn't pick it up (PR43267)
Reviewers: spatel, nikic, xbolva00
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67411
llvm-svn: 371718
This was actually the original intention in D67332,
but i messed up and forgot about it.
This patch was originally part of D67411, but precommitting this.
llvm-svn: 371630
Summary:
This is motivated by D67122 sanitizer check enhancement.
That patch seemingly worsens `-fsanitize=pointer-overflow`
overhead from 25% to 50%, which strongly implies missing folds.
In this particular case, given
```
char* test(char& base, unsigned long offset) {
return &base + offset;
}
```
it will end up producing something like
https://godbolt.org/z/LK5-iH
which after optimizations reduces down to roughly
```
define i1 @t0(i8* nonnull %base, i64 %offset) {
%base_int = ptrtoint i8* %base to i64
%adjusted = add i64 %base_int, %offset
%non_null_after_adjustment = icmp ne i64 %adjusted, 0
%no_overflow_during_adjustment = icmp uge i64 %adjusted, %base_int
%res = and i1 %non_null_after_adjustment, %no_overflow_during_adjustment
ret i1 %res
}
```
Without D67122 there was no `%non_null_after_adjustment`,
and in this particular case we can get rid of the overhead:
Here we add some offset to a non-null pointer,
and check that the result does not overflow and is not a null pointer.
But since the base pointer is already non-null, and we check for overflow,
that overflow check will already catch the null pointer,
so the separate null check is redundant and can be dropped.
Alive proofs:
https://rise4fun.com/Alive/WRzq
There are more patterns of "unsigned-add-with-overflow", they are not handled here,
but this is the main pattern, that we currently consider canonical,
so it makes sense to handle it.
https://bugs.llvm.org/show_bug.cgi?id=43246
Reviewers: spatel, nikic, vsk
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits, reames
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67332
llvm-svn: 371349
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
Summary:
Now that with D65143/D65144 we've produce `@llvm.umul.with.overflow`,
and with D65147 we've flattened the CFG, we now can see that
the guard may have been there to prevent division by zero is redundant.
We can simply drop it:
```
----------------------------------------
Name: no overflow or zero
%iszero = icmp eq i4 %y, 0
%umul = smul_overflow i4 %x, %y
%umul.ov = extractvalue {i4, i1} %umul, 1
%umul.ov.not = xor %umul.ov, -1
%retval.0 = or i1 %iszero, %umul.ov.not
ret i1 %retval.0
=>
%iszero = icmp eq i4 %y, 0
%umul = smul_overflow i4 %x, %y
%umul.ov = extractvalue {i4, i1} %umul, 1
%umul.ov.not = xor %umul.ov, -1
%retval.0 = or i1 %iszero, %umul.ov.not
ret i1 %umul.ov.not
Done: 1
Optimization is correct!
```
Note that this is inverted from what we have in a previous patch,
here we are looking for the inverted overflow bit.
And that inversion is kinda problematic - given this particular
pattern we neither hoist that `not` closer to `ret` (then the pattern
would have been identical to the one without inversion,
and would have been handled by the previous patch), neither
do the opposite transform. But regardless, we should handle this too.
I've filled [[ https://bugs.llvm.org/show_bug.cgi?id=42720 | PR42720 ]].
Reviewers: nikic, spatel, xbolva00, RKSimon
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65151
llvm-svn: 370351
Summary:
Now that with D65143/D65144 we've produce `@llvm.umul.with.overflow`,
and with D65147 we've flattened the CFG, we now can see that
the guard may have been there to prevent division by zero is redundant.
We can simply drop it:
```
----------------------------------------
Name: no overflow and not zero
%iszero = icmp ne i4 %y, 0
%umul = umul_overflow i4 %x, %y
%umul.ov = extractvalue {i4, i1} %umul, 1
%retval.0 = and i1 %iszero, %umul.ov
ret i1 %retval.0
=>
%iszero = icmp ne i4 %y, 0
%umul = umul_overflow i4 %x, %y
%umul.ov = extractvalue {i4, i1} %umul, 1
%retval.0 = and i1 %iszero, %umul.ov
ret %umul.ov
Done: 1
Optimization is correct!
```
Reviewers: nikic, spatel, xbolva00
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65150
llvm-svn: 370350
As discussed in PR42696:
https://bugs.llvm.org/show_bug.cgi?id=42696
...but won't help that case yet.
We have an odd situation where a select operand equivalence fold was
implemented in InstSimplify when it could have been done more generally
in InstCombine if we allow dropping of {nsw,nuw,exact} from a binop operand.
Here's an example:
https://rise4fun.com/Alive/Xplr
%cmp = icmp eq i32 %x, 2147483647
%add = add nsw i32 %x, 1
%sel = select i1 %cmp, i32 -2147483648, i32 %add
=>
%sel = add i32 %x, 1
I've left the InstSimplify code in place for now, but my guess is that we'd
prefer to remove that as a follow-up to save on code duplication and
compile-time.
Differential Revision: https://reviews.llvm.org/D65576
llvm-svn: 367695
Summary:
SimplifyFPBinOp is a variant of SimplifyBinOp that lets you specify
fast math flags, but the name is misleading because both functions
can simplify both FP and non-FP ops. Instead, overload SimplifyBinOp
so that you can optionally specify fast math flags.
Likewise for SimplifyFPUnOp.
Reviewers: spatel
Reviewed By: spatel
Subscribers: xbolva00, cameron.mcinally, eraman, hiraditya, haicheng, zzheng, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64902
llvm-svn: 366902
Summary:
- As the pointer stripping could trace through `addrspacecast` now, need
to sext/trunc the offset to ensure it has the same width as the
pointer after stripping.
Reviewers: jdoerfert
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64768
llvm-svn: 366162
The interface predates CallBase, so both it and implementation were
significantly more complicated than they needed to be. There was even
some redundancy that could be eliminated.
Should also help with OpaquePointers by not trying to derive a
function's type from it's PointerType.
llvm-svn: 365767
This patch replaces the three almost identical "strip & accumulate"
implementations for constant pointer offsets with a single one,
combining the respective functionalities. The old interfaces are kept
for now.
Differential Revision: https://reviews.llvm.org/D64468
llvm-svn: 365723
As discussed in PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
Improving the canonicalization for these patterns:
rL363956
...means we should adjust/enhance the related simplification.
https://rise4fun.com/Alive/w1cp
Name: isPow2 or zero
%x = and i32 %xx, 2048
%a = add i32 %x, -1
%r = and i32 %a, %x
=>
%r = i32 0
llvm-svn: 363997
Fix folds of addo and subo with an undef operand to be:
`@llvm.{u,s}{add,sub}.with.overflow` all fold to `{ undef, false }`,
as per LLVM undef rules.
Same for commuted variants.
Based on the original version of the patch by @nikic.
Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=42209 | PR42209 ]]
Differential Revision: https://reviews.llvm.org/D63065
llvm-svn: 363522
This is another step towards correcting our usage of fast-math-flags when applied on an fcmp.
In this case, we are checking for 'nnan' on the fcmp itself rather than the operand of
the fcmp. But I'm leaving that clause in until we're more confident that we can stop
relying on fcmp's FMF.
By using the more general "isKnownNeverNaN()", we gain a simplification shown on the
tests with 'uitofp' regardless of the FMF on the fcmp (uitofp never produces a NaN).
On the tests with 'fabs', we are now relying on the FMF for the call fabs instruction
in addition to the FMF on the fcmp.
This is a continuation of D62979 / rL362879.
llvm-svn: 362903
This is 1 step towards correcting our usage of fast-math-flags when applied on an fcmp.
In this case, we are checking for 'nnan' on the fcmp itself rather than the operand of
the fcmp. But I'm leaving that clause in until we're more confident that we can stop
relying on fcmp's FMF.
By using the more general "isKnownNeverNaN()", we gain a simplification shown on the
tests with 'uitofp' regardless of the FMF on the fcmp (uitofp never produces a NaN).
On the tests with 'fabs', we are now relying on the FMF for the call fabs instruction
in addition to the FMF on the fcmp.
I'll update the 'ult' case below here as a follow-up assuming no problems here.
Differential Revision: https://reviews.llvm.org/D62979
llvm-svn: 362879
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 the sibling transform for rL360899 (D61691):
maxnum(X, GreaterC) == C --> false
maxnum(X, GreaterC) <= C --> false
maxnum(X, GreaterC) < C --> false
maxnum(X, GreaterC) >= C --> true
maxnum(X, GreaterC) > C --> true
maxnum(X, GreaterC) != C --> true
llvm-svn: 361118
Roman Lebedev