DFAJumpThreading
JumpThreading
LibCallsShrink
LoopVectorize
SLPVectorizer
DeadStoreElimination
AggressiveDCE
CorrelatedValuePropagation
IndVarSimplify
These are part of the optimization pipeline, of which the legacy version is deprecated and being removed.
As a side-effect, this switchem them to use getConstantRange() rather
than getPredicateAt(). getPredicateAt() is not supposed to be more
powerful than getConstantRange() for non-equality comparisons (as
long as block values are used).
When an instruction is only used in a select or phi operand, we might
be able to make use of additional information from the select/branch
condition. For example in
%sub = call i16 @llvm.usub.sat.i16(i16 %x, i16 10)
%cmp = icmp uge i16 %x, 10
%sel = select i1 %cmp, i16 %sub, i16 42
the usub.sat is only used in a select where %x uge 10 is known to
hold, so we can fold it based on that knowledge.
This addresses the regression reported at
https://reviews.llvm.org/D140798#4039748, but also provides a
solution to a recurring problem we've had, where we fail to make
use of range information after a branch+phi has been converted
into a select. Our current solution to this is to hope that IPSCCP
can perform the fold before that happens, but handling this in LVI
is a somewhat more general solution.
Currently we only make use of this for the willNotOverflow() fold,
but I plan to adjust other folds to use the new API as well.
Differential Revision: https://reviews.llvm.org/D141482
For `srem x, y`, if abs(constant range of x) less than abs(constant
range of y), we can simplify it as:
`srem x, y => x` if y is guaranteed to be positive.
'srem x, y => -x' if y is guaranteed to be negative.
Differential Revision: https://reviews.llvm.org/D140405
As per the post-commit feedback - that was not the correct precondition
to avoid it here. I think we should generally start changing mentality
about `freeze`, the fact that we have been conditioned to be afraid of it
(or of anything in LLVM in general) is the key problem here.
This kind of thing happens really frequently in LLVM's very own
shuffle combining methods, and it is even considered bad practice
to use `%` there, instead of using this expansion directly.
Though, many of the cases there have variable divisors,
so this won't help everything.
Simple case: https://alive2.llvm.org/ce/z/PjvYf-
There's alternative expansion via `umin`:
https://alive2.llvm.org/ce/z/hWCVPb
BUT while we can transform the first expansion
into the `umin` one (e.g. for SCEV):
https://alive2.llvm.org/ce/z/iNxKmJ
... we can't go in the opposite direction.
Also, the non-`umin` expansion seems somewhat more codegen-friendly:
https://godbolt.org/z/qzjx5bqWKhttps://godbolt.org/z/a7bj1axbx
There's second variant of precondition:
https://alive2.llvm.org/ce/z/zE6cbM
but there the numerator must be non-undef / must be frozen.
CVP currently only tries to simplify comparisons if there is a
constant operand. However, even if both are non-constant, we may
be able to determine the result of the comparison based on range
information.
IPSCCP is already capable of doing this, but because it runs very
early, it may miss some cases.
Differential Revision: https://reviews.llvm.org/D137253
This patch fixes an issue in which CorrelatedValuePropagation::processSRem
would create new instructions to represent the SRem instruction, but would not
correctly copy any existing debug location metadata to the new instruction.
Differential Revision: https://reviews.llvm.org/D132218
Clang-format InstructionSimplify and convert all "FunctionName"s to
"functionName". This patch does touch a lot of files but gets done with
the cleanup of InstructionSimplify in one commit.
This is the alternative to the less invasive clang-format only patch: D126783
Reviewed By: spatel, rengolin
Differential Revision: https://reviews.llvm.org/D126889
Most clients only used these methods because they wanted to be able to
extend or truncate to the same bit width (which is a no-op). Now that
the standard zext, sext and trunc allow this, there is no reason to use
the OrSelf versions.
The OrSelf versions additionally have the strange behaviour of allowing
extending to a *smaller* width, or truncating to a *larger* width, which
are also treated as no-ops. A small amount of client code relied on this
(ConstantRange::castOp and MicrosoftCXXNameMangler::mangleNumber) and
needed rewriting.
Differential Revision: https://reviews.llvm.org/D125557
Previously we took the old name and always appended a numberic suffix.
Since we're doing a 1:1 replacement, it's clearer to keep the original
name exactly.
Reviewed By: fhahn
Differential Revision: https://reviews.llvm.org/D125281
The "Correlated Value Propagation" pass was missing a case when handling select instructions. It was only handling the "false" constant value, while in NVPTX the select may have the condition (and thus the branches) inverted, for example:
```
loop:
%phi = phi i32* [ %sel, %loop ], [ %x, %entry ]
%f = tail call i32* @f(i32* %phi)
%cmp1 = icmp ne i32* %f, %y
%sel = select i1 %cmp1, i32* %f, i32* null
%cmp2 = icmp eq i32* %sel, null
br i1 %cmp2, label %return, label %loop
```
But the select condition can be inverted:
```
%cmp1 = icmp eq i32* %f, %y
%sel = select i1 %cmp1, i32* null, i32* %f
```
The fix is to enhance "Correlated Value Propagation" to handle both branches of the select instruction.
Reviewed By: nikic, lebedev.ri
Differential Revision: https://reviews.llvm.org/D119643
Fixes PR#52190. There is already a check for converting ashr instructions with non-negative left-hand sides into lshr; this patch adds an optimization to remove ashr altogether if the left-hand side is known to be in the range [-1, 1).
Differential Revision: https://reviews.llvm.org/D113835
This canonicalization breaks the ability to discard checks in some cases.
Add a command line option to disable it. This option is on by default,
so the change is NFC.
See for details:
https://reviews.llvm.org/D112895#3149487
Now that the reasoning was added to ConstantRange in D90924,
this replicates IndVars variant of this transform (D111836)
in a pass that uses value range reasoning for the transform.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D112895
This renames the primary methods for creating a zero value to `getZero`
instead of `getNullValue` and renames predicates like `isAllOnesValue`
to simply `isAllOnes`. This achieves two things:
1) This starts standardizing predicates across the LLVM codebase,
following (in this case) ConstantInt. The word "Value" doesn't
convey anything of merit, and is missing in some of the other things.
2) Calling an integer "null" doesn't make any sense. The original sin
here is mine and I've regretted it for years. This moves us to calling
it "zero" instead, which is correct!
APInt is widely used and I don't think anyone is keen to take massive source
breakage on anything so core, at least not all in one go. As such, this
doesn't actually delete any entrypoints, it "soft deprecates" them with a
comment.
Included in this patch are changes to a bunch of the codebase, but there are
more. We should normalize SelectionDAG and other APIs as well, which would
make the API change more mechanical.
Differential Revision: https://reviews.llvm.org/D109483
This reverts commit 9934a5b2ed5aa6e6bbb2e55c3cd98839722c226e.
This patch may cause miscompiles because it missed a constraint
as shown in the examples from:
https://llvm.org/PR51531
The common phi value transform replaces constants with values that
have the same value as the constant on a given edge. However, LVI
generally only provides information that is correct up to poison,
so this can end up replacing a well-defined value with poison.
D69442 addressed an instance of this problem by clearing poison
flags on the generating instruction, which was sufficient at the
time. rGa917fb89dc28 made LVI's edge value analysis slightly more
powerful, and clearing poison flags is no longer sufficient.
This patch changes the transform to instead explicitly guard against
a poison value instead. This should be satisfied for most cases due
to a prior branch on poison.
Fixes https://bugs.llvm.org/show_bug.cgi?id=50399.
Differential Revision: https://reviews.llvm.org/D102966
Currently all AA analyses marked as preserved are stateless, not taking
into account their dependent analyses. So there's no need to mark them
as preserved, they won't be invalidated unless their analyses are.
SCEVAAResults was the one exception to this, it was treated like a
typical analysis result. Make it like the others and don't invalidate
unless SCEV is invalidated.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D102032
Recently processMinMaxIntrinsic has been added and we started to observe a number of analysis get invalidated after CVP. The problem is CVP conservatively returns 'true' even if there were no modifications to IR. I found one more place besides processMinMaxIntrinsic which has the same problem. I think processMinMaxIntrinsic and similar should better have boolean return status to prevent similar issue reappear in future.
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D100538
The default is likely wrong.
Out of all the callees, only a single one needs to pass-in false (JumpThread),
everything else either already passes true, or should pass true.
Until the default is flipped, at least make it harder to unintentionally
add new callees with UseBlockValue=false.
