These tests make sure that the range information is properly
understood during computeKnownBits analysis.
NFC
Differential Revision: https://reviews.llvm.org/D88934
The initial version of the patch was reverted because it missed the check that
the predicate being proved is actually guarded by this check on 1st iteration.
If it was not executed on 1st iteration (but possibly executes after that), then
it is incorrect to use reasoning about IV start to prove it.
Added the test where the miscompile was seen. Unfortunately, my attempts
to reduce it with bugpoint did not succeed; it can further be reduced when
we understand how to do it without losing the initial bug's notion.
Returning assuming the miscompiles are now gone.
Differential Revision: https://reviews.llvm.org/D88208
The logic there only considers `SLT/SGT` predicates. We can use the same logic
for proving `ULT/UGT` predicates if all involved values are non-negative.
Adding full-scale support for unsigned might be challenging because of code amount,
so we can consider this in the future.
Differential Revision: https://reviews.llvm.org/D88087
Reviewed By: reames
If we know that some predicate is true for AddRec and an invariant
(w.r.t. this AddRec's loop), this fact is, in particular, true on the first
iteration. We can try to prove the facts we need using the start value.
The motivating example is proving things like
```
isImpliedCondOperands(>=, X, 0, {X,+,-1}, 0}
```
Differential Revision: https://reviews.llvm.org/D88208
Reviewed By: reames
It was mentioned that D88276 that when a phi node is visited, terminators at their incoming edges should be used for CtxI.
This is a patch that makes two functions (ComputeNumSignBitsImpl, isGuaranteedNotToBeUndefOrPoison) to do so.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D88360
This is a patch that allows isGuaranteedNotToBeUndefOrPoison to return more precise result
when an argument is given, by looking through its uses at the entry block (and following blocks as well, if it is checking poison only).
This is useful when there is a function call with noundef arguments at the entry block.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D88207
For some expressions, we can use information from loop guards when
we are looking for a maximum. This patch applies information from
loop guards to the expression used to compute the maximum backedge
taken count in howFarToZero. It currently replaces an unknown
expression X with UMin(X, Y), if the loop is guarded by
X ult Y.
This patch is minimal in what conditions it applies, and there
are a few TODOs to generalize.
This partly addresses PR40961. We will also need an update to
LV to address it completely.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D67178
This takes the mapped instructions from the IRInstructionMapper, and
passes it to the Suffix Tree to find the repeated substrings. Within
each set of repeated substrings, the IRSimilarityCandidates are compared
against one another for structure, and ensuring that the operands in the
instructions are used in the same way. Each of these structurally
similarity IRSimilarityCandidates are contained in a SimilarityGroup.
Tests checking for identifying identity of structure, different
isomorphic structure, and different
nonisomoprhic structure are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.
Differential Revision: https://reviews.llvm.org/D86972
Just because sequences of instructions are similar to one another,
doesn't mean they are doing the same thing.
This introduces a structural check for the IRSimilarityCandidate that
compares two IRSimilarityCandidates against one another, and in each
instruction creates a mapping between the operands and results, or
checks that the existing mapping is valid. If this check passes, it
means we have structurally similar IRSimilarityCandidates.
Tests for whether the candidates are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.
Recommit of: b27db2bb68 for Differential
URL.
Differential Revision: https://reviews.llvm.org/D86971
Just because sequences of instructions are similar to one another,
doesn't mean they are doing the same thing.
This introduces a structural check for the IRSimilarityCandidate that
compares two IRSimilarityCandidates against one another, and in each
instruction creates a mapping between the operands and results, or
checks that the existing mapping is valid. If this check passes, it
means we have structurally similar IRSimilarityCandidates.
Tests for whether the candidates are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.
This seems to fit the CGSCC updates model better than calling
addNewFunctionInto{Ref,}SCC() on newly created/outlined functions.
Now addNewFunctionInto{Ref,}SCC() are no longer necessary.
However, this doesn't work on newly outlined functions that aren't
referenced by the original function. e.g. if a() was outlined into b()
and c(), but c() is only referenced by b() and not by a(), this will
trigger an assert.
This also fixes an issue I was seeing with newly created functions not
having passes run on them.
Ran check-llvm with expensive checks.
Reviewed By: asbirlea
Differential Revision: https://reviews.llvm.org/D87798
The IRSimilarityCandidate is a container to hold a region of
IRInstructions and offer interfaces for the starting instruction, ending
instruction, parent function, length. It also assigns a global value
number for each unique instance of a value in the region.
It also contains an interface to compare two IRSimilarity as to whether
they have the same sequence of similar instructions.
Tests for whether the instructions are similar are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.
Recommit of: 4944bb190f
Differential Revision: https://reviews.llvm.org/D86970
The IRSimilarityCandidate is a container to hold a region of
IRInstructions and offer interfaces for the starting instruction, ending
instruction, parent function, length. It also assigns a global value
number for each unique instance of a value in the region.
It also contains an interface to compare two IRSimilarity as to whether
they have the same sequence of similar instructions.
Tests for whether the instructions are similar are found in
unittests/Analysis/IRSimilarityIdentifierTest.cpp.
Differential Revision: https://reviews.llvm.org/D86970
The IRInstructionData structs are a different representation of the
program. This list treats the program as if it was "flattened" and
the only parent is this list. This lets us easily create ranges of
instructions.
Differential Revision: https://reviews.llvm.org/D86969
This patch extends SCEVParameterRewriter to support rewriting unknown
epxressions to arbitrary SCEV expressions. It will be used by further
patches.
Reviewed By: reames
Differential Revision: https://reviews.llvm.org/D67176
This introduces the IRInstructionMapper, and the associated wrapper for
instructions, IRInstructionData, that maps IR level Instructions to
unsigned integers.
Mapping is done mainly by using the "isSameOperationAs" comparison
between two instructions. If they return true, the opcode, result type,
and operand types of the instruction are used to hash the instruction
with an unsigned integer. The mapper accepts instruction ranges, and
adds each resulting integer to a list, and each wrapped instruction to
a separate list.
At present, branches, phi nodes are not mapping and exception handling
is illegal. Debug instructions are not considered.
The different mapping schemes are tested in
unittests/Analysis/IRSimilarityIdentifierTest.cpp
Recommit of: b04c1a9d31
Differential Revision: https://reviews.llvm.org/D86968
This introduces the IRInstructionMapper, and the associated wrapper for
instructions, IRInstructionData, that maps IR level Instructions to
unsigned integers.
Mapping is done mainly by using the "isSameOperationAs" comparison
between two instructions. If they return true, the opcode, result type,
and operand types of the instruction are used to hash the instruction
with an unsigned integer. The mapper accepts instruction ranges, and
adds each resulting integer to a list, and each wrapped instruction to
a separate list.
At present, branches, phi nodes are not mapping and exception handling
is illegal. Debug instructions are not considered.
The different mapping schemes are tested in
unittests/Analysis/IRSimilarityIdentifierTest.cpp
Differential Revision: https://reviews.llvm.org/D86968
When adding a new function via addNewFunctionIntoRefSCC(), it creates a
new node and immediately populates the edges. Since populateSlow() calls
G->get() on all referenced functions, it will create a node (but not
populate it) for functions that haven't yet been added. If we add two
mutually recursive functions, the assert that the node should never have
been created will fire when the second function is added. So here we
remove that assert since the node may have already been created (but not
yet populated).
createNode() is only called from addNewFunctionInto{,Ref}SCC().
https://bugs.llvm.org/show_bug.cgi?id=47502
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D87623
This patch adds a isConditionImplied function that
takes a constraint and returns true if the constraint
is implied by the current constraints in the system.
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D84545
This patch recommits "[ConstraintSystem] Add helpers to deal with linear constraints."
(it reverts the revert commit 8da6ae4ce1).
The reason for the revert was using __builtin_multiply_overflow, which
is not available for all compilers. The patch has been updated to use
MulOverflow from MathExtras.h
NOTE: There is a mailing list discussion on this: http://lists.llvm.org/pipermail/llvm-dev/2019-December/137632.html
Complemantary to the assumption outliner prototype in D71692, this patch
shows how we could simplify the code emitted for an alignemnt
assumption. The generated code is smaller, less fragile, and it makes it
easier to recognize the additional use as a "assumption use".
As mentioned in D71692 and on the mailing list, we could adopt this
scheme, and similar schemes for other patterns, without adopting the
assumption outlining.
This patch introduces a new ConstraintSystem class, that maintains a set
of linear constraints and uses Fourier–Motzkin elimination to eliminate
constraints to check if there are solutions for the system.
It also adds a convert-constraint-log-to-z3.py script, which can parse
the debug output of the constraint system and convert it to a python
script that feeds the constraints into Z3 and checks if it produces the
same result as the LLVM implementation. This is for verification
purposes.
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D84544
This implements support for isKnownNonZero, computeKnownBits when freeze is involved.
```
br (x != 0), BB1, BB2
BB1:
y = freeze x
```
In the above program, we can say that y is non-zero. The reason is as follows:
(1) If x was poison, `br (x != 0)` raised UB
(2) If x was fully undef, the branch again raised UB
(3) If x was non-zero partially undef, say `undef | 1`, `freeze x` will return a nondeterministic value which is also non-zero.
(4) If x was just a concrete value, it is trivial
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D75808
This patch adds isGuaranteedNotToBePoison and programUndefinedIfUndefOrPoison.
isGuaranteedNotToBePoison will be used at D75808. The latter function is used at isGuaranteedNotToBePoison.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D84242
This patch adds an initial, incomeplete and unsound implementation of
canReplacePointersIfEqual to check if a pointer value A can be replaced
by another pointer value B, that are deemed to be equivalent through
some means (e.g. information from conditions).
Note that is in general not sound to blindly replace pointers based on
equality, for example if they are based on different underlying objects.
LLVM's memory model is not completely settled as of now; see
https://bugs.llvm.org/show_bug.cgi?id=34548 for a more detailed
discussion.
The initial version of canReplacePointersIfEqual only rejects a very
specific case: replacing a pointer with a constant expression that is
not dereferenceable. Such a replacement is problematic and can be
restricted relatively easily without impacting most code. Using it to
limit replacements in GVN/SCCP/CVP only results in small differences in
7 programs out of MultiSource/SPEC2000/SPEC2006 on X86 with -O3 -flto.
This patch is supposed to be an initial step to improve the current
situation and the helper should be made stricter in the future. But this
will require careful analysis of the impact on performance.
Reviewed By: aqjune
Differential Revision: https://reviews.llvm.org/D85524
For StackLifetime after finding alloca we need to check that
values ponting to the begining of alloca.
Reviewed By: eugenis
Differential Revision: https://reviews.llvm.org/D86692
We only need the C++ type and the corresponding TF Enum. The other
parameter was used for the output spec json file, but we can just
standardize on the C++ type name there.
Differential Revision: https://reviews.llvm.org/D86549
These were implementation detail, but become necessary for generic data
copying.
Also added const variations to them, and move assignment, since we had a
move ctor (and the move assignment helps in a subsequent patch).
Differential Revision: https://reviews.llvm.org/D85262
Added a mechanism to check the element type, get the total element
count, and the size of an element.
Differential Revision: https://reviews.llvm.org/D85250
A JSON->TensorSpec utility we will use subsequently to specify
additional outputs needed for certain training scenarios.
Differential Revision: https://reviews.llvm.org/D84976
As discussed on D81500, this adds a more general ElementCount variant of the build helper and converts the (non-scalable) unsigned NumElts variant to use it internally.
Quentin Colombet