This change fixes a bug in EquivalenceRelation, changes the interface
of EquivalenceRelation to avoid exposing (potentially
nondeterministic) unordered sets, and changes the interface of
FactManager to allow querying data synonyms directly. These interface
changes have required a lot of corresponding changes to client code
and tests.
At present, TransformationReplaceIdWithSynonym both extracts elements
from composite objects and replaces uses of ids with synonyms. This
new TransformationCompositeExtract class will allow that
transformation to be broken into smaller transformations.
Class TransformationConstructComposite has been renamed to
TransformationCompositeConstruct, to correspond to the name of the
SPIR-V instruction (as is done with e.g. TransformationCopyObject).
Running tests revealed an issue related to checking dominance in
TransformationReplaceIdWithSynonym, which is also fixed here.
This change uses the recently-added equivalence relation class to
re-work the way synonyms between data values are managed by the fact
manager.
The tests for 'transformation_replace_id_with_synonym' have been
temporarily removed. This is because those tests are going to be
split into a number of test classes in an upcoming PR, once some other
refactorings have been applied, and it would be burdensome to
temporarily refactor all the tests to be in a working state for this
intermediate change.
Adds a templated class for representing an equivalence relation on a
value data type. This will be used by spirv-fuzz for representing
sets of distinct pieces of data in a shader that are known to have
equal values.
A new pass that gives spirv-fuzz the ability to adjust the memory
operand masks associated with memory access instructions (such as
OpLoad and OpCopy Memory).
Fixes#2940.
This change refactors the 'split blocks' transformation so that an
instruction is identified via a base, opcode, and number of those
opcodes to be skipped when searching from the base, as opposed to the
previous design which used a base and offset.
A refactoring that separates the identification of an instruction from
the identification of a use in an instruction, to enable the former to
be used independently of the latter.
A new pass that allows the fuzzer to change the 'loop control' operand
(and associated literal operands) of OpLoopMerge instructions.
Fixes#2938.
Fixes#2943.
Adds a fuzzer pass and transformation to create a composite (array,
matrix, struct or vector) from available constituent components, and
inform the fact manager that each component of the new composite is
synonymous with the id that was used to construct it. This allows the
"replace id with synonym" pass to then replace uses of said ids with
uses of elements extracted from the composite.
Fixes#2858.
Issue #2919 identifies a problem in spirv-fuzz's ability to determine
when it is safe to add a new control flow edge without breaking
dominance rules. This change adds a (currently disabled) test to
expose the issue, and a comment to document that the current solution
is incomplete.
Because dominance information becomes a bit unreliable when blocks are
unreachable, this change makes it so that the 'dead break'
transformation will not introduce a break to an unreachable block.
Fixes#2907.
This change introduces a robust check for whether an index in an
access chain is indexing into a struct, in which case the index needs
to be an OpConstant and cannot be replaced with a synonym.
Fixes#2906.
Issues #2898 and #2900 identify some cases where adding a dead
continue would lead to an invalid module, and these turned out to be
due to the lack of sensible dominance information when a continue
target is unreachable. This change requires that the header of a loop
dominates the loop's continue target if a dead continue is to be
added.
Furthermore, issue #2905 identified a shortcoming in the algorithm
being used to identify when it is OK, from a dominance point of view,
to add a new break/continue edge to a control flow graph. This change
replaces that algorithm with a simpler and more obviously correct
algorithm (that incidentally does not require the new edge to be a
break/continue edge in particular).
Fixes#2898.
Fixes#2900.
Fixes#2905.
Before this change, spirv-fuzz would replace a pointer argument to a
function call with a synonym, which is problematic when the synonym is
not a memory object declaration, since function call arguments are
required to be memory object declarations. This change adds a check
to ensure that such a replacement is not made.
Fixes#2896.
Before this change, spirv-fuzz would replace a constant boolean
argument to an OpPhi with the result of a binary operation, inserting
the instruction to compute the binary operation right before the
OpPhi, leading to an invalid module. This change conservatively
disallows replacing OpPhi arguments. Issue #2902 notes that there is
scope for being less conservative.
Fixes#2897.
This change to spirv-fuzz uses ideas from "Swarm Testing" (Groce et al. 2012), so that a random subset of fuzzer passes are enabled. These passes are then applied repeatedly in a randomized fashion, with the aggression with which they are applied being randomly chosen per pass.
There is plenty of scope for refining the probabilities introduce in this change; this is just meant to be a reasonable first effort.
A previous change that disabled long-running tests by default failed
to enable short-running tests when long-running tests are enabled.
This change fixes that problem.
To aid in debugging issues in spirv-fuzz, this change adds an option whereby the SPIR-V module is validated after each transformation is applied during replay. This can assist in finding a transformation that erroneously makes the module invalid, so that said transformation can be debugged.
spirv-fuzz has useful tests that run the fuzzer and shrinker, to give
the whole tool a good shake up, effectively "fuzzing the fuzzer". The
problems that this detects are sensitive to the source of randomness
that is used, which can change from test platform to test platform.
It is thus not a good idea to run these tests by default during
continuous integration - they may end up failing due to environtal
factors, making it look like an unrelated change has broken the fuzzer
when really the fuzzer has revealed an already-existing bug in itself.
This change makes the tests disabled by default; they can enabled
during dedicated testing of the fuzzer.
If the fuzzer's fact manager knows that ids A and B are synonymous, it
can replace a use of A with a use of B, so long as various conditions
hold (e.g. the definition of B must dominate the use of A, and it is
not legal to replace a use of an OpConstant in a struct's access chain
with a synonym that is not an OpConstant).
This change adds a fuzzer pass to sprinke such synonym replacements
through the module.
The implementation of these passes had overlooked the fact that adding
a new edge to a control flow graph can change dominance information.
Adding a dead break/continue risks causing uses to no longer be
dominated by their definitions. This change introduces various tests
to expose such scenarios, and augments the preconditions for these
transformations with checks to guard against the situation.
This transformation can introduce an instruction that uses
OpCopyObject to make a copy of some other result id. This change
introduces the transformation, but does not yet introduce a fuzzer
pass to actually apply it.
The recently added fuzzer_replayer and fuzzer_shrinker tests were
rather heavyweight and were leading to CI timeouts. This change
reduces the runtime of those tests by having them do fewer iterations.
Similar to the existing 'add dead breaks' pass, this adds a pass to
add dead continues to blocks in loops where such a transformation is
viable. Various functionality common to this new pass and 'add dead
breaks' has been factored into 'fuzzer_util', and some small
improvements to 'add dead breaks' that were identified while reviewing
that code again have been applied.
Fixes#2719.
Adds to spirv-fuzz the option to shrink a sequence of transformations
that lead to an interesting binary to be generated, to find a smaller
sub-sequence of transformations that still lead to an interesting (but
hopefully simpler) binary being generated. The notion of what counts
as "interesting" comes from a user-provided script, the
"interestingness function", similar to the way the spirv-reduce tool
works. The shrinking process will give up after a maximum number of
steps, which can be configured on the command line.
Tests for the combination of fuzzing and shrinking are included, using
a variety of interestingness functions.
Fixes#2695. Allowing unreachable blocks to be moved can lead to an
unreachable block A getting placed after an unreachable successor B,
which is a problem if B uses ids that A generates.
* Represent uniform facts via descriptor set and binding.
Previously uniform facts were expressed with resepect to the id of a
uniform variable. Describing them with respect to a descriptor set
and binding is more convenient from the point of view of expressing
facts about a shader without requiring analysis of its SPIR-V.
* Fix equality testing for uniform buffer element descriptors.
The equality test now checks that the lengths of the index vectors
match. Added a test that exposes the previous omission.
Adds a new transformation that can replace a constant with a uniform known to have the same value, and adds a fuzzer pass that (a) replaces a boolean with a comparison of literals (e.g. replacing "true" with "42 > 24"), and then (b) obfuscates the literals appearing in this comparison by replacing them with identically-valued uniforms, if available.
The fuzzer_replayer test file has also been updated to allow initial facts to be provided, and to do error checking of the status results returned by the fuzzer and replayer components.
The replayer takes an existing sequence of transformations and applies
them to a module. Replaying a sequence of transformations that were
obtained via fuzzing should lead to an identical module to the module
that was fuzzed. Tests have been added to check for this.
Adds a new (and first) kind of fact to the fact manager, which is that
a specific uniform value is guaranteed to be equal to a specific
constant. The point of this is that such information (if known to be
true by some external source) can be used by spirv-fuzz to transform
the module in interesting ways that a static compiler cannot reverse
via compile-time analysis.
This change introduces protobuf messages for the fact, and adds
capabilities to the fact manager to store this kind of fact and
provide information about it.
The transformation can, for example, replace "true" with "12.0 > 6.0",
if constants for those floating-point values are available.
This introduces a new 'id use descriptor' structure, which provides a
way to describe a particular use of an id, and which will be heavily
used in future transformations. Describing an id use is trivial if
the use occurs in an instruction that itself generates an id, but is
less straightforward if the id of interest is used by an instruction
such as OpStore that does not have a result id. The 'id use
descriptor' structure caters for such cases.
There turned out to be a bug in the 'split blocks' transformation due
to blocks being split while they were being iterated over. This
change fixes that issue, and adds tests that were able to expose the
issue by running the fuzzer on some example shaders.
This new pass adds some basic ingredients to a module on which future
passes are likely to depend, such as boolean constants and some
specfic integer and floating-point values. This is not a fuzzer pass
in the true sense in that it does not employ randomization, but it
makes sense to define it as a fuzzer pass since it is the first of a
number of transformations passes that the fuzzer will run on a module.
With this pass, the fuzzer can split blocks in the input module. This
is mainly useful in order to give other (future) transformations more
opportunities to apply.
