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.
Adds a spirv-fuzz option for converting a SPIR-V shader into a shader
that renders red, whilst containing the body of the original shader.
This is for aiding in compiler crash bug reporting.
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.
The performance of the fuzzer was unacceptable in the 'permute blocks'
transformation, due to dominator analysis being repeatedly invalidated
and recomputed. This change preserves the dominator analysis,
together with the CFG analysis, when a block is moved down.
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.
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 generates protobuf sources in a 'protobuf' directory. When
building with Unix Makefiles, compilation would fail due to to this
directory not existing. This change causes the directory to be
created when the build is prepared.
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.
A new fuzzer pass that randomly introduces OpCopyObject instructions
that make copies of ids, and uses the fact manager to record the fact
that an id %id is synonymous with an id generated by an OpCopyObject
applied to %id. (A future pass will exploit such synonym facts.)
Before this change there was quite a lot of duplication in the code
being used to choose random percentages, and some of it was incorrect
so that a percentage chance of (100-N)% instead of N% was being used.
Also there was a lot of duplicate code to choose a random index into a
vector. This change eliminates that duplication (fixing up the
percentage problem), and gets rid of direct access to the random
number generator being used for fuzzing, so that all randomization
requests must go through the FuzzerContext class, discouraging future
ad-hoc uses of the random number generator.
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.
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#2621.
Instead of aborting when an invalid input fact is provided, the tool
now warns about the invalid fact and then ignores it. This is
convenient for example if facts are specified about uniforms with
descriptor sets and bindings that happen to not be present in the
input binary.
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.
Adds a library for spirv-fuzz, consisting of a Fuzzer class that will
transform a module with respect to (a) facts about the module provided
via a FactManager class, and (b) a source of random numbers and
parameters to control the transformation process provided via a
FuzzerContext class. Transformations will be applied via classes that
implement a FuzzerPass interface, and both facts and transformations
will be represented via protobuf messages. Currently there are no
concrete facts, transformations nor fuzzer passes; these will follow.
