Changed a couple small parts of the algorithm to reduce time to build
the dominator trees. There should be no visible changes.
Add a depth first search algorithm that does not run a function on
backedges. The check if an edge is a back edge is time consuming, and
pointless if the function run on it is a nop.
Add name annotations to the generated instrumentation code to
make it easier to understand. Example spirv-cross output:
vec4 _140;
if (0u < inst_bindless_direct_read_4(0u, 0u, 1u, uint(_19)))
{
_140 = texture(textures[nonuniformEXT(_19)], inUV);
}
else
{
inst_bindless_stream_write_4(50u, 1u, uint(_19), 0u);
_140 = vec4(0.0);
}
* Improve algorithm to reorder blocks in a function
In dead branch elimination, blocks can end up in a the wrong order, so
there is code to reorder the blocks in structured order. The problem is
that the algorithm to do that is very poor. It involves many searchs in
the function for the correct position to place the block, as well as
moving many block in the vector.
The solution is to write a specialized function in the function class
that will reorder the blocks in structured order. After computing the
structured order, reordering the block can be done in linear time, with
very little overhead.
Using SinglePassRunAndMatch<> instead of SinglePassRunAndCheck<>
makes tests more concise and makes it possible to use pattern
matching features.
Using Effcee stateful pattern matching to make it less repetitive
to check for generated functions and global variables.
This approach isn't worth
it for DebugPrintf functions because the generated code will change
depending on how many parameters are passed to every debugPrintfEXT()
call.
* spirv-opt: fix copy-propagate-arrays index opti on structs.
As per SPIR-V spec:
OpAccessChain indices must be OpConstant when indexing into a structure.
This optimization tried to remove load cascade. But in some scenario
failed:
```c
cbuffer MyStruct {
uint my_field;
};
uint main(uint index) {
const uint my_array[1] = { my_field };
return my_array[index]
}
```
This is valid as the struct is indexed with a constant index, and then
the array is indexed using a dynamic index.
The optimization would consider the local array to be useless and
generated a load directly into the struct.
* spirv-opt: prevent creation of unused instructions
Copy-propagate-arrays optimization pass would create unused constants,
even if the optimization not completed.
This was caused by the way we handled OpAccessChain squashing: we
only referenced constants, and had to create them upfront.
Fixes#4887
Signed-off-by: Nathan Gauër <brioche@google.com>
Specifically, DebugSourceContinued, DebugCompilationUnit, and
DebugEntryPoint. These instructions are top-level instructions
which do not or may not have a user except for the tool and so
should not be eliminated.
The previous amend to the CHANGES file mentioned v2022.4. That was a
mistake as v2022.3 was never released.
Signed-off-by: Nathan Gauër <brioche@google.com>
When folding a vector shuffle with an undef literal, it is possible that the
literal is adjusted so that it will then be interpreted as an index into
the input operands. This is fixed by special casing that case, and not
adjusting those operands.
Fixes#4859
Disassembler was called with non-default params, loosing FRIENDLY_NAMES.
This commit changes the call options to allow the spirv-opt to show
friendly names instead of raw-ids. Might be more helpful when reading
the SPIRV-opt output.
Fixes#4882
Signed-off-by: Nathan Gauër <brioche@google.com>
An access chain instruction interpretes its index operands as signed.
The composite insert and extract instruction interpret their index
operands as unsigned, so it is not possible to represent a negative
number.
This commit adds a check to the local-access-chain-convert pass to check
for a negative number in the access chain and to not do the conversion.
Fixes#4856
These asserts are not valid for string literals, which may
contain several words:
assert(a_operand.words.size() == 1);
assert(b_operand.words.size() == 1);
It looks like they only make sense for the default case, which
assumes that both operands contain a single word.
Running a debug version of spirv-diff on any shader containing
a string literal will hit the original asserts.
A recent libc++ roll in Chrome warned of a deprecated copy. We're
still looking if this is a bug in libc++ or a valid warning, but
removing the redundant line is a safe workaround or fix in either
case.
See discussion in https://crrev.com/c/3791771
* spirv-as: Avoid overflow when parsing exponents on hex floats
When an exponent is so large that it would overflow the int
type in the parser, saturate the exponent.
This allows extremely large exponents, and saturates
to infinity when the exponent is positive, and zero when the exponent
is negative.
Fixes#4721.
* Avoid unexpected narrowing conversions from arithmetic operations
Co-authored-by: Alastair F. Donaldson <alastair.donaldson@imperial.ac.uk>
Excessive whitespace can lead to stack overflow during parsing as each
character of skipped whitespace involves a recursive call. An
iterative solution avoids this.
Fixes#4729.
This reverts commit d18d0d92e5.
This is reverted because it causes a 7X slowdown when legalizing
SPIR-V with NonSemantic.Shader.DebugInfo.100 instructions.
This is due to the creation of very large UseLists for several
heavily used operands for this extension combined with the fact
that the original commit changed the performance of Uselists to O(n).
Fix code that is traversing def-use user structure at the same time
that it is changing it. This is dicey at best and error prone at worst.
This was uncovered making a change to the id_to_user representation.
Fixes https://crbug.com/oss-fuzz48578
* Adds structural reachability to basic blocks
* calculated in same manner as reachability, but using structural
successors
* Change structured CFG validation to use structural reachability
instead of reachability
* Fix some invalid reducer cases
The fuzzer cretes code with very large array, and scalar replacement
times out. Adding a limit on the size of the composites that will be
split when fuzzing.
Fixes https://crbug.com/oss-fuzz/48630
Arrays do not have to have a size that is known at compile time. It
could be a spec constant. In these cases, treat the array
as if it is arbitrarily long. This commit will treat it like it is an
array of size UINT32_MAX.
Fixes https://crbug.com/oss-fuzz/47397.
If the `instruction` operand in an extended instruction instruction is
too large, it causes undefined behaviour when that value is cast to the
enum for the corresponding set. This is done with the
NonSemanticDebug100 instruction set. We need to avoid the undefined
behaviour.
Fixes#4727
Which functions are processed is determined by which ones are on the
call tree from the entry points before dead code is removed. So it is
possible that a function is process because it is called from an entry
point, but the CFG is not cleaned up because the call to the function
was removed.
The fix is to process and cleanup every function in the module. Since
all of the dead functions would have already been removed in an earlier
step of DCE, it should not make a different in compile time.
Fixes#4731
