This implements the conditional constant propagation pass proposed in
Constant propagation with conditional branches,
Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
The main logic resides in CCPPass::VisitInstruction. Instruction that
may produce a constant value are evaluated with the constant folder. If
they produce a new constant, the instruction is considered interesting.
Otherwise, it's considered varying (for unfoldable instructions) or
just not interesting (when not enough operands have a constant value).
The other main piece of logic is in CCPPass::VisitBranch. This
evaluates the selector of the branch. When it's found to be a known
value, it computes the destination basic block and sets it. This tells
the propagator which branches to follow.
The patch required extensions to the constant manager as well. Instead
of hashing the Constant pointers, this patch changes the constant pool
to hash the contents of the Constant. This allows the lookups to be
done using the actual values of the Constant, preventing duplicate
definitions.
* changed the way duplicate types are removed to stop copying
instructions
* Reworked RemoveDuplicatesPass::AreTypesSame to use type manager and
type equality
* Reworked TypeManager memory management to store a pool of unique
pointers of types
* removed unique pointers from id map
* fixed instances where free'd memory could be accessed
Changes the set of optimizations done for legalization. While doing
this, I added documentation to explain why we want each optimization.
A new option "--legalize-hlsl" is added so the legalization passes can
be easily run from the command line.
The legalize option implies skip-validation.
When a private variable is used in a single function, it can be
converted to a function scope variable in that function. This adds a
pass that does that. The pass can be enabled using the option
`--private-to-local`.
This transformation allows other transformations to act on these
variables.
Also moved `FindPointerToType` from the inline class to the type manager.
Adds a scalar replacement pass. The pass considers all function scope
variables of composite type. If there are accesses to individual
elements (and it is legal) the pass replaces the variable with a
variable for each composite element and updates all the uses.
Added the pass to -O
Added NumUses and NumUsers to DefUseManager
Added some helper methods for the inst to block mapping in context
Added some helper methods for specific constant types
No longer generate duplicate pointer types.
* Now searches for an existing pointer of the appropriate type instead
of failing validation
* Fixed spec constant extracts
* Addressed changes for review
* Changed RunSinglePassAndMatch to be able to run validation
* current users do not enable it
Added handling of acceptable decorations.
* Decorations are also transfered where appropriate
Refactored extension checking into FeatureManager
* Context now owns a feature manager
* consciously NOT an analysis
* added some test
* fixed some minor issues related to decorates
* added some decorate related tests for scalar replacement
The option --skip-validation is added. When used it will skip the
validation step.
Also rearranged the help text to fix two options that are out of order.
Adds a pass that looks for redundant instruction in a function, and
removes them. The algorithm is a hash table based value numbering
algorithm that traverses the dominator tree.
This pass removes completely redundant instructions, not partially
redundant ones.
Creates a pass that removes redundant instructions within the same basic
block. This will be implemented using a hash based value numbering
algorithm.
Added a number of functions that check for the Vulkan descriptor types.
These are used to determine if we are variables are read-only or not.
Implemented a function to check if loads and variables are read-only.
Implemented kernel specific and shader specific versions.
A big change is that the Combinator analysis in ADCE is factored out
into the IRContext as an analysis. This was done because it is being
reused in the value number table.
Works with current DefUseManager infrastructure.
Added merge return to the standard opts.
Added validation to passes.
Disabled pass for shader capabilty.
There are a number of users of spriv-opt that are hitting errors
because of stores with different types. In general, this is wrong, but,
in these cases, the types are the exact same except for decorations.
The options is "--relax-store-struct", and it can be used with the
validator or the optimizer.
We assume that if layout information is missing it is consistent. For
example if one struct has a offset of one of its members, and the other
one does not, we will still consider them as being layout compatible.
The problem will be if both struct has and offset decoration for
corresponding members, and the offset are different.
There does not seem to be any pass that remove global variables. I
think we could use one. This pass will look specifically for global
variables that are not referenced and are not exported. Any decoration
associated with the variable will also be removed. However, this could
cause types or constants to become unreferenced. They will not be
removed. Another pass will have to be called to remove those.
- Adds a new pass CFGCleanupPass. This serves as an umbrella pass to
remove unnecessary cruft from a CFG.
- Currently, the only cleanup operation done is the removal of
unreachable basic blocks.
- Adds unit tests.
- Adds a flag to spirvopt to execute the pass (--cfg-cleanup).
These flags are expanded to a series of spirv-opt flags with the
following semantics:
-O: expands to passes that attempt to improve the performance of the
generated code.
-Os: expands to passes that attempt to reduce the size of the generated
code.
-Oconfig=<file> expands to the sequence of passes determined by the
flags specified in the user-provided file.
Creates a pass called eliminate dead functions that looks for functions
that could never be called, and deletes them from the module.
To support this change a new function was added to the Pass class to
traverse the call trees from diffent starting points.
Includes a test to ensure that annotations are removed when deleting a
dead function. They were not, so fixed that up as well.
Did some cleanup of the assembly for the test in pass_test.cpp. Trying
to make them smaller and easier to read.
Create a new optimization pass, strength reduction, which will replace
integer multiplication by a constant power of 2 with an equivalent bit
shift. More changes could be added later.
- Does not duplicate constants
- Adds vector |Concat| utility function to a common test header.
Only inline calls to functions with opaque params or return
TODO: Handle parameter type or return type where the opqaue
type is buried within an array.
- UniformElim: Only process reachable blocks
- UniformElim: Don't reuse loads of samplers and images across blocks.
Added a second phase which only reuses loads within a block for samplers
and images.
- UniformElim: Upgrade CopyObject skipping in GetPtr
- UniformElim: Add extensions whitelist
Currently disallowing SPV_KHR_variable_pointers because it doesn't
handle extended pointer forms.
- UniformElim: Do not process shaders with GroupDecorate
- UniformElim: Bail on shaders with non-32-bit ints.
- UniformElim: Document support for only single index and add TODO.
Create aggressive dead code elimination pass
This pass eliminates unused code from functions. In addition,
it detects and eliminates code which may have spurious uses but which do
not contribute to the output of the function. The most common cause of
such code sequences is summations in loops whose result is no longer used
due to dead code elimination. This optimization has additional compile
time cost over standard dead code elimination.
This pass only processes entry point functions. It also only processes
shaders with logical addressing. It currently will not process functions
with function calls. It currently only supports the GLSL.std.450 extended
instruction set. It currently does not support any extensions.
This pass will be made more effective by first running passes that remove
dead control flow and inlines function calls.
This pass can be especially useful after running Local Access Chain
Conversion, which tends to cause cycles of dead code to be left after
Store/Load elimination passes are completed. These cycles cannot be
eliminated with standard dead code elimination.
Additionally: This transform uses a whitelist of instructions that it
knows do have side effects, (a.k.a. combinators). It assumes other
instructions have side effects: it will not remove them, and assumes
they have side effects via their ID operands.
A SSA local variable load/store elimination pass.
For every entry point function, eliminate all loads and stores of function
scope variables only referenced with non-access-chain loads and stores.
Eliminate the variables as well.
The presence of access chain references and function calls can inhibit
the above optimization.
Only shader modules with logical addressing are currently processed.
Currently modules with any extensions enabled are not processed. This
is left for future work.
This pass is most effective if preceeded by Inlining and
LocalAccessChainConvert. LocalSingleStoreElim and LocalSingleBlockElim
will reduce the work that this pass has to do.
Add --flatten-decorations to spirv-opt
Flattens decoration groups. That is, replace OpDecorationGroup
and its uses in OpGroupDecorate and OpGroupMemberDecorate with
ordinary OpDecorate and OpMemberDecorate instructions.
Fixes https://github.com/KhronosGroup/SPIRV-Tools/issues/602
Exercises our public APIs more, and avoid including most
internal headers. It also shortens the processing part
of the code, but does make adding passes look more complex.
Doing this exposed issue 611, a bug in spvtools::Optimizer.
Default-constructed Pass/PassManager will have a MessageConsumer
which ignores all messages. SetMessageConsumer() should be called
to supply a meaningful MessageConsumer.
De-duplicate constants and unifies the uses of constants for a SPIR-V
module. If two constants are defined exactly the same, only one of them
will be kept and all the uses of the removed constant will be redirected
to the kept one.
This pass handles normal constants (defined with
OpConstant{|True|False|Composite}), some spec constants (those defined
with OpSpecConstant{Op|Composite}) and null constants (defined with
OpConstantNull).
There are several cases not handled by this pass:
1) If there are decorations for the result id of a constant defining
instruction, that instruction will not be processed. This means the
instruction won't be used to replace other instructions and other
instructions won't be used to replace it either.
2) This pass does not unify null constants (defined with
OpConstantNull instruction) with their equivalent zero-valued normal
constants (defined with OpConstant{|False|Composite} with zero as the
operand values or component values).
For the spec constants defined by OpSpecConstantOp and
OpSpecContantComposite, if all of their operands are constants with
determined values (normal constants whose values are fixed), calculate
the correct values of the spec constants and re-define them as normal
constants.
In short, this pass replaces all the spec constants defined by
OpSpecContantOp and OpSpecConstantComposite with normal constants when
possible. So far not all valid operations of OpSpecConstantOp are
supported, we have several constriction here:
1) Only 32-bit integer and boolean (both scalar and vector) are
supported for any arithmetic operations. Integers in other width (like
64-bit) are not supported.
2) OpSConvert, OpFConvert, OpQuantizeToF16, and all the
operations under Kernel capability, are not supported.
3) OpCompositeInsert is not supported.
Note that this pass does not unify normal constants. This means it is
possible to have new generatd constants defining the same values.
