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https://github.com/KhronosGroup/SPIRV-Tools
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eb60e2945a
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).
59 lines
2.7 KiB
C++
59 lines
2.7 KiB
C++
// Copyright (c) 2016 Google Inc.
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//
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// Permission is hereby granted, free of charge, to any person obtaining a
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// copy of this software and/or associated documentation files (the
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// "Materials"), to deal in the Materials without restriction, including
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// without limitation the rights to use, copy, modify, merge, publish,
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// distribute, sublicense, and/or sell copies of the Materials, and to
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// permit persons to whom the Materials are furnished to do so, subject to
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// the following conditions:
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//
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// The above copyright notice and this permission notice shall be included
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// in all copies or substantial portions of the Materials.
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//
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// MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
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// KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
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// SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
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// https://www.khronos.org/registry/
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//
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// THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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// MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
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#ifndef LIBSPIRV_OPT_UNIFY_CONSTANT_PASS_H_
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#define LIBSPIRV_OPT_UNIFY_CONSTANT_PASS_H_
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#include "module.h"
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#include "pass.h"
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namespace spvtools {
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namespace opt {
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// The optimization pass to de-duplicate the constants. Constants with exactly
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// same values and identical form will be unified and only one constant will be
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// kept for each unique pair of type and value.
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// There are several cases not handled by this pass:
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// 1) Constants defined by OpConstantNull instructions (null constants) and
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// constants defined by OpConstantFalse, OpConstant or OpConstantComposite
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// with value(s) 0 (zero-valued normal constants) are not considered
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// equivalent. So null constants won't be used to replace zero-valued normal
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// constants, and other constants won't replace the null constants either.
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// 2) Whenever there are decorations to the constant's result id or its type
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// id, the constants won't be handled, which means, it won't be used to
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// replace any other constants, neither can other constants replace it.
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// 3) NaN in float point format with different bit patterns are not unified.
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class UnifyConstantPass : public Pass {
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public:
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const char* name() const override { return "unify-const"; }
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bool Process(ir::Module*) override;
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};
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} // namespace opt
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} // namespace spvtools
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#endif // LIBSPIRV_OPT_UNIFY_CONSTANT_PASS_H_
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