zero extension expression #8442
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kroening
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Sep 5, 2024
kroening
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I believe this is actually a necessary feature for unit tests to pass. |
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I think the support for zero_extend should be added to the simplifier before merging. Moving from expressions which are supported by the simplifier to a new one which is not may have a performance cost. |
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Now with simplifier support. |
Codecov ReportAttention: Patch coverage is
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## develop #8442 +/- ##
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Coverage ? 78.88%
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peterschrammel
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src/util/bitvector_expr.cpp
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| } | ||
| else // new_width <= old_width | ||
| { | ||
| return extractbits_exprt{op(), integer_typet{}.zero_expr(), type()}; |
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Isn't the index argument a sizet?
This introduces the zero_extend expression, which, given a bit-vector operand and a type, either a) pads the given operand with zeros from the left if the given type is wider than the type of the operand, or b) truncates the operand to the width of the given type if the given type is smaller than the operand, or c) reinterprets the operand as having the given type if the width of the type and the width of the operand match. This may differ from conversion if the types have different bit representations. This is easier to read and less prone to error than the current pattern, in which the operand is 1) converted to an unsigned type of the same width, and then 2) casted to an unsigned type of the wider width, and 3) finally casted to the target type.
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