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Use the custom implementation of multipliedFullWidth on arm64_32 #37905

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Merged
merged 1 commit into from
Jun 15, 2021
Merged

Use the custom implementation of multipliedFullWidth on arm64_32 #37905

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18 changes: 14 additions & 4 deletions stdlib/public/core/IntegerTypes.swift.gyb
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Original file line number Diff line number Diff line change
Expand Up @@ -1514,15 +1514,23 @@ ${assignmentOperatorComment(x.operator, True)}
% end

% dbits = bits*2
% if bits <= word_bits:
% if bits == 64:
#if !(arch(arm) || arch(i386) || arch(wasm32))
// On 32b architectures we fall back on the generic implementation,
// because LLVM doesn't know how to codegen the 128b multiply we use.
//
// Note that arm64_32 is a 64b architecture for the purposes of this
// check, because we have a 64x64 -> 128 multiply there (the actual
// ISA is AArch64).
% end
/// Returns a tuple containing the high and low parts of the result of
/// multiplying this value by the given value.
///
/// Use this method to calculate the full result of a product that would
/// otherwise overflow. Unlike traditional truncating multiplication, the
/// `multipliedFullWidth(by:)` method returns a tuple
/// containing both the `high` and `low` parts of the product of this value and
/// `other`. The following example uses this method to multiply two `UInt8`
/// `multipliedFullWidth(by:)` method returns a tuple containing both the
/// `high` and `low` parts of the product of this value and `other`.
/// The following example uses this method to multiply two `UInt8`
/// values that normally overflow when multiplied:
///
/// let x: UInt8 = 100
Expand Down Expand Up @@ -1557,6 +1565,8 @@ ${assignmentOperatorComment(x.operator, True)}
let high = ${Self}(Builtin.truncOrBitCast_Int${dbits}_Int${bits}(shifted))
return (high: high, low: low)
}
% if bits == 64:
#endif
% end

/// Returns a tuple containing the quotient and remainder of dividing the
Expand Down