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Add a feature for Builtin.assumeAlignment #40674

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Merged
merged 1 commit into from
Dec 22, 2021
Merged

Add a feature for Builtin.assumeAlignment #40674

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1 change: 1 addition & 0 deletions include/swift/Basic/Features.def
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Original file line number Diff line number Diff line change
Expand Up @@ -58,5 +58,6 @@ LANGUAGE_FEATURE(BuiltinMove, 0, "Builtin.move()", true)
LANGUAGE_FEATURE(BuiltinCopy, 0, "Builtin.copy()", true)
LANGUAGE_FEATURE(BuiltinStackAlloc, 0, "Builtin.stackAlloc", true)
LANGUAGE_FEATURE(SpecializeAttributeWithAvailability, 0, "@_specialize attribute with availability", true)
LANGUAGE_FEATURE(BuiltinAssumeAlignment, 0, "Builtin.assumeAlignment", true)

#undef LANGUAGE_FEATURE
4 changes: 4 additions & 0 deletions lib/AST/ASTPrinter.cpp
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Expand Up @@ -2891,6 +2891,10 @@ static bool usesFeatureBuiltinStackAlloc(Decl *decl) {
return false;
}

static bool usesFeatureBuiltinAssumeAlignment(Decl *decl) {
return false;
}

/// Determine the set of "new" features used on a given declaration.
///
/// Note: right now, all features we check for are "new". At some point, we'll
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8 changes: 8 additions & 0 deletions stdlib/public/core/UnsafeRawPointer.swift
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Expand Up @@ -357,11 +357,15 @@ public struct UnsafeRawPointer: _Pointer {

let rawPointer = (self + offset)._rawValue

#if compiler(>=5.5) && $BuiltinAssumeAlignment
// TODO: to support misaligned raw loads, simply remove this assumption.
let alignedPointer =
Builtin.assumeAlignment(rawPointer,
MemoryLayout<T>.alignment._builtinWordValue)
return Builtin.loadRaw(alignedPointer)
#else
return Builtin.loadRaw(rawPointer)
#endif
}

}
Expand Down Expand Up @@ -909,11 +913,15 @@ public struct UnsafeMutableRawPointer: _Pointer {

let rawPointer = (self + offset)._rawValue

#if compiler(>=5.5) && $BuiltinAssumeAlignment
// TODO: to support misaligned raw loads, simply remove this assumption.
let alignedPointer =
Builtin.assumeAlignment(rawPointer,
MemoryLayout<T>.alignment._builtinWordValue)
return Builtin.loadRaw(alignedPointer)
#else
return Builtin.loadRaw(rawPointer)
#endif
}

/// Stores the given value's bytes into raw memory at the specified offset.
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