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On targets smaller than 64 bits, emit a compile-time error if withUnsafeTemporaryAllocation(of:capacity:) byte count overflows #39976

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Merged
merged 1 commit into from
Nov 1, 2021
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On targets smaller than 64 bits, emit a compile-time error if withUnsafeTemporaryAllocation(of:capacity:) byte count overflows #39976

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8 changes: 8 additions & 0 deletions lib/IRGen/IRGenSIL.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3026,6 +3026,14 @@ static llvm::Value *getStackAllocationSize(IRGenSILFunction &IGF,
auto overflow = llvm::MulOverflow(*capacityValue, *strideValue, byteCount);
if (overflow) {
Diags.diagnose(loc, diag::temporary_allocation_size_overflow);
} else {
// For architectures narrower than 64 bits, check if the byte count fits
// in a (signed) size value.
auto maxByteCount = llvm::APInt::getSignedMaxValue(
IGF.IGM.SizeTy->getBitWidth()).getSExtValue();
if (byteCount > maxByteCount) {
Diags.diagnose(loc, diag::temporary_allocation_size_overflow);
}
}
result = llvm::ConstantInt::get(IGF.IGM.SizeTy, byteCount);

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4 changes: 2 additions & 2 deletions .../temporary_allocation/bad_constants.swift → ...temporary_allocation/size_too_large.swift
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Expand Up @@ -3,7 +3,7 @@
@_silgen_name("blackHole")
func blackHole(_ value: UnsafeMutableRawPointer?) -> Void

withUnsafeTemporaryAllocation(byteCount: 1, alignment: -1) { buffer in
withUnsafeTemporaryAllocation(of: Int.self, capacity: .max) { buffer in
blackHole(buffer.baseAddress)
}
// CHECK: error: alignment value must be greater than zero
// CHECK: error: allocation byte count too large