Bad alignment in convertUTF16ToUTF8String

[stoklund]

Bugzilla Link	18482
Version	trunk
OS	All
CC	@rnk

Extended Description

lib/Support/ConvertUTFWrapper.cpp contains this code:

bool convertUTF16ToUTF8String(ArrayRef SrcBytes, std::string &Out) {
...
const UTF16 *Src = reinterpret_cast<const UTF16 *>(SrcBytes.begin());
const UTF16 *SrcEnd = reinterpret_cast<const UTF16 *>(SrcBytes.end());
...
if (Src[0] == UNI_UTF16_BYTE_ORDER_MARK_SWAPPED) {

The UTF16 type is normally 2-byte aligned, and there is no guarantee that the ArrayRef points to aligned bytes.

This crashes the unit test ConvertUTFTest.ConvertUTF16LittleEndianToUTF8String on SPARC.

[rnk]

Yep. What's the usual way to do unaligned loads for something on SPARC?

[stoklund]

The code generator does the right thing if you give it an unaligned IR load. You can use a 2-byte memcpy or a pointer to a packed struct with a UTF16 member.

You can probable;y reproduce on Intel if you compile with -fsanitize=alignment and make sure the test case is passing an unaligned string.