The logic for x86_64 position-independent TType encodings was backwards, using 8 bytes where 4 were wanted and 4 where 8 were wanted. For regular x86_64, this was mostly harmless, exception tables are allowed to use 8-byte encodings even when it is not needed. For the large code model, and for X32, however, the generated exception tables were wrong. For the large code model, we cannot assume that the offset will fit in 4 bytes. For X32, we cannot use 64-bit relocations.