The PrologEpilogInserter need to insert a DW_OP_deref_size before prepending a memory location expression to an already implicit expression to avoid having the existing expression act on the memory address instead of the value behind it. The reason for using DW_OP_deref_size and not plain DW_OP_deref is that big-endian targets need to read the right size as simply truncating a larger read would yield the wrong result (LSB bytes are not at the lower address). This re-commit fixes issues reported in the first one. Namely deref was inserted under wrong conditions and additionally the deref_size argument was incorrectly encoded. Differential Revision: https://reviews.llvm.org/D59687 llvm-svn: 359535
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