[DebugInfo][InstrRef] Avoid producing broken DW_OP_deref_sizes (#123967) We use variable locations such as DBG_VALUE $xmm0 as shorthand to refer to "the low lane of $xmm0", and this is reflected in how DWARF is interpreted too. However InstrRefBasedLDV tries to be smart and interprets such a DBG_VALUE as a 128-bit reference. We then issue a DW_OP_deref_size of 128 bits to the stack, which isn't permitted by DWARF (it's larger than a pointer). Solve this for now by not using DW_OP_deref_size if it would be illegal. Instead we'll use DW_OP_deref, and the consumer will load the variable type from the stack, which should be correct. There's still a risk of imprecision when LLVM decides to use smaller or larger value types than the source-variable type, which manifests as too-little or too-much memory being read from the stack. However we can't solve that without putting more type information in debug-info. fixes #64093
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