Assembly files compiled with debug info generate `DW_TAG_label entries`
with `DW_AT_low_pc` but no `DW_AT_high_pc` attributes. Without address
range information, `dsymutil` would call `addLabelLowPc()` which only
records the start address, making the compilation unit appear "empty"
with no ranges. This caused dsymutil to discard all debug information
including line tables.
This patch adds infrastructure to query symbol sizes from the debug map
and use them to reconstruct address ranges for assembly labels.
rdar://166225328
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Co-authored-by: Ryan Mansfield <ryan_mansfield@apple.com>
8c49c53a7f