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DWARF: Fix a bug in array size computation

Description

DWARF: Fix a bug in array size computation

Summary:
r346165 introduced a bug, where we would fail to parse the size of an
array if that size happened to match an existing die offset.

The logic was:
if (DWARFDIE count = die.GetReferencedDie(DW_AT_count))

num_elements = compute_vla_size(count);

else

num_elements = die.GetUsigned(DW_AT_count); // a fixed-size array

The problem with this logic was that GetReferencedDie did not take the
form class of the attribute into account, and would happily return a die
reference for any form, if its value happened to match some die.

As this behavior is inconsistent with how llvm's DWARFFormValue class
operates, I chose to fix the problem by making our version of this class
match the llvm behavior. For this to work, I had to add an explicit form
class check to the .apple_XXX tables parsing code, because they do
(incorrectly?) use data forms as die references.

Reviewers: aprantl, clayborg

Subscribers: JDevlieghere, lldb-commits

Differential Revision: https://reviews.llvm.org/D55991

Details

Committed
labathDec 27 2018, 1:25 AM
Differential Revision
D55991: DWARF: Fix a bug in array size computation
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