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Summary:
The patch removes OffsetToFirstDefinition in the 'scope bytes total'
statistic computation. Thus it unifies the way the scope and the coverage
buckets are computed. The rationals behind that are the following:
1. OffsetToFirstDefinition was used to calculate the variable's life range.
However, there is no simple way to do it accurately, so the scope calculated
this way might be misleading. See D69027 for more details on the subject.
2. Both 'scope bytes total' and coverage buckets seem to be intended
to represent the same data in different ways. Otherwise, the statistics
might be controversial and confusing.
Note that the approach gives up a thorough evaluation of debug information
completeness (i.e. coverage buckets by themselves doesn't tell how good
the debug information is). Only changes in coverage over time make
a 'physical' sense.
Reviewers: djtodoro, aprantl, vsk, dblaikie, avl
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70548
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Summary:
This patch removes manual location list handling in the statistics code
and replaces it with the new DWARFDie api, which provides access to a
"cooked" location list. This has the following effects:
- the code now properly handles split-dwarf location lists
- it will automatically support dwarf5 location lists once support for
those is added
- it properly handles location lists with base address selection entries
- it fixes a bug where the location list code was using the first
DW_AT_ranges range as a "base address" of the compile unit (it should
have used DW_AT_low_pc instead. The effect of this was that the
computation of the start address of a variable in its scope was broken
for these kinds of compile units. This only manifested itself on
linked files, since in object files the first DW_AT_ranges range
normally starts at 0.
Since pretty much every kind of location list was broken in some way,
it's hard to verify that the new implementation is correct -- the output
will be different in all non-trivial cases, and mostly with good reason.
Most of the existing statistics tests continue to pass though, and a
visual inspection of the statistics for non-trivial inputs shows that
the data is more "reasonable" now. I have updated the "dwo statistics"
test to include the new numbers, as the previous ones were completely
bogus, and I have added a targeted test for the "base address" bug.
Reviewers: dblaikie, cmtice, vsk
Subscribers: aprantl, SouraVX, JDevlieghere, djtodoro, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D70444
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