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From: "vries at gcc dot" <>
Subject: [Bug default/25566] New: [dwz] Take reference size into account in heuristics
Date: Wed, 01 Jan 2020 00:00:00 -0000	[thread overview]
Message-ID: <> (raw)

            Bug ID: 25566
           Summary: [dwz] Take reference size into account in heuristics
           Product: dwz
           Version: unspecified
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: default
          Assignee: nobody at sourceware dot org
          Reporter: vries at gcc dot
                CC: dwz at sourceware dot org
  Target Milestone: ---

When looking at executables produced by a lazy DWARF producer, we find that all
the intra-CU references are done using DW_FORM_ref4:
$ readelf -wa cc1 \
  | grep DW_FORM_ref \
  | egrep -v "DW_FORM_ref4|DW_FORM_ref_addr" \
  | wc -l

In such a case, if we move a DIE out of a CU into a PU, we replace a
DW_FORM_ref4 (size 4 bytes) with a DW_FORM_ref_addr (size 4 bytes in 32-bit
DWARF), so, it's size neutral.

However, if we handle an executable containing minimal intra-CU references, the
substitution is no longer size-neutral. We should take that into account in the

In order to do that, we should track for lower top-level DIEs the number of
intra-cu references, and their combined size.

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                 reply	other threads:[~2020-02-17 13:38 UTC|newest]

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