Red Hat Bugzilla – Bug 840126
Last modified: 2015-02-17 09:21:02 EST
Description of problem:
Currently dwz-optimized DWARF may cause GDB internal-error (Bug 839596).
Going to fix GDB but that DWARF construct has no use anyway so posting it as missed DWZ optimization here.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
<0><1409ed>: Abbrev Number: 1 (DW_TAG_compile_unit)
<2><14637c>: Abbrev Number: 50 (DW_TAG_formal_parameter)
<14637d> DW_AT_name : key
<146381> DW_AT_decl_file : 2
<146382> DW_AT_decl_line : 114
<146383> DW_AT_type : <0x14639b>
<2><146711>: Abbrev Number: 66 (DW_TAG_GNU_call_site)
<146712> DW_AT_low_pc : 0x48894d
<14671a> DW_AT_abstract_origin: <0x146595>
<3><14671e>: Abbrev Number: 74 (DW_TAG_GNU_call_site_parameter)
<14671f> DW_AT_abstract_origin: <0x14637c>
<146723> DW_AT_GNU_call_site_value: 3 byte block: f3 1 54 (DW_OP_GNU_entry_value: (DW_OP_reg4 (rsi)))
not found: DW_OP_GNU_parameter_ref: <0x14637c>
<0><1c2a8>: Abbrev Number: 2 (DW_TAG_partial_unit)
<2><1c2dc>: Abbrev Number: 96 (DW_TAG_formal_parameter)
<1c2dd> DW_AT_name : key
<1c2e1> DW_AT_decl_file : 2
<1c2e2> DW_AT_decl_line : 114
<1c2e3> DW_AT_type : <0x1c2f5>
<0><110990>: Abbrev Number: 79 (DW_TAG_compile_unit)
<2><1134cd>: Abbrev Number: 115 (DW_TAG_GNU_call_site)
<1134ce> DW_AT_low_pc : 0x48894d
<1134d6> DW_AT_abstract_origin: <0x113370>
<3><1134d8>: Abbrev Number: 106 (DW_TAG_GNU_call_site_parameter)
<1134d9> DW_AT_abstract_origin: <0x1c2dc>
<1134dd> DW_AT_GNU_call_site_value: 3 byte block: f3 1 54 (DW_OP_GNU_entry_value: (DW_OP_reg4 (rsi)))
not found: DW_OP_GNU_parameter_ref: <0x1c2dc>
In optimized DWARF DW_TAG_GNU_call_site_parameter-DW_AT_abstract_origin points outside of its CU which was problem for GDB.
But as no callee is referencing this DIE <0x1c2dc> by DW_OP_GNU_parameter_ref this DIE can be dropped. No other CU can use the intra-cu binding DW_OP_GNU_parameter_ref-DW_TAG_GNU_call_site_parameter-DW_AT_abstract_origin.
Created attachment 598155 [details]
xorg-x11-server-1.12.3-1.fc18 Xorg.debug.xz original
Created attachment 598157 [details]
xorg-x11-server-1.12.3-1.fc18 Xorg.debug.xz dwz-optimized
As DW_OP_GNU_parameter_ref uses CU-relative reference in fact DW_TAG_GNU_call_site_parameter-DW_AT_abstract_origin cannot be moved into DW_TAG_partial_unit even if it was referenced (dwz probably already solves it although I do not know).
This bug appears to have been reported against 'rawhide' during the Fedora 19 development cycle.
Changing version to '19'.
(As we did not run this process for some time, it could affect also pre-Fedora 19 development
cycle bugs. We are very sorry. It will help us with cleanup during Fedora 19 End Of Life. Thank you.)
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