Bug 3813 - large overhead for exceptions on win32/win64? (switch to dwarf, SEH?)
Summary: large overhead for exceptions on win32/win64? (switch to dwarf, SEH?)
Status: NEW
Alias: None
Product: ThinLinc
Classification: Unclassified
Component: Build system (show other bugs)
Version: pre-1.0
Hardware: PC Unknown
: P2 Normal
Target Milestone: LowPrio
Assignee: Peter Åstrand
Depends on:
Reported: 2011-05-05 11:34 CEST by Pierre Ossman
Modified: 2017-06-13 13:33 CEST (History)
0 users

See Also:
Acceptance Criteria:


Description Pierre Ossman cendio 2011-05-05 11:34:56 CEST
There is some talk about preferring Dwarf exceptions instead of the older SJLJ ones with mingw. Unfortunately I cannot find any documentation as to what the tradeoffs are (more than that you cannot throw exceptions between the models).
Comment 2 Pierre Ossman cendio 2014-11-17 15:16:11 CET

With the main points:

 - SJLJ incurs a performance penalty even when no exceptions are thrown at runtime. The penalty is >10% for typical applications.
 - DW2 potentially generates bigger libraries. The overhead however is not big (< 10%) for typical applications.
 - if using DW2, things will go wrong (crashing?) if one tries to throw exceptions through stack frames not compiled with DW2 (typical case: Windows callbacks).
    - following from the above, one should never mix code compiled with DW2, and code compiled with SJLJ, in one project.
 - mingw.org has switched to DW2 since a while.
 - For gcc 4.7/64 bit, only SJLJ is available. gcc 4.8 will feature SEH, which solves the performance problems SJLJ has. Anyhow, gcc 4.8 most probably won't feature SEH for 32 bit.

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