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Bug 59658 - Document -f* flags enabled by -Og
Summary: Document -f* flags enabled by -Og
Status: NEW
Alias: None
Product: gcc
Classification: Unclassified
Component: middle-end (show other bugs)
Version: 4.9.0
: P3 normal
Target Milestone: ---
Assignee: Not yet assigned to anyone
Keywords: documentation
Depends on:
Reported: 2014-01-02 14:36 UTC by Tobias Burnus
Modified: 2014-01-07 11:50 UTC (History)
0 users

See Also:
Known to work:
Known to fail:
Last reconfirmed: 2014-01-07 00:00:00


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Description Tobias Burnus 2014-01-02 14:36:10 UTC documents the -f* flags enabled by -O*. And the -f* options document their respective -O* options which enables them.

However, for -Og this is not documented. The information can be obtained using:
  gcc -Q --help=optimizers -Og|grep enabled

It might be useful to have this information in the man page for -Og as well.
Comment 1 Richard Biener 2014-01-07 11:50:31 UTC
But it might be misleading (similar to -O0 vs -O2) - enabling for example
-ftree-pre won't enable PRE for -Og as it has a completely different
pass pipeline which is not based on -O[123].  Those enumerations are only
relevant for the 'numbered' optimization levels (excluding -O0).

So we miss to filter options in --help optimizers that can be enabled at all.