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[Bug target/64774] [ARM/thumb] missed optimization: pc relative ldr used when constant can be derived from register
- From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Wed, 28 Jan 2015 16:14:14 +0000
- Subject: [Bug target/64774] [ARM/thumb] missed optimization: pc relative ldr used when constant can be derived from register
- Auto-submitted: auto-generated
- References: <bug-64774-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64774
Richard Earnshaw <rearnsha at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target| |arm
Priority|P3 |P5
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-01-28
Ever confirmed|0 |1
--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
Although the compiler tries to find some common cases, it is generally
infeasible to detect all the possible permutations that exist. Furthermore, in
real code generating common expressions in this way can increase register
pressure and have additional impact on some optimization passes.
I don't hold out much hope of this sort of problem ever being entirely fixed.