[Bug target/39989] No need to save LR in some cases

[carrot at google dot com]

------- Comment #2 from carrot at google dot com  2009-05-01 06:21 -------
Actually gcc has already implemented this optimization, but it doesn't work for
this case.

Reload pass tries to determine the stack frame, so it needs to check the
push/pop lr optimization opportunity. One of the criteria is if there is any
far jump inside the function. Unfortunately at this time gcc can't decide each
instruction's length and basic block layout, so it can't know the offset of a
jump. To be conservative it assumes every jump is a far jump. So any jump in a
function will prevent this push/pop lr optimization.


-- 

carrot at google dot com changed:

           What    |Removed                     |Added
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                 CC|                            |carrot at google dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39989