[Bug rtl-optimization/31889] New: compiler misses opportunity to combine multiple identical function return paths

["raeburn at raeburn dot org" <gcc-bugzilla@gcc.gnu.org>]

The source file I'm submitting has two implementations of an inline function,
and a second function which calls it and then prints one of two strings
depending on the return value.  With the simpler implementation of the inline
function, one call to puts() is followed by a jump to the return sequence
emitted after the other puts() call.  With the more complicated (but
functionally equivalent) implementation of the inline function, the caller's
two paths aren't combined; two sets of instructions are emitted to restore the
same registers from the same stack slots before returning.  It should still be
able to combine them.

(A second possible missed optimization?  The branch could've been done to the
puts call, instead of to just after, saving one call instruction.  Unless a
branch to a call is slower than a call that returns to a branch instruction on
these processors.)


-- 
           Summary: compiler misses opportunity to combine multiple
                    identical function return paths
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: raeburn at raeburn dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31889