loop-split improvements, part 3
extend tree-ssa-loop-split to understand test of the form
if (i==0)
and
if (i!=0)
which triggers only during the first iteration. Naturally we should
also be able to trigger last iteration or split into 3 cases if
the test indeed can fire in the middle of the loop.
Last iteration is bit trickier pattern matching so I want to do it
incrementally, but I implemented easy case using value range that handled
loops with constant iterations.
The testcase gets misupdated profile, I will also fix that incrementally.
gcc/ChangeLog:
PR middle-end/77689
* tree-ssa-loop-split.cc: Include value-query.h.
(split_at_bb_p): Analyze cases where EQ/NE can be turned
into LT/LE/GT/GE; return updated guard code.
(split_loop): Use guard code.
gcc/testsuite/ChangeLog:
PR middle-end/77689
* g++.dg/tree-ssa/loop-split-1.C: New test.