Richard Biener
9e11ceef16
This allows loop unswitching to unswitch outer loops conditions are invariant in. We restrict ourselves to unswitch conditions in innermost loops and will only unswitch loop nests that do not contain any sibling loops. To simplify the implementation the loop nest unswitched is the deepest all unswitching candidates are invariant in. For 507.cactuBSSN_r it can be observed we unswitch the outer loops of the compute kernels for the fdOrder parameter. It seems to be within the existing growth limitations to perform the unswitchings, a performance benefit is not seen. * tree-ssa-loop-unswitch.cc (init_loop_unswitch_info): First collect candidates and determine the outermost loop to unswitch. (tree_ssa_unswitch_loops): First perform all guard hoisting, then perform unswitching on innermost loop predicates. (find_unswitching_predicates_for_bb): Keep track of the outermost loop to unswitch. (evaluate_bbs): Adjust exit test. (tree_unswitch_single_loop): Dump whether we unswitched an outer loop. (tree_unswitch_loop): Remove assert we unswitch only innermost loops. * gcc.dg/loop-unswitch-18.c: New testcase. * gcc.dg/tree-ssa/loopclosedphi.c: Disable unswitching, adjust expected counts. * gcc.dg/torture/pr71462.c: Add -w to ignore undefined behavior diagnostics after now unswitching outer loops.
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