dist/gcc/tree-ssa-loop-split.c

924    corresponds to one branch of a conditional statement).  If SKIP_HEAD is
960 /* Suppose one condition branch, led by SKIP_HEAD, is not executed since
1004      value, if excluding branch trace starting from SKIP_HEAD, except copy-
1029      true branch, which means that one source value to define x_3 in false
1030      branch (x_2) is skipped, x_3 only comes from x_1, and x_1 in next
1032      always chooses true branch from then on.  */
1239    branch, whether we can remove the branch's leading basic block (BRANCH_BB)
1259        /* The branch can be reached from opposite branch, or from some
1267 /* Find out which branch of a conditional statement (COND) is invariant in the
1268    execution context of LOOP.  That is: once the branch is selected in certain
1284       /* One branch directs to loop exit, no need to perform loop split upon
1285 	 this conditional statement.  Firstly, it is trivial if the exit branch
1287 	 if the opposite branch is semi-invariant, it means that the statement
1300       /* Given a semi-invariant branch, if its opposite branch dominates
1303 	 of the loop.  Similar to the above case that the branch is loop
1325    loop split upon certain branch (BRANCH_EDGE) of a conditional statement.  */
1331   unsigned branch = EDGE_SUCC (cond_bb, 1) == branch_edge;
1332   basic_block opposite_bb = EDGE_SUCC (cond_bb, !branch)->dest;
1338       /* Do no count basic blocks only in opposite branch.  */
1346      in new loop that contains only invariant branch.  This expression should
1403 /* Find out loop-invariant branch of a conditional statement (COND) if it has,
1405    this branch in LOOP.  */
1415      frequency of the branch is too low, just let it go.  */
1432 /* Given a loop (LOOP1) with a loop-invariant branch (INVAR_BRANCH) of some
1469    and one of its branch goes back to loop1 header as a latch edge, and the
1470    other branch goes to loop2 pre-header as an entry edge.  And also in loop2,
1471    we abandon the variant branch of the conditional statement by setting a
1472    constant bool condition, based on which branch is semi-invariant.  */
1485 		     "loop split on semi-invariant condition at %s branch\n",
1506      remove the variant branch after current pass completes.  */