diff options
Diffstat (limited to 'gcc/unroll.c')
| -rw-r--r-- | gcc/unroll.c | 31 |
1 files changed, 26 insertions, 5 deletions
diff --git a/gcc/unroll.c b/gcc/unroll.c index 501a6e5..2c0bdef 100644 --- a/gcc/unroll.c +++ b/gcc/unroll.c @@ -3480,22 +3480,43 @@ loop_iterations (loop_start, loop_end, loop_info) loop_info->unroll_number = 1; loop_info->vtop = 0; - /* First find the iteration variable. If the last insn is a conditional - branch, and the insn before tests a register value, make that the - iteration variable. */ - /* We used to use prev_nonnote_insn here, but that fails because it might accidentally get the branch for a contained loop if the branch for this loop was deleted. We can only trust branches immediately before the loop_end. */ last_loop_insn = PREV_INSN (loop_end); + /* ??? We should probably try harder to find the jump insn + at the end of the loop. The following code assumes that + the last loop insn is a jump to the top of the loop. */ + if (GET_CODE (last_loop_insn) != JUMP_INSN) + { + if (loop_dump_stream) + fprintf (loop_dump_stream, + "Loop iterations: No final conditional branch found.\n"); + return 0; + } + + /* If there is a more than a single jump to the top of the loop + we cannot (easily) determine the iteration count. */ + if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1) + { + if (loop_dump_stream) + fprintf (loop_dump_stream, + "Loop iterations: Loop has multiple back edges.\n"); + return 0; + } + + /* Find the iteration variable. If the last insn is a conditional + branch, and the insn before tests a register value, make that the + iteration variable. */ + comparison = get_condition_for_loop (last_loop_insn); if (comparison == 0) { if (loop_dump_stream) fprintf (loop_dump_stream, - "Loop iterations: No final conditional branch found.\n"); + "Loop iterations: No final comparison found.\n"); return 0; } |