diff options
Diffstat (limited to 'gcc/lambda-code.c')
| -rw-r--r-- | gcc/lambda-code.c | 19 |
1 files changed, 8 insertions, 11 deletions
diff --git a/gcc/lambda-code.c b/gcc/lambda-code.c index 9d61c77..a47f580 100644 --- a/gcc/lambda-code.c +++ b/gcc/lambda-code.c @@ -2257,18 +2257,15 @@ can_convert_to_perfect_nest (struct loop *loop, if (stmt_uses_op (stmt, iv)) goto fail; - /* If this is a simple operation like a cast that is - invariant in the inner loop, or after the inner loop, - then see if we can place it back where it came from. - This means that we will propagate casts and other - cheap invariant operations *back* into or after - the inner loop if we can interchange the loop, on the - theory that we are going to gain a lot more by - interchanging the loop than we are by leaving some - invariant code there for some other pass to clean - up. */ + /* If this is a scalar operation that can be put back + into the inner loop, or after the inner loop, through + copying, then do so. This works on the theory that + any amount of scalar code we have to reduplicate + into or after the loops is less expensive that the + win we get from rearranging the memory walk + the loop is doing so that it has better + cache behavior. */ if (TREE_CODE (stmt) == MODIFY_EXPR - && is_gimple_cast (TREE_OPERAND (stmt, 1)) && (can_put_in_inner_loop (loop->inner, stmt) || can_put_after_inner_loop (loop, stmt))) continue; |