diff options
Diffstat (limited to 'gcc/tree-scalar-evolution.c')
| -rw-r--r-- | gcc/tree-scalar-evolution.c | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/gcc/tree-scalar-evolution.c b/gcc/tree-scalar-evolution.c index f1914c3d51e..846d27414d5 100644 --- a/gcc/tree-scalar-evolution.c +++ b/gcc/tree-scalar-evolution.c @@ -2864,14 +2864,6 @@ scev_finalize (void) BITMAP_FREE (already_instantiated); } -/* Returns true if EXPR looks expensive. */ - -static bool -expression_expensive_p (tree expr) -{ - return force_expr_to_var_cost (expr) >= target_spill_cost; -} - /* Replace ssa names for that scev can prove they are constant by the appropriate constants. Also perform final value replacement in loops, in case the replacement expressions are cheap. @@ -2958,10 +2950,13 @@ scev_const_prop (void) continue; niter = number_of_latch_executions (loop); - if (niter == chrec_dont_know - /* If computing the number of iterations is expensive, it may be - better not to introduce computations involving it. */ - || expression_expensive_p (niter)) + /* We used to check here whether the computation of NITER is expensive, + and avoided final value elimination if that is the case. The problem + is that it is hard to evaluate whether the expression is too + expensive, as we do not know what optimization opportunities the + the elimination of the final value may reveal. Therefore, we now + eliminate the final values of induction variables unconditionally. */ + if (niter == chrec_dont_know) continue; /* Ensure that it is possible to insert new statements somewhere. */ |