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| author | Sebastian Pop <sebastian.pop@amd.com> | 2010-02-11 15:45:27 +0000 |
|---|---|---|
| committer | Sebastian Pop <spop@gcc.gnu.org> | 2010-02-11 15:45:27 +0000 |
| commit | 04eadb13265b69db0282da8803f13e357a129079 (patch) | |
| tree | 816517506e1c41ef333a3003809df242999218a4 /gcc/tree-ssa-loop-ivopts.c | |
| parent | 91753e21c33ee0f333e529487d67a1ff60b30655 (diff) | |
| download | gcc-04eadb13265b69db0282da8803f13e357a129079.zip gcc-04eadb13265b69db0282da8803f13e357a129079.tar.gz gcc-04eadb13265b69db0282da8803f13e357a129079.tar.bz2 | |
re PR regression/40886 (No loop counter reversal for simple loops anymore)
Fix PR40886.
2010-02-11 Sebastian Pop <sebastian.pop@amd.com>
Changpeng Fang <changpeng.fang@amd.com>
PR middle-end/40886
* tree-ssa-loop-ivopts.c (determine_use_iv_cost_condition): Decrement
the cost of an IV candidate when the IV is used in a test against zero.
* gcc.dg/tree-ssa/ivopts-3.c: New.
Co-Authored-By: Changpeng Fang <changpeng.fang@amd.com>
From-SVN: r156701
Diffstat (limited to 'gcc/tree-ssa-loop-ivopts.c')
| -rw-r--r-- | gcc/tree-ssa-loop-ivopts.c | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/gcc/tree-ssa-loop-ivopts.c b/gcc/tree-ssa-loop-ivopts.c index 436e6ce..74dadf7 100644 --- a/gcc/tree-ssa-loop-ivopts.c +++ b/gcc/tree-ssa-loop-ivopts.c @@ -4089,6 +4089,7 @@ determine_use_iv_cost_condition (struct ivopts_data *data, bitmap depends_on_elim = NULL, depends_on_express = NULL, depends_on; comp_cost elim_cost, express_cost, cost; bool ok; + tree *control_var, *bound_cst; /* Only consider real candidates. */ if (!cand->iv) @@ -4110,9 +4111,21 @@ determine_use_iv_cost_condition (struct ivopts_data *data, /* Try expressing the original giv. If it is compared with an invariant, note that we cannot get rid of it. */ - ok = extract_cond_operands (data, use->stmt, NULL, NULL, NULL, &cmp_iv); + ok = extract_cond_operands (data, use->stmt, &control_var, &bound_cst, + NULL, &cmp_iv); gcc_assert (ok); + /* When the condition is a comparison of the candidate IV against + zero, prefer this IV. + + TODO: The constant that we're substracting from the cost should + be target-dependent. This information should be added to the + target costs for each backend. */ + if (integer_zerop (*bound_cst) + && (operand_equal_p (*control_var, cand->var_after, 0) + || operand_equal_p (*control_var, cand->var_before, 0))) + elim_cost.cost -= 1; + express_cost = get_computation_cost (data, use, cand, false, &depends_on_express, NULL); fd_ivopts_data = data; |