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| author | Richard Sandiford <richard.sandiford@linaro.org> | 2017-08-16 07:51:13 +0000 |
|---|---|---|
| committer | Richard Sandiford <rsandifo@gcc.gnu.org> | 2017-08-16 07:51:13 +0000 |
| commit | 963aeaad25122bc507f9c72b9af6fc13cbeccde4 (patch) | |
| tree | 9c24e2074a1675f8b8a339be48ef9450a724feaf /gcc/tree-vect-loop.c | |
| parent | 60e095de004cd024b67875f3c1d2a382feba7cce (diff) | |
| download | gcc-963aeaad25122bc507f9c72b9af6fc13cbeccde4.zip gcc-963aeaad25122bc507f9c72b9af6fc13cbeccde4.tar.gz gcc-963aeaad25122bc507f9c72b9af6fc13cbeccde4.tar.bz2 | |
PR81815: Invalid conditional reduction
We weren't checking whether the phi in a conditional reduction was
used by the condition itself (which isn't a case we handle).
2017-08-11 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
PR tree-optimization/81835
* tree-vect-loop.c (vect_is_simple_reduction): Simply checks for
the phi SSA_NAME. Check that the condition in a COND_EXPR does
not depend on the phi.
gcc/testsuite/
PR tree-optimization/81835
* gcc.dg/vect/pr81815.c: New test.
From-SVN: r251117
Diffstat (limited to 'gcc/tree-vect-loop.c')
| -rw-r--r-- | gcc/tree-vect-loop.c | 19 |
1 files changed, 12 insertions, 7 deletions
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c index 8b2a61e..906323b 100644 --- a/gcc/tree-vect-loop.c +++ b/gcc/tree-vect-loop.c @@ -2690,15 +2690,15 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi, *double_reduc = false; *v_reduc_type = TREE_CODE_REDUCTION; - name = PHI_RESULT (phi); + tree phi_name = PHI_RESULT (phi); /* ??? If there are no uses of the PHI result the inner loop reduction won't be detected as possibly double-reduction by vectorizable_reduction because that tries to walk the PHI arg from the preheader edge which can be constant. See PR60382. */ - if (has_zero_uses (name)) + if (has_zero_uses (phi_name)) return NULL; nloop_uses = 0; - FOR_EACH_IMM_USE_FAST (use_p, imm_iter, name) + FOR_EACH_IMM_USE_FAST (use_p, imm_iter, phi_name) { gimple *use_stmt = USE_STMT (use_p); if (is_gimple_debug (use_stmt)) @@ -2847,10 +2847,7 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi, simply rewriting this into "res += -x[i]". Avoid changing gimple instruction for the first simple tests and only do this if we're allowed to change code at all. */ - if (code == MINUS_EXPR - && ! ((op1 = gimple_assign_rhs2 (def_stmt)) - && TREE_CODE (op1) == SSA_NAME - && SSA_NAME_DEF_STMT (op1) == phi)) + if (code == MINUS_EXPR && gimple_assign_rhs2 (def_stmt) != phi_name) code = PLUS_EXPR; if (code == COND_EXPR) @@ -2864,6 +2861,14 @@ vect_is_simple_reduction (loop_vec_info loop_info, gimple *phi, op4 = TREE_OPERAND (op3, 1); op3 = TREE_OPERAND (op3, 0); } + if (op3 == phi_name || op4 == phi_name) + { + if (dump_enabled_p ()) + report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt, + "reduction: condition depends on previous" + " iteration: "); + return NULL; + } op1 = gimple_assign_rhs2 (def_stmt); op2 = gimple_assign_rhs3 (def_stmt); |