diff options
Diffstat (limited to 'gcc/tree-ssa-dom.c')
| -rw-r--r-- | gcc/tree-ssa-dom.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/gcc/tree-ssa-dom.c b/gcc/tree-ssa-dom.c index 2b37166..a6f176c 100644 --- a/gcc/tree-ssa-dom.c +++ b/gcc/tree-ssa-dom.c @@ -1276,8 +1276,11 @@ record_equality (tree x, tree y, class const_and_copies *const_and_copies) /* Returns true when STMT is a simple iv increment. It detects the following situation: - i_1 = phi (..., i_2) - i_2 = i_1 +/- ... */ + i_1 = phi (..., i_k) + [...] + i_j = i_{j-1} for each j : 2 <= j <= k-1 + [...] + i_k = i_{k-1} +/- ... */ bool simple_iv_increment_p (gimple *stmt) @@ -1305,8 +1308,15 @@ simple_iv_increment_p (gimple *stmt) return false; phi = SSA_NAME_DEF_STMT (preinc); - if (gimple_code (phi) != GIMPLE_PHI) - return false; + while (gimple_code (phi) != GIMPLE_PHI) + { + /* Follow trivial copies, but not the DEF used in a back edge, + so that we don't prevent coalescing. */ + if (!gimple_assign_ssa_name_copy_p (phi)) + return false; + preinc = gimple_assign_rhs1 (phi); + phi = SSA_NAME_DEF_STMT (preinc); + } for (i = 0; i < gimple_phi_num_args (phi); i++) if (gimple_phi_arg_def (phi, i) == lhs) |