From 90bc462321f77fb63a04bb3d73bfa54267087b26 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Mon, 2 May 2011 13:11:27 +0000 Subject: re PR tree-optimization/48822 (G++ gets stucks and never finishes compilation when enabling -O2/3 optimization options.) 2011-05-02 Richard Guenther PR tree-optimization/48822 * tree-ssa-sccvn.c (set_ssa_val_to): Never go up the lattice. (process_scc): Indicate which iteration we start. * gcc.dg/torture/pr48822.c: New testcase. From-SVN: r173250 --- gcc/tree-ssa-sccvn.c | 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7 deletions(-) (limited to 'gcc/tree-ssa-sccvn.c') diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index ab56e3d..8f96d6c 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -2241,12 +2241,26 @@ print_scc (FILE *out, VEC (tree, heap) *scc) static inline bool set_ssa_val_to (tree from, tree to) { - tree currval; + tree currval = SSA_VAL (from); - if (from != to - && TREE_CODE (to) == SSA_NAME - && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (to)) - to = from; + if (from != to) + { + if (currval == from) + { + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "Not changing value number of "); + print_generic_expr (dump_file, from, 0); + fprintf (dump_file, " from VARYING to "); + print_generic_expr (dump_file, to, 0); + fprintf (dump_file, "\n"); + } + return false; + } + else if (TREE_CODE (to) == SSA_NAME + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (to)) + to = from; + } /* The only thing we allow as value numbers are VN_TOP, ssa_names and invariants. So assert that here. */ @@ -2263,8 +2277,6 @@ set_ssa_val_to (tree from, tree to) print_generic_expr (dump_file, to, 0); } - currval = SSA_VAL (from); - if (currval != to && !operand_equal_p (currval, to, OEP_PURE_SAME)) { VN_INFO (from)->valnum = to; @@ -3280,6 +3292,8 @@ process_scc (VEC (tree, heap) *scc) { changed = false; iterations++; + if (dump_file && (dump_flags & TDF_DETAILS)) + fprintf (dump_file, "Starting iteration %d\n", iterations); /* As we are value-numbering optimistically we have to clear the expression tables and the simplified expressions in each iteration until we converge. */ -- cgit v1.1