diff options
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/tree-outof-ssa.c | 70 |
2 files changed, 76 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 82ed1a1..1a3b594 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2009-05-13 Michael Matz <matz@suse.de> + + PR middle-end/39976 + * tree-outof-ssa.c (maybe_renumber_stmts_bb): New function. + (trivially_conflicts_p): New function. + (insert_backedge_copies): Use it. + 2009-05-13 Janis Johnson <janis187@us.ibm.com> * c-pragma.c (enum pragma_switch_t): Prefix constants with PRAGMA_. diff --git a/gcc/tree-outof-ssa.c b/gcc/tree-outof-ssa.c index 50d3089..4ed8e9f 100644 --- a/gcc/tree-outof-ssa.c +++ b/gcc/tree-outof-ssa.c @@ -853,6 +853,67 @@ remove_ssa_form (bool perform_ter, struct ssaexpand *sa) } +/* If not already done so for basic block BB, assign increasing uids + to each of its instructions. */ + +static void +maybe_renumber_stmts_bb (basic_block bb) +{ + unsigned i = 0; + gimple_stmt_iterator gsi; + + if (!bb->aux) + return; + bb->aux = NULL; + for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) + { + gimple stmt = gsi_stmt (gsi); + gimple_set_uid (stmt, i); + i++; + } +} + + +/* Return true if we can determine that the SSA_NAMEs RESULT (a result + of a PHI node) and ARG (one of its arguments) conflict. Return false + otherwise, also when we simply aren't sure. */ + +static bool +trivially_conflicts_p (basic_block bb, tree result, tree arg) +{ + use_operand_p use; + imm_use_iterator imm_iter; + gimple defa = SSA_NAME_DEF_STMT (arg); + + /* If ARG isn't defined in the same block it's too complicated for + our little mind. */ + if (gimple_bb (defa) != bb) + return false; + + FOR_EACH_IMM_USE_FAST (use, imm_iter, result) + { + gimple use_stmt = USE_STMT (use); + /* Now, if there's a use of RESULT that lies outside this basic block, + then there surely is a conflict with ARG. */ + if (gimple_bb (use_stmt) != bb) + return true; + if (gimple_code (use_stmt) == GIMPLE_PHI) + continue; + /* The use now is in a real stmt of BB, so if ARG was defined + in a PHI node (like RESULT) both conflict. */ + if (gimple_code (defa) == GIMPLE_PHI) + return true; + maybe_renumber_stmts_bb (bb); + /* If the use of RESULT occurs after the definition of ARG, + the two conflict too. */ + if (gimple_uid (defa) < gimple_uid (use_stmt)) + return true; + } + + return false; +} + + /* Search every PHI node for arguments associated with backedges which we can trivially determine will need a copy (the argument is either not an SSA_NAME or the argument has a different underlying variable @@ -870,6 +931,9 @@ insert_backedge_copies (void) FOR_EACH_BB (bb) { + /* Mark block as possibly needing calculation of UIDs. */ + bb->aux = &bb->aux; + for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) { gimple phi = gsi_stmt (gsi); @@ -892,7 +956,8 @@ insert_backedge_copies (void) needed. */ if ((e->flags & EDGE_DFS_BACK) && (TREE_CODE (arg) != SSA_NAME - || SSA_NAME_VAR (arg) != result_var)) + || SSA_NAME_VAR (arg) != result_var + || trivially_conflicts_p (bb, result, arg))) { tree name; gimple stmt, last = NULL; @@ -936,6 +1001,9 @@ insert_backedge_copies (void) } } } + + /* Unmark this block again. */ + bb->aux = NULL; } } |