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-rw-r--r--gcc/tree-ssa-dce.c100
1 files changed, 12 insertions, 88 deletions
diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 16ff4a30d1f..d8b32ef78b5 100644
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -222,11 +222,11 @@ mark_stmt_necessary (tree stmt, bool add_to_worklist)
VEC_safe_push (tree, heap, worklist, stmt);
}
-/* Mark the statement defining operand OP as necessary. PHIONLY is true
- if we should only mark it necessary if it is a phi node. */
+
+/* Mark the statement defining operand OP as necessary. */
static inline void
-mark_operand_necessary (tree op, bool phionly)
+mark_operand_necessary (tree op)
{
tree stmt;
int ver;
@@ -241,9 +241,7 @@ mark_operand_necessary (tree op, bool phionly)
stmt = SSA_NAME_DEF_STMT (op);
gcc_assert (stmt);
- if (NECESSARY (stmt)
- || IS_EMPTY_STMT (stmt)
- || (phionly && TREE_CODE (stmt) != PHI_NODE))
+ if (NECESSARY (stmt) || IS_EMPTY_STMT (stmt))
return;
NECESSARY (stmt) = 1;
@@ -489,7 +487,7 @@ propagate_necessity (struct edge_list *el)
{
tree arg = PHI_ARG_DEF (stmt, k);
if (TREE_CODE (arg) == SSA_NAME)
- mark_operand_necessary (arg, false);
+ mark_operand_necessary (arg);
}
if (aggressive)
@@ -509,87 +507,22 @@ propagate_necessity (struct edge_list *el)
else
{
/* Propagate through the operands. Examine all the USE, VUSE and
- V_MAY_DEF operands in this statement. Mark all the statements
- which feed this statement's uses as necessary. */
- ssa_op_iter iter;
- tree use;
-
- /* The operands of V_MAY_DEF expressions are also needed as they
+ VDEF operands in this statement. Mark all the statements
+ which feed this statement's uses as necessary. The
+ operands of VDEF expressions are also needed as they
represent potential definitions that may reach this
- statement (V_MAY_DEF operands allow us to follow def-def
+ statement (VDEF operands allow us to follow def-def
links). */
+ ssa_op_iter iter;
+ tree use;
FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_ALL_USES)
- mark_operand_necessary (use, false);
+ mark_operand_necessary (use);
}
}
}
-/* Propagate necessity around virtual phi nodes used in kill operands.
- The reason this isn't done during propagate_necessity is because we don't
- want to keep phis around that are just there for must-defs, unless we
- absolutely have to. After we've rewritten the reaching definitions to be
- correct in the previous part of the fixup routine, we can simply propagate
- around the information about which of these virtual phi nodes are really
- used, and set the NECESSARY flag accordingly.
- Note that we do the minimum here to ensure that we keep alive the phis that
- are actually used in the corrected SSA form. In particular, some of these
- phis may now have all of the same operand, and will be deleted by some
- other pass. */
-
-static void
-mark_really_necessary_kill_operand_phis (void)
-{
- basic_block bb;
- int i;
-
- /* Seed the worklist with the new virtual phi arguments and virtual
- uses */
- FOR_EACH_BB (bb)
- {
- block_stmt_iterator bsi;
- tree phi;
-
- for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
- {
- if (!is_gimple_reg (PHI_RESULT (phi)) && NECESSARY (phi))
- {
- for (i = 0; i < PHI_NUM_ARGS (phi); i++)
- mark_operand_necessary (PHI_ARG_DEF (phi, i), true);
- }
- }
-
- for (bsi = bsi_last (bb); !bsi_end_p (bsi); bsi_prev (&bsi))
- {
- tree stmt = bsi_stmt (bsi);
-
- if (NECESSARY (stmt))
- {
- use_operand_p use_p;
- ssa_op_iter iter;
- FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter,
- SSA_OP_VIRTUAL_USES | SSA_OP_VIRTUAL_KILLS)
- {
- tree use = USE_FROM_PTR (use_p);
- mark_operand_necessary (use, true);
- }
- }
- }
- }
-
- /* Mark all virtual phis still in use as necessary, and all of their
- arguments that are phis as necessary. */
- while (VEC_length (tree, worklist) > 0)
- {
- tree use = VEC_pop (tree, worklist);
-
- for (i = 0; i < PHI_NUM_ARGS (use); i++)
- mark_operand_necessary (PHI_ARG_DEF (use, i), true);
- }
-}
-
-
/* Remove dead PHI nodes from block BB. */
static void
@@ -634,9 +567,6 @@ static void
remove_dead_stmt (block_stmt_iterator *i, basic_block bb)
{
tree t = bsi_stmt (*i);
- def_operand_p def_p;
-
- ssa_op_iter iter;
if (dump_file && (dump_flags & TDF_DETAILS))
{
@@ -711,11 +641,6 @@ remove_dead_stmt (block_stmt_iterator *i, basic_block bb)
}
}
- FOR_EACH_SSA_DEF_OPERAND (def_p, t, iter, SSA_OP_VIRTUAL_DEFS)
- {
- tree def = DEF_FROM_PTR (def_p);
- mark_sym_for_renaming (SSA_NAME_VAR (def));
- }
bsi_remove (i, true);
release_defs (t);
}
@@ -875,7 +800,6 @@ perform_tree_ssa_dce (bool aggressive)
propagate_necessity (el);
- mark_really_necessary_kill_operand_phis ();
eliminate_unnecessary_stmts ();
if (aggressive)