static gimple
get_prop_dest_stmt (tree name, tree *final_name_p)
{
use_operand_p use;
gimple use_stmt;
do {
/* If name has multiple uses, bail out. */
if (!single_imm_use (name, &use, &use_stmt))
return NULL;
/* If this is not a trivial copy, we found it. */
if (!gimple_assign_copy_p (use_stmt)
|| TREE_CODE (gimple_assign_lhs (use_stmt)) != SSA_NAME
|| gimple_assign_rhs1 (use_stmt) != name)
break;
/* Continue searching uses of the copy destination. */
name = gimple_assign_lhs (use_stmt);
} while (1);
if (final_name_p)
*final_name_p = name;
return use_stmt;
}
static bool
forward_propagate_addr_expr (tree stmt)
{
int stmt_loop_depth = bb_for_stmt (stmt)->loop_depth;
tree name = TREE_OPERAND (stmt, 0);
use_operand_p imm_use;
tree use_stmt, lhs, rhs, array_ref;
/* We require that the SSA_NAME holding the result of the ADDR_EXPR
be used only once. That may be overly conservative in that we
could propagate into multiple uses. However, that would effectively
be un-cseing the ADDR_EXPR, which is probably not what we want. */
single_imm_use (name, &imm_use, &use_stmt);
if (!use_stmt)
return false;
/* If the use is not in a simple assignment statement, then
there is nothing we can do. */
if (TREE_CODE (use_stmt) != MODIFY_EXPR)
return false;
/* If the use is in a deeper loop nest, then we do not want
to propagate the ADDR_EXPR into the loop as that is likely
adding expression evaluations into the loop. */
if (bb_for_stmt (use_stmt)->loop_depth > stmt_loop_depth)
return false;
/* Strip away any outer COMPONENT_REF/ARRAY_REF nodes from the LHS.
ADDR_EXPR will not appear on the LHS. */
lhs = TREE_OPERAND (use_stmt, 0);
while (TREE_CODE (lhs) == COMPONENT_REF || TREE_CODE (lhs) == ARRAY_REF)
lhs = TREE_OPERAND (lhs, 0);
/* Now see if the LHS node is an INDIRECT_REF using NAME. If so,
propagate the ADDR_EXPR into the use of NAME and fold the result. */
if (TREE_CODE (lhs) == INDIRECT_REF && TREE_OPERAND (lhs, 0) == name)
{
/* This should always succeed in creating gimple, so there is
no need to save enough state to undo this propagation. */
TREE_OPERAND (lhs, 0) = unshare_expr (TREE_OPERAND (stmt, 1));
fold_stmt_inplace (use_stmt);
tidy_after_forward_propagate_addr (use_stmt);
return true;
}
/* Trivial case. The use statement could be a trivial copy. We
go ahead and handle that case here since it's trivial and
removes the need to run copy-prop before this pass to get
the best results. Also note that by handling this case here
we can catch some cascading effects, ie the single use is
in a copy, and the copy is used later by a single INDIRECT_REF
for example. */
if (TREE_CODE (lhs) == SSA_NAME && TREE_OPERAND (use_stmt, 1) == name)
{
TREE_OPERAND (use_stmt, 1) = unshare_expr (TREE_OPERAND (stmt, 1));
tidy_after_forward_propagate_addr (use_stmt);
return true;
}
/* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
nodes from the RHS. */
rhs = TREE_OPERAND (use_stmt, 1);
while (TREE_CODE (rhs) == COMPONENT_REF
|| TREE_CODE (rhs) == ARRAY_REF
|| TREE_CODE (rhs) == ADDR_EXPR)
rhs = TREE_OPERAND (rhs, 0);
/* Now see if the RHS node is an INDIRECT_REF using NAME. If so,
propagate the ADDR_EXPR into the use of NAME and fold the result. */
if (TREE_CODE (rhs) == INDIRECT_REF && TREE_OPERAND (rhs, 0) == name)
{
/* This should always succeed in creating gimple, so there is
no need to save enough state to undo this propagation. */
TREE_OPERAND (rhs, 0) = unshare_expr (TREE_OPERAND (stmt, 1));
fold_stmt_inplace (use_stmt);
tidy_after_forward_propagate_addr (use_stmt);
return true;
}
/* The remaining cases are all for turning pointer arithmetic into
array indexing. They only apply when we have the address of
element zero in an array. If that is not the case then there
is nothing to do. */
array_ref = TREE_OPERAND (TREE_OPERAND (stmt, 1), 0);
if (TREE_CODE (array_ref) != ARRAY_REF
|| TREE_CODE (TREE_TYPE (TREE_OPERAND (array_ref, 0))) != ARRAY_TYPE
|| !integer_zerop (TREE_OPERAND (array_ref, 1)))
return false;
/* If the use of the ADDR_EXPR must be a PLUS_EXPR, or else there
is nothing to do. */
if (TREE_CODE (rhs) != PLUS_EXPR)
return false;
/* Try to optimize &x[0] + C where C is a multiple of the size
of the elements in X into &x[C/element size]. */
if (TREE_OPERAND (rhs, 0) == name
&& TREE_CODE (TREE_OPERAND (rhs, 1)) == INTEGER_CST)
{
tree orig = unshare_expr (rhs);
TREE_OPERAND (rhs, 0) = unshare_expr (TREE_OPERAND (stmt, 1));
/* If folding succeeds, then we have just exposed new variables
in USE_STMT which will need to be renamed. If folding fails,
then we need to put everything back the way it was. */
if (fold_stmt_inplace (use_stmt))
{
tidy_after_forward_propagate_addr (use_stmt);
return true;
}
else
{
TREE_OPERAND (use_stmt, 1) = orig;
update_stmt (use_stmt);
return false;
}
}
/* Try to optimize &x[0] + OFFSET where OFFSET is defined by
converting a multiplication of an index by the size of the
array elements, then the result is converted into the proper
type for the arithmetic. */
if (TREE_OPERAND (rhs, 0) == name
&& TREE_CODE (TREE_OPERAND (rhs, 1)) == SSA_NAME
/* Avoid problems with IVopts creating PLUS_EXPRs with a
different type than their operands. */
&& lang_hooks.types_compatible_p (TREE_TYPE (name), TREE_TYPE (rhs)))
{
tree offset_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 1));
return forward_propagate_addr_into_variable_array_index (offset_stmt, lhs,
stmt, use_stmt);
}
/* Same as the previous case, except the operands of the PLUS_EXPR
were reversed. */
if (TREE_OPERAND (rhs, 1) == name
&& TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME
/* Avoid problems with IVopts creating PLUS_EXPRs with a
different type than their operands. */
&& lang_hooks.types_compatible_p (TREE_TYPE (name), TREE_TYPE (rhs)))
{
tree offset_stmt = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
return forward_propagate_addr_into_variable_array_index (offset_stmt, lhs,
stmt, use_stmt);
}
return false;
}
static tree
rewrite_bittest (block_stmt_iterator *bsi)
{
tree stmt, lhs, rhs, var, name, use_stmt, stmt1, stmt2, t;
use_operand_p use;
stmt = bsi_stmt (*bsi);
lhs = GENERIC_TREE_OPERAND (stmt, 0);
rhs = GENERIC_TREE_OPERAND (stmt, 1);
/* Verify that the single use of lhs is a comparison against zero. */
if (TREE_CODE (lhs) != SSA_NAME
|| !single_imm_use (lhs, &use, &use_stmt)
|| TREE_CODE (use_stmt) != COND_EXPR)
return stmt;
t = COND_EXPR_COND (use_stmt);
if (TREE_OPERAND (t, 0) != lhs
|| (TREE_CODE (t) != NE_EXPR
&& TREE_CODE (t) != EQ_EXPR)
|| !integer_zerop (TREE_OPERAND (t, 1)))
return stmt;
/* Get at the operands of the shift. The rhs is TMP1 & 1. */
stmt1 = SSA_NAME_DEF_STMT (TREE_OPERAND (rhs, 0));
if (TREE_CODE (stmt1) != GIMPLE_MODIFY_STMT)
return stmt;
/* There is a conversion in between possibly inserted by fold. */
t = GIMPLE_STMT_OPERAND (stmt1, 1);
if (TREE_CODE (t) == NOP_EXPR
|| TREE_CODE (t) == CONVERT_EXPR)
{
t = TREE_OPERAND (t, 0);
if (TREE_CODE (t) != SSA_NAME
|| !has_single_use (t))
return stmt;
stmt1 = SSA_NAME_DEF_STMT (t);
if (TREE_CODE (stmt1) != GIMPLE_MODIFY_STMT)
return stmt;
t = GIMPLE_STMT_OPERAND (stmt1, 1);
}
/* Verify that B is loop invariant but A is not. Verify that with
all the stmt walking we are still in the same loop. */
if (TREE_CODE (t) == RSHIFT_EXPR
&& loop_containing_stmt (stmt1) == loop_containing_stmt (stmt)
&& outermost_invariant_loop_expr (TREE_OPERAND (t, 1),
loop_containing_stmt (stmt1)) != NULL
&& outermost_invariant_loop_expr (TREE_OPERAND (t, 0),
loop_containing_stmt (stmt1)) == NULL)
{
tree a = TREE_OPERAND (t, 0);
tree b = TREE_OPERAND (t, 1);
/* 1 << B */
var = create_tmp_var (TREE_TYPE (a), "shifttmp");
add_referenced_var (var);
t = fold_build2 (LSHIFT_EXPR, TREE_TYPE (a),
build_int_cst (TREE_TYPE (a), 1), b);
stmt1 = build_gimple_modify_stmt (var, t);
name = make_ssa_name (var, stmt1);
GIMPLE_STMT_OPERAND (stmt1, 0) = name;
/* A & (1 << B) */
t = fold_build2 (BIT_AND_EXPR, TREE_TYPE (a), a, name);
stmt2 = build_gimple_modify_stmt (var, t);
name = make_ssa_name (var, stmt2);
GIMPLE_STMT_OPERAND (stmt2, 0) = name;
/* Replace the SSA_NAME we compare against zero. Adjust
the type of zero accordingly. */
SET_USE (use, name);
TREE_OPERAND (COND_EXPR_COND (use_stmt), 1)
= build_int_cst_type (TREE_TYPE (name), 0);
bsi_insert_before (bsi, stmt1, BSI_SAME_STMT);
bsi_replace (bsi, stmt2, true);
return stmt1;
}
return stmt;
}
static inline bool
is_replaceable_p (gimple stmt)
{
use_operand_p use_p;
tree def;
gimple use_stmt;
location_t locus1, locus2;
tree block1, block2;
/* Only consider modify stmts. */
if (!is_gimple_assign (stmt))
return false;
/* If the statement may throw an exception, it cannot be replaced. */
if (stmt_could_throw_p (stmt))
return false;
/* Punt if there is more than 1 def. */
def = SINGLE_SSA_TREE_OPERAND (stmt, SSA_OP_DEF);
if (!def)
return false;
/* Only consider definitions which have a single use. */
if (!single_imm_use (def, &use_p, &use_stmt))
return false;
/* If the use isn't in this block, it wont be replaced either. */
if (gimple_bb (use_stmt) != gimple_bb (stmt))
return false;
locus1 = gimple_location (stmt);
block1 = gimple_block (stmt);
if (gimple_code (use_stmt) == GIMPLE_PHI)
{
locus2 = 0;
block2 = NULL_TREE;
}
else
{
locus2 = gimple_location (use_stmt);
block2 = gimple_block (use_stmt);
}
if (!optimize
&& ((locus1 && locus1 != locus2) || (block1 && block1 != block2)))
return false;
/* Used in this block, but at the TOP of the block, not the end. */
if (gimple_code (use_stmt) == GIMPLE_PHI)
return false;
/* There must be no VDEFs. */
if (!(ZERO_SSA_OPERANDS (stmt, SSA_OP_VDEF)))
return false;
/* Without alias info we can't move around loads. */
if (gimple_references_memory_p (stmt) && !optimize)
return false;
/* Float expressions must go through memory if float-store is on. */
if (flag_float_store
&& FLOAT_TYPE_P (gimple_expr_type (stmt)))
return false;
/* An assignment with a register variable on the RHS is not
replaceable. */
if (gimple_assign_rhs_code (stmt) == VAR_DECL
&& DECL_HARD_REGISTER (gimple_assign_rhs1 (stmt)))
return false;
/* No function calls can be replaced. */
if (is_gimple_call (stmt))
return false;
/* Leave any stmt with volatile operands alone as well. */
if (gimple_has_volatile_ops (stmt))
return false;
return true;
}
