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Commit 14886ab7 by Jeff Law Committed by Jeff Law
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* tree-ssa-phiopt.c: Fix various formatting issues. 

From-SVN: r81995
parent 81f4be3c
Showing with 80 additions and 79 deletions
gcc/ChangeLog
2004-05-18 Jeff Law <law@redhat.com>
* tree-ssa-phiopt.c: Fix various formatting issues.
2004-05-18 Steven Bosscher <stevenb@suse.de>
* config/s390/s390.c (s390_expand_movstr, s390_expand_clrstr,
......
gcc/tree-ssa-phiopt.c
......@@ -37,8 +37,8 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
static void tree_ssa_phiopt (void);
static bool conditional_replacement (basic_block bb, tree phi, tree arg0,
tree arg1);
tree arg1);
/* This pass eliminates PHI nodes which can be trivially implemented as
an assignment from a conditional expression. ie if we have something
like:
......@@ -49,16 +49,16 @@ static bool conditional_replacement (basic_block bb, tree phi, tree arg0,
bb2:
x = PHI (0 (bb1), 1 (bb0)
We can rewrite that as:
We can rewrite that as:
bb0:
bb1:
bb2:
bb0:
bb1:
bb2:
x = cond;
bb1 will become unreachable and bb0 and bb2 will almost always
be merged into a single block. This occurs often due to gimplification
of conditionals. */
bb1 will become unreachable and bb0 and bb2 will almost always
be merged into a single block. This occurs often due to gimplification
of conditionals. */
static void
tree_ssa_phiopt (void)
......@@ -77,19 +77,18 @@ tree_ssa_phiopt (void)
phi = phi_nodes (bb);
if (phi && TREE_CHAIN (phi) == NULL
&& PHI_NUM_ARGS (phi) == 2)
{
arg0 = PHI_ARG_DEF (phi, 0);
arg1 = PHI_ARG_DEF (phi, 1);
/* Do the replacement of conditional if it can be done. */
if (conditional_replacement (bb, phi, arg0, arg1))
{
/* We have done the replacement so we need to rebuild the cfg. */
removed_phis = true;
continue;
}
}
{
arg0 = PHI_ARG_DEF (phi, 0);
arg1 = PHI_ARG_DEF (phi, 1);
/* Do the replacement of conditional if it can be done. */
if (conditional_replacement (bb, phi, arg0, arg1))
{
/* We have done the replacement so we need to rebuild the cfg. */
removed_phis = true;
continue;
}
}
}
/* If we removed any PHIs, then we have unreachable blocks and blocks
......@@ -98,10 +97,11 @@ tree_ssa_phiopt (void)
cleanup_tree_cfg ();
}
/* The function conditional_replacement does the main work of doing the conditional
replacement. Return true if the replacement is done. Otherwise return false.
bb is the basic block where the replacement is going to be done on. arg0
is argument 0 from the phi. Likewise for arg1. */
/* The function conditional_replacement does the main work of doing the
conditional replacement. Return true if the replacement is done.
Otherwise return false.
BB is the basic block where the replacement is going to be done on. ARG0
is argument 0 from PHI. Likewise for ARG1. */
static bool
conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
......@@ -116,7 +116,7 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
tree new_var = NULL;
/* The PHI arguments have the constants 0 and 1, then convert
it to the conditional. */
it to the conditional. */
if ((integer_zerop (arg0) && integer_onep (arg1))
|| (integer_zerop (arg1) && integer_onep (arg0)))
;
......@@ -124,8 +124,8 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
return false;
/* One of the alternatives must come from a block ending with
a COND_EXPR. The other block must be entirely empty, except
for labels. */
a COND_EXPR. The other block must be entirely empty, except
for labels. */
last0 = last_stmt (bb->pred->src);
last1 = last_stmt (bb->pred->pred_next->src);
if (last0 && TREE_CODE (last0) == COND_EXPR)
......@@ -142,7 +142,7 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
return false;
/* COND_BLOCK must have precisely two successors. We indirectly
verify that those successors are BB and OTHER_BLOCK. */
verify that those successors are BB and OTHER_BLOCK. */
if (!cond_block->succ
|| !cond_block->succ->succ_next
|| cond_block->succ->succ_next->succ_next
......@@ -151,8 +151,8 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
return false;
/* OTHER_BLOCK must have a single predecessor which is COND_BLOCK,
OTHER_BLOCK must have a single successor which is BB and
OTHER_BLOCK must have no PHI nodes. */
OTHER_BLOCK must have a single successor which is BB and
OTHER_BLOCK must have no PHI nodes. */
if (!other_block->pred
|| other_block->pred->src != cond_block
|| other_block->pred->pred_next
......@@ -165,19 +165,18 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
/* OTHER_BLOCK must have no executable statements. */
bsi = bsi_start (other_block);
while (!bsi_end_p (bsi)
&& (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR
|| IS_EMPTY_STMT (bsi_stmt (bsi))))
&& (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR
|| IS_EMPTY_STMT (bsi_stmt (bsi))))
bsi_next (&bsi);
if (!bsi_end_p (bsi))
return false;
/* If the condition is not a naked SSA_NAME and its type does not
match the type of the result, then we have to create a new
variable to optimize this case as it would likely create
non-gimple code when the condition was converted to the
result's type. */
match the type of the result, then we have to create a new
variable to optimize this case as it would likely create
non-gimple code when the condition was converted to the
result's type. */
cond = COND_EXPR_COND (last_stmt (cond_block));
result = PHI_RESULT (phi);
if (TREE_CODE (cond) != SSA_NAME
......@@ -189,13 +188,13 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
}
/* If the condition was a naked SSA_NAME and the type is not the
same as the type of the result, then convert the type of the
condition. */
same as the type of the result, then convert the type of the
condition. */
if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result)))
cond = fold_convert (TREE_TYPE (result), cond);
/* We need to know which is the true edge and which is the false
edge so that we know when to invert the condition below. */
edge so that we know when to invert the condition below. */
extract_true_false_edges_from_block (cond_block, &true_edge, &false_edge);
/* Insert our new statement at the head of our block. */
......@@ -205,43 +204,41 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
{
tree new1;
if (TREE_CODE_CLASS (TREE_CODE (old_result)) != '<')
return false;
return false;
new1 = build (TREE_CODE (old_result), TREE_TYPE (result),
TREE_OPERAND (old_result, 0),
TREE_OPERAND (old_result, 1));
TREE_OPERAND (old_result, 0),
TREE_OPERAND (old_result, 1));
new1 = build (MODIFY_EXPR, TREE_TYPE (result),
new_var, new1);
new_var, new1);
bsi_insert_after (&bsi, new1, BSI_NEW_STMT);
}
/* At this point we know we have a COND_EXPR with two successors.
One successor is BB, the other successor is an empty block which
falls through into BB.
There is a single PHI node at the join point (BB) and its arguments
are constants (0, 1).
One successor is BB, the other successor is an empty block which
falls through into BB.
So, given the condition COND, and the two PHI arguments, we can
rewrite this PHI into non-branching code:
There is a single PHI node at the join point (BB) and its arguments
are constants (0, 1).
dest = (COND) or dest = COND'
So, given the condition COND, and the two PHI arguments, we can
rewrite this PHI into non-branching code:
We use the condition as-is if the argument associated with the
true edge has the value one or the argument associated with the
false edge as the value zero. Note that those conditions are not
the same since only one of the outgoing edges from the COND_EXPR
will directly reach BB and thus be associated with an argument. */
dest = (COND) or dest = COND'
We use the condition as-is if the argument associated with the
true edge has the value one or the argument associated with the
false edge as the value zero. Note that those conditions are not
the same since only one of the outgoing edges from the COND_EXPR
will directly reach BB and thus be associated with an argument. */
if ((PHI_ARG_EDGE (phi, 0) == true_edge && integer_onep (arg0))
|| (PHI_ARG_EDGE (phi, 0) == false_edge && integer_zerop (arg0))
|| (PHI_ARG_EDGE (phi, 1) == true_edge && integer_onep (arg1))
|| (PHI_ARG_EDGE (phi, 1) == false_edge && integer_zerop (arg1)))
{
new = build (MODIFY_EXPR, TREE_TYPE (PHI_RESULT (phi)),
PHI_RESULT (phi), cond);
PHI_RESULT (phi), cond);
}
else
{
......@@ -254,35 +251,35 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
return false;
/* If what we get back is not gimple try to create it as gimple by
using a temporary variable. */
using a temporary variable. */
if (is_gimple_cast (cond)
&& !is_gimple_val (TREE_OPERAND (cond, 0)))
{
tree temp = TREE_OPERAND (cond, 0);
tree new_var_1 = make_rename_temp (TREE_TYPE (temp), NULL);
new = build (MODIFY_EXPR, TREE_TYPE (new_var_1), new_var_1, temp);
bsi_insert_after (&bsi, new, BSI_NEW_STMT);
cond = fold_convert (TREE_TYPE (result), new_var_1);
}
{
tree temp = TREE_OPERAND (cond, 0);
tree new_var_1 = make_rename_temp (TREE_TYPE (temp), NULL);
new = build (MODIFY_EXPR, TREE_TYPE (new_var_1), new_var_1, temp);
bsi_insert_after (&bsi, new, BSI_NEW_STMT);
cond = fold_convert (TREE_TYPE (result), new_var_1);
}
if (TREE_CODE (cond) == TRUTH_NOT_EXPR
&& !is_gimple_val (TREE_OPERAND (cond, 0)))
return false;
&& !is_gimple_val (TREE_OPERAND (cond, 0)))
return false;
new = build (MODIFY_EXPR, TREE_TYPE (PHI_RESULT (phi)),
PHI_RESULT (phi), cond);
PHI_RESULT (phi), cond);
}
bsi_insert_after (&bsi, new, BSI_NEW_STMT);
/* Register our new statement as the defining statement for
the result. */
the result. */
SSA_NAME_DEF_STMT (PHI_RESULT (phi)) = new;
/* Remove the now useless PHI node.
We do not want to use remove_phi_node since that releases the
SSA_NAME as well and the SSA_NAME is still being used. */
We do not want to use remove_phi_node since that releases the
SSA_NAME as well and the SSA_NAME is still being used. */
release_phi_node (phi);
bb_ann (bb)->phi_nodes = NULL;
......@@ -308,10 +305,10 @@ conditional_replacement (basic_block bb, tree phi, tree arg0, tree arg1)
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file,
"COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
cond_block->index,
bb->index);
"COND_EXPR in block %d and PHI in block %d converted to straightline code.\n",
cond_block->index,
bb->index);
/* Note that we optimized this PHI. */
return true;
}
......
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