/* Convert a program in SSA form into Normal form.
- Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
+ Free Software Foundation, Inc.
Contributed by Andrew Macleod <amacleod@redhat.com>
This file is part of GCC.
#include "tree.h"
#include "ggc.h"
#include "basic-block.h"
-#include "diagnostic.h"
+#include "tree-pretty-print.h"
+#include "gimple-pretty-print.h"
#include "bitmap.h"
#include "tree-flow.h"
#include "timevar.h"
#include "tree-dump.h"
#include "tree-pass.h"
-#include "toplev.h"
-#include "expr.h"
+#include "diagnostic-core.h"
#include "ssaexpand.h"
+/* FIXME: A lot of code here deals with expanding to RTL. All that code
+ should be in cfgexpand.c. */
+#include "expr.h"
+
+
+DEF_VEC_I(source_location);
+DEF_VEC_ALLOC_I(source_location,heap);
/* Used to hold all the components required to do SSA PHI elimination.
The node and pred/succ list is a simple linear list of nodes and
edges represented as pairs of nodes.
The predecessor and successor list: Nodes are entered in pairs, where
- [0] ->PRED, [1]->SUCC. All the even indexes in the array represent
- predecessors, all the odd elements are successors.
-
+ [0] ->PRED, [1]->SUCC. All the even indexes in the array represent
+ predecessors, all the odd elements are successors.
+
Rationale:
- When implemented as bitmaps, very large programs SSA->Normal times were
+ When implemented as bitmaps, very large programs SSA->Normal times were
being dominated by clearing the interference graph.
- Typically this list of edges is extremely small since it only includes
- PHI results and uses from a single edge which have not coalesced with
+ Typically this list of edges is extremely small since it only includes
+ PHI results and uses from a single edge which have not coalesced with
each other. This means that no virtual PHI nodes are included, and
empirical evidence suggests that the number of edges rarely exceed
3, and in a bootstrap of GCC, the maximum size encountered was 7.
This also limits the number of possible nodes that are involved to
rarely more than 6, and in the bootstrap of gcc, the maximum number
of nodes encountered was 12. */
-
+
typedef struct _elim_graph {
/* Size of the elimination vectors. */
int size;
/* The predecessor and successor edge list. */
VEC(int,heap) *edge_list;
+ /* Source locus on each edge */
+ VEC(source_location,heap) *edge_locus;
+
/* Visited vector. */
sbitmap visited;
/* Stack for visited nodes. */
VEC(int,heap) *stack;
-
+
/* The variable partition map. */
var_map map;
/* List of constant copies to emit. These are pushed on in pairs. */
VEC(int,heap) *const_dests;
VEC(tree,heap) *const_copies;
+
+ /* Source locations for any constant copies. */
+ VEC(source_location,heap) *copy_locus;
} *elim_graph;
for (gsi = gsi_last_bb (bb); !gsi_end_p (gsi); gsi_prev (&gsi))
{
gimple stmt = gsi_stmt (gsi);
+ if (is_gimple_debug (stmt))
+ continue;
if (gimple_has_location (stmt) || gimple_block (stmt))
{
set_curr_insn_source_location (gimple_location (stmt));
}
}
-/* Emit insns to copy SRC into DEST converting SRC if necessary. */
+/* Emit insns to copy SRC into DEST converting SRC if necessary. As
+ SRC/DEST might be BLKmode memory locations SIZEEXP is a tree from
+ which we deduce the size to copy in that case. */
static inline rtx
-emit_partition_copy (rtx dest, rtx src, int unsignedsrcp)
+emit_partition_copy (rtx dest, rtx src, int unsignedsrcp, tree sizeexp)
{
rtx seq;
if (GET_MODE (src) != VOIDmode && GET_MODE (src) != GET_MODE (dest))
src = convert_to_mode (GET_MODE (dest), src, unsignedsrcp);
- emit_move_insn (dest, src);
+ if (GET_MODE (src) == BLKmode)
+ {
+ gcc_assert (GET_MODE (dest) == BLKmode);
+ emit_block_move (dest, src, expr_size (sizeexp), BLOCK_OP_NORMAL);
+ }
+ else
+ emit_move_insn (dest, src);
seq = get_insns ();
end_sequence ();
/* Insert a copy instruction from partition SRC to DEST onto edge E. */
static void
-insert_partition_copy_on_edge (edge e, int dest, int src)
+insert_partition_copy_on_edge (edge e, int dest, int src, source_location locus)
{
+ tree var;
rtx seq;
if (dump_file && (dump_flags & TDF_DETAILS))
{
gcc_assert (SA.partition_to_pseudo[src]);
set_location_for_edge (e);
+ /* If a locus is provided, override the default. */
+ if (locus)
+ set_curr_insn_source_location (locus);
+ var = partition_to_var (SA.map, src);
seq = emit_partition_copy (SA.partition_to_pseudo[dest],
SA.partition_to_pseudo[src],
- TYPE_UNSIGNED (TREE_TYPE (
- partition_to_var (SA.map, src))));
+ TYPE_UNSIGNED (TREE_TYPE (var)),
+ var);
insert_insn_on_edge (seq, e);
}
onto edge E. */
static void
-insert_value_copy_on_edge (edge e, int dest, tree src)
+insert_value_copy_on_edge (edge e, int dest, tree src, source_location locus)
{
rtx seq, x;
- enum machine_mode mode;
+ enum machine_mode dest_mode, src_mode;
+ int unsignedp;
+ tree var;
+
if (dump_file && (dump_flags & TDF_DETAILS))
{
fprintf (dump_file,
gcc_assert (SA.partition_to_pseudo[dest]);
set_location_for_edge (e);
+ /* If a locus is provided, override the default. */
+ if (locus)
+ set_curr_insn_source_location (locus);
start_sequence ();
- mode = GET_MODE (SA.partition_to_pseudo[dest]);
- x = expand_expr (src, SA.partition_to_pseudo[dest], mode, EXPAND_NORMAL);
- if (GET_MODE (x) != VOIDmode && GET_MODE (x) != mode)
- x = convert_to_mode (mode, x, TYPE_UNSIGNED (TREE_TYPE (src)));
- if (CONSTANT_P (x) && GET_MODE (x) == VOIDmode
- && mode != TYPE_MODE (TREE_TYPE (src)))
- x = convert_modes (mode, TYPE_MODE (TREE_TYPE (src)),
- x, TYPE_UNSIGNED (TREE_TYPE (src)));
+
+ var = SSA_NAME_VAR (partition_to_var (SA.map, dest));
+ src_mode = TYPE_MODE (TREE_TYPE (src));
+ dest_mode = GET_MODE (SA.partition_to_pseudo[dest]);
+ gcc_assert (src_mode == TYPE_MODE (TREE_TYPE (var)));
+ gcc_assert (!REG_P (SA.partition_to_pseudo[dest])
+ || dest_mode == promote_decl_mode (var, &unsignedp));
+
+ if (src_mode != dest_mode)
+ {
+ x = expand_expr (src, NULL, src_mode, EXPAND_NORMAL);
+ x = convert_modes (dest_mode, src_mode, x, unsignedp);
+ }
+ else if (src_mode == BLKmode)
+ {
+ x = SA.partition_to_pseudo[dest];
+ store_expr (src, x, 0, false);
+ }
+ else
+ x = expand_expr (src, SA.partition_to_pseudo[dest],
+ dest_mode, EXPAND_NORMAL);
+
if (x != SA.partition_to_pseudo[dest])
emit_move_insn (SA.partition_to_pseudo[dest], x);
seq = get_insns ();
onto edge E. */
static void
-insert_rtx_to_part_on_edge (edge e, int dest, rtx src, int unsignedsrcp)
+insert_rtx_to_part_on_edge (edge e, int dest, rtx src, int unsignedsrcp,
+ source_location locus)
{
rtx seq;
if (dump_file && (dump_flags & TDF_DETAILS))
}
gcc_assert (SA.partition_to_pseudo[dest]);
- set_location_for_edge (e);
+ set_location_for_edge (e);
+ /* If a locus is provided, override the default. */
+ if (locus)
+ set_curr_insn_source_location (locus);
+
+ /* We give the destination as sizeexp in case src/dest are BLKmode
+ mems. Usually we give the source. As we result from SSA names
+ the left and right size should be the same (and no WITH_SIZE_EXPR
+ involved), so it doesn't matter. */
seq = emit_partition_copy (SA.partition_to_pseudo[dest],
- src,
- unsignedsrcp);
+ src, unsignedsrcp,
+ partition_to_var (SA.map, dest));
insert_insn_on_edge (seq, e);
}
onto edge E. */
static void
-insert_part_to_rtx_on_edge (edge e, rtx dest, int src)
+insert_part_to_rtx_on_edge (edge e, rtx dest, int src, source_location locus)
{
+ tree var;
rtx seq;
if (dump_file && (dump_flags & TDF_DETAILS))
{
}
gcc_assert (SA.partition_to_pseudo[src]);
+
set_location_for_edge (e);
+ /* If a locus is provided, override the default. */
+ if (locus)
+ set_curr_insn_source_location (locus);
+ var = partition_to_var (SA.map, src);
seq = emit_partition_copy (dest,
SA.partition_to_pseudo[src],
- TYPE_UNSIGNED (TREE_TYPE (
- partition_to_var (SA.map, src))));
+ TYPE_UNSIGNED (TREE_TYPE (var)),
+ var);
insert_insn_on_edge (seq, e);
}
g->nodes = VEC_alloc (int, heap, 30);
g->const_dests = VEC_alloc (int, heap, 20);
g->const_copies = VEC_alloc (tree, heap, 20);
+ g->copy_locus = VEC_alloc (source_location, heap, 10);
g->edge_list = VEC_alloc (int, heap, 20);
+ g->edge_locus = VEC_alloc (source_location, heap, 10);
g->stack = VEC_alloc (int, heap, 30);
-
+
g->visited = sbitmap_alloc (size);
return g;
{
VEC_truncate (int, g->nodes, 0);
VEC_truncate (int, g->edge_list, 0);
+ VEC_truncate (source_location, g->edge_locus, 0);
}
VEC_free (tree, heap, g->const_copies);
VEC_free (int, heap, g->const_dests);
VEC_free (int, heap, g->nodes);
+ VEC_free (source_location, heap, g->copy_locus);
+ VEC_free (source_location, heap, g->edge_locus);
+
free (g);
}
/* Add NODE to graph G, if it doesn't exist already. */
-static inline void
+static inline void
elim_graph_add_node (elim_graph g, int node)
{
int x;
int t;
- for (x = 0; VEC_iterate (int, g->nodes, x, t); x++)
+ FOR_EACH_VEC_ELT (int, g->nodes, x, t)
if (t == node)
return;
VEC_safe_push (int, heap, g->nodes, node);
/* Add the edge PRED->SUCC to graph G. */
static inline void
-elim_graph_add_edge (elim_graph g, int pred, int succ)
+elim_graph_add_edge (elim_graph g, int pred, int succ, source_location locus)
{
VEC_safe_push (int, heap, g->edge_list, pred);
VEC_safe_push (int, heap, g->edge_list, succ);
+ VEC_safe_push (source_location, heap, g->edge_locus, locus);
}
return the successor node. -1 is returned if there is no such edge. */
static inline int
-elim_graph_remove_succ_edge (elim_graph g, int node)
+elim_graph_remove_succ_edge (elim_graph g, int node, source_location *locus)
{
int y;
unsigned x;
VEC_replace (int, g->edge_list, x, -1);
y = VEC_index (int, g->edge_list, x + 1);
VEC_replace (int, g->edge_list, x + 1, -1);
+ *locus = VEC_index (source_location, g->edge_locus, x / 2);
+ VEC_replace (source_location, g->edge_locus, x / 2, UNKNOWN_LOCATION);
return y;
}
+ *locus = UNKNOWN_LOCATION;
return -1;
}
edge list. VAR will hold the partition number found. CODE is the
code fragment executed for every node found. */
-#define FOR_EACH_ELIM_GRAPH_SUCC(GRAPH, NODE, VAR, CODE) \
+#define FOR_EACH_ELIM_GRAPH_SUCC(GRAPH, NODE, VAR, LOCUS, CODE) \
do { \
unsigned x_; \
int y_; \
y_ = VEC_index (int, (GRAPH)->edge_list, x_); \
if (y_ != (NODE)) \
continue; \
- (VAR) = VEC_index (int, (GRAPH)->edge_list, x_ + 1); \
+ (void) ((VAR) = VEC_index (int, (GRAPH)->edge_list, x_ + 1)); \
+ (void) ((LOCUS) = VEC_index (source_location, \
+ (GRAPH)->edge_locus, x_ / 2)); \
CODE; \
} \
} while (0)
GRAPH. VAR will hold the partition number found. CODE is the
code fragment executed for every node found. */
-#define FOR_EACH_ELIM_GRAPH_PRED(GRAPH, NODE, VAR, CODE) \
+#define FOR_EACH_ELIM_GRAPH_PRED(GRAPH, NODE, VAR, LOCUS, CODE) \
do { \
unsigned x_; \
int y_; \
y_ = VEC_index (int, (GRAPH)->edge_list, x_ + 1); \
if (y_ != (NODE)) \
continue; \
- (VAR) = VEC_index (int, (GRAPH)->edge_list, x_); \
+ (void) ((VAR) = VEC_index (int, (GRAPH)->edge_list, x_)); \
+ (void) ((LOCUS) = VEC_index (source_location, \
+ (GRAPH)->edge_locus, x_ / 2)); \
CODE; \
} \
} while (0)
gimple_stmt_iterator gsi;
clear_elim_graph (g);
-
+
for (gsi = gsi_start_phis (g->e->dest); !gsi_end_p (gsi); gsi_next (&gsi))
{
gimple phi = gsi_stmt (gsi);
+ source_location locus;
p0 = var_to_partition (g->map, gimple_phi_result (phi));
/* Ignore results which are not in partitions. */
continue;
Ti = PHI_ARG_DEF (phi, g->e->dest_idx);
+ locus = gimple_phi_arg_location_from_edge (phi, g->e);
/* If this argument is a constant, or a SSA_NAME which is being
left in SSA form, just queue a copy to be emitted on this
on this edge. */
VEC_safe_push (int, heap, g->const_dests, p0);
VEC_safe_push (tree, heap, g->const_copies, Ti);
+ VEC_safe_push (source_location, heap, g->copy_locus, locus);
}
else
{
{
eliminate_name (g, p0);
eliminate_name (g, pi);
- elim_graph_add_edge (g, p0, pi);
+ elim_graph_add_edge (g, p0, pi, locus);
}
}
}
/* Push successors of T onto the elimination stack for G. */
-static void
+static void
elim_forward (elim_graph g, int T)
{
int S;
+ source_location locus;
+
SET_BIT (g->visited, T);
- FOR_EACH_ELIM_GRAPH_SUCC (g, T, S,
+ FOR_EACH_ELIM_GRAPH_SUCC (g, T, S, locus,
{
if (!TEST_BIT (g->visited, S))
elim_forward (g, S);
elim_unvisited_predecessor (elim_graph g, int T)
{
int P;
- FOR_EACH_ELIM_GRAPH_PRED (g, T, P,
+ source_location locus;
+
+ FOR_EACH_ELIM_GRAPH_PRED (g, T, P, locus,
{
if (!TEST_BIT (g->visited, P))
return 1;
elim_backward (elim_graph g, int T)
{
int P;
+ source_location locus;
+
SET_BIT (g->visited, T);
- FOR_EACH_ELIM_GRAPH_PRED (g, T, P,
+ FOR_EACH_ELIM_GRAPH_PRED (g, T, P, locus,
{
if (!TEST_BIT (g->visited, P))
{
elim_backward (g, P);
- insert_partition_copy_on_edge (g->e, P, T);
+ insert_partition_copy_on_edge (g->e, P, T, locus);
}
});
}
{
tree var = TREE_CODE (name) == SSA_NAME ? SSA_NAME_VAR (name) : name;
tree type = TREE_TYPE (var);
- int unsignedp = TYPE_UNSIGNED (type);
- enum machine_mode reg_mode
- = promote_mode (type, DECL_MODE (var), &unsignedp, 0);
+ int unsignedp;
+ enum machine_mode reg_mode = promote_decl_mode (var, &unsignedp);
rtx x = gen_reg_rtx (reg_mode);
if (POINTER_TYPE_P (type))
mark_reg_pointer (x, TYPE_ALIGN (TREE_TYPE (TREE_TYPE (var))));
return x;
}
-/* Insert required copies for T in graph G. Check for a strongly connected
+/* Insert required copies for T in graph G. Check for a strongly connected
region, and create a temporary to break the cycle if one is found. */
-static void
+static void
elim_create (elim_graph g, int T)
{
int P, S;
+ source_location locus;
if (elim_unvisited_predecessor (g, T))
{
rtx U = get_temp_reg (var);
int unsignedsrcp = TYPE_UNSIGNED (TREE_TYPE (var));
- insert_part_to_rtx_on_edge (g->e, U, T);
- FOR_EACH_ELIM_GRAPH_PRED (g, T, P,
+ insert_part_to_rtx_on_edge (g->e, U, T, UNKNOWN_LOCATION);
+ FOR_EACH_ELIM_GRAPH_PRED (g, T, P, locus,
{
if (!TEST_BIT (g->visited, P))
{
elim_backward (g, P);
- insert_rtx_to_part_on_edge (g->e, P, U, unsignedsrcp);
+ insert_rtx_to_part_on_edge (g->e, P, U, unsignedsrcp, locus);
}
});
}
else
{
- S = elim_graph_remove_succ_edge (g, T);
+ S = elim_graph_remove_succ_edge (g, T, &locus);
if (S != -1)
{
SET_BIT (g->visited, T);
- insert_partition_copy_on_edge (g->e, T, S);
+ insert_partition_copy_on_edge (g->e, T, S, locus);
}
}
}
int x;
gcc_assert (VEC_length (tree, g->const_copies) == 0);
+ gcc_assert (VEC_length (source_location, g->copy_locus) == 0);
/* Abnormal edges already have everything coalesced. */
if (e->flags & EDGE_ABNORMAL)
sbitmap_zero (g->visited);
VEC_truncate (int, g->stack, 0);
- for (x = 0; VEC_iterate (int, g->nodes, x, part); x++)
+ FOR_EACH_VEC_ELT (int, g->nodes, x, part)
{
if (!TEST_BIT (g->visited, part))
elim_forward (g, part);
}
-
+
sbitmap_zero (g->visited);
while (VEC_length (int, g->stack) > 0)
{
{
int dest;
tree src;
+ source_location locus;
+
src = VEC_pop (tree, g->const_copies);
dest = VEC_pop (int, g->const_dests);
- insert_value_copy_on_edge (e, dest, src);
+ locus = VEC_pop (source_location, g->copy_locus);
+ insert_value_copy_on_edge (e, dest, src, locus);
}
}
-/* Remove each argument from PHI. If an arg was the last use of an SSA_NAME,
+/* Remove each argument from PHI. If an arg was the last use of an SSA_NAME,
check to see if this allows another PHI node to be removed. */
static void
for (i = 0; i < gimple_phi_num_args (phi); i++)
{
tree arg = PHI_ARG_DEF (phi, i);
- if (TREE_CODE (arg) == SSA_NAME
+ if (TREE_CODE (arg) == SSA_NAME
&& is_gimple_reg (SSA_NAME_VAR (arg)))
{
fprintf (stderr, "Argument of PHI is not virtual (");
/* This function will rewrite the current program using the variable mapping
- found in MAP. If the replacement vector VALUES is provided, any
- occurrences of partitions with non-null entries in the vector will be
- replaced with the expression in the vector instead of its mapped
+ found in MAP. If the replacement vector VALUES is provided, any
+ occurrences of partitions with non-null entries in the vector will be
+ replaced with the expression in the vector instead of its mapped
variable. */
static void
}
+/* 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);
+ if (is_gimple_debug (use_stmt))
+ continue;
+ /* 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
basic_block bb;
gimple_stmt_iterator gsi;
+ mark_dfs_back_edges ();
+
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);
tree arg = gimple_phi_arg_def (phi, i);
edge e = gimple_phi_arg_edge (phi, i);
- /* If the argument is not an SSA_NAME, then we will need a
+ /* If the argument is not an SSA_NAME, then we will need a
constant initialization. If the argument is an SSA_NAME with
- a different underlying variable then a copy statement will be
+ a different underlying variable then a copy statement will be
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;
/* In theory the only way we ought to get back to the
start of a loop should be with a COND_EXPR or GOTO_EXPR.
- However, better safe than sorry.
+ However, better safe than sorry.
If the block ends with a control statement or
something that might throw, then we have to
insert this assignment before the last
continue;
}
- /* Create a new instance of the underlying variable of the
+ /* Create a new instance of the underlying variable of the
PHI result. */
stmt = gimple_build_assign (result_var,
gimple_phi_arg_def (phi, i));
name = make_ssa_name (result_var, stmt);
gimple_assign_set_lhs (stmt, name);
+ /* copy location if present. */
+ if (gimple_phi_arg_has_location (phi, i))
+ gimple_set_location (stmt,
+ gimple_phi_arg_location (phi, i));
+
/* Insert the new statement into the block and update
the PHI node. */
if (last && stmt_ends_bb_p (last))
}
}
}
+
+ /* Unmark this block again. */
+ bb->aux = NULL;
}
}
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