/* If-conversion for vectorizer.
- Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
+ Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
Free Software Foundation, Inc.
Contributed by Devang Patel <dpatel@apple.com>
#include "tree-data-ref.h"
#include "tree-scalar-evolution.h"
#include "tree-pass.h"
+#include "dbgcnt.h"
/* List of basic blocks in if-conversion-suitable order. */
static basic_block *ifc_bbs;
-/* Create a new temp variable of type TYPE. Add GIMPLE_ASSIGN to assign EXP
- to the new variable. */
+/* Structure used to predicate basic blocks. This is attached to the
+ ->aux field of the BBs in the loop to be if-converted. */
+typedef struct bb_predicate_s {
-static gimple
-ifc_temp_var (tree type, tree exp)
+ /* The condition under which this basic block is executed. */
+ tree predicate;
+
+ /* PREDICATE is gimplified, and the sequence of statements is
+ recorded here, in order to avoid the duplication of computations
+ that occur in previous conditions. See PR44483. */
+ gimple_seq predicate_gimplified_stmts;
+} *bb_predicate_p;
+
+/* Returns true when the basic block BB has a predicate. */
+
+static inline bool
+bb_has_predicate (basic_block bb)
+{
+ return bb->aux != NULL;
+}
+
+/* Returns the gimplified predicate for basic block BB. */
+
+static inline tree
+bb_predicate (basic_block bb)
+{
+ return ((bb_predicate_p) bb->aux)->predicate;
+}
+
+/* Sets the gimplified predicate COND for basic block BB. */
+
+static inline void
+set_bb_predicate (basic_block bb, tree cond)
+{
+ gcc_assert ((TREE_CODE (cond) == TRUTH_NOT_EXPR
+ && is_gimple_condexpr (TREE_OPERAND (cond, 0)))
+ || is_gimple_condexpr (cond));
+ ((bb_predicate_p) bb->aux)->predicate = cond;
+}
+
+/* Returns the sequence of statements of the gimplification of the
+ predicate for basic block BB. */
+
+static inline gimple_seq
+bb_predicate_gimplified_stmts (basic_block bb)
+{
+ return ((bb_predicate_p) bb->aux)->predicate_gimplified_stmts;
+}
+
+/* Sets the sequence of statements STMTS of the gimplification of the
+ predicate for basic block BB. */
+
+static inline void
+set_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts)
+{
+ ((bb_predicate_p) bb->aux)->predicate_gimplified_stmts = stmts;
+}
+
+/* Adds the sequence of statements STMTS to the sequence of statements
+ of the predicate for basic block BB. */
+
+static inline void
+add_bb_predicate_gimplified_stmts (basic_block bb, gimple_seq stmts)
+{
+ gimple_seq_add_seq
+ (&(((bb_predicate_p) bb->aux)->predicate_gimplified_stmts), stmts);
+}
+
+/* Initializes to TRUE the predicate of basic block BB. */
+
+static inline void
+init_bb_predicate (basic_block bb)
+{
+ bb->aux = XNEW (struct bb_predicate_s);
+ set_bb_predicate_gimplified_stmts (bb, NULL);
+ set_bb_predicate (bb, boolean_true_node);
+}
+
+/* Free the predicate of basic block BB. */
+
+static inline void
+free_bb_predicate (basic_block bb)
+{
+ gimple_seq stmts;
+
+ if (!bb_has_predicate (bb))
+ return;
+
+ /* Release the SSA_NAMEs created for the gimplification of the
+ predicate. */
+ stmts = bb_predicate_gimplified_stmts (bb);
+ if (stmts)
+ {
+ gimple_stmt_iterator i;
+
+ for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i))
+ free_stmt_operands (gsi_stmt (i));
+ }
+
+ free (bb->aux);
+ bb->aux = NULL;
+}
+
+/* Free the predicate of BB and reinitialize it with the true
+ predicate. */
+
+static inline void
+reset_bb_predicate (basic_block bb)
+{
+ free_bb_predicate (bb);
+ init_bb_predicate (bb);
+}
+
+/* Returns a new SSA_NAME of type TYPE that is assigned the value of
+ the expression EXPR. Inserts the statement created for this
+ computation before GSI and leaves the iterator GSI at the same
+ statement. */
+
+static tree
+ifc_temp_var (tree type, tree expr, gimple_stmt_iterator *gsi)
{
const char *name = "_ifc_";
tree var, new_name;
var = create_tmp_var (type, name);
add_referenced_var (var);
- /* Build new statement to assign EXP to new variable. */
- stmt = gimple_build_assign (var, exp);
+ /* Build new statement to assign EXPR to new variable. */
+ stmt = gimple_build_assign (var, expr);
/* Get SSA name for the new variable and set make new statement
its definition statement. */
SSA_NAME_DEF_STMT (new_name) = stmt;
update_stmt (stmt);
- return stmt;
+ gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
+ return gimple_assign_lhs (stmt);
}
/* Return true when COND is a true predicate. */
static inline bool
is_predicated (basic_block bb)
{
- return !is_true_predicate ((tree) bb->aux);
+ return !is_true_predicate (bb_predicate (bb));
+}
+
+/* Parses the predicate COND and returns its comparison code and
+ operands OP0 and OP1. */
+
+static enum tree_code
+parse_predicate (tree cond, tree *op0, tree *op1)
+{
+ gimple s;
+
+ if (TREE_CODE (cond) == SSA_NAME
+ && is_gimple_assign (s = SSA_NAME_DEF_STMT (cond)))
+ {
+ if (TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison)
+ {
+ *op0 = gimple_assign_rhs1 (s);
+ *op1 = gimple_assign_rhs2 (s);
+ return gimple_assign_rhs_code (s);
+ }
+
+ else if (gimple_assign_rhs_code (s) == TRUTH_NOT_EXPR)
+ {
+ tree op = gimple_assign_rhs1 (s);
+ tree type = TREE_TYPE (op);
+ enum tree_code code = parse_predicate (op, op0, op1);
+
+ return code == ERROR_MARK ? ERROR_MARK
+ : invert_tree_comparison (code, HONOR_NANS (TYPE_MODE (type)));
+ }
+
+ return ERROR_MARK;
+ }
+
+ if (TREE_CODE_CLASS (TREE_CODE (cond)) == tcc_comparison)
+ {
+ *op0 = TREE_OPERAND (cond, 0);
+ *op1 = TREE_OPERAND (cond, 1);
+ return TREE_CODE (cond);
+ }
+
+ return ERROR_MARK;
+}
+
+/* Returns the fold of predicate C1 OR C2 at location LOC. */
+
+static tree
+fold_or_predicates (location_t loc, tree c1, tree c2)
+{
+ tree op1a, op1b, op2a, op2b;
+ enum tree_code code1 = parse_predicate (c1, &op1a, &op1b);
+ enum tree_code code2 = parse_predicate (c2, &op2a, &op2b);
+
+ if (code1 != ERROR_MARK && code2 != ERROR_MARK)
+ {
+ tree t = maybe_fold_or_comparisons (code1, op1a, op1b,
+ code2, op2a, op2b);
+ if (t)
+ return t;
+ }
+
+ return fold_build2_loc (loc, TRUTH_OR_EXPR, boolean_type_node, c1, c2);
}
-/* Add condition NEW_COND to the predicate list of basic block BB. */
+/* Add condition NC to the predicate list of basic block BB. */
static inline void
-add_to_predicate_list (basic_block bb, tree new_cond)
+add_to_predicate_list (basic_block bb, tree nc)
{
- tree cond = (tree) bb->aux;
+ tree bc, *tp;
+
+ if (is_true_predicate (nc))
+ return;
+
+ if (!is_predicated (bb))
+ bc = nc;
+ else
+ {
+ bc = bb_predicate (bb);
+ bc = fold_or_predicates (EXPR_LOCATION (bc), nc, bc);
+ if (is_true_predicate (bc))
+ {
+ reset_bb_predicate (bb);
+ return;
+ }
+ }
- bb->aux = is_true_predicate (cond) ? new_cond :
- fold_build2_loc (EXPR_LOCATION (cond),
- TRUTH_OR_EXPR, boolean_type_node,
- cond, new_cond);
+ /* Allow a TRUTH_NOT_EXPR around the main predicate. */
+ if (TREE_CODE (bc) == TRUTH_NOT_EXPR)
+ tp = &TREE_OPERAND (bc, 0);
+ else
+ tp = &bc;
+ if (!is_gimple_condexpr (*tp))
+ {
+ gimple_seq stmts;
+ *tp = force_gimple_operand_1 (*tp, &stmts, is_gimple_condexpr, NULL_TREE);
+ add_bb_predicate_gimplified_stmts (bb, stmts);
+ }
+ set_bb_predicate (bb, bc);
}
/* Add the condition COND to the previous condition PREV_COND, and add
and it belongs to basic block BB.
PHI is not if-convertible if:
- - it has more than 2 arguments,
- - virtual PHI is immediately used in another PHI node,
- - virtual PHI on BB other than header. */
+ - it has more than 2 arguments.
+
+ When the flag_tree_loop_if_convert_stores is not set, PHI is not
+ if-convertible if:
+ - a virtual PHI is immediately used in another PHI node,
+ - there is a virtual PHI in a BB other than the loop->header. */
static bool
if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
return false;
}
+ if (flag_tree_loop_if_convert_stores)
+ return true;
+
+ /* When the flag_tree_loop_if_convert_stores is not set, check
+ that there are no memory writes in the branches of the loop to be
+ if-converted. */
if (!is_gimple_reg (SSA_NAME_VAR (gimple_phi_result (phi))))
{
imm_use_iterator imm_iter;
if (bb != loop->header)
{
if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "Virtual phi not on loop header.\n");
+ fprintf (dump_file, "Virtual phi not on loop->header.\n");
return false;
}
+
FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_phi_result (phi))
{
if (gimple_code (USE_STMT (use_p)) == GIMPLE_PHI)
return true;
}
+/* Records the status of a data reference. This struct is attached to
+ each DR->aux field. */
+
+struct ifc_dr {
+ /* -1 when not initialized, 0 when false, 1 when true. */
+ int written_at_least_once;
+
+ /* -1 when not initialized, 0 when false, 1 when true. */
+ int rw_unconditionally;
+};
+
+#define IFC_DR(DR) ((struct ifc_dr *) (DR)->aux)
+#define DR_WRITTEN_AT_LEAST_ONCE(DR) (IFC_DR (DR)->written_at_least_once)
+#define DR_RW_UNCONDITIONALLY(DR) (IFC_DR (DR)->rw_unconditionally)
+
+/* Returns true when the memory references of STMT are read or written
+ unconditionally. In other words, this function returns true when
+ for every data reference A in STMT there exist other accesses to
+ a data reference with the same base with predicates that add up (OR-up) to
+ the true predicate: this ensures that the data reference A is touched
+ (read or written) on every iteration of the if-converted loop. */
+
+static bool
+memrefs_read_or_written_unconditionally (gimple stmt,
+ VEC (data_reference_p, heap) *drs)
+{
+ int i, j;
+ data_reference_p a, b;
+ tree ca = bb_predicate (gimple_bb (stmt));
+
+ for (i = 0; VEC_iterate (data_reference_p, drs, i, a); i++)
+ if (DR_STMT (a) == stmt)
+ {
+ bool found = false;
+ int x = DR_RW_UNCONDITIONALLY (a);
+
+ if (x == 0)
+ return false;
+
+ if (x == 1)
+ continue;
+
+ for (j = 0; VEC_iterate (data_reference_p, drs, j, b); j++)
+ {
+ tree ref_base_a = DR_REF (a);
+ tree ref_base_b = DR_REF (b);
+
+ if (DR_STMT (b) == stmt)
+ continue;
+
+ while (TREE_CODE (ref_base_a) == COMPONENT_REF
+ || TREE_CODE (ref_base_a) == IMAGPART_EXPR
+ || TREE_CODE (ref_base_a) == REALPART_EXPR)
+ ref_base_a = TREE_OPERAND (ref_base_a, 0);
+
+ while (TREE_CODE (ref_base_b) == COMPONENT_REF
+ || TREE_CODE (ref_base_b) == IMAGPART_EXPR
+ || TREE_CODE (ref_base_b) == REALPART_EXPR)
+ ref_base_b = TREE_OPERAND (ref_base_b, 0);
+
+ if (!operand_equal_p (ref_base_a, ref_base_b, 0))
+ {
+ tree cb = bb_predicate (gimple_bb (DR_STMT (b)));
+
+ if (DR_RW_UNCONDITIONALLY (b) == 1
+ || is_true_predicate (cb)
+ || is_true_predicate (ca
+ = fold_or_predicates (EXPR_LOCATION (cb), ca, cb)))
+ {
+ DR_RW_UNCONDITIONALLY (a) = 1;
+ DR_RW_UNCONDITIONALLY (b) = 1;
+ found = true;
+ break;
+ }
+ }
+ }
+
+ if (!found)
+ {
+ DR_RW_UNCONDITIONALLY (a) = 0;
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/* Returns true when the memory references of STMT are unconditionally
+ written. In other words, this function returns true when for every
+ data reference A written in STMT, there exist other writes to the
+ same data reference with predicates that add up (OR-up) to the true
+ predicate: this ensures that the data reference A is written on
+ every iteration of the if-converted loop. */
+
+static bool
+write_memrefs_written_at_least_once (gimple stmt,
+ VEC (data_reference_p, heap) *drs)
+{
+ int i, j;
+ data_reference_p a, b;
+ tree ca = bb_predicate (gimple_bb (stmt));
+
+ for (i = 0; VEC_iterate (data_reference_p, drs, i, a); i++)
+ if (DR_STMT (a) == stmt
+ && DR_IS_WRITE (a))
+ {
+ bool found = false;
+ int x = DR_WRITTEN_AT_LEAST_ONCE (a);
+
+ if (x == 0)
+ return false;
+
+ if (x == 1)
+ continue;
+
+ for (j = 0; VEC_iterate (data_reference_p, drs, j, b); j++)
+ if (DR_STMT (b) != stmt
+ && DR_IS_WRITE (b)
+ && same_data_refs_base_objects (a, b))
+ {
+ tree cb = bb_predicate (gimple_bb (DR_STMT (b)));
+
+ if (DR_WRITTEN_AT_LEAST_ONCE (b) == 1
+ || is_true_predicate (cb)
+ || is_true_predicate (ca = fold_or_predicates (EXPR_LOCATION (cb),
+ ca, cb)))
+ {
+ DR_WRITTEN_AT_LEAST_ONCE (a) = 1;
+ DR_WRITTEN_AT_LEAST_ONCE (b) = 1;
+ found = true;
+ break;
+ }
+ }
+
+ if (!found)
+ {
+ DR_WRITTEN_AT_LEAST_ONCE (a) = 0;
+ return false;
+ }
+ }
+
+ return true;
+}
+
+/* Return true when the memory references of STMT won't trap in the
+ if-converted code. There are two things that we have to check for:
+
+ - writes to memory occur to writable memory: if-conversion of
+ memory writes transforms the conditional memory writes into
+ unconditional writes, i.e. "if (cond) A[i] = foo" is transformed
+ into "A[i] = cond ? foo : A[i]", and as the write to memory may not
+ be executed at all in the original code, it may be a readonly
+ memory. To check that A is not const-qualified, we check that
+ there exists at least an unconditional write to A in the current
+ function.
+
+ - reads or writes to memory are valid memory accesses for every
+ iteration. To check that the memory accesses are correctly formed
+ and that we are allowed to read and write in these locations, we
+ check that the memory accesses to be if-converted occur at every
+ iteration unconditionally. */
+
+static bool
+ifcvt_memrefs_wont_trap (gimple stmt, VEC (data_reference_p, heap) *refs)
+{
+ return write_memrefs_written_at_least_once (stmt, refs)
+ && memrefs_read_or_written_unconditionally (stmt, refs);
+}
+
+/* Wrapper around gimple_could_trap_p refined for the needs of the
+ if-conversion. Try to prove that the memory accesses of STMT could
+ not trap in the innermost loop containing STMT. */
+
+static bool
+ifcvt_could_trap_p (gimple stmt, VEC (data_reference_p, heap) *refs)
+{
+ if (gimple_vuse (stmt)
+ && !gimple_could_trap_p_1 (stmt, false, false)
+ && ifcvt_memrefs_wont_trap (stmt, refs))
+ return false;
+
+ return gimple_could_trap_p (stmt);
+}
+
/* Return true when STMT is if-convertible.
GIMPLE_ASSIGN statement is not if-convertible if,
- it is not movable,
- it could trap,
- - LHS is not var decl.
-
- GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP. */
+ - LHS is not var decl. */
static bool
-if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
- gimple stmt)
+if_convertible_gimple_assign_stmt_p (gimple stmt,
+ VEC (data_reference_p, heap) *refs)
{
tree lhs = gimple_assign_lhs (stmt);
+ basic_block bb;
if (dump_file && (dump_flags & TDF_DETAILS))
{
print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
}
+ if (!is_gimple_reg_type (TREE_TYPE (lhs)))
+ return false;
+
/* Some of these constrains might be too conservative. */
if (stmt_ends_bb_p (stmt)
|| gimple_has_volatile_ops (stmt)
return false;
}
+ if (flag_tree_loop_if_convert_stores)
+ {
+ if (ifcvt_could_trap_p (stmt, refs))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "tree could trap...\n");
+ return false;
+ }
+ return true;
+ }
+
if (gimple_assign_rhs_could_trap_p (stmt))
{
if (dump_file && (dump_flags & TDF_DETAILS))
return false;
}
+ bb = gimple_bb (stmt);
+
if (TREE_CODE (lhs) != SSA_NAME
- && bb != loop->header
- && !bb_with_exit_edge_p (loop, bb))
+ && bb != bb->loop_father->header
+ && !bb_with_exit_edge_p (bb->loop_father, bb))
{
if (dump_file && (dump_flags & TDF_DETAILS))
{
A statement is if-convertible if:
- it is an if-convertible GIMPLE_ASSGIN,
- - it is a GIMPLE_LABEL or a GIMPLE_COND.
-
- STMT is inside BB, which is inside loop LOOP. */
+ - it is a GIMPLE_LABEL or a GIMPLE_COND. */
static bool
-if_convertible_stmt_p (struct loop *loop, basic_block bb, gimple stmt)
+if_convertible_stmt_p (gimple stmt, VEC (data_reference_p, heap) *refs)
{
switch (gimple_code (stmt))
{
return true;
case GIMPLE_ASSIGN:
- return if_convertible_gimple_assign_stmt_p (loop, bb, stmt);
+ return if_convertible_gimple_assign_stmt_p (stmt, refs);
+
+ case GIMPLE_CALL:
+ {
+ tree fndecl = gimple_call_fndecl (stmt);
+ if (fndecl)
+ {
+ int flags = gimple_call_flags (stmt);
+ if ((flags & ECF_CONST)
+ && !(flags & ECF_LOOPING_CONST_OR_PURE)
+ /* We can only vectorize some builtins at the moment,
+ so restrict if-conversion to those. */
+ && DECL_BUILT_IN (fndecl))
+ return true;
+ }
+ return false;
+ }
default:
/* Don't know what to do with 'em so don't do anything. */
return true;
}
+/* Return true when BB post-dominates all its predecessors. */
+
+static bool
+bb_postdominates_preds (basic_block bb)
+{
+ unsigned i;
+
+ for (i = 0; i < EDGE_COUNT (bb->preds); i++)
+ if (!dominated_by_p (CDI_POST_DOMINATORS, EDGE_PRED (bb, i)->src, bb))
+ return false;
+
+ return true;
+}
+
/* Return true when BB is if-convertible. This routine does not check
basic block's statements and phis.
return false;
}
+ if (EDGE_COUNT (bb->preds) == 2
+ && bb != loop->header
+ && !bb_postdominates_preds (bb))
+ return false;
+
return true;
}
/* Returns true when the analysis of the predicates for all the basic
blocks in LOOP succeeded.
- predicate_bbs first clears the ->aux fields of the basic blocks.
+ predicate_bbs first allocates the predicates of the basic blocks.
These fields are then initialized with the tree expressions
representing the predicates under which a basic block is executed
in the LOOP. As the loop->header is executed at each iteration, it
| else
| S2;
- S1 will be predicated with "x", and S2 will be predicated with
- "!x". */
+ S1 will be predicated with "x", and
+ S2 will be predicated with "!x". */
static bool
predicate_bbs (loop_p loop)
unsigned int i;
for (i = 0; i < loop->num_nodes; i++)
- ifc_bbs[i]->aux = NULL;
+ init_bb_predicate (ifc_bbs[i]);
for (i = 0; i < loop->num_nodes; i++)
{
- basic_block bb = ifc_bbs [i];
- tree cond = (tree) bb->aux;
+ basic_block bb = ifc_bbs[i];
+ tree cond;
gimple_stmt_iterator itr;
+ /* The loop latch is always executed and has no extra conditions
+ to be processed: skip it. */
+ if (bb == loop->latch)
+ {
+ reset_bb_predicate (loop->latch);
+ continue;
+ }
+
+ cond = bb_predicate (bb);
+
for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
{
gimple stmt = gsi_stmt (itr);
case GIMPLE_LABEL:
case GIMPLE_ASSIGN:
case GIMPLE_CALL:
- break;
-
case GIMPLE_DEBUG:
- /* ??? Should there be conditional GIMPLE_DEBUG_BINDs? */
- if (gimple_debug_bind_p (gsi_stmt (itr)))
- {
- gimple_debug_bind_reset_value (gsi_stmt (itr));
- update_stmt (gsi_stmt (itr));
- }
break;
case GIMPLE_COND:
{
- tree c2;
+ tree c2, tem;
edge true_edge, false_edge;
location_t loc = gimple_location (stmt);
tree c = fold_build2_loc (loc, gimple_cond_code (stmt),
gimple_cond_lhs (stmt),
gimple_cond_rhs (stmt));
+ /* Add new condition into destination's predicate list. */
extract_true_false_edges_from_block (gimple_bb (stmt),
&true_edge, &false_edge);
- /* Add new condition into destination's predicate list. */
-
/* If C is true, then TRUE_EDGE is taken. */
- add_to_dst_predicate_list (loop, true_edge, cond, c);
+ add_to_dst_predicate_list (loop, true_edge,
+ unshare_expr (cond),
+ unshare_expr (c));
/* If C is false, then FALSE_EDGE is taken. */
c2 = invert_truthvalue_loc (loc, unshare_expr (c));
- add_to_dst_predicate_list (loop, false_edge, cond, c2);
+ tem = canonicalize_cond_expr_cond (c2);
+ if (tem)
+ c2 = tem;
+ add_to_dst_predicate_list (loop, false_edge,
+ unshare_expr (cond), c2);
cond = NULL_TREE;
break;
}
- case GIMPLE_SWITCH:
+ default:
/* Not handled yet in if-conversion. */
return false;
-
- default:
- gcc_unreachable ();
}
}
}
/* The loop header is always executed. */
- loop->header->aux = boolean_true_node;
+ reset_bb_predicate (loop->header);
+ gcc_assert (bb_predicate_gimplified_stmts (loop->header) == NULL
+ && bb_predicate_gimplified_stmts (loop->latch) == NULL);
return true;
}
-/* Return true when LOOP is if-convertible.
- LOOP is if-convertible if:
- - it is innermost,
- - it has two or more basic blocks,
- - it has only one exit,
- - loop header is not the exit edge,
- - if its basic blocks and phi nodes are if convertible. */
+/* Return true when LOOP is if-convertible. This is a helper function
+ for if_convertible_loop_p. REFS and DDRS are initialized and freed
+ in if_convertible_loop_p. */
static bool
-if_convertible_loop_p (struct loop *loop)
+if_convertible_loop_p_1 (struct loop *loop,
+ VEC (loop_p, heap) **loop_nest,
+ VEC (data_reference_p, heap) **refs,
+ VEC (ddr_p, heap) **ddrs)
{
+ bool res;
unsigned int i;
- edge e;
- edge_iterator ei;
basic_block exit_bb = NULL;
- /* Handle only innermost loop. */
- if (!loop || loop->inner)
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "not innermost loop\n");
- return false;
- }
-
- /* If only one block, no need for if-conversion. */
- if (loop->num_nodes <= 2)
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "less than 2 basic blocks\n");
- return false;
- }
-
- /* More than one loop exit is too much to handle. */
- if (!single_exit (loop))
- {
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "multiple exits\n");
- return false;
- }
-
- /* ??? Check target's vector conditional operation support for vectorizer. */
-
- /* If one of the loop header's edge is exit edge then do not apply
- if-conversion. */
- FOR_EACH_EDGE (e, ei, loop->header->succs)
- {
- if (loop_exit_edge_p (loop, e))
- return false;
- }
-
/* Don't if-convert the loop when the data dependences cannot be
computed: the loop won't be vectorized in that case. */
- {
- VEC (data_reference_p, heap) *refs = VEC_alloc (data_reference_p, heap, 5);
- VEC (ddr_p, heap) *ddrs = VEC_alloc (ddr_p, heap, 25);
- bool res = compute_data_dependences_for_loop (loop, true, &refs, &ddrs);
-
- free_data_refs (refs);
- free_dependence_relations (ddrs);
-
- if (!res)
- return false;
- }
+ res = compute_data_dependences_for_loop (loop, true, loop_nest, refs, ddrs);
+ if (!res)
+ return false;
calculate_dominance_info (CDI_DOMINATORS);
+ calculate_dominance_info (CDI_POST_DOMINATORS);
/* Allow statements that can be handled during if-conversion. */
ifc_bbs = get_loop_body_in_if_conv_order (loop);
exit_bb = bb;
}
- if (!predicate_bbs (loop))
+ res = predicate_bbs (loop);
+ if (!res)
return false;
+ if (flag_tree_loop_if_convert_stores)
+ {
+ data_reference_p dr;
+
+ for (i = 0; VEC_iterate (data_reference_p, *refs, i, dr); i++)
+ {
+ dr->aux = XNEW (struct ifc_dr);
+ DR_WRITTEN_AT_LEAST_ONCE (dr) = -1;
+ DR_RW_UNCONDITIONALLY (dr) = -1;
+ }
+ }
+
for (i = 0; i < loop->num_nodes; i++)
{
basic_block bb = ifc_bbs[i];
if (!if_convertible_phi_p (loop, bb, gsi_stmt (itr)))
return false;
- /* For non predicated BBs, don't check their statements. */
- if (!is_predicated (bb))
- continue;
-
- for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
- if (!if_convertible_stmt_p (loop, bb, gsi_stmt (itr)))
- return false;
+ /* Check the if-convertibility of statements in predicated BBs. */
+ if (is_predicated (bb))
+ for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
+ if (!if_convertible_stmt_p (gsi_stmt (itr), *refs))
+ return false;
}
if (dump_file)
return true;
}
-/* During if-conversion, the bb->aux field is used to hold a predicate
- list. This function cleans for all the basic blocks in the given
- LOOP their predicate list. */
+/* Return true when LOOP is if-convertible.
+ LOOP is if-convertible if:
+ - it is innermost,
+ - it has two or more basic blocks,
+ - it has only one exit,
+ - loop header is not the exit edge,
+ - if its basic blocks and phi nodes are if convertible. */
-static void
-clean_predicate_lists (struct loop *loop)
+static bool
+if_convertible_loop_p (struct loop *loop)
{
- unsigned int i;
- basic_block *bbs = get_loop_body (loop);
+ edge e;
+ edge_iterator ei;
+ bool res = false;
+ VEC (data_reference_p, heap) *refs;
+ VEC (ddr_p, heap) *ddrs;
+ VEC (loop_p, heap) *loop_nest;
- for (i = 0; i < loop->num_nodes; i++)
- bbs[i]->aux = NULL;
+ /* Handle only innermost loop. */
+ if (!loop || loop->inner)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "not innermost loop\n");
+ return false;
+ }
+
+ /* If only one block, no need for if-conversion. */
+ if (loop->num_nodes <= 2)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "less than 2 basic blocks\n");
+ return false;
+ }
+
+ /* More than one loop exit is too much to handle. */
+ if (!single_exit (loop))
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "multiple exits\n");
+ return false;
+ }
+
+ /* If one of the loop header's edge is an exit edge then do not
+ apply if-conversion. */
+ FOR_EACH_EDGE (e, ei, loop->header->succs)
+ if (loop_exit_edge_p (loop, e))
+ return false;
- free (bbs);
+ refs = VEC_alloc (data_reference_p, heap, 5);
+ ddrs = VEC_alloc (ddr_p, heap, 25);
+ loop_nest = VEC_alloc (loop_p, heap, 3);
+ res = if_convertible_loop_p_1 (loop, &loop_nest, &refs, &ddrs);
+
+ if (flag_tree_loop_if_convert_stores)
+ {
+ data_reference_p dr;
+ unsigned int i;
+
+ for (i = 0; VEC_iterate (data_reference_p, refs, i, dr); i++)
+ free (dr->aux);
+ }
+
+ VEC_free (loop_p, heap, loop_nest);
+ free_data_refs (refs);
+ free_dependence_relations (ddrs);
+ return res;
}
-/* Basic block BB has two predecessors. Using predecessor's bb->aux
- field, set appropriate condition COND for the PHI node replacement.
- Return true block whose phi arguments are selected when cond is
- true. LOOP is the loop containing the if-converted region, GSI is
- the place to insert the code for the if-conversion. */
+/* Basic block BB has two predecessors. Using predecessor's bb
+ predicate, set an appropriate condition COND for the PHI node
+ replacement. Return the true block whose phi arguments are
+ selected when cond is true. LOOP is the loop containing the
+ if-converted region, GSI is the place to insert the code for the
+ if-conversion. */
static basic_block
find_phi_replacement_condition (struct loop *loop,
basic_block bb, tree *cond,
- gimple_stmt_iterator *gsi)
+ gimple_stmt_iterator *gsi)
{
edge first_edge, second_edge;
tree tmp_cond;
See PR23115. */
/* Select condition that is not TRUTH_NOT_EXPR. */
- tmp_cond = (tree) (first_edge->src)->aux;
+ tmp_cond = bb_predicate (first_edge->src);
gcc_assert (tmp_cond);
if (TREE_CODE (tmp_cond) == TRUTH_NOT_EXPR)
|| dominated_by_p (CDI_DOMINATORS,
second_edge->src, first_edge->src))
{
- *cond = (tree) (second_edge->src)->aux;
+ *cond = bb_predicate (second_edge->src);
if (TREE_CODE (*cond) == TRUTH_NOT_EXPR)
- *cond = invert_truthvalue (*cond);
+ *cond = TREE_OPERAND (*cond, 0);
else
/* Select non loop header bb. */
first_edge = second_edge;
}
else
- *cond = (tree) (first_edge->src)->aux;
-
- /* Gimplify the condition: the vectorizer prefers to have gimple
- values as conditions. Various targets use different means to
- communicate conditions in vector compare operations. Using a
- gimple value allows the compiler to emit vector compare and
- select RTL without exposing compare's result. */
- *cond = force_gimple_operand_gsi (gsi, unshare_expr (*cond),
- false, NULL_TREE,
- true, GSI_SAME_STMT);
- if (!is_gimple_reg (*cond) && !is_gimple_condexpr (*cond))
- {
- gimple new_stmt;
+ *cond = bb_predicate (first_edge->src);
- new_stmt = ifc_temp_var (TREE_TYPE (*cond), unshare_expr (*cond));
- gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
- *cond = gimple_assign_lhs (new_stmt);
- }
-
- gcc_assert (*cond);
+ /* Gimplify the condition to a valid cond-expr conditonal operand. */
+ *cond = force_gimple_operand_gsi_1 (gsi, unshare_expr (*cond),
+ is_gimple_condexpr, NULL_TREE,
+ true, GSI_SAME_STMT);
return first_edge->src;
}
-/* Replace PHI node with conditional modify expr using COND. This
- routine does not handle PHI nodes with more than two arguments.
+/* Replace a scalar PHI node with a COND_EXPR using COND as condition.
+ This routine does not handle PHI nodes with more than two
+ arguments.
For example,
- S1: A = PHI <x1(1), x2(5)
+ S1: A = PHI <x1(1), x2(5)>
is converted into,
S2: A = cond ? x1 : x2;
TRUE_BB is selected. */
static void
-replace_phi_with_cond_gimple_assign_stmt (gimple phi, tree cond,
- basic_block true_bb,
- gimple_stmt_iterator *gsi)
+predicate_scalar_phi (gimple phi, tree cond,
+ basic_block true_bb,
+ gimple_stmt_iterator *gsi)
{
gimple new_stmt;
basic_block bb;
- tree rhs;
- tree arg;
+ tree rhs, res, arg, scev;
gcc_assert (gimple_code (phi) == GIMPLE_PHI
&& gimple_phi_num_args (phi) == 2);
+ res = gimple_phi_result (phi);
+ /* Do not handle virtual phi nodes. */
+ if (!is_gimple_reg (SSA_NAME_VAR (res)))
+ return;
+
bb = gimple_bb (phi);
- arg = degenerate_phi_result (phi);
- if (arg)
+ if ((arg = degenerate_phi_result (phi))
+ || ((scev = analyze_scalar_evolution (gimple_bb (phi)->loop_father,
+ res))
+ && !chrec_contains_undetermined (scev)
+ && scev != res
+ && (arg = gimple_phi_arg_def (phi, 0))))
rhs = arg;
else
{
arg_1 = gimple_phi_arg_def (phi, 1);
}
+ gcc_checking_assert (bb == bb->loop_father->header
+ || bb_postdominates_preds (bb));
+
/* Build new RHS using selected condition and arguments. */
- rhs = build3 (COND_EXPR, TREE_TYPE (PHI_RESULT (phi)),
+ rhs = build3 (COND_EXPR, TREE_TYPE (res),
unshare_expr (cond), arg_0, arg_1);
}
- new_stmt = gimple_build_assign (PHI_RESULT (phi), rhs);
+ new_stmt = gimple_build_assign (res, rhs);
SSA_NAME_DEF_STMT (gimple_phi_result (phi)) = new_stmt;
gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
update_stmt (new_stmt);
}
}
-/* Process phi nodes for the given LOOP. Replace phi nodes with
- conditional modify expressions. */
+/* Replaces in LOOP all the scalar phi nodes other than those in the
+ LOOP->header block with conditional modify expressions. */
static void
-process_phi_nodes (struct loop *loop)
+predicate_all_scalar_phis (struct loop *loop)
{
basic_block bb;
unsigned int orig_loop_num_nodes = loop->num_nodes;
continue;
phi_gsi = gsi_start_phis (bb);
- gsi = gsi_after_labels (bb);
+ if (gsi_end_p (phi_gsi))
+ continue;
/* BB has two predecessors. Using predecessor's aux field, set
appropriate condition for the PHI node replacement. */
- if (!gsi_end_p (phi_gsi))
- true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
+ gsi = gsi_after_labels (bb);
+ true_bb = find_phi_replacement_condition (loop, bb, &cond, &gsi);
while (!gsi_end_p (phi_gsi))
{
phi = gsi_stmt (phi_gsi);
- replace_phi_with_cond_gimple_assign_stmt (phi, cond, true_bb, &gsi);
+ predicate_scalar_phi (phi, cond, true_bb, &gsi);
release_phi_node (phi);
gsi_next (&phi_gsi);
}
+
set_phi_nodes (bb, NULL);
}
}
+/* Insert in each basic block of LOOP the statements produced by the
+ gimplification of the predicates. */
+
+static void
+insert_gimplified_predicates (loop_p loop)
+{
+ unsigned int i;
+
+ for (i = 0; i < loop->num_nodes; i++)
+ {
+ basic_block bb = ifc_bbs[i];
+ gimple_seq stmts;
+
+ if (!is_predicated (bb))
+ {
+ /* Do not insert statements for a basic block that is not
+ predicated. Also make sure that the predicate of the
+ basic block is set to true. */
+ reset_bb_predicate (bb);
+ continue;
+ }
+
+ stmts = bb_predicate_gimplified_stmts (bb);
+ if (stmts)
+ {
+ if (flag_tree_loop_if_convert_stores)
+ {
+ /* Insert the predicate of the BB just after the label,
+ as the if-conversion of memory writes will use this
+ predicate. */
+ gimple_stmt_iterator gsi = gsi_after_labels (bb);
+ gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT);
+ }
+ else
+ {
+ /* Insert the predicate of the BB at the end of the BB
+ as this would reduce the register pressure: the only
+ use of this predicate will be in successor BBs. */
+ gimple_stmt_iterator gsi = gsi_last_bb (bb);
+
+ if (gsi_end_p (gsi)
+ || stmt_ends_bb_p (gsi_stmt (gsi)))
+ gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT);
+ else
+ gsi_insert_seq_after (&gsi, stmts, GSI_SAME_STMT);
+ }
+
+ /* Once the sequence is code generated, set it to NULL. */
+ set_bb_predicate_gimplified_stmts (bb, NULL);
+ }
+ }
+}
+
+/* Predicate each write to memory in LOOP.
+
+ This function transforms control flow constructs containing memory
+ writes of the form:
+
+ | for (i = 0; i < N; i++)
+ | if (cond)
+ | A[i] = expr;
+
+ into the following form that does not contain control flow:
+
+ | for (i = 0; i < N; i++)
+ | A[i] = cond ? expr : A[i];
+
+ The original CFG looks like this:
+
+ | bb_0
+ | i = 0
+ | end_bb_0
+ |
+ | bb_1
+ | if (i < N) goto bb_5 else goto bb_2
+ | end_bb_1
+ |
+ | bb_2
+ | cond = some_computation;
+ | if (cond) goto bb_3 else goto bb_4
+ | end_bb_2
+ |
+ | bb_3
+ | A[i] = expr;
+ | goto bb_4
+ | end_bb_3
+ |
+ | bb_4
+ | goto bb_1
+ | end_bb_4
+
+ insert_gimplified_predicates inserts the computation of the COND
+ expression at the beginning of the destination basic block:
+
+ | bb_0
+ | i = 0
+ | end_bb_0
+ |
+ | bb_1
+ | if (i < N) goto bb_5 else goto bb_2
+ | end_bb_1
+ |
+ | bb_2
+ | cond = some_computation;
+ | if (cond) goto bb_3 else goto bb_4
+ | end_bb_2
+ |
+ | bb_3
+ | cond = some_computation;
+ | A[i] = expr;
+ | goto bb_4
+ | end_bb_3
+ |
+ | bb_4
+ | goto bb_1
+ | end_bb_4
+
+ predicate_mem_writes is then predicating the memory write as follows:
+
+ | bb_0
+ | i = 0
+ | end_bb_0
+ |
+ | bb_1
+ | if (i < N) goto bb_5 else goto bb_2
+ | end_bb_1
+ |
+ | bb_2
+ | if (cond) goto bb_3 else goto bb_4
+ | end_bb_2
+ |
+ | bb_3
+ | cond = some_computation;
+ | A[i] = cond ? expr : A[i];
+ | goto bb_4
+ | end_bb_3
+ |
+ | bb_4
+ | goto bb_1
+ | end_bb_4
+
+ and finally combine_blocks removes the basic block boundaries making
+ the loop vectorizable:
+
+ | bb_0
+ | i = 0
+ | if (i < N) goto bb_5 else goto bb_1
+ | end_bb_0
+ |
+ | bb_1
+ | cond = some_computation;
+ | A[i] = cond ? expr : A[i];
+ | if (i < N) goto bb_5 else goto bb_4
+ | end_bb_1
+ |
+ | bb_4
+ | goto bb_1
+ | end_bb_4
+*/
+
+static void
+predicate_mem_writes (loop_p loop)
+{
+ unsigned int i, orig_loop_num_nodes = loop->num_nodes;
+
+ for (i = 1; i < orig_loop_num_nodes; i++)
+ {
+ gimple_stmt_iterator gsi;
+ basic_block bb = ifc_bbs[i];
+ tree cond = bb_predicate (bb);
+ bool swap;
+ gimple stmt;
+
+ if (is_true_predicate (cond))
+ continue;
+
+ swap = false;
+ if (TREE_CODE (cond) == TRUTH_NOT_EXPR)
+ {
+ swap = true;
+ cond = TREE_OPERAND (cond, 0);
+ }
+
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ if ((stmt = gsi_stmt (gsi))
+ && gimple_assign_single_p (stmt)
+ && gimple_vdef (stmt))
+ {
+ tree lhs = gimple_assign_lhs (stmt);
+ tree rhs = gimple_assign_rhs1 (stmt);
+ tree type = TREE_TYPE (lhs);
+
+ lhs = ifc_temp_var (type, unshare_expr (lhs), &gsi);
+ rhs = ifc_temp_var (type, unshare_expr (rhs), &gsi);
+ if (swap)
+ {
+ tree tem = lhs;
+ lhs = rhs;
+ rhs = tem;
+ }
+ cond = force_gimple_operand_gsi_1 (&gsi, unshare_expr (cond),
+ is_gimple_condexpr, NULL_TREE,
+ true, GSI_SAME_STMT);
+ rhs = build3 (COND_EXPR, type, unshare_expr (cond), rhs, lhs);
+ gimple_assign_set_rhs1 (stmt, ifc_temp_var (type, rhs, &gsi));
+ update_stmt (stmt);
+ }
+ }
+}
+
/* Remove all GIMPLE_CONDs and GIMPLE_LABELs of all the basic blocks
- other than the exit and latch of the LOOP. */
+ other than the exit and latch of the LOOP. Also resets the
+ GIMPLE_DEBUG information. */
static void
remove_conditions_and_labels (loop_p loop)
for (i = 0; i < loop->num_nodes; i++)
{
- basic_block bb = ifc_bbs [i];
+ basic_block bb = ifc_bbs[i];
if (bb_with_exit_edge_p (loop, bb)
|| bb == loop->latch)
continue;
for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
- if (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND
- || gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL)
- gsi_remove (&gsi, true);
- else
- gsi_next (&gsi);
+ switch (gimple_code (gsi_stmt (gsi)))
+ {
+ case GIMPLE_COND:
+ case GIMPLE_LABEL:
+ gsi_remove (&gsi, true);
+ break;
+
+ case GIMPLE_DEBUG:
+ /* ??? Should there be conditional GIMPLE_DEBUG_BINDs? */
+ if (gimple_debug_bind_p (gsi_stmt (gsi)))
+ {
+ gimple_debug_bind_reset_value (gsi_stmt (gsi));
+ update_stmt (gsi_stmt (gsi));
+ }
+ gsi_next (&gsi);
+ break;
+
+ default:
+ gsi_next (&gsi);
+ }
}
}
edge_iterator ei;
remove_conditions_and_labels (loop);
+ insert_gimplified_predicates (loop);
+ predicate_all_scalar_phis (loop);
- /* Process phi nodes to prepare blocks for merge. */
- process_phi_nodes (loop);
+ if (flag_tree_loop_if_convert_stores)
+ predicate_mem_writes (loop);
/* Merge basic blocks: first remove all the edges in the loop,
except for those from the exit block. */
for (i = 0; i < orig_loop_num_nodes; i++)
{
bb = ifc_bbs[i];
+ free_bb_predicate (bb);
if (bb_with_exit_edge_p (loop, bb))
{
exit_bb = bb;
/* If possible, merge loop header to the block with the exit edge.
This reduces the number of basic blocks to two, to please the
- vectorizer that handles only loops with two nodes.
-
- FIXME: Call cleanup_tree_cfg. */
+ vectorizer that handles only loops with two nodes. */
if (exit_bb
&& exit_bb != loop->header
&& can_merge_blocks_p (loop->header, exit_bb))
merge_blocks (loop->header, exit_bb);
+
+ free (ifc_bbs);
+ ifc_bbs = NULL;
}
/* If-convert LOOP when it is legal. For the moment this pass has no
- profitability analysis. */
+ profitability analysis. Returns true when something changed. */
-static void
+static bool
tree_if_conversion (struct loop *loop)
{
+ bool changed = false;
ifc_bbs = NULL;
- if (!if_convertible_loop_p (loop))
+ if (!if_convertible_loop_p (loop)
+ || !dbg_cnt (if_conversion_tree))
goto cleanup;
/* Now all statements are if-convertible. Combine all the basic
on-the-fly. */
combine_blocks (loop);
+ if (flag_tree_loop_if_convert_stores)
+ mark_sym_for_renaming (gimple_vop (cfun));
+
+ changed = true;
+
cleanup:
- clean_predicate_lists (loop);
if (ifc_bbs)
{
+ unsigned int i;
+
+ for (i = 0; i < loop->num_nodes; i++)
+ free_bb_predicate (ifc_bbs[i]);
+
free (ifc_bbs);
ifc_bbs = NULL;
}
+
+ return changed;
}
/* Tree if-conversion pass management. */
{
loop_iterator li;
struct loop *loop;
+ bool changed = false;
+ unsigned todo = 0;
if (number_of_loops () <= 1)
return 0;
FOR_EACH_LOOP (li, loop, 0)
- tree_if_conversion (loop);
+ changed |= tree_if_conversion (loop);
+
+ if (changed)
+ todo |= TODO_cleanup_cfg;
- return 0;
+ if (changed && flag_tree_loop_if_convert_stores)
+ todo |= TODO_update_ssa_only_virtuals;
+
+ free_dominance_info (CDI_POST_DOMINATORS);
+
+ return todo;
}
+/* Returns true when the if-conversion pass is enabled. */
+
static bool
gate_tree_if_conversion (void)
{
- return flag_tree_vectorize != 0;
+ return ((flag_tree_vectorize && flag_tree_loop_if_convert != 0)
+ || flag_tree_loop_if_convert == 1
+ || flag_tree_loop_if_convert_stores == 1);
}
struct gimple_opt_pass pass_if_conversion =
0, /* properties_provided */
0, /* properties_destroyed */
0, /* todo_flags_start */
- TODO_dump_func | TODO_verify_stmts | TODO_verify_flow
+ TODO_verify_stmts | TODO_verify_flow
/* todo_flags_finish */
}
};
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