#include "expmed.h"
#include "params.h"
#include "tree-ssa-address.h"
+#include "tree-affine.h"
\f
/* Information about a strength reduction candidate. Each statement
in the candidate table represents an expression of one of the
/* Hash table embodying a mapping from base exprs to chains of candidates. */
static hash_table <cand_chain_hasher> base_cand_map;
\f
+/* Pointer map used by tree_to_aff_combination_expand. */
+static struct pointer_map_t *name_expansions;
+/* Pointer map embodying a mapping from bases to alternative bases. */
+static struct pointer_map_t *alt_base_map;
+
+/* Given BASE, use the tree affine combiniation facilities to
+ find the underlying tree expression for BASE, with any
+ immediate offset excluded. */
+
+static tree
+get_alternative_base (tree base)
+{
+ tree *result = (tree *) pointer_map_contains (alt_base_map, base);
+
+ if (result == NULL)
+ {
+ tree expr;
+ aff_tree aff;
+
+ tree_to_aff_combination_expand (base, TREE_TYPE (base),
+ &aff, &name_expansions);
+ aff.offset = tree_to_double_int (integer_zero_node);
+ expr = aff_combination_to_tree (&aff);
+
+ result = (tree *) pointer_map_insert (alt_base_map, base);
+ gcc_assert (!*result);
+
+ if (expr == base)
+ *result = NULL;
+ else
+ *result = expr;
+ }
+
+ return *result;
+}
+
/* Look in the candidate table for a CAND_PHI that defines BASE and
return it if found; otherwise return NULL. */
}
/* Helper routine for find_basis_for_candidate. May be called twice:
- once for the candidate's base expr, and optionally again for the
- candidate's phi definition. */
+ once for the candidate's base expr, and optionally again either for
+ the candidate's phi definition or for a CAND_REF's alternative base
+ expression. */
static slsr_cand_t
find_basis_for_base_expr (slsr_cand_t c, tree base_expr)
}
}
+ if (!basis && c->kind == CAND_REF)
+ {
+ tree alt_base_expr = get_alternative_base (c->base_expr);
+ if (alt_base_expr)
+ basis = find_basis_for_base_expr (c, alt_base_expr);
+ }
+
if (basis)
{
c->sibling = basis->dependent;
return 0;
}
-/* Record a mapping from the base expression of C to C itself, indicating that
- C may potentially serve as a basis using that base expression. */
+/* Record a mapping from BASE to C, indicating that C may potentially serve
+ as a basis using that base expression. BASE may be the same as
+ C->BASE_EXPR; alternatively BASE can be a different tree that share the
+ underlining expression of C->BASE_EXPR. */
static void
-record_potential_basis (slsr_cand_t c)
+record_potential_basis (slsr_cand_t c, tree base)
{
cand_chain_t node;
cand_chain **slot;
+ gcc_assert (base);
+
node = (cand_chain_t) obstack_alloc (&chain_obstack, sizeof (cand_chain));
- node->base_expr = c->base_expr;
+ node->base_expr = base;
node->cand = c;
node->next = NULL;
slot = base_cand_map.find_slot (node, INSERT);
}
/* Allocate storage for a new candidate and initialize its fields.
- Attempt to find a basis for the candidate. */
+ Attempt to find a basis for the candidate.
+
+ For CAND_REF, an alternative base may also be recorded and used
+ to find a basis. This helps cases where the expression hidden
+ behind BASE (which is usually an SSA_NAME) has immediate offset,
+ e.g.
+
+ a2[i][j] = 1;
+ a2[i + 20][j] = 2; */
static slsr_cand_t
-alloc_cand_and_find_basis (enum cand_kind kind, gimple gs, tree base,
+alloc_cand_and_find_basis (enum cand_kind kind, gimple gs, tree base,
double_int index, tree stride, tree ctype,
unsigned savings)
{
else
c->basis = find_basis_for_candidate (c);
- record_potential_basis (c);
+ record_potential_basis (c, base);
+ if (kind == CAND_REF)
+ {
+ tree alt_base = get_alternative_base (base);
+ if (alt_base)
+ record_potential_basis (c, alt_base);
+ }
return c;
}
static void
replace_refs (slsr_cand_t c)
{
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fputs ("Replacing reference: ", dump_file);
+ print_gimple_stmt (dump_file, c->cand_stmt, 0, 0);
+ }
+
if (gimple_vdef (c->cand_stmt))
{
tree *lhs = gimple_assign_lhs_ptr (c->cand_stmt);
replace_ref (rhs, c);
}
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fputs ("With: ", dump_file);
+ print_gimple_stmt (dump_file, c->cand_stmt, 0, 0);
+ fputs ("\n", dump_file);
+ }
+
if (c->sibling)
replace_refs (lookup_cand (c->sibling));
/* Allocate the mapping from base expressions to candidate chains. */
base_cand_map.create (500);
+ /* Allocate the mapping from bases to alternative bases. */
+ alt_base_map = pointer_map_create ();
+
/* Initialize the loop optimizer. We need to detect flow across
back edges, and this gives us dominator information as well. */
loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
dump_cand_chains ();
}
+ pointer_map_destroy (alt_base_map);
+ free_affine_expand_cache (&name_expansions);
+
/* Analyze costs and make appropriate replacements. */
analyze_candidates_and_replace ();
projects / gcc.git / commitdiff