#define REGNO_QTY_VALID_P(N) (REG_QTY (N) >= 0)
+/* Compare table_elt X and Y and return true iff X is cheaper than Y. */
+
+#define CHEAPER(X, Y) \
+ (preferable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0)
+
static struct table_elt *table[HASH_SIZE];
/* Chain of `struct table_elt's made so far for this function
static struct table_elt *lookup (rtx, unsigned, enum machine_mode);
static struct table_elt *lookup_for_remove (rtx, unsigned, enum machine_mode);
static rtx lookup_as_function (rtx, enum rtx_code);
+static struct table_elt *insert_with_costs (rtx, struct table_elt *, unsigned,
+ enum machine_mode, int, int);
static struct table_elt *insert (rtx, struct table_elt *, unsigned,
enum machine_mode);
static void merge_equiv_classes (struct table_elt *, struct table_elt *);
return mention_regs (x);
}
\f
+
+/* Compute upper and lower anchors for CST. Also compute the offset of CST
+ from these anchors/bases such that *_BASE + *_OFFS = CST. Return false iff
+ CST is equal to an anchor. */
+
+static bool
+compute_const_anchors (rtx cst,
+ HOST_WIDE_INT *lower_base, HOST_WIDE_INT *lower_offs,
+ HOST_WIDE_INT *upper_base, HOST_WIDE_INT *upper_offs)
+{
+ HOST_WIDE_INT n = INTVAL (cst);
+
+ *lower_base = n & ~(targetm.const_anchor - 1);
+ if (*lower_base == n)
+ return false;
+
+ *upper_base =
+ (n + (targetm.const_anchor - 1)) & ~(targetm.const_anchor - 1);
+ *upper_offs = n - *upper_base;
+ *lower_offs = n - *lower_base;
+ return true;
+}
+
+/* Insert the equivalence between ANCHOR and (REG + OFF) in mode MODE. */
+
+static void
+insert_const_anchor (HOST_WIDE_INT anchor, rtx reg, HOST_WIDE_INT offs,
+ enum machine_mode mode)
+{
+ struct table_elt *elt;
+ unsigned hash;
+ rtx anchor_exp;
+ rtx exp;
+
+ anchor_exp = GEN_INT (anchor);
+ hash = HASH (anchor_exp, mode);
+ elt = lookup (anchor_exp, hash, mode);
+ if (!elt)
+ elt = insert (anchor_exp, NULL, hash, mode);
+
+ exp = plus_constant (reg, offs);
+ /* REG has just been inserted and the hash codes recomputed. */
+ mention_regs (exp);
+ hash = HASH (exp, mode);
+
+ /* Use the cost of the register rather than the whole expression. When
+ looking up constant anchors we will further offset the corresponding
+ expression therefore it does not make sense to prefer REGs over
+ reg-immediate additions. Prefer instead the oldest expression. Also
+ don't prefer pseudos over hard regs so that we derive constants in
+ argument registers from other argument registers rather than from the
+ original pseudo that was used to synthesize the constant. */
+ insert_with_costs (exp, elt, hash, mode, COST (reg), 1);
+}
+
+/* The constant CST is equivalent to the register REG. Create
+ equivalences between the two anchors of CST and the corresponding
+ register-offset expressions using REG. */
+
+static void
+insert_const_anchors (rtx reg, rtx cst, enum machine_mode mode)
+{
+ HOST_WIDE_INT lower_base, lower_offs, upper_base, upper_offs;
+
+ if (!compute_const_anchors (cst, &lower_base, &lower_offs,
+ &upper_base, &upper_offs))
+ return;
+
+ /* Ignore anchors of value 0. Constants accessible from zero are
+ simple. */
+ if (lower_base != 0)
+ insert_const_anchor (lower_base, reg, -lower_offs, mode);
+
+ if (upper_base != 0)
+ insert_const_anchor (upper_base, reg, -upper_offs, mode);
+}
+
+/* We need to express ANCHOR_ELT->exp + OFFS. Walk the equivalence list of
+ ANCHOR_ELT and see if offsetting any of the entries by OFFS would create a
+ valid expression. Return the cheapest and oldest of such expressions. In
+ *OLD, return how old the resulting expression is compared to the other
+ equivalent expressions. */
+
+static rtx
+find_reg_offset_for_const (struct table_elt *anchor_elt, HOST_WIDE_INT offs,
+ unsigned *old)
+{
+ struct table_elt *elt;
+ unsigned idx;
+ struct table_elt *match_elt;
+ rtx match;
+
+ /* Find the cheapest and *oldest* expression to maximize the chance of
+ reusing the same pseudo. */
+
+ match_elt = NULL;
+ match = NULL_RTX;
+ for (elt = anchor_elt->first_same_value, idx = 0;
+ elt;
+ elt = elt->next_same_value, idx++)
+ {
+ if (match_elt && CHEAPER (match_elt, elt))
+ return match;
+
+ if (REG_P (elt->exp)
+ || (GET_CODE (elt->exp) == PLUS
+ && REG_P (XEXP (elt->exp, 0))
+ && GET_CODE (XEXP (elt->exp, 1)) == CONST_INT))
+ {
+ rtx x;
+
+ /* Ignore expressions that are no longer valid. */
+ if (!REG_P (elt->exp) && !exp_equiv_p (elt->exp, elt->exp, 1, false))
+ continue;
+
+ x = plus_constant (elt->exp, offs);
+ if (REG_P (x)
+ || (GET_CODE (x) == PLUS
+ && IN_RANGE (INTVAL (XEXP (x, 1)),
+ -targetm.const_anchor,
+ targetm.const_anchor - 1)))
+ {
+ match = x;
+ match_elt = elt;
+ *old = idx;
+ }
+ }
+ }
+
+ return match;
+}
+
+/* Try to express the constant SRC_CONST using a register+offset expression
+ derived from a constant anchor. Return it if successful or NULL_RTX,
+ otherwise. */
+
+static rtx
+try_const_anchors (rtx src_const, enum machine_mode mode)
+{
+ struct table_elt *lower_elt, *upper_elt;
+ HOST_WIDE_INT lower_base, lower_offs, upper_base, upper_offs;
+ rtx lower_anchor_rtx, upper_anchor_rtx;
+ rtx lower_exp = NULL_RTX, upper_exp = NULL_RTX;
+ unsigned lower_old, upper_old;
+
+ if (!compute_const_anchors (src_const, &lower_base, &lower_offs,
+ &upper_base, &upper_offs))
+ return NULL_RTX;
+
+ lower_anchor_rtx = GEN_INT (lower_base);
+ upper_anchor_rtx = GEN_INT (upper_base);
+ lower_elt = lookup (lower_anchor_rtx, HASH (lower_anchor_rtx, mode), mode);
+ upper_elt = lookup (upper_anchor_rtx, HASH (upper_anchor_rtx, mode), mode);
+
+ if (lower_elt)
+ lower_exp = find_reg_offset_for_const (lower_elt, lower_offs, &lower_old);
+ if (upper_elt)
+ upper_exp = find_reg_offset_for_const (upper_elt, upper_offs, &upper_old);
+
+ if (!lower_exp)
+ return upper_exp;
+ if (!upper_exp)
+ return lower_exp;
+
+ /* Return the older expression. */
+ return (upper_old > lower_old ? upper_exp : lower_exp);
+}
+\f
/* Look in or update the hash table. */
/* Remove table element ELT from use in the table.
return 0;
}
-/* Insert X in the hash table, assuming HASH is its hash code
- and CLASSP is an element of the class it should go in
- (or 0 if a new class should be made).
- It is inserted at the proper position to keep the class in
- the order cheapest first.
+/* Insert X in the hash table, assuming HASH is its hash code and
+ CLASSP is an element of the class it should go in (or 0 if a new
+ class should be made). COST is the code of X and reg_cost is the
+ cost of registers in X. It is inserted at the proper position to
+ keep the class in the order cheapest first.
MODE is the machine-mode of X, or if X is an integer constant
with VOIDmode then MODE is the mode with which X will be used.
If necessary, update table showing constant values of quantities. */
-#define CHEAPER(X, Y) \
- (preferable ((X)->cost, (X)->regcost, (Y)->cost, (Y)->regcost) < 0)
-
static struct table_elt *
-insert (rtx x, struct table_elt *classp, unsigned int hash, enum machine_mode mode)
+insert_with_costs (rtx x, struct table_elt *classp, unsigned int hash,
+ enum machine_mode mode, int cost, int reg_cost)
{
struct table_elt *elt;
elt->exp = x;
elt->canon_exp = NULL_RTX;
- elt->cost = COST (x);
- elt->regcost = approx_reg_cost (x);
+ elt->cost = cost;
+ elt->regcost = reg_cost;
elt->next_same_value = 0;
elt->prev_same_value = 0;
elt->next_same_hash = table[hash];
return elt;
}
+
+/* Wrap insert_with_costs by passing the default costs. */
+
+static struct table_elt *
+insert (rtx x, struct table_elt *classp, unsigned int hash,
+ enum machine_mode mode)
+{
+ return
+ insert_with_costs (x, classp, hash, mode, COST (x), approx_reg_cost (x));
+}
+
\f
/* Given two equivalence classes, CLASS1 and CLASS2, put all the entries from
CLASS2 into CLASS1. This is done when we have reached an insn which makes
rtx src_eqv_here;
rtx src_const = 0;
rtx src_related = 0;
+ bool src_related_is_const_anchor = false;
struct table_elt *src_const_elt = 0;
int src_cost = MAX_COST;
int src_eqv_cost = MAX_COST;
}
#endif /* LOAD_EXTEND_OP */
+ /* Try to express the constant using a register+offset expression
+ derived from a constant anchor. */
+
+ if (targetm.const_anchor
+ && !src_related
+ && src_const
+ && GET_CODE (src_const) == CONST_INT)
+ {
+ src_related = try_const_anchors (src_const, mode);
+ src_related_is_const_anchor = src_related != NULL_RTX;
+ }
+
+
if (src == src_folded)
src_folded = 0;
{
src_related_cost = COST (src_related);
src_related_regcost = approx_reg_cost (src_related);
+
+ /* If a const-anchor is used to synthesize a constant that
+ normally requires multiple instructions then slightly prefer
+ it over the original sequence. These instructions are likely
+ to become redundant now. We can't compare against the cost
+ of src_eqv_here because, on MIPS for example, multi-insn
+ constants have zero cost; they are assumed to be hoisted from
+ loops. */
+ if (src_related_is_const_anchor
+ && src_related_cost == src_cost
+ && src_eqv_here)
+ src_related_cost--;
}
}
elt = insert (dest, sets[i].src_elt,
sets[i].dest_hash, GET_MODE (dest));
+ /* If this is a constant, insert the constant anchors with the
+ equivalent register-offset expressions using register DEST. */
+ if (targetm.const_anchor
+ && REG_P (dest)
+ && SCALAR_INT_MODE_P (GET_MODE (dest))
+ && GET_CODE (sets[i].src_elt->exp) == CONST_INT)
+ insert_const_anchors (dest, sets[i].src_elt->exp, GET_MODE (dest));
+
elt->in_memory = (MEM_P (sets[i].inner_dest)
&& !MEM_READONLY_P (sets[i].inner_dest));
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