check_iv_ref_table_size ();
}
+/* Return true if D_REF is defined in an immediate predecessor of the
+ current loop's latch block. Otherwise return false. */
+
+static bool
+def_pred_latch_p (df_ref d_ref)
+{
+ basic_block bb = DF_REF_BB (d_ref);
+ edge_iterator ei;
+ edge e;
+
+ FOR_EACH_EDGE (e, ei, current_loop->latch->preds)
+ {
+ if (e->src == bb)
+ return true;
+ }
+ return false;
+}
+
/* Finds the definition of REG that dominates loop latch and stores
it to DEF. Returns false if there is not a single definition
- dominating the latch. If REG has no definition in loop, DEF
+ dominating the latch or all defs are same and they are on different
+ predecessors of loop latch. If REG has no definition in loop, DEF
is set to NULL and true is returned. */
static bool
latch_dominating_def (rtx reg, df_ref *def)
{
df_ref single_rd = NULL, adef;
- unsigned regno = REGNO (reg);
+ unsigned regno = REGNO (reg), def_num = 0;
struct df_rd_bb_info *bb_info = DF_RD_BB_INFO (current_loop->latch);
for (adef = DF_REG_DEF_CHAIN (regno); adef; adef = DF_REF_NEXT_REG (adef))
{
+ /* Initialize this to true for the very first iteration when
+ SINGLE_RD is NULL. */
+ bool def_pred_latch = true;
+
if (!bitmap_bit_p (df->blocks_to_analyze, DF_REF_BBNO (adef))
|| !bitmap_bit_p (&bb_info->out, DF_REF_ID (adef)))
continue;
- /* More than one reaching definition. */
+ /* More than one reaching definition is ok in case definitions are
+ in predecessors of latch block and those definitions are the same.
+ Probably this could be relaxed and check for sub-dominance instead
+ predecessor. */
+ def_num++;
if (single_rd)
- return false;
-
- if (!just_once_each_iteration_p (current_loop, DF_REF_BB (adef)))
- return false;
+ {
+ if (!(def_pred_latch = def_pred_latch_p (adef))
+ || !rtx_equal_p (PATTERN (DF_REF_INSN (single_rd)),
+ PATTERN (DF_REF_INSN (adef))))
+ return false;
+ }
single_rd = adef;
}
+ /* If we have single definition it has to be executed on each iteration. */
+ if ((def_num == 1) && single_rd
+ && !just_once_each_iteration_p (current_loop, DF_REF_BB (single_rd)))
+ return false;
+
+ /* Make sure all preds contain definitions. */
+ if (def_num != EDGE_COUNT (current_loop->latch->preds))
+ return false;
+
*def = single_rd;
return true;
}
static enum iv_grd_result
iv_get_reaching_def (rtx_insn *insn, rtx reg, df_ref *def)
{
- df_ref use, adef;
+ df_ref use, adef = NULL;
basic_block def_bb, use_bb;
rtx_insn *def_insn;
- bool dom_p;
+ bool dom_p, dom_latch_p = false;
*def = NULL;
if (!simple_reg_p (reg))
if (!DF_REF_CHAIN (use))
return GRD_INVARIANT;
- /* More than one reaching def. */
+ adef = DF_REF_CHAIN (use)->ref;
+ /* Having more than one reaching def is ok once all defs are in blocks which
+ are latch's predecessors. */
if (DF_REF_CHAIN (use)->next)
- return GRD_INVALID;
+ {
+ df_link* defs;
+ unsigned int def_num = 0;
- adef = DF_REF_CHAIN (use)->ref;
+ for (defs = DF_REF_CHAIN (use); defs; defs = defs->next)
+ {
+ if (!def_pred_latch_p (defs->ref))
+ return GRD_INVALID;
+ def_num++;
+ }
+ /* Make sure all preds contain definitions. */
+ if (def_num != EDGE_COUNT (current_loop->latch->preds))
+ return GRD_INVALID;
+
+ dom_latch_p = true;
+ }
/* We do not handle setting only part of the register. */
if (DF_REF_FLAGS (adef) & DF_REF_READ_WRITE)
/* The definition does not dominate the use. This is still OK if
this may be a use of a biv, i.e. if the def_bb dominates loop
- latch. */
- if (just_once_each_iteration_p (current_loop, def_bb))
+ latch or all defs are in latch's predecessors. */
+ if (dom_latch_p || just_once_each_iteration_p (current_loop, def_bb))
return GRD_MAYBE_BIV;
return GRD_INVALID;
return;
}
+/* Return true if LOOP has a complex exit, but is still good for further
+ analysis. Return false otherwise. BB is LOOP's exit block. */
+
+static bool
+check_complex_exit_p (struct loop* loop, basic_block bb)
+{
+ edge e;
+ basic_block pred, exit;
+
+ if (EDGE_COUNT (bb->preds) > 1)
+ return false;
+
+ e = EDGE_PRED (bb, 0);
+
+ pred = e->src;
+ if (EDGE_COUNT (pred->succs) != 2)
+ return false;
+
+ /* Predecessor must be tested (at least) once during any iteration. */
+ if (!dominated_by_p (CDI_DOMINATORS, loop->latch, pred))
+ return false;
+
+ if (EDGE_SUCC (pred, 0)->dest == bb)
+ exit = EDGE_SUCC (pred, 1)->dest;
+ else
+ exit = EDGE_SUCC (pred, 0)->dest;
+
+ /* Check that EXIT is really loop exit. */
+ if (flow_bb_inside_loop_p (loop, exit))
+ {
+ edge_iterator eei;
+ edge ee;
+
+ FOR_EACH_EDGE (ee, eei, exit->succs)
+ {
+ if (!flow_bb_inside_loop_p (loop, ee->dest))
+ return true;
+ }
+ }
+ return false;
+
+}
+
/* Checks whether E is a simple exit from LOOP and stores its description
into DESC. */
return;
/* It must be tested (at least) once during any iteration. */
- if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit_bb))
+ if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit_bb)
+ && !check_complex_exit_p (loop, exit_bb))
return;
/* It must end in a simple conditional jump. */
projects / gcc.git / commitdiff