the accumulator. If REUSE_EXPANSION is 0 reuse
the original accumulator. Else use
var_expansions[REUSE_EXPANSION - 1]. */
+ unsigned accum_pos; /* The position in which the accumulator is placed in
+ the insn src. For example in x = x + something
+ accum_pos is 0 while in x = something + x accum_pos
+ is 1. */
};
/* Information about optimization applied in
{
sbitmap wont_exit;
unsigned HOST_WIDE_INT npeel;
- unsigned n_remove_edges, i;
- edge *remove_edges, ein;
+ unsigned i;
+ VEC (edge, heap) *remove_edges;
+ edge ein;
struct niter_desc *desc = get_simple_loop_desc (loop);
struct opt_info *opt_info = NULL;
if (desc->noloop_assumptions)
RESET_BIT (wont_exit, 1);
- remove_edges = XCNEWVEC (edge, npeel);
- n_remove_edges = 0;
+ remove_edges = NULL;
if (flag_split_ivs_in_unroller)
opt_info = analyze_insns_in_loop (loop);
ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
npeel,
wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ
| DLTHE_FLAG_COMPLETTE_PEEL
| (opt_info
}
/* Remove the exit edges. */
- for (i = 0; i < n_remove_edges; i++)
- remove_path (remove_edges[i]);
- free (remove_edges);
+ for (i = 0; VEC_iterate (edge, remove_edges, i, ein); i++)
+ remove_path (ein);
+ VEC_free (edge, heap, remove_edges);
}
ein = desc->in_edge;
unsigned HOST_WIDE_INT niter;
unsigned exit_mod;
sbitmap wont_exit;
- unsigned n_remove_edges, i;
- edge *remove_edges;
+ unsigned i;
+ VEC (edge, heap) *remove_edges;
+ edge e;
unsigned max_unroll = loop->lpt_decision.times;
struct niter_desc *desc = get_simple_loop_desc (loop);
bool exit_at_end = loop_exit_at_end_p (loop);
wont_exit = sbitmap_alloc (max_unroll + 1);
sbitmap_ones (wont_exit);
- remove_edges = XCNEWVEC (edge, max_unroll + exit_mod + 1);
- n_remove_edges = 0;
+ remove_edges = NULL;
if (flag_split_ivs_in_unroller
|| flag_variable_expansion_in_unroller)
opt_info = analyze_insns_in_loop (loop);
ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
exit_mod,
wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ
| (opt_info && exit_mod > 1
? DLTHE_RECORD_COPY_NUMBER
ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
exit_mod + 1,
wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ
| (opt_info && exit_mod > 0
? DLTHE_RECORD_COPY_NUMBER
ok = duplicate_loop_to_header_edge (loop, loop_latch_edge (loop),
max_unroll,
wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ
| (opt_info
? DLTHE_RECORD_COPY_NUMBER
desc->niter_expr = GEN_INT (desc->niter);
/* Remove the edges. */
- for (i = 0; i < n_remove_edges; i++)
- remove_path (remove_edges[i]);
- free (remove_edges);
+ for (i = 0; VEC_iterate (edge, remove_edges, i, e); i++)
+ remove_path (e);
+ VEC_free (edge, heap, remove_edges);
if (dump_file)
fprintf (dump_file,
return NULL;
bb = split_edge (e);
emit_insn_after (insns, BB_END (bb));
- bb->flags |= BB_SUPERBLOCK;
+
+ /* ??? We used to assume that INSNS can contain control flow insns, and
+ that we had to try to find sub basic blocks in BB to maintain a valid
+ CFG. For this purpose we used to set the BB_SUPERBLOCK flag on BB
+ and call break_superblocks when going out of cfglayout mode. But it
+ turns out that this never happens; and that if it does ever happen,
+ the verify_flow_info call in loop_optimizer_finalize would fail.
+
+ There are two reasons why we expected we could have control flow insns
+ in INSNS. The first is when a comparison has to be done in parts, and
+ the second is when the number of iterations is computed for loops with
+ the number of iterations known at runtime. In both cases, test cases
+ to get control flow in INSNS appear to be impossible to construct:
+
+ * If do_compare_rtx_and_jump needs several branches to do comparison
+ in a mode that needs comparison by parts, we cannot analyze the
+ number of iterations of the loop, and we never get to unrolling it.
+
+ * The code in expand_divmod that was suspected to cause creation of
+ branching code seems to be only accessed for signed division. The
+ divisions used by # of iterations analysis are always unsigned.
+ Problems might arise on architectures that emits branching code
+ for some operations that may appear in the unroller (especially
+ for division), but we have no such architectures.
+
+ Considering all this, it was decided that we should for now assume
+ that INSNS can in theory contain control flow insns, but in practice
+ it never does. So we don't handle the theoretical case, and should
+ a real failure ever show up, we have a pretty good clue for how to
+ fix it. */
+
return bb;
}
unsigned n_dom_bbs;
sbitmap wont_exit;
int may_exit_copy;
- unsigned n_peel, n_remove_edges;
- edge *remove_edges, e;
+ unsigned n_peel;
+ VEC (edge, heap) *remove_edges;
+ edge e;
bool extra_zero_check, last_may_exit;
unsigned max_unroll = loop->lpt_decision.times;
struct niter_desc *desc = get_simple_loop_desc (loop);
/* Precondition the loop. */
split_edge_and_insert (loop_preheader_edge (loop), init_code);
- remove_edges = XCNEWVEC (edge, max_unroll + n_peel + 1);
- n_remove_edges = 0;
+ remove_edges = NULL;
wont_exit = sbitmap_alloc (max_unroll + 2);
ezc_swtch = loop_preheader_edge (loop)->src;
ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
1, wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ);
gcc_assert (ok);
SET_BIT (wont_exit, 1);
ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
1, wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ);
gcc_assert (ok);
ok = duplicate_loop_to_header_edge (loop, loop_latch_edge (loop),
max_unroll,
wont_exit, desc->out_edge,
- remove_edges, &n_remove_edges,
+ &remove_edges,
DLTHE_FLAG_UPDATE_FREQ
| (opt_info
? DLTHE_RECORD_COPY_NUMBER
}
/* Remove the edges. */
- for (i = 0; i < n_remove_edges; i++)
- remove_path (remove_edges[i]);
- free (remove_edges);
+ for (i = 0; VEC_iterate (edge, remove_edges, i, e); i++)
+ remove_path (e);
+ VEC_free (edge, heap, remove_edges);
/* We must be careful when updating the number of iterations due to
preconditioning and the fact that the value must be valid at entry
opt_info_start_duplication (opt_info);
ok = duplicate_loop_to_header_edge (loop, loop_preheader_edge (loop),
- npeel, wont_exit,
- NULL, NULL,
+ npeel, wont_exit, NULL,
NULL, DLTHE_FLAG_UPDATE_FREQ
| (opt_info
? DLTHE_RECORD_COPY_NUMBER
ok = duplicate_loop_to_header_edge (loop, loop_latch_edge (loop),
nunroll, wont_exit,
- NULL, NULL, NULL,
+ NULL, NULL,
DLTHE_FLAG_UPDATE_FREQ
| (opt_info
? DLTHE_RECORD_COPY_NUMBER
static struct var_to_expand *
analyze_insn_to_expand_var (struct loop *loop, rtx insn)
{
- rtx set, dest, src, op1;
+ rtx set, dest, src, op1, op2, something;
struct var_to_expand *ves;
enum machine_mode mode1, mode2;
-
+ unsigned accum_pos;
+
set = single_set (insn);
if (!set)
return NULL;
if (!have_insn_for (GET_CODE (src), GET_MODE (src)))
return NULL;
- if (!XEXP (src, 0))
- return NULL;
-
op1 = XEXP (src, 0);
+ op2 = XEXP (src, 1);
if (!REG_P (dest)
&& !(GET_CODE (dest) == SUBREG
&& REG_P (SUBREG_REG (dest))))
return NULL;
- if (!rtx_equal_p (dest, op1))
- return NULL;
-
+ if (rtx_equal_p (dest, op1))
+ accum_pos = 0;
+ else if (rtx_equal_p (dest, op2))
+ accum_pos = 1;
+ else
+ return NULL;
+
+ /* The method of expansion that we are using; which includes
+ the initialization of the expansions with zero and the summation of
+ the expansions at the end of the computation will yield wrong results
+ for (x = something - x) thus avoid using it in that case. */
+ if (accum_pos == 1
+ && GET_CODE (src) == MINUS)
+ return NULL;
+
+ something = (accum_pos == 0)? op2 : op1;
+
if (!referenced_in_one_insn_in_loop_p (loop, dest))
return NULL;
- if (rtx_referenced_p (dest, XEXP (src, 1)))
+ if (rtx_referenced_p (dest, something))
return NULL;
mode1 = GET_MODE (dest);
- mode2 = GET_MODE (XEXP (src, 1));
+ mode2 = GET_MODE (something);
if ((FLOAT_MODE_P (mode1)
|| FLOAT_MODE_P (mode2))
&& !flag_unsafe_math_optimizations)
return NULL;
-
+
+ if (dump_file)
+ {
+ fprintf (dump_file,
+ "\n;; Expanding Accumulator ");
+ print_rtl (dump_file, dest);
+ fprintf (dump_file, "\n");
+ }
+
/* Record the accumulator to expand. */
ves = XNEW (struct var_to_expand);
ves->insn = insn;
ves->op = GET_CODE (src);
ves->expansion_count = 0;
ves->reuse_expansion = 0;
+ ves->accum_pos = accum_pos;
return ves;
}
new_reg = get_expansion (ve);
validate_change (insn, &SET_DEST (set), new_reg, 1);
- validate_change (insn, &XEXP (SET_SRC (set), 0), new_reg, 1);
+ validate_change (insn, &XEXP (SET_SRC (set), ve->accum_pos), new_reg, 1);
if (apply_change_group ())
if (really_new_expansion)
/* Initialize the variable expansions in loop preheader.
Callbacks for htab_traverse. PLACE_P is the loop-preheader
basic block where the initialization of the expansions
- should take place. */
+ should take place. The expansions are initialized with (-0)
+ when the operation is plus or minus to honor sign zero.
+ This way we can prevent cases where the sign of the final result is
+ effected by the sign of the expansion.
+ Here is an example to demonstrate this:
+
+ for (i = 0 ; i < n; i++)
+ sum += something;
+
+ ==>
+
+ sum += something
+ ....
+ i = i+1;
+ sum1 += something
+ ....
+ i = i+1
+ sum2 += something;
+ ....
+
+ When SUM is initialized with -zero and SOMETHING is also -zero; the
+ final result of sum should be -zero thus the expansions sum1 and sum2
+ should be initialized with -zero as well (otherwise we will get +zero
+ as the final result). */
static int
insert_var_expansion_initialization (void **slot, void *place_p)
basic_block place = (basic_block)place_p;
rtx seq, var, zero_init, insn;
unsigned i;
-
+ enum machine_mode mode = GET_MODE (ve->reg);
+ bool honor_signed_zero_p = HONOR_SIGNED_ZEROS (mode);
+
if (VEC_length (rtx, ve->var_expansions) == 0)
return 1;
if (ve->op == PLUS || ve->op == MINUS)
for (i = 0; VEC_iterate (rtx, ve->var_expansions, i, var); i++)
{
- zero_init = CONST0_RTX (GET_MODE (var));
+ if (honor_signed_zero_p)
+ zero_init = simplify_gen_unary (NEG, mode, CONST0_RTX (mode), mode);
+ else
+ zero_init = CONST0_RTX (mode);
+
emit_move_insn (var, zero_init);
}
else if (ve->op == MULT)
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