The following patch fixes
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55154
The insn in question has 2 alternatives. The first alternative is
rejected because operand constraint is class containing non-allocated
hard reg for given options. The second alternative was rejected by LRA
as the maximal cost was achieved. Reload sets up to close to maximal
cost when it sees ! and this is the last operand (imho setting to max
reject in reload is wrong as if ! were in the 1st operand, reload would
also reject the alternative). LRA accumulates the costs and with
reloads of previous operands it easily achieved maximal cost. The patch
affects a sensible code of LRA and therefore was rigorously tested.
The patch was successfully bootstrapped and tested on x86/x86-64.
Committed as rev. 193364.
2012-11-09 Vladimir Makarov <vmaka...@redhat.com>
PR tree-optimization/55154
* lra-int.h (LRA_LOSER_COST_FACTOR, LRA_MAX_REJECT): New macros.
* lra.c (setup_operand_alternative): Use them.
* lra-constraints.c (LOSER_COST_FACTOR, MAX_OVERALL_COST_BOUND):
Remove.
(process_alt_operands): Use LRA_LOSER_COST_FACTOR and
LRA_MAX_REJECT. Accumulate reject instead of setting for
non-const.
(curr_insn_transform): Initialize best_losers and best_overall by
INT_MAX.
2012-11-09 Vladimir Makarov <vmaka...@redhat.com>
PR rtl-optimization/55154
* gcc.target/i386/pr55154.c: New test.
Index: lra.c
===================================================================
--- lra.c (revision 193349)
+++ lra.c (working copy)
@@ -784,10 +784,10 @@ setup_operand_alternative (lra_insn_reco
break;
case '?':
- op_alt->reject += 6;
+ op_alt->reject += LRA_LOSER_COST_FACTOR;
break;
case '!':
- op_alt->reject += 600;
+ op_alt->reject += LRA_MAX_REJECT;
break;
case '&':
op_alt->earlyclobber = 1;
Index: lra-constraints.c
===================================================================
--- lra-constraints.c (revision 193349)
+++ lra-constraints.c (working copy)
@@ -1282,12 +1282,6 @@ general_constant_p (rtx x)
return CONSTANT_P (x) && (! flag_pic || LEGITIMATE_PIC_OPERAND_P (x));
}
-/* Cost factor for each additional reload and maximal cost bound for
- insn reloads. One might ask about such strange numbers. Their
- values occurred historically from former reload pass. */
-#define LOSER_COST_FACTOR 6
-#define MAX_OVERALL_COST_BOUND 600
-
/* Major function to choose the current insn alternative and what
operands should be reloaded and how. If ONLY_ALTERNATIVE is not
negative we should consider only this alternative. Return false if
@@ -1576,6 +1570,7 @@ process_alt_operands (int only_alternati
badop = false;
this_alternative = curr_alt[m];
COPY_HARD_REG_SET (this_alternative_set, curr_alt_set[m]);
+ winreg = this_alternative != NO_REGS;
break;
}
@@ -1828,7 +1823,7 @@ process_alt_operands (int only_alternati
might cost something but probably less than old
reload pass believes. */
if (lra_former_scratch_p (REGNO (operand_reg[nop])))
- reject += LOSER_COST_FACTOR;
+ reject += LRA_LOSER_COST_FACTOR;
}
}
else if (did_match)
@@ -1912,20 +1907,15 @@ process_alt_operands (int only_alternati
&& no_input_reloads_p && ! const_to_mem))
goto fail;
- /* If we can't reload this value at all, reject this
- alternative. Note that we could also lose due to
- LIMIT_RELOAD_CLASS, but we don't check that here. */
- if (! CONSTANT_P (op) && ! no_regs_p)
- {
- if (targetm.preferred_reload_class
- (op, this_alternative) == NO_REGS)
- reject = MAX_OVERALL_COST_BOUND;
-
- if (curr_static_id->operand[nop].type == OP_OUT
- && (targetm.preferred_output_reload_class
- (op, this_alternative) == NO_REGS))
- reject = MAX_OVERALL_COST_BOUND;
- }
+ /* Check strong discouragement of reload of non-constant
+ into class THIS_ALTERNATIVE. */
+ if (! CONSTANT_P (op) && ! no_regs_p
+ && (targetm.preferred_reload_class
+ (op, this_alternative) == NO_REGS
+ || (curr_static_id->operand[nop].type == OP_OUT
+ && (targetm.preferred_output_reload_class
+ (op, this_alternative) == NO_REGS))))
+ reject += LRA_MAX_REJECT;
if (! ((const_to_mem && constmemok)
|| (MEM_P (op) && offmemok)))
@@ -1966,7 +1956,7 @@ process_alt_operands (int only_alternati
Should we update the cost (may be approximately) here
because of early clobber register reloads or it is a rare
or non-important thing to be worth to do it. */
- overall = losers * LOSER_COST_FACTOR + reject;
+ overall = losers * LRA_LOSER_COST_FACTOR + reject;
if ((best_losers == 0 || losers != 0) && best_overall < overall)
goto fail;
@@ -2019,7 +2009,7 @@ process_alt_operands (int only_alternati
{
curr_alt_match_win[j] = false;
losers++;
- overall += LOSER_COST_FACTOR;
+ overall += LRA_LOSER_COST_FACTOR;
}
if (! curr_alt_match_win[i])
curr_alt_dont_inherit_ops[curr_alt_dont_inherit_ops_num++] = i;
@@ -2032,7 +2022,7 @@ process_alt_operands (int only_alternati
}
curr_alt_win[i] = curr_alt_match_win[i] = false;
losers++;
- overall += LOSER_COST_FACTOR;
+ overall += LRA_LOSER_COST_FACTOR;
}
small_class_operands_num = 0;
for (nop = 0; nop < n_operands; nop++)
@@ -2635,7 +2625,7 @@ curr_insn_transform (void)
the wrong kind of hard reg. For this, we must consider all the
operands together against the register constraints. */
- best_losers = best_overall = MAX_RECOG_OPERANDS * 2 + MAX_OVERALL_COST_BOUND;
+ best_losers = best_overall = INT_MAX;
best_small_class_operands_num = best_reload_sum = 0;
curr_swapped = false;
Index: lra-int.h
===================================================================
--- lra-int.h (revision 193349)
+++ lra-int.h (working copy)
@@ -243,6 +243,12 @@ typedef struct lra_insn_recog_data *lra_
#define LRA_TEMP_CLOBBER_P(x) \
(RTL_FLAG_CHECK1 ("TEMP_CLOBBER_P", (x), CLOBBER)->unchanging)
+/* Cost factor for each additional reload and maximal cost reject for
+ insn reloads. One might ask about such strange numbers. Their
+ values occurred historically from former reload pass. */
+#define LRA_LOSER_COST_FACTOR 6
+#define LRA_MAX_REJECT 600
+
/* lra.c: */
extern FILE *lra_dump_file;
Index: testsuite/gcc.target/i386/pr55154.c
===================================================================
--- testsuite/gcc.target/i386/pr55154.c (revision 0)
+++ testsuite/gcc.target/i386/pr55154.c (working copy)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-require-effective-target fpic } */
+/* { dg-options "-O2 -mcx16 -fpic -mcmodel=large -fno-split-wide-types" } */
+
+__int128 i;
+
+void test ()
+{
+ __sync_val_compare_and_swap (&i, i, i);
+}
