Hi!
This patch fixes the attached execute/ testcases. In some cases
get_best_mode was ignoring bitregion_* restrictions and returned
mode that overlapped into adjacent non-bitfields, or store_bit_field_1
for insv could ignore those restrictions completely.
After fixing that I've run into several issues that the other parts
of the patch fix, namely that get_best_mode returning VOIDmode more often
now may lead to store_split_bit_field being called when it wasn't before,
and when approaching the bitregion_end point we can't just keep using
large units (modes), but need to decrease their size in order not to
overwrite adjacent non-bitfields. The get_best_mode dropping of % align
change prevents a mutual recursion, e.g. for bitregion_end == 103
it would prevent using > QImode even far before the bit region boundary,
even when not touching anything close to that bit region end.
But the extra
+ && (bitregion_end == 0
+ || bitpos - (bitpos % unit) + unit <= bitregion_end + 1))
needed to be added after that change, otherwise we'd regress on
c-c++-common/simulate-thread/bitfields-2.c.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
2012-04-25 Jakub Jelinek <ja...@redhat.com>
PR middle-end/52979
* stor-layout.c (get_best_mode): Don't return mode with bitsize
larger than maxbits. Don't compute maxbits modulo align.
Also check that unit bytes long store at bitpos / unit * unit
doesn't affect bits beyond bitregion_end.
* expmed.c (store_bit_field_1): Avoid trying insv if OP_MODE MEM
would not fit into bitregion_start ... bitregion_end + 1 bit
region.
(store_split_bit_field): Decrease unit close to end of bitregion_end
if access is restricted in order to avoid mutual recursion.
* gcc.c-torture/compile/pr52979-1.c: New test.
* gcc.c-torture/execute/pr52979-1.c: New test.
* gcc.c-torture/execute/pr52979-2.c: New test.
--- gcc/stor-layout.c.jj 2012-03-26 11:53:20.000000000 +0200
+++ gcc/stor-layout.c 2012-04-25 10:26:18.881631697 +0200
@@ -2624,7 +2624,7 @@ get_best_mode (int bitsize, int bitpos,
if (!bitregion_end)
maxbits = MAX_FIXED_MODE_SIZE;
else
- maxbits = (bitregion_end - bitregion_start) % align + 1;
+ maxbits = bitregion_end - bitregion_start + 1;
/* Find the narrowest integer mode that contains the bit field. */
for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
@@ -2645,7 +2645,10 @@ get_best_mode (int bitsize, int bitpos,
(Though at least one Unix compiler ignores this problem:
that on the Sequent 386 machine. */
|| MIN (unit, BIGGEST_ALIGNMENT) > align
- || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode)))
+ || (largest_mode != VOIDmode && unit > GET_MODE_BITSIZE (largest_mode))
+ || unit > maxbits
+ || (bitregion_end
+ && bitpos - (bitpos % unit) + unit > bitregion_end + 1))
return VOIDmode;
if ((SLOW_BYTE_ACCESS && ! volatilep)
@@ -2663,7 +2666,9 @@ get_best_mode (int bitsize, int bitpos,
&& unit <= MIN (align, BIGGEST_ALIGNMENT)
&& unit <= maxbits
&& (largest_mode == VOIDmode
- || unit <= GET_MODE_BITSIZE (largest_mode)))
+ || unit <= GET_MODE_BITSIZE (largest_mode))
+ && (bitregion_end == 0
+ || bitpos - (bitpos % unit) + unit <= bitregion_end + 1))
wide_mode = tmode;
}
--- gcc/expmed.c.jj 2012-04-19 11:09:13.000000000 +0200
+++ gcc/expmed.c 2012-04-24 17:14:34.264897874 +0200
@@ -640,7 +640,13 @@ store_bit_field_1 (rtx str_rtx, unsigned
&& !(MEM_P (op0) && MEM_VOLATILE_P (op0)
&& flag_strict_volatile_bitfields > 0)
&& ! ((REG_P (op0) || GET_CODE (op0) == SUBREG)
- && (bitsize + bitpos > GET_MODE_BITSIZE (op_mode))))
+ && (bitsize + bitpos > GET_MODE_BITSIZE (op_mode)))
+ /* Do not use insv if the bit region is restricted and
+ op_mode integer at offset doesn't fit into the
+ restricted region. */
+ && !(MEM_P (op0) && bitregion_end
+ && bitnum - bitpos + GET_MODE_BITSIZE (op_mode)
+ > bitregion_end + 1))
{
struct expand_operand ops[4];
int xbitpos = bitpos;
@@ -760,7 +766,7 @@ store_bit_field_1 (rtx str_rtx, unsigned
|| GET_MODE_BITSIZE (GET_MODE (op0)) > maxbits
|| (op_mode != MAX_MACHINE_MODE
&& GET_MODE_SIZE (GET_MODE (op0)) > GET_MODE_SIZE (op_mode)))
- bestmode = get_best_mode (bitsize, bitnum,
+ bestmode = get_best_mode (bitsize, bitnum,
bitregion_start, bitregion_end,
MEM_ALIGN (op0),
(op_mode == MAX_MACHINE_MODE
@@ -1096,6 +1102,16 @@ store_split_bit_field (rtx op0, unsigned
offset = (bitpos + bitsdone) / unit;
thispos = (bitpos + bitsdone) % unit;
+ /* When region of bytes we can touch is restricted, decrease
+ UNIT close to the end of the region as needed. */
+ if (bitregion_end
+ && unit > BITS_PER_UNIT
+ && bitpos + bitsdone - thispos + unit > bitregion_end + 1)
+ {
+ unit = unit / 2;
+ continue;
+ }
+
/* THISSIZE must not overrun a word boundary. Otherwise,
store_fixed_bit_field will call us again, and we will mutually
recurse forever. */
--- gcc/testsuite/gcc.c-torture/compile/pr52979-1.c.jj 2012-04-25
08:27:48.188902802 +0200
+++ gcc/testsuite/gcc.c-torture/compile/pr52979-1.c 2012-04-25
08:27:29.000000000 +0200
@@ -0,0 +1,15 @@
+/* PR middle-end/52979 */
+
+struct S
+{
+ unsigned int a : 16, b : 16, c : 16, d : 16, e : 14;
+ unsigned int f : 4, g : 14, h : 8;
+ char i;
+ int j;
+};
+
+void
+foo (struct S *s)
+{
+ s->f = 1;
+}
--- gcc/testsuite/gcc.c-torture/execute/pr52979-1.c.jj 2012-04-24
17:20:51.246662745 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr52979-1.c 2012-04-24
17:21:03.526586921 +0200
@@ -0,0 +1,40 @@
+/* PR middle-end/52979 */
+
+extern void abort (void);
+int c, d, e;
+
+void
+foo (void)
+{
+}
+
+struct __attribute__((packed)) S { int g : 31; int h : 6; };
+struct S a = { 1 };
+static struct S b = { 1 };
+
+void
+bar (void)
+{
+ a.h = 1;
+ struct S f = { };
+ b = f;
+ e = 0;
+ if (d)
+ c = a.g;
+}
+
+void
+baz (void)
+{
+ bar ();
+ a = b;
+}
+
+int
+main ()
+{
+ baz ();
+ if (a.g)
+ abort ();
+ return 0;
+}
--- gcc/testsuite/gcc.c-torture/execute/pr52979-2.c.jj 2012-04-24
17:20:54.603642467 +0200
+++ gcc/testsuite/gcc.c-torture/execute/pr52979-2.c 2012-04-24
17:19:15.000000000 +0200
@@ -0,0 +1,40 @@
+/* PR middle-end/52979 */
+
+extern void abort (void);
+int c, d, e;
+
+void
+foo (void)
+{
+}
+
+struct __attribute__((packed)) S { int g : 31; int h : 6; };
+static struct S b = { 1 };
+struct S a = { 1 };
+
+void
+bar (void)
+{
+ a.h = 1;
+ struct S f = { };
+ b = f;
+ e = 0;
+ if (d)
+ c = a.g;
+}
+
+void
+baz (void)
+{
+ bar ();
+ a = b;
+}
+
+int
+main ()
+{
+ baz ();
+ if (a.g)
+ abort ();
+ return 0;
+}
Jakub
