On 05/27/11 14:18, Jason Merrill wrote:
On 05/26/2011 02:37 PM, Aldy Hernandez wrote:
The narrowest integer mode containing the bit field is still 32, so we
access the bitfield with an SI instruction as expected.
OK, then:
struct A
{
int i: 4;
int j: 4;
int k: 8;
int l: 8;
int m: 8;
};
now the narrowest mode containing 'j' is QI/8, but it would still be
safe to use SI.
Hi Jason.
Sorry to have dropped the ball on this. Your last review coincided with
me going on vacation.
Here is another stab at it. I am now taking into account alignment,
which I believe addresses your issue. I have also added the new
testcase above, which the patch also fixes.
Tested on x86-64 Linux.
How is this?
Aldy
* params.h (ALLOW_STORE_DATA_RACES): New.
* params.def (PARAM_ALLOW_STORE_DATA_RACES): New.
* Makefile.in (expr.o): Depend on PARAMS_H.
* machmode.h (get_best_mode): Add argument.
* fold-const.c (optimize_bit_field_compare): Add argument to
get_best_mode.
(fold_truthop): Same.
* ifcvt.c (noce_emit_move_insn): Add argument to store_bit_field.
* expr.c (emit_group_store): Same.
(copy_blkmode_from_reg): Same.
(write_complex_part): Same.
(optimize_bitfield_assignment_op): Add argument.
Add argument to get_best_mode.
(get_bit_range): New.
(expand_assignment): Calculate maxbits and pass it down
accordingly.
(store_field): New argument.
(expand_expr_real_2): New argument to store_field.
Include params.h.
* expr.h (store_bit_field): New argument.
* stor-layout.c (get_best_mode): Restrict mode expansion by taking
into account maxbits.
* calls.c (store_unaligned_arguments_into_pseudos): New argument
to store_bit_field.
* expmed.c (store_bit_field_1): New argument. Use it.
(store_bit_field): Same.
(store_fixed_bit_field): Same.
(store_split_bit_field): Same.
(extract_bit_field_1): Pass new argument to get_best_mode.
(extract_bit_field): Same.
* stmt.c (store_bit_field): Pass new argument to store_bit_field.
* tree.h (DECL_THREAD_VISIBLE_P): New.
* doc/invoke.texi: Document parameter allow-store-data-races.
Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi (revision 176280)
+++ doc/invoke.texi (working copy)
@@ -9027,6 +9027,11 @@ The maximum number of conditional stores
if either vectorization (@option{-ftree-vectorize}) or if-conversion
(@option{-ftree-loop-if-convert}) is disabled. The default is 2.
+@item allow-store-data-races
+Allow optimizers to introduce new data races on stores.
+Set to 1 to allow, otherwise to 0. This option is enabled by default
+unless implicitly set by the @option{-fmemory-model=} option.
+
@item case-values-threshold
The smallest number of different values for which it is best to use a
jump-table instead of a tree of conditional branches. If the value is
Index: machmode.h
===================================================================
--- machmode.h (revision 176280)
+++ machmode.h (working copy)
@@ -248,7 +248,10 @@ extern enum machine_mode mode_for_vector
/* Find the best mode to use to access a bit field. */
-extern enum machine_mode get_best_mode (int, int, unsigned int,
+extern enum machine_mode get_best_mode (int, int,
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ unsigned int,
enum machine_mode, int);
/* Determine alignment, 1<=result<=BIGGEST_ALIGNMENT. */
Index: tree.h
===================================================================
--- tree.h (revision 176280)
+++ tree.h (working copy)
@@ -3213,6 +3213,10 @@ struct GTY(()) tree_parm_decl {
#define DECL_THREAD_LOCAL_P(NODE) \
(VAR_DECL_CHECK (NODE)->decl_with_vis.tls_model >= TLS_MODEL_REAL)
+/* Return true if a VAR_DECL is visible from another thread. */
+#define DECL_THREAD_VISIBLE_P(NODE) \
+ (TREE_STATIC (NODE) && !DECL_THREAD_LOCAL_P (NODE))
+
/* In a non-local VAR_DECL with static storage duration, true if the
variable has an initialization priority. If false, the variable
will be initialized at the DEFAULT_INIT_PRIORITY. */
Index: fold-const.c
===================================================================
--- fold-const.c (revision 176280)
+++ fold-const.c (working copy)
@@ -3394,7 +3394,7 @@ optimize_bit_field_compare (location_t l
&& flag_strict_volatile_bitfields > 0)
nmode = lmode;
else
- nmode = get_best_mode (lbitsize, lbitpos,
+ nmode = get_best_mode (lbitsize, lbitpos, 0, 0,
const_p ? TYPE_ALIGN (TREE_TYPE (linner))
: MIN (TYPE_ALIGN (TREE_TYPE (linner)),
TYPE_ALIGN (TREE_TYPE (rinner))),
@@ -5222,7 +5222,7 @@ fold_truthop (location_t loc, enum tree_
to be relative to a field of that size. */
first_bit = MIN (ll_bitpos, rl_bitpos);
end_bit = MAX (ll_bitpos + ll_bitsize, rl_bitpos + rl_bitsize);
- lnmode = get_best_mode (end_bit - first_bit, first_bit,
+ lnmode = get_best_mode (end_bit - first_bit, first_bit, 0, 0,
TYPE_ALIGN (TREE_TYPE (ll_inner)), word_mode,
volatilep);
if (lnmode == VOIDmode)
@@ -5287,7 +5287,7 @@ fold_truthop (location_t loc, enum tree_
first_bit = MIN (lr_bitpos, rr_bitpos);
end_bit = MAX (lr_bitpos + lr_bitsize, rr_bitpos + rr_bitsize);
- rnmode = get_best_mode (end_bit - first_bit, first_bit,
+ rnmode = get_best_mode (end_bit - first_bit, first_bit, 0, 0,
TYPE_ALIGN (TREE_TYPE (lr_inner)), word_mode,
volatilep);
if (rnmode == VOIDmode)
Index: params.h
===================================================================
--- params.h (revision 176280)
+++ params.h (working copy)
@@ -211,4 +211,6 @@ extern void init_param_values (int *para
PARAM_VALUE (PARAM_MIN_NONDEBUG_INSN_UID)
#define MAX_STORES_TO_SINK \
PARAM_VALUE (PARAM_MAX_STORES_TO_SINK)
+#define ALLOW_STORE_DATA_RACES \
+ PARAM_VALUE (PARAM_ALLOW_STORE_DATA_RACES)
#endif /* ! GCC_PARAMS_H */
Index: testsuite/gcc.dg/20110509.c
===================================================================
--- testsuite/gcc.dg/20110509.c (revision 0)
+++ testsuite/gcc.dg/20110509.c (revision 0)
@@ -0,0 +1,18 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+/* Test that we don't store past VAR.A. */
+
+struct S
+{
+ volatile unsigned int a : 4;
+ unsigned char b;
+ unsigned int c : 6;
+} var;
+
+void set_a()
+{
+ var.a = 12;
+}
+
+/* { dg-final { scan-assembler-not "movl.*, var" } } */
Index: testsuite/gcc.dg/20110509-2.c
===================================================================
--- testsuite/gcc.dg/20110509-2.c (revision 0)
+++ testsuite/gcc.dg/20110509-2.c (revision 0)
@@ -0,0 +1,19 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+/* Test that we don't store past VAR.K. */
+
+struct S
+{
+ volatile int i;
+ volatile int j: 32;
+ volatile int k: 15;
+ volatile char c[2];
+} var;
+
+void setit()
+{
+ var.k = 13;
+}
+
+/* { dg-final { scan-assembler-not "movl.*, var" } } */
Index: testsuite/gcc.dg/20110509-3.c
===================================================================
--- testsuite/gcc.dg/20110509-3.c (revision 0)
+++ testsuite/gcc.dg/20110509-3.c (revision 0)
@@ -0,0 +1,21 @@
+/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
+
+/* Make sure we don't narrow down to a QI or HI to store into VAR.J,
+ but instead use an SI. */
+
+struct S
+{
+ volatile int i: 4;
+ volatile int j: 4;
+ volatile int k: 8;
+ volatile int l: 8;
+ volatile int m: 8;
+} var;
+
+void setit()
+{
+ var.j = 5;
+}
+
+/* { dg-final { scan-assembler "movl.*, var" } } */
Index: ifcvt.c
===================================================================
--- ifcvt.c (revision 176280)
+++ ifcvt.c (working copy)
@@ -885,7 +885,7 @@ noce_emit_move_insn (rtx x, rtx y)
}
gcc_assert (start < (MEM_P (op) ? BITS_PER_UNIT : BITS_PER_WORD));
- store_bit_field (op, size, start, GET_MODE (x), y);
+ store_bit_field (op, size, start, 0, 0, GET_MODE (x), y);
return;
}
@@ -939,7 +939,8 @@ noce_emit_move_insn (rtx x, rtx y)
inner = XEXP (outer, 0);
outmode = GET_MODE (outer);
bitpos = SUBREG_BYTE (outer) * BITS_PER_UNIT;
- store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos, outmode, y);
+ store_bit_field (inner, GET_MODE_BITSIZE (outmode), bitpos,
+ 0, 0, outmode, y);
}
/* Return sequence of instructions generated by if conversion. This
Index: expr.c
===================================================================
--- expr.c (revision 176280)
+++ expr.c (working copy)
@@ -55,6 +55,7 @@ along with GCC; see the file COPYING3.
#include "diagnostic.h"
#include "ssaexpand.h"
#include "target-globals.h"
+#include "params.h"
/* Decide whether a function's arguments should be processed
from first to last or from last to first.
@@ -143,7 +144,9 @@ static void store_constructor_field (rtx
HOST_WIDE_INT, enum machine_mode,
tree, tree, int, alias_set_type);
static void store_constructor (tree, rtx, int, HOST_WIDE_INT);
-static rtx store_field (rtx, HOST_WIDE_INT, HOST_WIDE_INT, enum machine_mode,
+static rtx store_field (rtx, HOST_WIDE_INT, HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT, unsigned HOST_WIDE_INT,
+ enum machine_mode,
tree, tree, alias_set_type, bool);
static unsigned HOST_WIDE_INT highest_pow2_factor_for_target (const_tree,
const_tree);
@@ -2074,7 +2077,7 @@ emit_group_store (rtx orig_dst, rtx src,
emit_move_insn (adjust_address (dest, mode, bytepos), tmps[i]);
else
store_bit_field (dest, bytelen * BITS_PER_UNIT, bytepos * BITS_PER_UNIT,
- mode, tmps[i]);
+ 0, 0, mode, tmps[i]);
}
/* Copy from the pseudo into the (probable) hard reg. */
@@ -2168,7 +2171,7 @@ copy_blkmode_from_reg (rtx tgtblk, rtx s
/* Use xbitpos for the source extraction (right justified) and
bitpos for the destination store (left justified). */
- store_bit_field (dst, bitsize, bitpos % BITS_PER_WORD, copy_mode,
+ store_bit_field (dst, bitsize, bitpos % BITS_PER_WORD, 0, 0, copy_mode,
extract_bit_field (src, bitsize,
xbitpos % BITS_PER_WORD, 1, false,
NULL_RTX, copy_mode, copy_mode));
@@ -2805,7 +2808,7 @@ write_complex_part (rtx cplx, rtx val, b
gcc_assert (MEM_P (cplx) && ibitsize < BITS_PER_WORD);
}
- store_bit_field (cplx, ibitsize, imag_p ? ibitsize : 0, imode, val);
+ store_bit_field (cplx, ibitsize, imag_p ? ibitsize : 0, 0, 0, imode, val);
}
/* Extract one of the components of the complex value CPLX. Extract the
@@ -3940,6 +3943,8 @@ get_subtarget (rtx x)
static bool
optimize_bitfield_assignment_op (unsigned HOST_WIDE_INT bitsize,
unsigned HOST_WIDE_INT bitpos,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
enum machine_mode mode1, rtx str_rtx,
tree to, tree src)
{
@@ -4001,6 +4006,7 @@ optimize_bitfield_assignment_op (unsigne
if (str_bitsize == 0 || str_bitsize > BITS_PER_WORD)
str_mode = word_mode;
str_mode = get_best_mode (bitsize, bitpos,
+ bitregion_start, bitregion_end,
MEM_ALIGN (str_rtx), str_mode, 0);
if (str_mode == VOIDmode)
return false;
@@ -4109,6 +4115,111 @@ optimize_bitfield_assignment_op (unsigne
return false;
}
+/* In the C++ memory model, consecutive bit fields in a structure are
+ considered one memory location.
+
+ Given a COMPONENT_REF, this function returns the bit range of
+ consecutive bits in which this COMPONENT_REF belongs in. The
+ values are returned in *BITSTART and *BITEND. If either the C++
+ memory model is not activated, or this memory access is not thread
+ visible, 0 is returned in *BITSTART and *BITEND.
+
+ EXP is the COMPONENT_REF.
+ INNERDECL is the actual object being referenced.
+ BITPOS is the position in bits where the bit starts within the structure.
+ BITSIZE is size in bits of the field being referenced in EXP.
+
+ For example, while storing into FOO.A here...
+
+ struct {
+ BIT 0:
+ unsigned int a : 4;
+ unsigned int b : 1;
+ BIT 8:
+ unsigned char c;
+ unsigned int d : 6;
+ } foo;
+
+ ...we are not allowed to store past <b>, so for the layout above, a
+ range of 0..7 (because no one cares if we store into the
+ padding). */
+
+static void
+get_bit_range (unsigned HOST_WIDE_INT *bitstart,
+ unsigned HOST_WIDE_INT *bitend,
+ tree exp, tree innerdecl,
+ HOST_WIDE_INT bitpos, HOST_WIDE_INT bitsize)
+{
+ tree field, record_type, fld;
+ bool found_field = false;
+ bool prev_field_is_bitfield;
+
+ gcc_assert (TREE_CODE (exp) == COMPONENT_REF);
+
+ /* If other threads can't see this value, no need to restrict stores. */
+ if (ALLOW_STORE_DATA_RACES
+ || !DECL_THREAD_VISIBLE_P (innerdecl))
+ {
+ *bitstart = *bitend = 0;
+ return;
+ }
+
+ /* Bit field we're storing into. */
+ field = TREE_OPERAND (exp, 1);
+ record_type = DECL_FIELD_CONTEXT (field);
+
+ /* Count the contiguous bitfields for the memory location that
+ contains FIELD. */
+ *bitstart = 0;
+ prev_field_is_bitfield = true;
+ for (fld = TYPE_FIELDS (record_type); fld; fld = DECL_CHAIN (fld))
+ {
+ tree t, offset;
+ enum machine_mode mode;
+ int unsignedp, volatilep;
+
+ if (TREE_CODE (fld) != FIELD_DECL)
+ continue;
+
+ t = build3 (COMPONENT_REF, TREE_TYPE (exp),
+ unshare_expr (TREE_OPERAND (exp, 0)),
+ fld, NULL_TREE);
+ get_inner_reference (t, &bitsize, &bitpos, &offset,
+ &mode, &unsignedp, &volatilep, true);
+
+ if (field == fld)
+ found_field = true;
+
+ if (DECL_BIT_FIELD_TYPE (fld) && bitsize > 0)
+ {
+ if (prev_field_is_bitfield == false)
+ {
+ *bitstart = bitpos;
+ prev_field_is_bitfield = true;
+ }
+ }
+ else
+ {
+ prev_field_is_bitfield = false;
+ if (found_field)
+ break;
+ }
+ }
+ gcc_assert (found_field);
+
+ if (fld)
+ {
+ /* We found the end of the bit field sequence. Include the
+ padding up to the next field and be done. */
+ *bitend = bitpos - 1;
+ }
+ else
+ {
+ /* If this is the last element in the structure, include the padding
+ at the end of structure. */
+ *bitend = TREE_INT_CST_LOW (TYPE_SIZE (record_type));
+ }
+}
/* Expand an assignment that stores the value of FROM into TO. If NONTEMPORAL
is true, try generating a nontemporal store. */
@@ -4208,6 +4319,8 @@ expand_assignment (tree to, tree from, b
{
enum machine_mode mode1;
HOST_WIDE_INT bitsize, bitpos;
+ unsigned HOST_WIDE_INT bitregion_start = 0;
+ unsigned HOST_WIDE_INT bitregion_end = 0;
tree offset;
int unsignedp;
int volatilep = 0;
@@ -4217,6 +4330,11 @@ expand_assignment (tree to, tree from, b
tem = get_inner_reference (to, &bitsize, &bitpos, &offset, &mode1,
&unsignedp, &volatilep, true);
+ if (TREE_CODE (to) == COMPONENT_REF
+ && DECL_BIT_FIELD_TYPE (TREE_OPERAND (to, 1)))
+ get_bit_range (&bitregion_start, &bitregion_end,
+ to, tem, bitpos, bitsize);
+
/* If we are going to use store_bit_field and extract_bit_field,
make sure to_rtx will be safe for multiple use. */
@@ -4298,11 +4416,14 @@ expand_assignment (tree to, tree from, b
nontemporal);
else if (bitpos + bitsize <= mode_bitsize / 2)
result = store_field (XEXP (to_rtx, 0), bitsize, bitpos,
+ bitregion_start, bitregion_end,
mode1, from, TREE_TYPE (tem),
get_alias_set (to), nontemporal);
else if (bitpos >= mode_bitsize / 2)
result = store_field (XEXP (to_rtx, 1), bitsize,
- bitpos - mode_bitsize / 2, mode1, from,
+ bitpos - mode_bitsize / 2,
+ bitregion_start, bitregion_end,
+ mode1, from,
TREE_TYPE (tem), get_alias_set (to),
nontemporal);
else if (bitpos == 0 && bitsize == mode_bitsize)
@@ -4323,7 +4444,9 @@ expand_assignment (tree to, tree from, b
0);
write_complex_part (temp, XEXP (to_rtx, 0), false);
write_complex_part (temp, XEXP (to_rtx, 1), true);
- result = store_field (temp, bitsize, bitpos, mode1, from,
+ result = store_field (temp, bitsize, bitpos,
+ bitregion_start, bitregion_end,
+ mode1, from,
TREE_TYPE (tem), get_alias_set (to),
nontemporal);
emit_move_insn (XEXP (to_rtx, 0), read_complex_part (temp,
false));
@@ -4348,11 +4471,15 @@ expand_assignment (tree to, tree from, b
MEM_KEEP_ALIAS_SET_P (to_rtx) = 1;
}
- if (optimize_bitfield_assignment_op (bitsize, bitpos, mode1,
+ if (optimize_bitfield_assignment_op (bitsize, bitpos,
+ bitregion_start, bitregion_end,
+ mode1,
to_rtx, to, from))
result = NULL;
else
- result = store_field (to_rtx, bitsize, bitpos, mode1, from,
+ result = store_field (to_rtx, bitsize, bitpos,
+ bitregion_start, bitregion_end,
+ mode1, from,
TREE_TYPE (tem), get_alias_set (to),
nontemporal);
}
@@ -4745,7 +4872,7 @@ store_expr (tree exp, rtx target, int ca
: BLOCK_OP_NORMAL));
else if (GET_MODE (target) == BLKmode)
store_bit_field (target, INTVAL (expr_size (exp)) * BITS_PER_UNIT,
- 0, GET_MODE (temp), temp);
+ 0, 0, 0, GET_MODE (temp), temp);
else
convert_move (target, temp, unsignedp);
}
@@ -5210,7 +5337,8 @@ store_constructor_field (rtx target, uns
store_constructor (exp, target, cleared, bitsize / BITS_PER_UNIT);
}
else
- store_field (target, bitsize, bitpos, mode, exp, type, alias_set, false);
+ store_field (target, bitsize, bitpos, 0, 0, mode, exp, type, alias_set,
+ false);
}
/* Store the value of constructor EXP into the rtx TARGET.
@@ -5784,6 +5912,11 @@ store_constructor (tree exp, rtx target,
BITSIZE bits, starting BITPOS bits from the start of TARGET.
If MODE is VOIDmode, it means that we are storing into a bit-field.
+ BITREGION_START is bitpos of the first bitfield in this region.
+ BITREGION_END is the bitpos of the ending bitfield in this region.
+ These two fields are 0, if the C++ memory model does not apply,
+ or we are not interested in keeping track of bitfield regions.
+
Always return const0_rtx unless we have something particular to
return.
@@ -5797,6 +5930,8 @@ store_constructor (tree exp, rtx target,
static rtx
store_field (rtx target, HOST_WIDE_INT bitsize, HOST_WIDE_INT bitpos,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
enum machine_mode mode, tree exp, tree type,
alias_set_type alias_set, bool nontemporal)
{
@@ -5829,8 +5964,9 @@ store_field (rtx target, HOST_WIDE_INT b
if (bitsize != (HOST_WIDE_INT) GET_MODE_BITSIZE (GET_MODE (target)))
emit_move_insn (object, target);
- store_field (blk_object, bitsize, bitpos, mode, exp, type, alias_set,
- nontemporal);
+ store_field (blk_object, bitsize, bitpos,
+ bitregion_start, bitregion_end,
+ mode, exp, type, alias_set, nontemporal);
emit_move_insn (target, object);
@@ -5944,7 +6080,9 @@ store_field (rtx target, HOST_WIDE_INT b
}
/* Store the value in the bitfield. */
- store_bit_field (target, bitsize, bitpos, mode, temp);
+ store_bit_field (target, bitsize, bitpos,
+ bitregion_start, bitregion_end,
+ mode, temp);
return const0_rtx;
}
@@ -7354,7 +7492,7 @@ expand_expr_real_2 (sepops ops, rtx targ
(treeop0))
* BITS_PER_UNIT),
(HOST_WIDE_INT) GET_MODE_BITSIZE (mode)),
- 0, TYPE_MODE (valtype), treeop0,
+ 0, 0, 0, TYPE_MODE (valtype), treeop0,
type, 0, false);
}
Index: expr.h
===================================================================
--- expr.h (revision 176280)
+++ expr.h (working copy)
@@ -665,7 +665,10 @@ extern enum machine_mode
mode_for_extraction (enum extraction_pattern, int);
extern void store_bit_field (rtx, unsigned HOST_WIDE_INT,
- unsigned HOST_WIDE_INT, enum machine_mode, rtx);
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ enum machine_mode, rtx);
extern rtx extract_bit_field (rtx, unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT, int, bool, rtx,
enum machine_mode, enum machine_mode);
Index: stor-layout.c
===================================================================
--- stor-layout.c (revision 176280)
+++ stor-layout.c (working copy)
@@ -2361,6 +2361,13 @@ fixup_unsigned_type (tree type)
/* Find the best machine mode to use when referencing a bit field of length
BITSIZE bits starting at BITPOS.
+ BITREGION_START is the bit position of the first bit in this
+ sequence of bit fields. BITREGION_END is the last bit in this
+ sequence. If these two fields are non-zero, we should restrict the
+ memory access to a maximum sized chunk of
+ BITREGION_END - BITREGION_START + 1. Otherwise, we are allowed to touch
+ any adjacent non bit-fields.
+
The underlying object is known to be aligned to a boundary of ALIGN bits.
If LARGEST_MODE is not VOIDmode, it means that we should not use a mode
larger than LARGEST_MODE (usually SImode).
@@ -2378,11 +2385,21 @@ fixup_unsigned_type (tree type)
decide which of the above modes should be used. */
enum machine_mode
-get_best_mode (int bitsize, int bitpos, unsigned int align,
+get_best_mode (int bitsize, int bitpos,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
+ unsigned int align,
enum machine_mode largest_mode, int volatilep)
{
enum machine_mode mode;
unsigned int unit = 0;
+ unsigned HOST_WIDE_INT maxbits;
+
+ /* If unset, no restriction. */
+ if (!bitregion_end)
+ maxbits = 0;
+ else
+ maxbits = (bitregion_end - bitregion_start) % align;
/* Find the narrowest integer mode that contains the bit field. */
for (mode = GET_CLASS_NARROWEST_MODE (MODE_INT); mode != VOIDmode;
@@ -2419,6 +2436,7 @@ get_best_mode (int bitsize, int bitpos,
&& bitpos / unit == (bitpos + bitsize - 1) / unit
&& unit <= BITS_PER_WORD
&& unit <= MIN (align, BIGGEST_ALIGNMENT)
+ && (!maxbits || unit <= maxbits)
&& (largest_mode == VOIDmode
|| unit <= GET_MODE_BITSIZE (largest_mode)))
wide_mode = tmode;
Index: calls.c
===================================================================
--- calls.c (revision 176280)
+++ calls.c (working copy)
@@ -924,8 +924,8 @@ store_unaligned_arguments_into_pseudos (
emit_move_insn (reg, const0_rtx);
bytes -= bitsize / BITS_PER_UNIT;
- store_bit_field (reg, bitsize, endian_correction, word_mode,
- word);
+ store_bit_field (reg, bitsize, endian_correction, 0, 0,
+ word_mode, word);
}
}
}
Index: expmed.c
===================================================================
--- expmed.c (revision 176280)
+++ expmed.c (working copy)
@@ -47,9 +47,15 @@ struct target_expmed *this_target_expmed
static void store_fixed_bit_field (rtx, unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT,
- unsigned HOST_WIDE_INT, rtx);
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ rtx);
static void store_split_bit_field (rtx, unsigned HOST_WIDE_INT,
- unsigned HOST_WIDE_INT, rtx);
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ unsigned HOST_WIDE_INT,
+ rtx);
static rtx extract_fixed_bit_field (enum machine_mode, rtx,
unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT,
@@ -333,7 +339,10 @@ mode_for_extraction (enum extraction_pat
static bool
store_bit_field_1 (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
- unsigned HOST_WIDE_INT bitnum, enum machine_mode fieldmode,
+ unsigned HOST_WIDE_INT bitnum,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
+ enum machine_mode fieldmode,
rtx value, bool fallback_p)
{
unsigned int unit
@@ -547,7 +556,9 @@ store_bit_field_1 (rtx str_rtx, unsigned
if (!store_bit_field_1 (op0, MIN (BITS_PER_WORD,
bitsize - i * BITS_PER_WORD),
- bitnum + bit_offset, word_mode,
+ bitnum + bit_offset,
+ bitregion_start, bitregion_end,
+ word_mode,
value_word, fallback_p))
{
delete_insns_since (last);
@@ -710,6 +721,12 @@ store_bit_field_1 (rtx str_rtx, unsigned
if (HAVE_insv && MEM_P (op0))
{
enum machine_mode bestmode;
+ unsigned HOST_WIDE_INT maxbits;
+
+ if (!bitregion_end)
+ maxbits = 0;
+ else
+ maxbits = bitregion_end - bitregion_start;
/* Get the mode to use for inserting into this field. If OP0 is
BLKmode, get the smallest mode consistent with the alignment. If
@@ -717,9 +734,12 @@ store_bit_field_1 (rtx str_rtx, unsigned
mode. Otherwise, use the smallest mode containing the field. */
if (GET_MODE (op0) == BLKmode
+ || (bitregion_end && 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, MEM_ALIGN (op0),
+ bestmode = get_best_mode (bitsize, bitnum,
+ bitregion_start, bitregion_end,
+ MEM_ALIGN (op0),
(op_mode == MAX_MACHINE_MODE
? VOIDmode : op_mode),
MEM_VOLATILE_P (op0));
@@ -748,6 +768,7 @@ store_bit_field_1 (rtx str_rtx, unsigned
the unit. */
tempreg = copy_to_reg (xop0);
if (store_bit_field_1 (tempreg, bitsize, xbitpos,
+ bitregion_start, bitregion_end,
fieldmode, orig_value, false))
{
emit_move_insn (xop0, tempreg);
@@ -760,21 +781,33 @@ store_bit_field_1 (rtx str_rtx, unsigned
if (!fallback_p)
return false;
- store_fixed_bit_field (op0, offset, bitsize, bitpos, value);
+ store_fixed_bit_field (op0, offset, bitsize, bitpos,
+ bitregion_start, bitregion_end, value);
return true;
}
/* Generate code to store value from rtx VALUE
into a bit-field within structure STR_RTX
containing BITSIZE bits starting at bit BITNUM.
+
+ BITREGION_START is bitpos of the first bitfield in this region.
+ BITREGION_END is the bitpos of the ending bitfield in this region.
+ These two fields are 0, if the C++ memory model does not apply,
+ or we are not interested in keeping track of bitfield regions.
+
FIELDMODE is the machine-mode of the FIELD_DECL node for this field. */
void
store_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
- unsigned HOST_WIDE_INT bitnum, enum machine_mode fieldmode,
+ unsigned HOST_WIDE_INT bitnum,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
+ enum machine_mode fieldmode,
rtx value)
{
- if (!store_bit_field_1 (str_rtx, bitsize, bitnum, fieldmode, value, true))
+ if (!store_bit_field_1 (str_rtx, bitsize, bitnum,
+ bitregion_start, bitregion_end,
+ fieldmode, value, true))
gcc_unreachable ();
}
@@ -790,7 +823,10 @@ store_bit_field (rtx str_rtx, unsigned H
static void
store_fixed_bit_field (rtx op0, unsigned HOST_WIDE_INT offset,
unsigned HOST_WIDE_INT bitsize,
- unsigned HOST_WIDE_INT bitpos, rtx value)
+ unsigned HOST_WIDE_INT bitpos,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
+ rtx value)
{
enum machine_mode mode;
unsigned int total_bits = BITS_PER_WORD;
@@ -811,12 +847,23 @@ store_fixed_bit_field (rtx op0, unsigned
/* Special treatment for a bit field split across two registers. */
if (bitsize + bitpos > BITS_PER_WORD)
{
- store_split_bit_field (op0, bitsize, bitpos, value);
+ store_split_bit_field (op0, bitsize, bitpos,
+ bitregion_start, bitregion_end,
+ value);
return;
}
}
else
{
+ unsigned HOST_WIDE_INT maxbits;
+
+ if (!bitregion_end)
+ maxbits = 0;
+ else if (1||bitpos + offset * BITS_PER_UNIT < bitregion_start)
+ maxbits = bitregion_end - bitregion_start;
+ else
+ maxbits = bitregion_end - (bitpos + offset * BITS_PER_UNIT) + 1;
+
/* Get the proper mode to use for this field. We want a mode that
includes the entire field. If such a mode would be larger than
a word, we won't be doing the extraction the normal way.
@@ -829,10 +876,12 @@ store_fixed_bit_field (rtx op0, unsigned
if (MEM_VOLATILE_P (op0)
&& GET_MODE_BITSIZE (GET_MODE (op0)) > 0
+ && GET_MODE_BITSIZE (GET_MODE (op0)) <= maxbits
&& flag_strict_volatile_bitfields > 0)
mode = GET_MODE (op0);
else
mode = get_best_mode (bitsize, bitpos + offset * BITS_PER_UNIT,
+ bitregion_start, bitregion_end,
MEM_ALIGN (op0), mode, MEM_VOLATILE_P (op0));
if (mode == VOIDmode)
@@ -840,7 +889,7 @@ store_fixed_bit_field (rtx op0, unsigned
/* The only way this should occur is if the field spans word
boundaries. */
store_split_bit_field (op0, bitsize, bitpos + offset * BITS_PER_UNIT,
- value);
+ bitregion_start, bitregion_end, value);
return;
}
@@ -960,7 +1009,10 @@ store_fixed_bit_field (rtx op0, unsigned
static void
store_split_bit_field (rtx op0, unsigned HOST_WIDE_INT bitsize,
- unsigned HOST_WIDE_INT bitpos, rtx value)
+ unsigned HOST_WIDE_INT bitpos,
+ unsigned HOST_WIDE_INT bitregion_start,
+ unsigned HOST_WIDE_INT bitregion_end,
+ rtx value)
{
unsigned int unit;
unsigned int bitsdone = 0;
@@ -1075,7 +1127,7 @@ store_split_bit_field (rtx op0, unsigned
it is just an out-of-bounds access. Ignore it. */
if (word != const0_rtx)
store_fixed_bit_field (word, offset * unit / BITS_PER_UNIT, thissize,
- thispos, part);
+ thispos, bitregion_start, bitregion_end, part);
bitsdone += thissize;
}
}
@@ -1515,7 +1567,7 @@ extract_bit_field_1 (rtx str_rtx, unsign
if (GET_MODE (op0) == BLKmode
|| (ext_mode != MAX_MACHINE_MODE
&& GET_MODE_SIZE (GET_MODE (op0)) > GET_MODE_SIZE (ext_mode)))
- bestmode = get_best_mode (bitsize, bitnum, MEM_ALIGN (op0),
+ bestmode = get_best_mode (bitsize, bitnum, 0, 0, MEM_ALIGN (op0),
(ext_mode == MAX_MACHINE_MODE
? VOIDmode : ext_mode),
MEM_VOLATILE_P (op0));
@@ -1641,7 +1693,7 @@ extract_fixed_bit_field (enum machine_mo
mode = tmode;
}
else
- mode = get_best_mode (bitsize, bitpos + offset * BITS_PER_UNIT,
+ mode = get_best_mode (bitsize, bitpos + offset * BITS_PER_UNIT, 0, 0,
MEM_ALIGN (op0), word_mode, MEM_VOLATILE_P (op0));
if (mode == VOIDmode)
Index: Makefile.in
===================================================================
--- Makefile.in (revision 176280)
+++ Makefile.in (working copy)
@@ -2908,7 +2908,7 @@ expr.o : expr.c $(CONFIG_H) $(SYSTEM_H)
reload.h langhooks.h intl.h $(TM_P_H) $(TARGET_H) \
tree-iterator.h gt-expr.h $(MACHMODE_H) $(TIMEVAR_H) $(TREE_FLOW_H) \
$(TREE_PASS_H) $(DF_H) $(DIAGNOSTIC_H) vecprim.h $(SSAEXPAND_H) \
- $(COMMON_TARGET_H)
+ $(PARAMS_H) $(COMMON_TARGET_H)
dojump.o : dojump.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(RTL_H)
$(TREE_H) \
$(FLAGS_H) $(FUNCTION_H) $(EXPR_H) $(OPTABS_H) $(INSN_ATTR_H) insn-config.h
\
langhooks.h $(GGC_H) gt-dojump.h vecprim.h $(BASIC_BLOCK_H) output.h
Index: stmt.c
===================================================================
--- stmt.c (revision 176280)
+++ stmt.c (working copy)
@@ -1759,7 +1759,8 @@ expand_return (tree retval)
/* Use bitpos for the source extraction (left justified) and
xbitpos for the destination store (right justified). */
- store_bit_field (dst, bitsize, xbitpos % BITS_PER_WORD, word_mode,
+ store_bit_field (dst, bitsize, xbitpos % BITS_PER_WORD,
+ 0, 0, word_mode,
extract_bit_field (src, bitsize,
bitpos % BITS_PER_WORD, 1, false,
NULL_RTX, word_mode, word_mode));
Index: params.def
===================================================================
--- params.def (revision 176280)
+++ params.def (working copy)
@@ -902,6 +902,12 @@ DEFPARAM (PARAM_CASE_VALUES_THRESHOLD,
"if 0, use the default for the machine",
0, 0, 0)
+/* Data race flags for C++0x memory model compliance. */
+DEFPARAM (PARAM_ALLOW_STORE_DATA_RACES,
+ "allow-store-data-races",
+ "Allow new data races on stores to be introduced",
+ 1, 0, 1)
+
/*
Local variables:
