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re PR middle-end/23623 (volatile keyword changes bitfield access size from 32bit to 8bit) 

2013-12-11  Bernd Edlinger  <bernd.edlinger@hotmail.de>
            Sandra Loosemore  <sandra@codesourcery.com>

        PR middle-end/23623
        PR middle-end/48784
        PR middle-end/56341
        PR middle-end/56997
        * expmed.c (strict_volatile_bitfield_p): Add bitregion_start
        and bitregion_end parameters.  Test for compliance with C++
        memory model.
        (store_bit_field): Adjust call to strict_volatile_bitfield_p.
        Add fallback logic for cases where -fstrict-volatile-bitfields
        is supposed to apply, but cannot.
        (extract_bit_field): Likewise. Use narrow_bit_field_mem and
        extract_fixed_bit_field_1 to do the extraction.
        (extract_fixed_bit_field): Revert to previous mode selection algorithm.
        Call extract_fixed_bit_field_1 to do the real work.
        (extract_fixed_bit_field_1): New function.

testsuite:        
        * gcc.dg/pr23623.c: Update to test interaction with C++
        memory model.

Co-Authored-By: Sandra Loosemore <sandra@codesourcery.com>

From-SVN: r205897
This commit is contained in:
Bernd Edlinger 2013-12-11 16:59:24 +00:00 committed by Bernd Edlinger
parent f5d4f18c53
commit 6f4e9cf842
4 changed files with 70 additions and 15 deletions
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19
gcc/ChangeLog
View File

@ -1,3 +1,22 @@
2013-12-11 Bernd Edlinger <bernd.edlinger@hotmail.de>
Sandra Loosemore <sandra@codesourcery.com>
PR middle-end/23623
PR middle-end/48784
PR middle-end/56341
PR middle-end/56997
* expmed.c (strict_volatile_bitfield_p): Add bitregion_start
and bitregion_end parameters. Test for compliance with C++
memory model.
(store_bit_field): Adjust call to strict_volatile_bitfield_p.
Add fallback logic for cases where -fstrict-volatile-bitfields
is supposed to apply, but cannot.
(extract_bit_field): Likewise. Use narrow_bit_field_mem and
extract_fixed_bit_field_1 to do the extraction.
(extract_fixed_bit_field): Revert to previous mode selection algorithm.
Call extract_fixed_bit_field_1 to do the real work.
(extract_fixed_bit_field_1): New function.
2013-12-11 Sandra Loosemore <sandra@codesourcery.com>
PR middle-end/23623

57
gcc/expmed.c
View File

@ -56,6 +56,9 @@ static void store_split_bit_field (rtx, unsigned HOST_WIDE_INT,
static rtx extract_fixed_bit_field (enum machine_mode, rtx,
unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT, rtx, int);
static rtx extract_fixed_bit_field_1 (enum machine_mode, rtx,
unsigned HOST_WIDE_INT,
unsigned HOST_WIDE_INT, rtx, int);
static rtx mask_rtx (enum machine_mode, int, int, int);
static rtx lshift_value (enum machine_mode, unsigned HOST_WIDE_INT, int);
static rtx extract_split_bit_field (rtx, unsigned HOST_WIDE_INT,
@ -417,12 +420,17 @@ lowpart_bit_field_p (unsigned HOST_WIDE_INT bitnum,
}
/* Return true if -fstrict-volatile-bitfields applies an access of OP0
containing BITSIZE bits starting at BITNUM, with field mode FIELDMODE. */
containing BITSIZE bits starting at BITNUM, with field mode FIELDMODE.
Return false if the access would touch memory outside the range
BITREGION_START to BITREGION_END for conformance to the C++ memory
model. */
static bool
strict_volatile_bitfield_p (rtx op0, unsigned HOST_WIDE_INT bitsize,
unsigned HOST_WIDE_INT bitnum,
enum machine_mode fieldmode)
enum machine_mode fieldmode,
unsigned HOST_WIDE_INT bitregion_start,
unsigned HOST_WIDE_INT bitregion_end)
{
unsigned HOST_WIDE_INT modesize = GET_MODE_BITSIZE (fieldmode);
@ -449,6 +457,12 @@ strict_volatile_bitfield_p (rtx op0, unsigned HOST_WIDE_INT bitsize,
&& bitnum % GET_MODE_ALIGNMENT (fieldmode) + bitsize > modesize))
return false;
/* Check for cases where the C++ memory model applies. */
if (bitregion_end != 0
&& (bitnum - bitnum % modesize < bitregion_start
|| bitnum - bitnum % modesize + modesize > bitregion_end))
return false;
return true;
}
@ -920,7 +934,8 @@ store_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
rtx value)
{
/* Handle -fstrict-volatile-bitfields in the cases where it applies. */
if (strict_volatile_bitfield_p (str_rtx, bitsize, bitnum, fieldmode))
if (strict_volatile_bitfield_p (str_rtx, bitsize, bitnum, fieldmode,
bitregion_start, bitregion_end))
{
/* Storing any naturally aligned field can be done with a simple
@ -1711,7 +1726,7 @@ extract_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
else
mode1 = tmode;
if (strict_volatile_bitfield_p (str_rtx, bitsize, bitnum, mode1))
if (strict_volatile_bitfield_p (str_rtx, bitsize, bitnum, mode1, 0, 0))
{
rtx result;
@ -1721,8 +1736,13 @@ extract_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
result = adjust_bitfield_address (str_rtx, mode1,
bitnum / BITS_PER_UNIT);
else
result = extract_fixed_bit_field (mode, str_rtx, bitsize, bitnum,
target, unsignedp);
{
str_rtx = narrow_bit_field_mem (str_rtx, mode1, bitsize, bitnum,
&bitnum);
result = extract_fixed_bit_field_1 (mode, str_rtx, bitsize, bitnum,
target, unsignedp);
}
return convert_extracted_bit_field (result, mode, tmode, unsignedp);
}
@ -1748,16 +1768,8 @@ extract_fixed_bit_field (enum machine_mode tmode, rtx op0,
if (MEM_P (op0))
{
/* 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. */
mode = GET_MODE (op0);
if (GET_MODE_BITSIZE (mode) == 0
|| GET_MODE_BITSIZE (mode) > GET_MODE_BITSIZE (word_mode))
mode = word_mode;
mode = get_best_mode (bitsize, bitnum, 0, 0,
MEM_ALIGN (op0), mode, MEM_VOLATILE_P (op0));
MEM_ALIGN (op0), word_mode, MEM_VOLATILE_P (op0));
if (mode == VOIDmode)
/* The only way this should occur is if the field spans word
@ -1767,6 +1779,21 @@ extract_fixed_bit_field (enum machine_mode tmode, rtx op0,
op0 = narrow_bit_field_mem (op0, mode, bitsize, bitnum, &bitnum);
}
return extract_fixed_bit_field_1 (tmode, op0, bitsize, bitnum,
target, unsignedp);
}
/* Helper function for extract_fixed_bit_field, extracts
the bit field always using the MODE of OP0. */
static rtx
extract_fixed_bit_field_1 (enum machine_mode tmode, rtx op0,
unsigned HOST_WIDE_INT bitsize,
unsigned HOST_WIDE_INT bitnum, rtx target,
int unsignedp)
{
enum machine_mode mode;
mode = GET_MODE (op0);
gcc_assert (SCALAR_INT_MODE_P (mode));

6
gcc/testsuite/ChangeLog
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@ -1,3 +1,9 @@
2013-12-11 Bernd Edlinger <bernd.edlinger@hotmail.de>
Sandra Loosemore <sandra@codesourcery.com>
* gcc.dg/pr23623.c: Update to test interaction with C++
memory model.
2013-12-11 Sandra Loosemore <sandra@codesourcery.com>
PR middle-end/23623

3
gcc/testsuite/gcc.dg/pr23623.c
View File

@ -8,16 +8,19 @@
extern struct
{
unsigned int b : 1;
unsigned int : 31;
} bf1;
extern volatile struct
{
unsigned int b : 1;
unsigned int : 31;
} bf2;
extern struct
{
volatile unsigned int b : 1;
volatile unsigned int : 31;
} bf3;
void writeb(void)