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

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

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3234542f92930aa0695b5db600246af839ac3db8..b75f6a59214520fca7e77525a8a06c63cf258006 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -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

diff --git a/gcc/expmed.c b/gcc/expmed.c
index 185e66b6b822468ebd68e9f53c3f87b44e05be88..08ad9e0c10dac023b9fa58ae077adaa123508a60 100644 (file)
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -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));
 

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index ac0b5fb1add1ff4ebf3b7d47911641f49ce3e25a..47ac2c3b44a44b30ce7f9f2c7579fcdbc1b8d2de 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -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

diff --git a/gcc/testsuite/gcc.dg/pr23623.c b/gcc/testsuite/gcc.dg/pr23623.c
index 22da21d489b1b8cc0dcee712dc3028400f3b57a1..c844f945e1a1e5e954d5015ba0622e892434105c 100644 (file)
--- a/gcc/testsuite/gcc.dg/pr23623.c
+++ b/gcc/testsuite/gcc.dg/pr23623.c
@@ -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)