re PR rtl-optimization/65067 (regression on accessing volatile bit field)

gcc:
2015-03-05  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        PR rtl-optimization/65067
        * expmed.c (store_bit_field, extract_bit_field): Reworked the
        strict volatile bitfield handling.

testsuite:
2015-03-05  Bernd Edlinger  <bernd.edlinger@hotmail.de>

        * gcc.target/arm/pr65067.c: New test.

From-SVN: r221222

4 files changed, 49 insertions, 17 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f780919..3ec2d1c 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2015-03-05  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	PR rtl-optimization/65067
+	* expmed.c (store_bit_field, extract_bit_field): Reworked the
+	strict volatile bitfield handling.
+
 2015-03-05  Martin Liska  <mliska@suse.cz>
 
 	PR ipa/65318
diff --git a/gcc/expmed.c b/gcc/expmed.c
index 18e62a0..0034203 100644
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -976,7 +976,7 @@ store_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
       /* Storing any naturally aligned field can be done with a simple
 	 store.  For targets that support fast unaligned memory, any
 	 naturally sized, unit aligned field can be done directly.  */
-      if (simple_mem_bitfield_p (str_rtx, bitsize, bitnum, fieldmode))
+      if (bitsize == GET_MODE_BITSIZE (fieldmode))
 	{
 	  str_rtx = adjust_bitfield_address (str_rtx, fieldmode,
 					     bitnum / BITS_PER_UNIT);
@@ -984,12 +984,16 @@ store_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
 	}
       else
 	{
+	  rtx temp;
+
 	  str_rtx = narrow_bit_field_mem (str_rtx, fieldmode, bitsize, bitnum,
 					  &bitnum);
-	  /* Explicitly override the C/C++ memory model; ignore the
-	     bit range so that we can do the access in the mode mandated
-	     by -fstrict-volatile-bitfields instead.  */
-	  store_fixed_bit_field_1 (str_rtx, bitsize, bitnum, value);
+	  temp = copy_to_reg (str_rtx);
+	  if (!store_bit_field_1 (temp, bitsize, bitnum, 0, 0,
+				  fieldmode, value, true))
+	    gcc_unreachable ();
+
+	  emit_move_insn (str_rtx, temp);
 	}
 
       return;
@@ -1786,24 +1790,20 @@ extract_bit_field (rtx str_rtx, unsigned HOST_WIDE_INT bitsize,
 
   if (strict_volatile_bitfield_p (str_rtx, bitsize, bitnum, mode1, 0, 0))
     {
-      rtx result;
-
       /* Extraction of a full MODE1 value can be done with a load as long as
 	 the field is on a byte boundary and is sufficiently aligned.  */
-      if (simple_mem_bitfield_p (str_rtx, bitsize, bitnum, mode1))
-	result = adjust_bitfield_address (str_rtx, mode1,
-					  bitnum / BITS_PER_UNIT);
-      else
+      if (bitsize == GET_MODE_BITSIZE(mode1))
 	{
-	  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);
+	  rtx result = adjust_bitfield_address (str_rtx, mode1,
+						bitnum / BITS_PER_UNIT);
+	  return convert_extracted_bit_field (result, mode, tmode, unsignedp);
 	}
 
-      return convert_extracted_bit_field (result, mode, tmode, unsignedp);
+      str_rtx = narrow_bit_field_mem (str_rtx, mode1, bitsize, bitnum,
+				      &bitnum);
+      str_rtx = copy_to_reg (str_rtx);
     }
-  
+
   return extract_bit_field_1 (str_rtx, bitsize, bitnum, unsignedp,
 			      target, mode, tmode, true);
 }
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 09d42b3..321db12 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2015-03-05  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	* gcc.target/arm/pr65067.c: New test.
+
 2015-03-05  Martin Liska  <mliska@suse.cz>
 
 	PR ipa/65318
diff --git a/gcc/testsuite/gcc.target/arm/pr65067.c b/gcc/testsuite/gcc.target/arm/pr65067.c
new file mode 100644
index 0000000..9ddd7bb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pr65067.c
@@ -0,0 +1,22 @@
+/* { dg-do compile } */
+/* { dg-options "-mthumb -mcpu=cortex-m3 -O2" } */
+
+struct tmp {
+ unsigned int dummy;
+ union {
+  struct {
+   unsigned int xyz : 1;
+   unsigned int mode: 3;
+   unsigned int res : 28;
+  } bf;
+  unsigned int wordval;
+ } reg;
+};
+
+void set_mode(int mode)
+{
+ volatile struct tmp *t = (struct tmp *) 0x1000;
+ t->reg.bf.mode = mode;
+}
+
+/* { dg-final { scan-assembler "bfi" } } */