Patchwork Continue strict-volatile-bitfields fixes

login
register
mail settings
Submitter Ye Joey
Date Dec. 15, 2011, 8:02 a.m.
Message ID <CAL0py24TZByxOYCZwgS20hWYQjjjOyDQrC27pTS0m-db1ZyPCg@mail.gmail.com>
Download mbox | patch
Permalink /patch/131531/
State New
Headers show

Comments

Ye Joey - Dec. 15, 2011, 8:02 a.m.
Ping, PR middle-end/51200

Tailored from Bernd's, and added target independent test case. Now it
is a pure middle-end fix.

OK for trunk and 4.6?

        Bernd Schmidt  <bernds_cb1@t-online.de>
	gcc/
	* expr.c (store_field): Avoid a direct store if the mode is larger
	than the size of the bit field.
	* stor-layout.c (layout_decl): If flag_strict_volatile_bitfields,
	treat non-volatile bit fields like volatile ones.
	* toplev.c (process_options): Disallow combination of
	-fstrict-volatile-bitfields and ABI versions less than 2.

	gcc/testsuite/
	* gcc.target/arm/volatile-bitfields-4.c: New test.
	* c-c++-common/abi-bf.c: New test.

         Joey Ye  <joey.ye@arm.com>
        * gcc.dg/volatile-bitfields-2.c: New test.
        * g++.dg/abi/bitfield12.C: no-strict-volatile-bitfields.

Patch

Index: gcc/toplev.c
===================================================================
--- gcc/toplev.c	(revision 182353)
+++ gcc/toplev.c	(working copy)
@@ -1330,6 +1330,13 @@ 
     flag_ira_region
       = optimize_size || !optimize ? IRA_REGION_ONE : IRA_REGION_MIXED;
 
+  if (flag_strict_volatile_bitfields > 0 && !abi_version_at_least (2))
+    {
+      warning (0, "-fstrict-volatile-bitfields disabled; "
+	       "it is incompatible with ABI versions < 2");
+      flag_strict_volatile_bitfields = 0;
+    }
+
   /* Unrolling all loops implies that standard loop unrolling must also
      be done.  */
   if (flag_unroll_all_loops)
Index: gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c
===================================================================
--- gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c	(revision 0)
+++ gcc/testsuite/gcc.target/arm/volatile-bitfields-4.c	(revision 0)
@@ -0,0 +1,30 @@ 
+/* { dg-require-effective-target arm_eabi } */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "ldr\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" 2 } } */
+/* { dg-final { scan-assembler-times "str\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" 2 } } */
+/* { dg-final { scan-assembler-not "strb" } } */
+
+struct thing {
+  unsigned a: 8;
+  unsigned b: 8;
+  unsigned c: 8;
+  unsigned d: 8;
+};
+
+struct thing2 {
+  volatile unsigned a: 8;
+  volatile unsigned b: 8;
+  volatile unsigned c: 8;
+  volatile unsigned d: 8;
+};
+
+void test1(volatile struct thing *t)
+{
+  t->a = 5;
+}
+
+void test2(struct thing2 *t)
+{
+  t->a = 5;
+}
Index: gcc/testsuite/gcc.dg/volatile-bitfields-2.c
===================================================================
--- gcc/testsuite/gcc.dg/volatile-bitfields-2.c	(revision 0)
+++ gcc/testsuite/gcc.dg/volatile-bitfields-2.c	(revision 0)
@@ -0,0 +1,15 @@ 
+/* { dg-do run } */
+/* { dg-options "-fstrict-volatile-bitfields" } */
+
+extern void abort(void);
+struct thing {
+  volatile unsigned short a: 8;
+  volatile unsigned short b: 8;
+} t = {1,2};
+
+int main()
+{
+  t.a = 3;
+  if (t.a !=3 || t.b !=2) abort();
+  return 0;
+}
Index: gcc/testsuite/g++.dg/abi/bitfield12.C
===================================================================
--- gcc/testsuite/g++.dg/abi/bitfield12.C	(revision 182353)
+++ gcc/testsuite/g++.dg/abi/bitfield12.C	(working copy)
@@ -1,4 +1,4 @@ 
-// { dg-options "-Wabi -fabi-version=1" }
+// { dg-options "-Wabi -fabi-version=1 -fno-strict-volatile-bitfields" }
 
 struct S { // { dg-warning "ABI" }
   char c : 1024; // { dg-warning "width" }
Index: gcc/testsuite/c-c++-common/abi-bf.c
===================================================================
--- gcc/testsuite/c-c++-common/abi-bf.c	(revision 0)
+++ gcc/testsuite/c-c++-common/abi-bf.c	(revision 0)
@@ -0,0 +1,3 @@ 
+/* { dg-warning "incompatible" } */
+/* { dg-do compile } */
+/* { dg-options "-fstrict-volatile-bitfields -fabi-version=1" } */
Index: gcc/expr.c
===================================================================
--- gcc/expr.c	(revision 182353)
+++ gcc/expr.c	(working copy)
@@ -6327,6 +6327,8 @@ 
 		|| bitpos % GET_MODE_ALIGNMENT (mode))
 	       && SLOW_UNALIGNED_ACCESS (mode, MEM_ALIGN (target)))
 	      || (bitpos % BITS_PER_UNIT != 0)))
+      || (bitsize >= 0 && mode != BLKmode
+	  && GET_MODE_BITSIZE (mode) > bitsize)
       /* If the RHS and field are a constant size and the size of the
 	 RHS isn't the same size as the bitfield, we must use bitfield
 	 operations.  */
Index: gcc/stor-layout.c
===================================================================
--- gcc/stor-layout.c	(revision 182353)
+++ gcc/stor-layout.c	(working copy)
@@ -622,12 +622,13 @@ 
 	  /* See if we can use an ordinary integer mode for a bit-field.
 	     Conditions are: a fixed size that is correct for another mode,
 	     occupying a complete byte or bytes on proper boundary,
-	     and not volatile or not -fstrict-volatile-bitfields.  */
+	     and not -fstrict-volatile-bitfields.  If the latter is set,
+	     we unfortunately can't check TREE_THIS_VOLATILE, as a cast
+	     may make a volatile object later.  */
 	  if (TYPE_SIZE (type) != 0
 	      && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
 	      && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT
-	      && !(TREE_THIS_VOLATILE (decl)
-		   && flag_strict_volatile_bitfields > 0))
+	      && flag_strict_volatile_bitfields <= 0)
 	    {
 	      enum machine_mode xmode
 		= mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);