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2010-10-26 Jie Zhang <jie@codesourcery.com>
Issue #1259
Backport from mainline:
gcc/
2010-10-26 Jie Zhang <jie@codesourcery.com>
* stor-layout.c (layout_decl): Use the field's type to
determine the mode and keep DECL_BIT_FIELD for a volatile
bit-field.
* config/arm/arm.c (arm_override_options): Default to
-fstrict-volatile-bitfields.
gcc/testsuite/
2010-10-26 Jie Zhang <jie@codesourcery.com>
* gcc.target/arm/volatile-bitfields-1.c: New test.
* gcc.target/arm/volatile-bitfields-2.c: New test.
* gcc.target/arm/volatile-bitfields-3.c: New test.
=== modified file 'gcc/config/arm/arm.c'
--- old/gcc/config/arm/arm.c 2010-11-04 10:45:05 +0000
+++ new/gcc/config/arm/arm.c 2010-11-04 12:49:37 +0000
@@ -1933,6 +1933,10 @@
calculation, which is 2 instructions. */
set_param_value ("gcse-unrestricted-cost", 2);
+ /* ARM EABI defaults to strict volatile bitfields. */
+ if (TARGET_AAPCS_BASED && flag_strict_volatile_bitfields < 0)
+ flag_strict_volatile_bitfields = 1;
+
/* Register global variables with the garbage collector. */
arm_add_gc_roots ();
=== modified file 'gcc/stor-layout.c'
--- old/gcc/stor-layout.c 2010-04-02 18:54:46 +0000
+++ new/gcc/stor-layout.c 2010-11-04 12:49:37 +0000
@@ -593,11 +593,14 @@
}
/* See if we can use an ordinary integer mode for a bit-field.
- Conditions are: a fixed size that is correct for another mode
- and occupying a complete byte or bytes on proper boundary. */
+ 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. */
if (TYPE_SIZE (type) != 0
&& TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
- && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT)
+ && GET_MODE_CLASS (TYPE_MODE (type)) == MODE_INT
+ && !(TREE_THIS_VOLATILE (decl)
+ && flag_strict_volatile_bitfields > 0))
{
enum machine_mode xmode
= mode_for_size_tree (DECL_SIZE (decl), MODE_INT, 1);
=== added file 'gcc/testsuite/gcc.target/arm/volatile-bitfields-1.c'
--- old/gcc/testsuite/gcc.target/arm/volatile-bitfields-1.c 1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/volatile-bitfields-1.c 2010-11-04 12:49:37 +0000
@@ -0,0 +1,18 @@
+/* { dg-require-effective-target arm_eabi } */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef struct {
+ char a:1;
+ char b:7;
+ int c;
+} BitStruct;
+
+volatile BitStruct bits;
+
+int foo ()
+{
+ return bits.b;
+}
+
+/* { dg-final { scan-assembler "ldrb\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" } } */
=== added file 'gcc/testsuite/gcc.target/arm/volatile-bitfields-2.c'
--- old/gcc/testsuite/gcc.target/arm/volatile-bitfields-2.c 1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/volatile-bitfields-2.c 2010-11-04 12:49:37 +0000
@@ -0,0 +1,18 @@
+/* { dg-require-effective-target arm_eabi } */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef struct {
+ volatile unsigned long a:8;
+ volatile unsigned long b:8;
+ volatile unsigned long c:16;
+} BitStruct;
+
+BitStruct bits;
+
+unsigned long foo ()
+{
+ return bits.b;
+}
+
+/* { dg-final { scan-assembler "ldr\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" } } */
=== added file 'gcc/testsuite/gcc.target/arm/volatile-bitfields-3.c'
--- old/gcc/testsuite/gcc.target/arm/volatile-bitfields-3.c 1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/volatile-bitfields-3.c 2010-11-04 12:49:37 +0000
@@ -0,0 +1,18 @@
+/* { dg-require-effective-target arm_eabi } */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+typedef struct {
+ volatile unsigned long a:8;
+ volatile unsigned long b:8;
+ volatile unsigned long c:16;
+} BitStruct;
+
+BitStruct bits;
+
+unsigned long foo ()
+{
+ return bits.c;
+}
+
+/* { dg-final { scan-assembler "ldr\[\\t \]+\[^\n\]*,\[\\t \]*\\\[\[^\n\]*\\\]" } } */
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