Hi Richard, Hi Paul, Hi Ramana,
I am planning to check in the patch below to add comments to the
.eabi_attribute directives emitted by the ARM GCC backend. So for
example a simple hello world source file might compile to something
like this:
.cpu arm7tdmi
.fpu softvfp
.eabi_attribute 20, 1 @ Tag_ABI_FP_denormal
.eabi_attribute 21, 1 @ Tag_ABI_FP_exceptions
.eabi_attribute 23, 3 @ Tag_ABI_FP_number_model
Apart from making the assembler output easier to understand, the patch
also makes use of the enumerated tag values in the elf/arm.h header
file, thus making sure that the compiler stays in sync with the
header.
I stuck with using numerical values in the actual .eabi_attribute
directive as versions of GAS prior to 2.20 require this.
Any comments or objections to this patch ? If not, I will apply it
next week.
Cheers
Nick
gcc/ChangeLog
2011-09-27 Nick Clifton <ni...@redhat.com>
* config/arm/arm.c (EMIT_EABI_ATTRIBUTE): New macro.
(arm_file_start): Use it to generate .eabi_attribute assembler
pseudo-ops.
Index: gcc/config/arm/arm.c
===================================================================
--- gcc/config/arm/arm.c (revision 179269)
+++ gcc/config/arm/arm.c (working copy)
@@ -22220,6 +22220,24 @@
asm_fprintf (stream, "%U%s", name);
}
+/* Get the definitions of the ARM EABI Attribute tag values. */
+#define BFD_ARCH_SIZE
+#include "elf/arm.h"
+
+/* This macro is used to emit an EABI tag and its associated value.
+ We emit the numerical value of the tag in case the assembler does not
+ support textual tags. (Eg gas prior to 2.20). We include the tag
+ name in a comment so that anyone reading the assembler output will
+ know which tag is being set. */
+#define EMIT_EABI_ATTRIBUTE(name,val) \
+ do \
+ { \
+ asm_fprintf (asm_out_file, "\t.eabi_attribute %d, %d\t%s " #name "\n", \
+ name, val, ASM_COMMENT_START); \
+ } \
+ while (0)
+
+
static void
arm_file_start (void)
{
@@ -22248,12 +22266,13 @@
else
{
fpu_name = arm_fpu_desc->name;
+
if (arm_fpu_desc->model == ARM_FP_MODEL_VFP)
{
if (TARGET_HARD_FLOAT)
- asm_fprintf (asm_out_file, "\t.eabi_attribute 27, 3\n");
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_HardFP_use, 3);
if (TARGET_HARD_FLOAT_ABI)
- asm_fprintf (asm_out_file, "\t.eabi_attribute 28, 1\n");
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_VFP_args, 1);
}
}
asm_fprintf (asm_out_file, "\t.fpu %s\n", fpu_name);
@@ -22262,31 +22281,25 @@
are used. However we don't have any easy way of figuring this out.
Conservatively record the setting that would have been used. */
- /* Tag_ABI_FP_rounding. */
if (flag_rounding_math)
- asm_fprintf (asm_out_file, "\t.eabi_attribute 19, 1\n");
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_FP_rounding, 1);
+
if (!flag_unsafe_math_optimizations)
{
- /* Tag_ABI_FP_denomal. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 20, 1\n");
- /* Tag_ABI_FP_exceptions. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 21, 1\n");
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_FP_denormal, 1);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_FP_exceptions, 1);
}
- /* Tag_ABI_FP_user_exceptions. */
+
if (flag_signaling_nans)
- asm_fprintf (asm_out_file, "\t.eabi_attribute 22, 1\n");
- /* Tag_ABI_FP_number_model. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 23, %d\n",
- flag_finite_math_only ? 1 : 3);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_FP_user_exceptions, 1);
- /* Tag_ABI_align8_needed. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 24, 1\n");
- /* Tag_ABI_align8_preserved. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 25, 1\n");
- /* Tag_ABI_enum_size. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 26, %d\n",
- flag_short_enums ? 1 : 2);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_FP_number_model,
+ flag_finite_math_only ? 1 : 3);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_align8_needed, 1);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_align8_preserved, 1);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_enum_size, flag_short_enums ? 1 : 2);
+
/* Tag_ABI_optimization_goals. */
if (optimize_size)
val = 4;
@@ -22296,21 +22309,18 @@
val = 1;
else
val = 6;
- asm_fprintf (asm_out_file, "\t.eabi_attribute 30, %d\n", val);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_optimization_goals, val);
- /* Tag_CPU_unaligned_access. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 34, %d\n",
- unaligned_access);
+ EMIT_EABI_ATTRIBUTE (Tag_CPU_unaligned_access, unaligned_access);
- /* Tag_ABI_FP_16bit_format. */
if (arm_fp16_format)
- asm_fprintf (asm_out_file, "\t.eabi_attribute 38, %d\n",
- (int)arm_fp16_format);
+ EMIT_EABI_ATTRIBUTE (Tag_ABI_FP_16bit_format, (int) arm_fp16_format);
if (arm_lang_output_object_attributes_hook)
arm_lang_output_object_attributes_hook();
}
- default_file_start();
+
+ default_file_start ();
}
static void
Index: gcc/config/arm/arm-c.c
===================================================================
--- gcc/config/arm/arm-c.c (revision 179247)
+++ gcc/config/arm/arm-c.c (working copy)
@@ -32,8 +32,9 @@
static void arm_output_c_attributes(void)
{
/* Tag_ABI_PCS_wchar_t. */
- asm_fprintf (asm_out_file, "\t.eabi_attribute 18, %d\n",
- (int)(TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT));
+ asm_fprintf (asm_out_file, "\t.eabi_attribute 18, %d\t%s
Tag_ABI_PCS_wchar_t\n",
+ (int)(TYPE_PRECISION (wchar_type_node) / BITS_PER_UNIT),
+ ASM_COMMENT_START);
}
