Patchwork [v2] ARM: Use different linker path for hardfloat ABI

login
register
mail settings
Submitter Michael Hope
Date April 26, 2012, 11:27 p.m.
Message ID <CANLjY-m8udADuOo1gMfR9NWa-iw_JHbtnsoRAF1of1cvzdxSTg@mail.gmail.com>
Download mbox | patch
Permalink /patch/155342/
State New
Headers show

Comments

Michael Hope - April 26, 2012, 11:27 p.m.
On 27 April 2012 08:20, Carlos O'Donell <carlos@systemhalted.org> wrote:
> On Mon, Apr 23, 2012 at 5:36 PM, Michael Hope <michael.hope@linaro.org> wrote:
>> 2012-04-24  Michael Hope  <michael.hope@linaro.org>
>>            Richard Earnshaw  <rearnsha@arm.com>
>>
>>        * config/arm/linux-eabi.h (GLIBC_DYNAMIC_LINKER_SOFT_FLOAT): Define.
>>        (GLIBC_DYNAMIC_LINKER_HARD_FLOAT): Define.
>>        (GLIBC_DYNAMIC_LINKER_DEFAULT): Define.
>>        (GLIBC_DYNAMIC_LINKER): Redefine to use the hard float path.
>>
>> diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
>> index 80bd825..2ace6f0 100644
>> --- a/gcc/config/arm/linux-eabi.h
>> +++ b/gcc/config/arm/linux-eabi.h
>> @@ -62,7 +62,17 @@
>>  /* Use ld-linux.so.3 so that it will be possible to run "classic"
>>    GNU/Linux binaries on an EABI system.  */
>>  #undef  GLIBC_DYNAMIC_LINKER
>> -#define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.3"
>> +#define GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "/lib/ld-linux.so.3"
>> +#define GLIBC_DYNAMIC_LINKER_HARD_FLOAT "/lib/ld-linux-armhf.so.3"
>> +#if TARGET_DEFAULT_FLOAT_ABI == ARM_FLOAT_ABI_HARD
>> +#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_HARD_FLOAT
>> +#else
>> +#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_SOFT_FLOAT
>> +#endif
>> +#define GLIBC_DYNAMIC_LINKER \
>> +   "%{mfloat-abi=hard:" GLIBC_DYNAMIC_LINKER_HARD_FLOAT "} \
>> +    %{mfloat-abi=soft*:" GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "} \
>> +    %{!mfloat-abi=*:" GLIBC_DYNAMIC_LINKER_DEFAULT "}"
>>
>>  /* At this point, bpabi.h will have clobbered LINK_SPEC.  We want to
>>    use the GNU/Linux version, not the generic BPABI version.  */
>
> This patch is broken. Please fix this.
>
> You can't use a named enumeration in cpp equality.
>
> The type ARM_FLOAT_ABI_HARD is a named enumeration and evaluates to 0
> as an unknown identifier.
>
> Therefore "#if TARGET_DEFAULT_FLOAT_ABI == ARM_FLOAT_ABI_HARD"
> evaluates to "#if 0 == 0" and is always true.
>
> Watch out that "#define ARM_FLOAT_ABI_HARD ARM_FLOAT_ABI_HARD" for
> such enums is not conforming C99/C11.
>
> I suggest you define the types as macros and then set the named enum
> to those values, then use the macros in the header equality checks.
>
> e.g.
> #define VAL1 0 then enum FOO { RVAL1 = VAL1, ... }
>
> Look at arm.h for the enum definition.

I've looked further into this and I think the original pre-#if version
is correct.

The float ABI comes from these places:
 * The -mfloat-abi= command line argument, else
 * The --with-float= configure time argument, else
 * TARGET_DEFAULT_FLOAT_ABI from linux-eabi.h

In the first case the ABI is explicit.  In the second
OPTION_DEFAULT_SPECS turns the configure time argument into an explict
-mfloat-abi=.

The patch below covers all cases, keeps the logic in the spec file,
and adds a comment linking the two #defines.

Tested by building with no configure flags, --wtih-float=softfp,
--with-float=hard, and then running with all combinations of
{,-mfloat-abi=softfp,-mfloat-abi=hard} {,-mglibc,-muclibc,-mbionic}.

OK?

-- Michael

2012-04-27  Michael Hope  <michael.hope@linaro.org>

	* config/arm/linux-eabi.h (GLIBC_DYNAMIC_LINKER): Pick the loader
	using a spec rule.

Patch

diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
index 2ace6f0..e3cba57 100644
--- a/gcc/config/arm/linux-eabi.h
+++ b/gcc/config/arm/linux-eabi.h
@@ -60,19 +60,17 @@ 
 #define SUBTARGET_EXTRA_LINK_SPEC " -m " TARGET_LINKER_EMULATION

 /* Use ld-linux.so.3 so that it will be possible to run "classic"
-   GNU/Linux binaries on an EABI system.  */
+   GNU/Linux binaries on an EABI system.
+   Use ld-linux-armhf.so.3 so that it will be possible to install both
+   hard and soft float binaries on a system.  */
 #undef  GLIBC_DYNAMIC_LINKER
 #define GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "/lib/ld-linux.so.3"
 #define GLIBC_DYNAMIC_LINKER_HARD_FLOAT "/lib/ld-linux-armhf.so.3"
-#if TARGET_DEFAULT_FLOAT_ABI == ARM_FLOAT_ABI_HARD
-#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_HARD_FLOAT
-#else
-#define GLIBC_DYNAMIC_LINKER_DEFAULT GLIBC_DYNAMIC_LINKER_SOFT_FLOAT
-#endif
+/* Update this rule if TARGET_DEFAULT_FLOAT_ABI changes from
+   ARM_FLOAT_ABI_SOFT.  */
 #define GLIBC_DYNAMIC_LINKER \
-   "%{mfloat-abi=hard:" GLIBC_DYNAMIC_LINKER_HARD_FLOAT "} \
-    %{mfloat-abi=soft*:" GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "} \
-    %{!mfloat-abi=*:" GLIBC_DYNAMIC_LINKER_DEFAULT "}"
+  "%{mfloat-abi=hard:" GLIBC_DYNAMIC_LINKER_HARD_FLOAT \
+  "; :" GLIBC_DYNAMIC_LINKER_SOFT_FLOAT "}"

 /* At this point, bpabi.h will have clobbered LINK_SPEC.  We want to
    use the GNU/Linux version, not the generic BPABI version.  */