jdk9-arm3264 libjvm.so link error with arm-sflt

[Bob Vandette]

> On Nov 6, 2016, at 1:07 PM, Simon Nash <simon at cjnash.com> wrote:
> 
> Bob Vandette wrote:
>> In the soft-float binaries we’ve distributed in the past, we linked our binary against an external library.
>> In order to achieve Java level floating point accuracy (and pass the TCK), you’ll need to do the same.
>> Here’s the library that we used:
>> http://www.jhauser.us/arithmetic/SoftFloat.html
>> We modify this library to map their fadd,dadd,fsub,dsub functions to __aeabi_xxxx_glibc function names.
>> You should be able to temporarily work around your link problems by removing the _glibc from the references
>> in the hotspot and jdk sources.  There are only a few files that are impacted.
>> The problem stems from the fact that the normal glibc functions prefer speed over accuracy.  The accuracy difference is extremely minimal but we fail the TCK for a few tests causing us to use this extra library.
>> Hope this help,
>> Bob.
> Thanks very much!  I thought about removing the _glibc suffix but the signatures
> are different.  For example, __aeabi_fadd_glibc takes two floats and returns double
> but __aeabi_fadd takes two floats and returns float.
> 
> From a quick look at the Hauser library, there is a similar signature mismatch there
> as well, so I presume it would be necessary to write a small wrapper function to
> convert both float32 arguments to float64 and then call the f64_add function in the
> library.  If I have misunderstood this, please correct my assumption.

Here’s the wrapper code we used with softfloat-2b.  Notice that we build two different libraries.
The JDK functions override the normal entry point but the hotspot version uses a unique name.
This was done to allow the normal float/double operations done by the VM to use the faster
inlined glibc functions but the functions called during bytecode processing use the accurate 
ones.

/* GLIBC Equivalent Soft-Float Implementations */
#ifndef JDK_BUILD
double __aeabi_dadd_glibc( double a, double b )
#else
double __aeabi_dadd( double a, double b )
#endif
{
    flag aSign, bSign;
    float64 f64a, f64b;

    f64a.d = a;
    f64b.d = b;

    aSign = extractFloat64Sign( f64a );
    bSign = extractFloat64Sign( f64b );


    if ( aSign == bSign ) {
        return addFloat64Sigs( f64a, f64b, aSign ).d;
    }
    else {
        return subFloat64Sigs( f64a, f64b, aSign ).d;
    }

}

#ifndef JDK_BUILD
double __aeabi_dsub_glibc( double a, double b )
#else
double __aeabi_dsub( double a, double b )
#endif
{
    flag aSign, bSign;
    float64 f64a, f64b;

    f64a.d = a;
    f64b.d = b;

    aSign = extractFloat64Sign( f64a );
    bSign = extractFloat64Sign( f64b );
    if ( aSign == bSign ) {
        return subFloat64Sigs( f64a, f64b, aSign ).d;
    }
    else {
        return addFloat64Sigs( f64a, f64b, aSign ).d;
    }

}

#ifndef JDK_BUILD
float __aeabi_fadd_glibc( float a, float b ) 
#else
float __aeabi_fadd( float a, float b )
#endif
{
    ufloat32 f32a, f32b, f32result;
    

    f32a.f = a;
    f32b.f = b;

    f32result.i32 = float32_add(f32a.i32, f32b.i32);
    return (f32result.f);
}

#ifndef JDK_BUILD
float __aeabi_fsub_glibc( float a, float b )
#else
float __aeabi_fsub( float a, float b )
#endif
{
    ufloat32 f32a, f32b, f32result;

    f32a.f = a;
    f32b.f = b;

    f32result.i32 = float32_sub(f32a.i32, f32b.i32);
    return (f32result.f);
}

Bob.
> 
> Best regards,
> Simon
> 
>>> On Nov 6, 2016, at 11:06 AM, Simon Nash <simon at cjnash.com> wrote:
>>> 
>>> I am trying to build the current jdk9-arm3264 source for arm-sflt and I am
>>> getting some link errors from libjvm.so as follows:
>>> 
>>> /sd1/jdk9-arm3264/build/softfp/hotspot/variant-server/libjvm/objs/c1_LIRGenerator_arm.o: In function `GrowableArray<Instruction*>::at_put_grow(int, Instruction* const&, Instruction* const&)':
>>> /sd1/jdk9-arm3264/hotspot/src/share/vm/utilities/growableArray.hpp:291: undefined reference to `__aeabi_fadd_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/share/vm/utilities/growableArray.hpp:291: undefined reference to `__aeabi_dadd_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/share/vm/utilities/growableArray.hpp:291: undefined reference to `__aeabi_fsub_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/share/vm/utilities/growableArray.hpp:291: undefined reference to `__aeabi_dsub_glibc'
>>> /sd1/jdk9-arm3264/build/softfp/hotspot/variant-server/libjvm/objs/c1_Runtime1_arm.o: In function `Runtime1::pd_name_for_address(unsigned char*)':
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/c1_Runtime1_arm.cpp:1220: undefined reference to `__aeabi_fadd_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/c1_Runtime1_arm.cpp:1220: undefined reference to `__aeabi_fsub_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/c1_Runtime1_arm.cpp:1220: undefined reference to `__aeabi_dadd_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/c1_Runtime1_arm.cpp:1220: undefined reference to `__aeabi_dsub_glibc'
>>> /sd1/jdk9-arm3264/build/softfp/hotspot/variant-server/libjvm/objs/templateTable_arm.o: In function `TemplateTable::fop2(TemplateTable::Operation)':
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/templateTable_arm.cpp:1718: undefined reference to `__aeabi_fadd_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/templateTable_arm.cpp:1718: undefined reference to `__aeabi_fsub_glibc'
>>> /sd1/jdk9-arm3264/build/softfp/hotspot/variant-server/libjvm/objs/templateTable_arm.o: In function `TemplateTable::dop2(TemplateTable::Operation)':
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/templateTable_arm.cpp:1761: undefined reference to `__aeabi_dadd_glibc'
>>> /sd1/jdk9-arm3264/hotspot/src/cpu/arm/vm/templateTable_arm.cpp:1761: undefined reference to `__aeabi_dsub_glibc'
>>> collect2: error: ld returned 1 exit status
>>> 
>>> I am using a soft-float Linaro cross-compiler to do the build.  Here is my configure command:
>>> 
>>> bash ./configure --with-jdk-variant=normal --with-jvm-variants=server --with-abi-profile=arm-sflt --with-conf-name=softfp \
>>> --with-debug-level=release --disable-warnings-as-errors --with-extra-cflags=-D__SOFTFP__ --openjdk-target=arm-linux-gnueabi \
>>> --with-tools-dir=/sd1/linaro/gcc-linaro-arm-linux-gnueabi-2012.04-20120426_linux/bin \
>>> --with-sys-root=/sd1/linaro/gcc-linaro-arm-linux-gnueabi-2012.04-20120426_linux/arm-linux-gnueabi/libc \
>>> --with-cups=/sd1/armel/cups --with-freetype=/sd1/armel/freetype2 --with-alsa=/sd1/armel/alsa \
>>> --x-includes=/sd1/armel/X11/include --x-libraries=/sd1/armel/X11/lib \
>>> --disable-freetype-bundling --disable-hotspot-gtest --with-boot-jdk=/sd1/java/jdk1.8.0_25 \
>>> CC=arm-linux-gnueabi-gcc CXX=arm-linux-gnueabi-g++ CPP=arm-linux-gnueabi-cpp CXXCPP=arm-linux-gnueabi-cpp \
>>> LIBS="-Wl,-rpath-link /sd1/armel/freetype2/lib -Wl,-rpath-link /sd1/armel/X11/lib"
>>> 
>>> Where are the missing functions such as __aeabi_fadd_glibc defined?  I have found
>>> __aeabi_fadd but I have not been able to find __aeabi_fadd_glibc.
>>> 
>>> Simon
>