ext: Update softfloat to 3d full version

* Add all softfloat source files without any change.
* Remove useless file softfloat.mk.in, since gem5 use Scons.
* Add `use_fast_int64` in SConscript to distinguish src of two strategies for data
  larger than 64 bits.
  * The SoftFloat library uses two strategies to handle data larger than 64bit. One is
    spliting data into `fast_int64`, and the other is using pointer. Two strategies
    are distinguished by macro `SOFTFLOAT_FAST_INT64`. But not all "*.c" files are
    guarded by this macro, which leads to including useless files in compiling progress
    and compiling error. `use_fast_int64` used in SConscript can exclude unnecessary
    files.

Change-Id: I7cec10412c00a35c247299cd92d83cdee9066410
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/66552
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Hoa Nguyen <hoanguyen@ucdavis.edu>

ext/softfloat/f128M_lt.c

@@ -0,0 +1,93 @@
+
+/*============================================================================
+
+This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
+Package, Release 3d, by John R. Hauser.
+
+Copyright 2011, 2012, 2013, 2014 The Regents of the University of California.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice,
+    this list of conditions, and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions, and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+ 3. Neither the name of the University nor the names of its contributors may
+    be used to endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
+DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+=============================================================================*/
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "platform.h"
+#include "internals.h"
+#include "softfloat.h"
+
+#ifdef SOFTFLOAT_FAST_INT64
+
+bool f128M_lt( const float128_t *aPtr, const float128_t *bPtr )
+{
+
+    return f128_lt( *aPtr, *bPtr );
+
+}
+
+#else
+
+bool f128M_lt( const float128_t *aPtr, const float128_t *bPtr )
+{
+    const uint32_t *aWPtr, *bWPtr;
+    uint32_t uiA96, uiB96;
+    bool signA, signB;
+    uint32_t wordA, wordB;
+
+    aWPtr = (const uint32_t *) aPtr;
+    bWPtr = (const uint32_t *) bPtr;
+    if ( softfloat_isNaNF128M( aWPtr ) || softfloat_isNaNF128M( bWPtr ) ) {
+        softfloat_raiseFlags( softfloat_flag_invalid );
+        return false;
+    }
+    uiA96 = aWPtr[indexWordHi( 4 )];
+    uiB96 = bWPtr[indexWordHi( 4 )];
+    signA = signF128UI96( uiA96 );
+    signB = signF128UI96( uiB96 );
+    if ( signA != signB ) {
+        if ( signB ) return false;
+        if ( (uiA96 | uiB96) & 0x7FFFFFFF ) return true;
+        wordA = aWPtr[indexWord( 4, 2 )];
+        wordB = bWPtr[indexWord( 4, 2 )];
+        if ( wordA | wordB ) return true;
+        wordA = aWPtr[indexWord( 4, 1 )];
+        wordB = bWPtr[indexWord( 4, 1 )];
+        if ( wordA | wordB ) return true;
+        wordA = aWPtr[indexWord( 4, 0 )];
+        wordB = bWPtr[indexWord( 4, 0 )];
+        return ((wordA | wordB) != 0);
+    }
+    if ( signA ) {
+        aWPtr = (const uint32_t *) bPtr;
+        bWPtr = (const uint32_t *) aPtr;
+    }
+    return (softfloat_compare128M( aWPtr, bWPtr ) < 0);
+
+}
+
+#endif
+