Stop powerpc copysignl raising "invalid" for sNaN argument (bug 20718).

The powerpc (hard-float) implementations of copysignl, both 32-bit and
64-bit, raise spurious "invalid" exceptions when the first argument is
a signaling NaN.  copysign functions should never raise exceptions
even for signaling NaNs.

The problem is the use of an fcmpu instruction to test the sign of the
high part of the long double argument.  This patch fixes the functions
to use fsel instead (as used for fabsl following my fixes for a
similar bug there), or to examine the integer representation for older
32-bit processors without fsel.

Tested for powerpc64 and powerpc32 (configurations with and without
fsel used).

	[BZ #20718]
	* sysdeps/powerpc/powerpc32/fpu/s_copysignl.S (__copysignl): Do
	not use floating-point comparisons to test sign.
	* sysdeps/powerpc/powerpc64/fpu/s_copysignl.S (__copysignl):
	Likewise.

diff --git a/ChangeLog b/ChangeLog
index 9b22678..49436bc 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,11 @@
 2016-10-19  Joseph Myers  <joseph@codesourcery.com>
 
+       [BZ #20718]
+       * sysdeps/powerpc/powerpc32/fpu/s_copysignl.S (__copysignl): Do
+       not use floating-point comparisons to test sign.
+       * sysdeps/powerpc/powerpc64/fpu/s_copysignl.S (__copysignl):
+       Likewise.
+
        * math/bits/mathcalls.h [__GLIBC_USE (IEC_60559_BFP_EXT)]
        (getpayload): New declaration.
        * math/Versions (getpayload): New libm symbol at version

diff --git a/sysdeps/powerpc/powerpc32/fpu/s_copysignl.S b/sysdeps/powerpc/powerpc32/fpu/s_copysignl.S
index aed783a..1eec847 100644 (file)
--- a/sysdeps/powerpc/powerpc32/fpu/s_copysignl.S
+++ b/sysdeps/powerpc/powerpc32/fpu/s_copysignl.S
@@ -24,22 +24,39 @@ ENTRY(__copysignl)
 /* long double [f1,f2] copysign (long double [f1,f2] x, long double [f3,f4] y);
    copysign(x,y) returns a value with the magnitude of x and
    with the sign bit of y.  */
+#ifdef _ARCH_PPCGR
+       /* fsel available.  */
        stwu    r1,-16(r1)
        cfi_adjust_cfa_offset (16)
        stfd    fp3,8(r1)
        fmr     fp0,fp1
        fabs    fp1,fp1
-       fcmpu   cr7,fp0,fp1
        lwz     r3,8+HIWORD(r1)
        cmpwi   cr6,r3,0
        addi    r1,r1,16
        cfi_adjust_cfa_offset (-16)
-       beq     cr7,L(0)
+       fneg    fp3,fp2
+       fsel    fp2,fp0,fp2,fp3
+       bgelr   cr6
+       fneg    fp1,fp1
        fneg    fp2,fp2
-L(0):  bgelr   cr6
+       blr
+#else
+       stwu    r1,-32(r1)
+       cfi_adjust_cfa_offset (32)
+       stfd    fp3,8(r1)
+       stfd    fp1,16(r1)
+       lwz     r3,8+HIWORD(r1)
+       lwz     r4,16+HIWORD(r1)
+       xor     r3,r3,r4
+       cmpwi   cr6,r3,0
+       addi    r1,r1,32
+       cfi_adjust_cfa_offset (-32)
+       bgelr   cr6
        fneg    fp1,fp1
        fneg    fp2,fp2
        blr
+#endif
 END (__copysignl)
 
 #if IS_IN (libm)

diff --git a/sysdeps/powerpc/powerpc64/fpu/s_copysignl.S b/sysdeps/powerpc/powerpc64/fpu/s_copysignl.S
index 1e1b9d4..548076d 100644 (file)
--- a/sysdeps/powerpc/powerpc64/fpu/s_copysignl.S
+++ b/sysdeps/powerpc/powerpc64/fpu/s_copysignl.S
@@ -30,16 +30,14 @@ ENTRY(__copysignl)
        blt     L(0)
        fmr     fp0,fp1
        fabs    fp1,fp1
-       fcmpu   cr1,fp0,fp1
-       beqlr   cr1
-       fneg    fp2,fp2
+       fneg    fp3,fp2
+       fsel    fp2,fp0,fp2,fp3
        blr
 L(0):
        fmr     fp0,fp1
        fnabs   fp1,fp1
-       fcmpu   cr1,fp0,fp1
-       beqlr   cr1
-       fneg    fp2,fp2
+       fneg    fp3,fp2
+       fsel    fp2,fp0,fp3,fp2
        blr
 END (__copysignl)