PowerPC: remove wrong truncl implementation for PowerPC64

The truncl assembly implementation (sysdeps/powerpc/powerpc64/fpu/s_truncl.S)
returns wrong results for some inputs where first double is a exact integer
and the precision is determined by second long double.

Checking on implementation comments and history, I am very confident the
assembly implementation was based on a version before commit
5c68d401698a58cf7da150d9cce769fa6679ba5f that fixes BZ#2423 (Errors in
long double (ldbl-128ibm) rounding functions in glibc-2.4).

By just removing the implementation and make the build select
sysdeps/ieee754/ldbl-128ibm/s_truncl.c instead it fixes tgammal
issues regarding wrong result sign.

4 files changed, 9 insertions, 125 deletions

diff --git a/ChangeLog b/ChangeLog
index 62ebe4b584..1b19405fd2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,11 @@
-2013-01-08  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+2014-01-08  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
+
+	[BZ #16414]
+	* sysdeps/powerpc/powerpc64/fpu/s_truncl.S: Remove wrong
+	implementation.
+	* sysdeps/ieee754/ldbl-128ibm/s_truncl.c: Remove bogus comment.
+
+2014-01-08  Adhemerval Zanella  <azanella@linux.vnet.ibm.com>
 
 	* sysdeps/powerpc/fpu/libm-test-ulps: Update.
 
diff --git a/NEWS b/NEWS
index 486e892c65..4fe23146fc 100644
--- a/NEWS
+++ b/NEWS
@@ -24,7 +24,7 @@ Version 2.19
   16103, 16112, 16143, 16144, 16146, 16150, 16151, 16153, 16167, 16172,
   16195, 16214, 16245, 16271, 16274, 16283, 16289, 16293, 16314, 16316,
   16330, 16337, 16338, 16356, 16365, 16366, 16369, 16372, 16375, 16379,
-  16384, 16385, 16386, 16387, 16390, 16400, 16407, 16408.
+  16384, 16385, 16386, 16387, 16390, 16400, 16407, 16408, 16414.
 
 * Slovenian translations for glibc messages have been contributed by the
   Translation Project's Slovenian team of translators.
diff --git a/sysdeps/ieee754/ldbl-128ibm/s_truncl.c b/sysdeps/ieee754/ldbl-128ibm/s_truncl.c
index 490ad266d4..aca3f3efc2 100644
--- a/sysdeps/ieee754/ldbl-128ibm/s_truncl.c
+++ b/sysdeps/ieee754/ldbl-128ibm/s_truncl.c
@@ -17,9 +17,6 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-/* This has been coded in assembler because GCC makes such a mess of it
-   when it's coded in C.  */
-
 #include <math.h>
 #include <math_ldbl_opt.h>
 #include <float.h>
diff --git a/sysdeps/powerpc/powerpc64/fpu/s_truncl.S b/sysdeps/powerpc/powerpc64/fpu/s_truncl.S
deleted file mode 100644
index e5a3008beb..0000000000
--- a/sysdeps/powerpc/powerpc64/fpu/s_truncl.S
+++ /dev/null
@@ -1,120 +0,0 @@
-/* long double trunc function.
-   IBM extended format long double version.
-   Copyright (C) 2004-2014 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <http://www.gnu.org/licenses/>.  */
-
-#include <sysdep.h>
-#include <math_ldbl_opt.h>
-
-	.section	".toc","aw"
-.LC0:	/* 2**52 */
-	.tc FD_43300000_0[TC],0x4330000000000000
-.LC1:	/* 0.5 */
-	.tc FD_3fe00000_0[TC],0x3fe0000000000000
-	.section	".text"
-
-/* long double [fp1,fp2] truncl (long double x [fp1,fp2])  */
-
-ENTRY (__truncl)
-	mffs	fp11		/* Save current FPU rounding mode.  */
-	lfd	fp13,.LC0@toc(2)
-	fabs	fp0,fp1
-	fabs	fp9,fp2
-	fsub	fp12,fp13,fp13	/* generate 0.0  */
-	fcmpu	cr7,fp0,fp13	/* if (fabs(x) > TWO52)  */
-	fcmpu	cr6,fp1,fp12	/* if (x > 0.0)  */
-	bnl-	cr7,.L2
-	mtfsfi	7,1		/* Set rounding mode toward 0.  */
-	ble-	cr6,.L1
-	fneg	fp2,fp12
-	fadd	fp1,fp1,fp13	/* x+= TWO52;  */
-	fsub	fp1,fp1,fp13	/* x-= TWO52;  */
-	fabs	fp1,fp1		/* if (x == 0.0) x = 0.0;  */
-.L0:
-	mtfsf	0x01,fp11	/* restore previous rounding mode.  */
-	blr
-.L1:
-	fneg	fp2,fp12
-	bge-	cr6,.L0		/* if (x < 0.0)  */
-	fsub	fp1,fp1,fp13	/* x-= TWO52;  */
-	fadd	fp1,fp1,fp13	/* x+= TWO52;  */
-	fnabs	fp1,fp1		/* if (x == 0.0) x = -0.0;  */
-	mtfsf	0x01,fp11	/* restore previous rounding mode.  */
-	blr
-
-/* The high double is > TWO52 so we need to round the low double and
-   perhaps the high double.  In this case we have to round the low
-   double and handle any adjustment to the high double that may be
-   caused by rounding (up).  This is complicated by the fact that the
-   high double may already be rounded and the low double may have the
-   opposite sign to compensate.This gets a bit tricky so we use the
-   following algorithm:
-
-   tau = floor(x_high/TWO52);
-   x0 = x_high - tau;
-   x1 = x_low + tau;
-   r1 = rint(x1);
-   y_high = x0 + r1;
-   y_low = x0 - y_high + r1;
-   return y;  */
-.L2:
-	fcmpu	cr7,fp9,fp13	/* if (|x_low| > TWO52)  */
-	fcmpu	cr0,fp9,fp12	/* || (|x_low| == 0.0)  */
-	fcmpu	cr5,fp2,fp12	/* if (x_low > 0.0)  */
-	bgelr-	cr7		/*   return x;	*/
-	beqlr-  cr0
-	mtfsfi	7,1		/* Set rounding mode toward 0.  */
-	fdiv	fp8,fp1,fp13	/* x_high/TWO52  */
-
-	bng-	cr6,.L6		/* if (x > 0.0)  */
-	fctidz	fp0,fp8
-	fcfid	fp8,fp0		/* tau = floor(x_high/TWO52);  */
-	fadd	fp8,fp8,fp8	/* tau++; Make tau even  */
-	bng	cr5,.L4		/* if (x_low > 0.0)  */
-	fmr	fp3,fp1
-	fmr	fp4,fp2
-	b	.L5
-.L4:				/* if (x_low < 0.0)  */
-	fsub	fp3,fp1,fp8	/* x0 = x_high - tau;  */
-	fadd	fp4,fp2,fp8	/* x1 = x_low + tau;  */
-.L5:
-	fadd	fp5,fp4,fp13	/* r1 = r1 + TWO52;  */
-	fsub	fp5,fp5,fp13	/* r1 = r1 - TWO52;  */
-	b	.L9
-.L6:				/* if (x < 0.0)  */
-	fctidz	fp0,fp8
-	fcfid	fp8,fp0		/* tau = floor(x_high/TWO52);  */
-	fadd	fp8,fp8,fp8	/* tau++; Make tau even  */
-	bnl	cr5,.L7		/* if (x_low < 0.0)  */
-	fmr	fp3,fp1
-	fmr	fp4,fp2
-	b	.L8
-.L7:				/* if (x_low > 0.0)  */
-	fsub	fp3,fp1,fp8	/* x0 = x_high - tau;  */
-	fadd	fp4,fp2,fp8	/* x1 = x_low + tau;  */
-.L8:
-	fsub	fp5,fp4,fp13	/* r1-= TWO52;  */
-	fadd	fp5,fp5,fp13	/* r1+= TWO52;  */
-.L9:
-	mtfsf	0x01,fp11	/* restore previous rounding mode.  */
-	fadd	fp1,fp3,fp5	/* y_high = x0 + r1;  */
-	fsub	fp2,fp3,fp1	/* y_low = x0 - y_high + r1;  */
-	fadd	fp2,fp2,fp5
-	blr
-END (__truncl)
-
-long_double_symbol (libm, __truncl, truncl)