Fix powerpc32 llrint, llrintf bad exceptions (bug 16422) [committed]

[Joseph Myers <joseph at codesourcery dot com>]

The versions of llrint and llrintf for older powerpc32 processors
convert the results of __rint / __rintf to long long int, resulting in
spurious exceptions from such casts in certain cases.  This patch
makes glibc work around the problems with the libgcc conversions when
the compiler used to build glibc doesn't use the fctidz instruction
for them.

Tested for powerpc.  Committed.

2015-10-13  Joseph Myers  <joseph@codesourcery.com>

	[BZ #16422]
	* sysdeps/powerpc/powerpc32/fpu/configure.ac (libc_cv_ppc_fctidz):
	New configure test.
	* sysdeps/powerpc/powerpc32/fpu/configure: Regenerated.
	* config.h.in [_LIBC] (HAVE_PPC_FCTIDZ): New macro.
	* sysdeps/powerpc/powerpc32/fpu/s_llrint.c: Include <limits.h>,
	<math_private.h> and <stdint.h>.
	(__llrint): Avoid conversions to long long int where those might
	raise spurious exceptions.
	* sysdeps/powerpc/powerpc32/fpu/s_llrintf.c: Include
	<math_private.h> and <stdint.h>.
	(__llrintf): Avoid conversions to long long int where those might
	raise spurious exceptions.

diff --git a/config.h.in b/config.h.in
index 7c851c9..5fd4897 100644
--- a/config.h.in
+++ b/config.h.in
@@ -251,4 +251,7 @@
 /* PowerPC32 uses fcfid for integer to floating point conversions.  */
 #define HAVE_PPC_FCFID 0
 
+/* PowerPC32 uses fctidz for floating point to long long conversions.  */
+#define HAVE_PPC_FCTIDZ 0
+
 #endif
diff --git a/sysdeps/powerpc/powerpc32/fpu/configure b/sysdeps/powerpc/powerpc32/fpu/configure
index 69a151b..98c6f30 100644
--- a/sysdeps/powerpc/powerpc32/fpu/configure
+++ b/sysdeps/powerpc/powerpc32/fpu/configure
@@ -27,3 +27,30 @@ if test $libc_cv_ppc_fcfid = yes; then
   $as_echo "#define HAVE_PPC_FCFID 1" >>confdefs.h
 
 fi
+
+# Test whether floating point to long long conversions use fctidz.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for fctidz use" >&5
+$as_echo_n "checking for fctidz use... " >&6; }
+if ${libc_cv_ppc_fctidz+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  echo 'long long int foo (double x) { return (long long int) x; }' > conftest.c
+libc_cv_ppc_fctidz=no
+if { ac_try='${CC-cc} -S $CFLAGS conftest.c -o conftest.s 1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }; then
+  if grep '[ 	]fctidz' conftest.s > /dev/null 2>&1; then
+    libc_cv_ppc_fctidz=yes
+  fi
+fi
+rm -rf conftest*
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ppc_fctidz" >&5
+$as_echo "$libc_cv_ppc_fctidz" >&6; }
+if test $libc_cv_ppc_fctidz = yes; then
+  $as_echo "#define HAVE_PPC_FCTIDZ 1" >>confdefs.h
+
+fi
diff --git a/sysdeps/powerpc/powerpc32/fpu/configure.ac b/sysdeps/powerpc/powerpc32/fpu/configure.ac
index e596e79..1899705 100644
--- a/sysdeps/powerpc/powerpc32/fpu/configure.ac
+++ b/sysdeps/powerpc/powerpc32/fpu/configure.ac
@@ -16,3 +16,19 @@ rm -rf conftest*])
 if test $libc_cv_ppc_fcfid = yes; then
   AC_DEFINE([HAVE_PPC_FCFID])
 fi
+
+# Test whether floating point to long long conversions use fctidz.
+AC_CACHE_CHECK([for fctidz use], [libc_cv_ppc_fctidz], [dnl
+echo 'long long int foo (double x) { return (long long int) x; }' > conftest.c
+libc_cv_ppc_fctidz=no
+if AC_TRY_COMMAND(${CC-cc} -S $CFLAGS conftest.c -o conftest.s 1>&AS_MESSAGE_LOG_FD); then
+changequote(,)dnl
+  if grep '[ 	]fctidz' conftest.s > /dev/null 2>&1; then
+    libc_cv_ppc_fctidz=yes
+  fi
+changequote([,])dnl
+fi
+rm -rf conftest*])
+if test $libc_cv_ppc_fctidz = yes; then
+  AC_DEFINE([HAVE_PPC_FCTIDZ])
+fi
diff --git a/sysdeps/powerpc/powerpc32/fpu/s_llrint.c b/sysdeps/powerpc/powerpc32/fpu/s_llrint.c
index 48af9eb..bb12272 100644
--- a/sysdeps/powerpc/powerpc32/fpu/s_llrint.c
+++ b/sysdeps/powerpc/powerpc32/fpu/s_llrint.c
@@ -16,13 +16,42 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#include <limits.h>
 #include <math.h>
 #include <math_ldbl_opt.h>
+#include <math_private.h>
+#include <stdint.h>
 
 long long int
 __llrint (double x)
 {
-  return (long long int) __rint (x);
+  double rx = __rint (x);
+  if (HAVE_PPC_FCTIDZ || rx != x)
+    return (long long int) rx;
+  else
+    {
+      /* Avoid incorrect exceptions from libgcc conversions (as of GCC
+	 5): <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59412>.  */
+      if (fabs (rx) < 0x1p31)
+	return (long long int) (long int) rx;
+      uint64_t i0;
+      EXTRACT_WORDS64 (i0, rx);
+      int exponent = ((i0 >> 52) & 0x7ff) - 0x3ff;
+      if (exponent < 63)
+	{
+	  unsigned long long int mant
+	    = (i0 & ((1ULL << 52) - 1)) | (1ULL << 52);
+	  if (exponent < 52)
+	    mant >>= 52 - exponent;
+	  else
+	    mant <<= exponent - 52;
+	  return (long long int) ((i0 & (1ULL << 63)) != 0 ? -mant : mant);
+	}
+      else if (rx == (double) LLONG_MIN)
+	return LLONG_MIN;
+      else
+	return (long long int) (long int) rx << 32;
+    }
 }
 weak_alias (__llrint, llrint)
 #ifdef NO_LONG_DOUBLE
diff --git a/sysdeps/powerpc/powerpc32/fpu/s_llrintf.c b/sysdeps/powerpc/powerpc32/fpu/s_llrintf.c
index 205df4e..bcee020 100644
--- a/sysdeps/powerpc/powerpc32/fpu/s_llrintf.c
+++ b/sysdeps/powerpc/powerpc32/fpu/s_llrintf.c
@@ -17,10 +17,30 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <math.h>
+#include <math_private.h>
+#include <stdint.h>
 
 long long int
 __llrintf (float x)
 {
-  return (long long int) __rintf (x);
+  float rx = __rintf (x);
+  if (HAVE_PPC_FCTIDZ || rx != x)
+    return (long long int) rx;
+  else
+    {
+      float arx = fabsf (rx);
+      /* Avoid incorrect exceptions from libgcc conversions (as of GCC
+	 5): <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59412>.  */
+      if (arx < 0x1p31f)
+	return (long long int) (long int) rx;
+      else if (!(arx < 0x1p55f))
+	return (long long int) (long int) (rx * 0x1p-32f) << 32;
+      uint32_t i0;
+      GET_FLOAT_WORD (i0, rx);
+      int exponent = ((i0 >> 23) & 0xff) - 0x7f;
+      unsigned long long int mant = (i0 & 0x7fffff) | 0x800000;
+      mant <<= exponent - 23;
+      return (long long int) ((i0 & 0x80000000) != 0 ? -mant : mant);
+    }
 }
 weak_alias (__llrintf, llrintf)

-- 
Joseph S. Myers
joseph@codesourcery.com