Set errno for scalb errors (bug 6803, bug 6804).

This patch fixes the default mode of scalb to set errno (bugs 6803 and
6804).

Previously, the _LIB_VERSION == _SVID_ mode would set errno but only
in some relevant cases, and with various peculiarities (such as errno
setting when an exact infinity or zero result arises with an argument
to scalb being an infinity).  This patch leaves this mode
bug-compatible, while making the default mode set errno in accordance
with normal practice (so an exact infinity from an infinite argument
is not an error, and nor is an exact zero result).  gen-libm-test.pl
is taught new notation such as ERRNO_PLUS_OFLOW to facilitate writing
the tests of errno setting for underflow / overflow in libm-test.inc.

Note that bug 6803 also covers scalbn and scalbln, but this patch only
addresses the scalb parts of that bug (along with the whole of bug
6804).

Tested x86_64 and x86.

	[BZ #6803]
	[BZ #6804]
	* math/w_scalb.c (__scalb): For non-SVID mode, check result and
	set errno as appropriate.
	* math/w_scalbf.c (__scalbf): Likewise.
	* math/w_scalbl.c (__scalbl): Likewise.
	* math/gen-libm-test.pl (parse_args): Handle ERRNO_PLUS_OFLOW,
	ERRNO_MINUS_OFLOW, ERRNO_PLUS_UFLOW and ERRNO_MINUS_UFLOW.
	* math/libm-test.inc (scalb_test_data): Add errno expectations.
	Add more NaN tests.

5 files changed, 159 insertions, 75 deletions

diff --git a/math/gen-libm-test.pl b/math/gen-libm-test.pl
index 6b3a21df40..5f62872b21 100755
--- a/math/gen-libm-test.pl
+++ b/math/gen-libm-test.pl
@@ -160,6 +160,8 @@ sub parse_args {
   my ($ignore_result_any, $ignore_result_all);
   my ($num_res, @args_res, @start_rm, $rm);
   my (@plus_oflow, @minus_oflow, @plus_uflow, @minus_uflow);
+  my (@errno_plus_oflow, @errno_minus_oflow);
+  my (@errno_plus_uflow, @errno_minus_uflow);
 
   ($descr_args, $descr_res) = split /_/,$descr, 2;
 
@@ -258,6 +260,10 @@ sub parse_args {
   @minus_oflow = qw(minus_infty minus_infty -max_value -max_value);
   @plus_uflow = qw(plus_zero plus_zero plus_zero min_subnorm_value);
   @minus_uflow = qw(-min_subnorm_value minus_zero minus_zero minus_zero);
+  @errno_plus_oflow = qw(0 ERRNO_ERANGE 0 ERRNO_ERANGE);
+  @errno_minus_oflow = qw(ERRNO_ERANGE ERRNO_ERANGE 0 0);
+  @errno_plus_uflow = qw(ERRNO_ERANGE ERRNO_ERANGE ERRNO_ERANGE 0);
+  @errno_minus_uflow = qw(0 ERRNO_ERANGE ERRNO_ERANGE ERRNO_ERANGE);
   for ($rm = 0; $rm <= 3; $rm++) {
     $current_arg = $start_rm[$rm];
     $ignore_result_any = 0;
@@ -322,6 +328,10 @@ sub parse_args {
     $cline_res =~ s/minus_oflow/$minus_oflow[$rm]/g;
     $cline_res =~ s/plus_uflow/$plus_uflow[$rm]/g;
     $cline_res =~ s/minus_uflow/$minus_uflow[$rm]/g;
+    $cline_res =~ s/ERRNO_PLUS_OFLOW/$errno_plus_oflow[$rm]/g;
+    $cline_res =~ s/ERRNO_MINUS_OFLOW/$errno_minus_oflow[$rm]/g;
+    $cline_res =~ s/ERRNO_PLUS_UFLOW/$errno_plus_uflow[$rm]/g;
+    $cline_res =~ s/ERRNO_MINUS_UFLOW/$errno_minus_uflow[$rm]/g;
     $cline .= ", { $cline_res }";
   }
   print $file "    $cline },\n";
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 0eff34a0ca..19194f63e9 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -9087,72 +9087,74 @@ round_test (void)
 
 static const struct test_ff_f_data scalb_test_data[] =
   {
-    TEST_ff_f (scalb, 2.0, 0.5, qnan_value, INVALID_EXCEPTION),
-    TEST_ff_f (scalb, 3.0, -2.5, qnan_value, INVALID_EXCEPTION),
-
-    TEST_ff_f (scalb, 0, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, 1, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-
-    TEST_ff_f (scalb, 1, 0, 1),
-    TEST_ff_f (scalb, -1, 0, -1),
-
-    TEST_ff_f (scalb, 0, plus_infty, qnan_value, INVALID_EXCEPTION),
-    TEST_ff_f (scalb, minus_zero, plus_infty, qnan_value, INVALID_EXCEPTION),
-
-    TEST_ff_f (scalb, 0, 2, 0),
-    TEST_ff_f (scalb, minus_zero, -4, minus_zero),
-    TEST_ff_f (scalb, 0, 0, 0),
-    TEST_ff_f (scalb, minus_zero, 0, minus_zero),
-    TEST_ff_f (scalb, 0, -1, 0),
-    TEST_ff_f (scalb, minus_zero, -10, minus_zero),
-    TEST_ff_f (scalb, 0, minus_infty, 0),
-    TEST_ff_f (scalb, minus_zero, minus_infty, minus_zero),
-
-    TEST_ff_f (scalb, plus_infty, -1, plus_infty),
-    TEST_ff_f (scalb, minus_infty, -10, minus_infty),
-    TEST_ff_f (scalb, plus_infty, 0, plus_infty),
-    TEST_ff_f (scalb, minus_infty, 0, minus_infty),
-    TEST_ff_f (scalb, plus_infty, 2, plus_infty),
-    TEST_ff_f (scalb, minus_infty, 100, minus_infty),
-
-    TEST_ff_f (scalb, 0.1L, minus_infty, 0.0),
-    TEST_ff_f (scalb, -0.1L, minus_infty, minus_zero),
-
-    TEST_ff_f (scalb, 1, plus_infty, plus_infty),
-    TEST_ff_f (scalb, -1, plus_infty, minus_infty),
-    TEST_ff_f (scalb, plus_infty, plus_infty, plus_infty),
-    TEST_ff_f (scalb, minus_infty, plus_infty, minus_infty),
-
-    TEST_ff_f (scalb, plus_infty, minus_infty, qnan_value, INVALID_EXCEPTION),
-    TEST_ff_f (scalb, minus_infty, minus_infty, qnan_value, INVALID_EXCEPTION),
-
-    TEST_ff_f (scalb, qnan_value, 1, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, 1, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, qnan_value, 0, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, 0, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, qnan_value, plus_infty, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, plus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-    TEST_ff_f (scalb, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION),
-
-    TEST_ff_f (scalb, max_value, max_value, plus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, max_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, 1, max_value, plus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, 1, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, min_value, max_value, plus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, min_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, min_subnorm_value, max_value, plus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, min_subnorm_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -max_value, max_value, minus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -max_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -1, max_value, minus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -1, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -min_value, max_value, minus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -min_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -min_subnorm_value, max_value, minus_oflow, OVERFLOW_EXCEPTION),
-    TEST_ff_f (scalb, -min_subnorm_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION),
-
-    TEST_ff_f (scalb, 0.8L, 4, 12.8L),
-    TEST_ff_f (scalb, -0.854375L, 5, -27.34L),
+    TEST_ff_f (scalb, 2.0, 0.5, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+    TEST_ff_f (scalb, 3.0, -2.5, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+
+    TEST_ff_f (scalb, 0, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 1, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, 1, 0, 1, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, -1, 0, -1, ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, 0, plus_infty, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+    TEST_ff_f (scalb, minus_zero, plus_infty, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+
+    TEST_ff_f (scalb, 0, 2, 0, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_zero, -4, minus_zero, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 0, 0, 0, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_zero, 0, minus_zero, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 0, -1, 0, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_zero, -10, minus_zero, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 0, minus_infty, 0, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_zero, minus_infty, minus_zero, ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, plus_infty, -1, plus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_infty, -10, minus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, plus_infty, 0, plus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_infty, 0, minus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, plus_infty, 2, plus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_infty, 100, minus_infty, ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, 0.1L, minus_infty, 0.0, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, -0.1L, minus_infty, minus_zero, ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, 1, plus_infty, plus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, -1, plus_infty, minus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, plus_infty, plus_infty, plus_infty, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, minus_infty, plus_infty, minus_infty, ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, plus_infty, minus_infty, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+    TEST_ff_f (scalb, minus_infty, minus_infty, qnan_value, INVALID_EXCEPTION|ERRNO_EDOM),
+
+    TEST_ff_f (scalb, qnan_value, 1, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 1, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, qnan_value, 0.5, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 0.5, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, qnan_value, 0, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, 0, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, qnan_value, plus_infty, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, plus_infty, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, qnan_value, qnan_value, qnan_value, NO_INEXACT_EXCEPTION|ERRNO_UNCHANGED),
+
+    TEST_ff_f (scalb, max_value, max_value, plus_oflow, OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW),
+    TEST_ff_f (scalb, max_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION|ERRNO_PLUS_UFLOW),
+    TEST_ff_f (scalb, 1, max_value, plus_oflow, OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW),
+    TEST_ff_f (scalb, 1, -max_value, plus_uflow, UNDERFLOW_EXCEPTION|ERRNO_PLUS_UFLOW),
+    TEST_ff_f (scalb, min_value, max_value, plus_oflow, OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW),
+    TEST_ff_f (scalb, min_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION|ERRNO_PLUS_UFLOW),
+    TEST_ff_f (scalb, min_subnorm_value, max_value, plus_oflow, OVERFLOW_EXCEPTION|ERRNO_PLUS_OFLOW),
+    TEST_ff_f (scalb, min_subnorm_value, -max_value, plus_uflow, UNDERFLOW_EXCEPTION|ERRNO_PLUS_UFLOW),
+    TEST_ff_f (scalb, -max_value, max_value, minus_oflow, OVERFLOW_EXCEPTION|ERRNO_MINUS_OFLOW),
+    TEST_ff_f (scalb, -max_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION|ERRNO_MINUS_UFLOW),
+    TEST_ff_f (scalb, -1, max_value, minus_oflow, OVERFLOW_EXCEPTION|ERRNO_MINUS_OFLOW),
+    TEST_ff_f (scalb, -1, -max_value, minus_uflow, UNDERFLOW_EXCEPTION|ERRNO_MINUS_UFLOW),
+    TEST_ff_f (scalb, -min_value, max_value, minus_oflow, OVERFLOW_EXCEPTION|ERRNO_MINUS_OFLOW),
+    TEST_ff_f (scalb, -min_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION|ERRNO_MINUS_UFLOW),
+    TEST_ff_f (scalb, -min_subnorm_value, max_value, minus_oflow, OVERFLOW_EXCEPTION|ERRNO_MINUS_OFLOW),
+    TEST_ff_f (scalb, -min_subnorm_value, -max_value, minus_uflow, UNDERFLOW_EXCEPTION|ERRNO_MINUS_UFLOW),
+
+    TEST_ff_f (scalb, 0.8L, 4, 12.8L, ERRNO_UNCHANGED),
+    TEST_ff_f (scalb, -0.854375L, 5, -27.34L, ERRNO_UNCHANGED),
   };
 
 static void
diff --git a/math/w_scalb.c b/math/w_scalb.c
index dbfefaf9d5..0f1e2df8ef 100644
--- a/math/w_scalb.c
+++ b/math/w_scalb.c
@@ -45,9 +45,33 @@ sysv_scalb (double x, double fn)
 double
 __scalb (double x, double fn)
 {
-  return (__builtin_expect (_LIB_VERSION == _SVID_, 0)
-	  ? sysv_scalb (x, fn)
-	  : __ieee754_scalb (x, fn));
+  if (__glibc_unlikely (_LIB_VERSION == _SVID_))
+    return sysv_scalb (x, fn);
+  else
+    {
+      double z = __ieee754_scalb (x, fn);
+
+      if (__glibc_unlikely (!__finite (z) || z == 0.0))
+	{
+	  if (__isnan (z))
+	    {
+	      if (!__isnan (x) && !__isnan (fn))
+		__set_errno (EDOM);
+	    }
+	  else if (__isinf_ns (z))
+	    {
+	      if (!__isinf_ns (x) && !__isinf_ns (fn))
+		__set_errno (ERANGE);
+	    }
+	  else
+	    {
+	      /* z == 0.  */
+	      if (x != 0.0 && !__isinf_ns (fn))
+		__set_errno (ERANGE);
+	    }
+	}
+      return z;
+    }
 }
 weak_alias (__scalb, scalb)
 #ifdef NO_LONG_DOUBLE
diff --git a/math/w_scalbf.c b/math/w_scalbf.c
index 244fd1e91b..7ab0b8a4ac 100644
--- a/math/w_scalbf.c
+++ b/math/w_scalbf.c
@@ -45,8 +45,32 @@ sysv_scalbf (float x, float fn)
 float
 __scalbf (float x, float fn)
 {
-  return (__builtin_expect (_LIB_VERSION == _SVID_, 0)
-	  ? sysv_scalbf (x, fn)
-	  : __ieee754_scalbf (x, fn));
+  if (__glibc_unlikely (_LIB_VERSION == _SVID_))
+    return sysv_scalbf (x, fn);
+  else
+    {
+      float z = __ieee754_scalbf (x, fn);
+
+      if (__glibc_unlikely (!__finitef (z) || z == 0.0f))
+	{
+	  if (__isnanf (z))
+	    {
+	      if (!__isnanf (x) && !__isnanf (fn))
+		__set_errno (EDOM);
+	    }
+	  else if (__isinf_nsf (z))
+	    {
+	      if (!__isinf_nsf (x) && !__isinf_nsf (fn))
+		__set_errno (ERANGE);
+	    }
+	  else
+	    {
+	      /* z == 0.  */
+	      if (x != 0.0f && !__isinf_nsf (fn))
+		__set_errno (ERANGE);
+	    }
+	}
+      return z;
+    }
 }
 weak_alias (__scalbf, scalbf)
diff --git a/math/w_scalbl.c b/math/w_scalbl.c
index cffaa67cc7..40cc68e865 100644
--- a/math/w_scalbl.c
+++ b/math/w_scalbl.c
@@ -45,8 +45,32 @@ sysv_scalbl (long double x, long double fn)
 long double
 __scalbl (long double x, long double fn)
 {
-  return (__builtin_expect (_LIB_VERSION == _SVID_, 0)
-	  ? sysv_scalbl (x, fn)
-	  : __ieee754_scalbl (x, fn));
+  if (__glibc_unlikely (_LIB_VERSION == _SVID_))
+    return sysv_scalbl (x, fn);
+  else
+    {
+      long double z = __ieee754_scalbl (x, fn);
+
+      if (__glibc_unlikely (!__finitel (z) || z == 0.0L))
+	{
+	  if (__isnanl (z))
+	    {
+	      if (!__isnanl (x) && !__isnanl (fn))
+		__set_errno (EDOM);
+	    }
+	  else if (__isinf_nsl (z))
+	    {
+	      if (!__isinf_nsl (x) && !__isinf_nsl (fn))
+		__set_errno (ERANGE);
+	    }
+	  else
+	    {
+	      /* z == 0.  */
+	      if (x != 0.0L && !__isinf_nsl (fn))
+		__set_errno (ERANGE);
+	    }
+	}
+      return z;
+    }
 }
 weak_alias (__scalbl, scalbl)