Fix nearbyintf rounding (bugs 2547, 11365)

[Joseph S. Myers]

The nearbyintf implementation is substantially the same as rintf (the
only difference being that nearbyintf does not raise the "inexact"
exception, so there are feholdexcept/fesetenv pairs).  So it has the
same bugs, and much the same fix as in
<http://sourceware.org/ml/libc-alpha/2012-02/msg00397.html> applies.
This fix adds both the tests added for rint and the specific testcases
from the bug reports for nearbyint.

2012-02-19  Joseph Myers  <joseph@codesourcery.com>

	[BZ #2547]
	[BZ #11365]
	* sysdeps/ieee754/flt-32/s_nearbyintf.c (__nearbyintf): Do not
	manipulate bits before adding and subtracting TWO23[sx].
	* math/libm-test.inc (nearbyint_test): Add more tests.

diff --git a/math/libm-test.inc b/math/libm-test.inc
index 6243e1e..d904543 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -4632,6 +4632,29 @@ nearbyint_test (void)
   TEST_f_f (nearbyint, 524286.75, 524287.0);
   TEST_f_f (nearbyint, 524288.75, 524289.0);
 
+  TEST_f_f (nearbyint, 1048576.75, 1048577.0);
+  TEST_f_f (nearbyint, 2097152.75, 2097153.0);
+  TEST_f_f (nearbyint, 2492472.75, 2492473.0);
+  TEST_f_f (nearbyint, 2886220.75, 2886221.0);
+  TEST_f_f (nearbyint, 3058792.75, 3058793.0);
+  TEST_f_f (nearbyint, -1048576.75, -1048577.0);
+  TEST_f_f (nearbyint, -2097152.75, -2097153.0);
+  TEST_f_f (nearbyint, -2492472.75, -2492473.0);
+  TEST_f_f (nearbyint, -2886220.75, -2886221.0);
+  TEST_f_f (nearbyint, -3058792.75, -3058793.0);
+#ifndef TEST_FLOAT
+  TEST_f_f (nearbyint, 70368744177664.75, 70368744177665.0);
+  TEST_f_f (nearbyint, 140737488355328.75, 140737488355329.0);
+  TEST_f_f (nearbyint, 281474976710656.75, 281474976710657.0);
+  TEST_f_f (nearbyint, 562949953421312.75, 562949953421313.0);
+  TEST_f_f (nearbyint, 1125899906842624.75, 1125899906842625.0);
+  TEST_f_f (nearbyint, -70368744177664.75, -70368744177665.0);
+  TEST_f_f (nearbyint, -140737488355328.75, -140737488355329.0);
+  TEST_f_f (nearbyint, -281474976710656.75, -281474976710657.0);
+  TEST_f_f (nearbyint, -562949953421312.75, -562949953421313.0);
+  TEST_f_f (nearbyint, -1125899906842624.75, -1125899906842625.0);
+#endif
+
   END (nearbyint);
 }
 
diff --git a/sysdeps/ieee754/flt-32/s_nearbyintf.c b/sysdeps/ieee754/flt-32/s_nearbyintf.c
index 04ef9ab..a6d602b 100644
--- a/sysdeps/ieee754/flt-32/s_nearbyintf.c
+++ b/sysdeps/ieee754/flt-32/s_nearbyintf.c
@@ -30,18 +30,12 @@ __nearbyintf(float x)
 {
 	fenv_t env;
 	int32_t i0,j0,sx;
-	u_int32_t i,i1;
 	float w,t;
 	GET_FLOAT_WORD(i0,x);
 	sx = (i0>>31)&1;
 	j0 = ((i0>>23)&0xff)-0x7f;
 	if(j0<23) {
 	    if(j0<0) {
-		if((i0&0x7fffffff)==0) return x;
-		i1 = (i0&0x07fffff);
-		i0 &= 0xfff00000;
-		i0 |= ((i1|-i1)>>9)&0x400000;
-		SET_FLOAT_WORD(x,i0);
 		libc_feholdexceptf (&env);
 		w = TWO23[sx]+x;
 		t =  w-TWO23[sx];
@@ -49,17 +43,11 @@ __nearbyintf(float x)
 		GET_FLOAT_WORD(i0,t);
 		SET_FLOAT_WORD(t,(i0&0x7fffffff)|(sx<<31));
 		return t;
-	    } else {
-		i = (0x007fffff)>>j0;
-		if((i0&i)==0) return x; /* x is integral */
-		i>>=1;
-		if((i0&i)!=0) i0 = (i0&(~i))|((0x100000)>>j0);
 	    }
 	} else {
 	    if(__builtin_expect(j0==0x80, 0)) return x+x;	/* inf or NaN */
 	    else return x;		/* x is integral */
 	}
-	SET_FLOAT_WORD(x,i0);
 	libc_feholdexceptf (&env);
 	w = TWO23[sx]+x;
 	t = w-TWO23[sx];

-- 
Joseph S. Myers
joseph@codesourcery.com