2010-08-03 Craig Howland <howland@LGSInnovations.com>

* libm/common/s_lrint.c (lrint):  Annotate shift operations with
        possible shift amount ranges, and use SAFE_RIGHT_SHIFT to avoid
        undefined behaviour.
        * libm/common/s_llrint.c (llrint):  Likewise.
        * libm/common/s_lround.c (lround):  Correct some comments on ranges.
        * libm/common/s_llround.c (llround):  Likewise.

newlib/ChangeLog

@@ -1,3 +1,12 @@
+2010-08-03  Craig Howland <howland@LGSInnovations.com>
+
+	* libm/common/s_lrint.c (lrint):  Annotate shift operations with
+	possible shift amount ranges, and use SAFE_RIGHT_SHIFT to avoid
+	undefined behaviour.
+	* libm/common/s_llrint.c (llrint):  Likewise.
+	* libm/common/s_lround.c (lround):  Correct some comments on ranges.
+	* libm/common/s_llround.c (llround):  Likewise.
+
 2010-07-30  Anthony Green  <green@moxielogic.com>
 
 	* libc/sys/rtems/machine/_types.h: Add moxie support.

newlib/libm/common/s_llrint.c

@@ -61,40 +61,56 @@ long long int
 
   /* Extract exponent field. */
   j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
+  /* j0 in [-1023,1024] */
   
   if(j0 < 20)
     {
+      /* j0 in [-1023,19] */
       if(j0 < -1)
         return 0;
       else
         {
+          /* j0 in [0,19] */
+	  /* shift amt in [0,19] */
           w = TWO52[sx] + x;
           t = w - TWO52[sx];
           GET_HIGH_WORD(i0, t);
           /* Detect the all-zeros representation of plus and
              minus zero, which fails the calculation below. */
-          if ((i0 & ~(1 << 31)) == 0)
+          if ((i0 & ~((__int32_t)1 << 31)) == 0)
               return 0;
+          /* After round:  j0 in [0,20] */
           j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
           i0 &= 0x000fffff;
           i0 |= 0x00100000;
+	  /* shift amt in [20,0] */
           result = i0 >> (20 - j0);
         }
     }
   else if (j0 < (int)(8 * sizeof (long long int)) - 1)
     {
+      /* 64bit return: j0 in [20,62] */
       if (j0 >= 52)
+	/* 64bit return: j0 in [52,62] */
+	/* 64bit return: left shift amt in [32,42] */
         result = ((long long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) | 
+		/* 64bit return: right shift amt in [0,10] */
                    (i1 << (j0 - 52));
       else
         {
+	  /* 64bit return: j0 in [20,51] */
           w = TWO52[sx] + x;
           t = w - TWO52[sx];
           EXTRACT_WORDS (i0, i1, t);
           j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
           i0 &= 0x000fffff;
           i0 |= 0x00100000;
-          result = ((long long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
+          /* After round:
+	   * 64bit return: j0 in [20,52] */
+	  /* 64bit return: left shift amt in [0,32] */
+          /* ***64bit return: right shift amt in [32,0] */
+          result = ((long long int) i0 << (j0 - 20))
+			| SAFE_RIGHT_SHIFT (i1, (52 - j0));
         }
     }
   else

newlib/libm/common/s_llround.c

@@ -31,10 +31,10 @@ llround(double x)
   msw &= 0x000fffff;
   msw |= 0x00100000;
 
-  /* exponent_less_1023 in [-1024,1023] */
+  /* exponent_less_1023 in [-1023,1024] */
   if (exponent_less_1023 < 20)
     {
-      /* exponent_less_1023 in [-1024,19] */
+      /* exponent_less_1023 in [-1023,19] */
       if (exponent_less_1023 < 0)
         {
           if (exponent_less_1023 < -1)

newlib/libm/common/s_lrint.c

@@ -98,13 +98,17 @@ TWO52[2]={
 
   /* Extract exponent field. */
   j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
+  /* j0 in [-1023,1024] */
   
   if(j0 < 20)
     {
+      /* j0 in [-1023,19] */
       if(j0 < -1)
         return 0;
       else
         {
+          /* j0 in [0,19] */
+	  /* shift amt in [0,19] */
           w = TWO52[sx] + x;
           t = w - TWO52[sx];
           GET_HIGH_WORD(i0, t);
@@ -112,26 +116,43 @@ TWO52[2]={
              minus zero, which fails the calculation below. */
           if ((i0 & ~(1L << 31)) == 0)
               return 0;
+          /* After round:  j0 in [0,20] */
           j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
           i0 &= 0x000fffff;
           i0 |= 0x00100000;
+	  /* shift amt in [20,0] */
           result = i0 >> (20 - j0);
         }
     }
   else if (j0 < (int)(8 * sizeof (long int)) - 1)
     {
+      /* 32bit return: j0 in [20,30] */
+      /* 64bit return: j0 in [20,62] */
       if (j0 >= 52)
+	/* 64bit return: j0 in [52,62] */
+	/* 64bit return: left shift amt in [32,42] */
         result = ((long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) | 
+		/* 64bit return: right shift amt in [0,10] */
                    (i1 << (j0 - 52));
       else
         {
+	  /* 32bit return: j0 in [20,30] */
+	  /* 64bit return: j0 in [20,51] */
           w = TWO52[sx] + x;
           t = w - TWO52[sx];
           EXTRACT_WORDS (i0, i1, t);
           j0 = ((i0 & 0x7ff00000) >> 20) - 1023;
           i0 &= 0x000fffff;
           i0 |= 0x00100000;
-          result = ((long int) i0 << (j0 - 20)) | (i1 >> (52 - j0));
+          /* After round:
+	   * 32bit return: j0 in [20,31];
+	   * 64bit return: j0 in [20,52] */
+	  /* 32bit return: left shift amt in [0,11] */
+	  /* 64bit return: left shift amt in [0,32] */
+          /* ***32bit return: right shift amt in [32,21] */
+          /* ***64bit return: right shift amt in [32,0] */
+          result = ((long int) i0 << (j0 - 20))
+			| SAFE_RIGHT_SHIFT (i1, (52 - j0));
         }
     }
   else

newlib/libm/common/s_lround.c

@@ -71,10 +71,10 @@ ANSI C, POSIX
   exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
   msw &= 0x000fffff;
   msw |= 0x00100000;
-  /* exponent_less_1023 in [-1024,1023] */
+  /* exponent_less_1023 in [-1023,1024] */
   if (exponent_less_1023 < 20)
     {
-      /* exponent_less_1023 in [-1024,19] */
+      /* exponent_less_1023 in [-1023,19] */
       if (exponent_less_1023 < 0)
         {
           if (exponent_less_1023 < -1)