2008-01-30 Andreas Krebbel <krebbel1@de.ibm.com>

	* config/s390/fixdfdi.h (__fixunstfdi, __fixtfdi): Rearrange
	the overflow check to make it easier to read.
	(__fixtfdi): Change the type of the ll member in union
	long_double to UDItype_x.

2008-01-30  Andreas Krebbel  <krebbel1@de.ibm.com>

	* gcc.target/s390/tf_to_di-1.c: New testcase.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@131957 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 20 insertions, 14 deletions

diff --git a/gcc/config/s390/fixdfdi.h b/gcc/config/s390/fixdfdi.h
index f3e48ac8f9d..865bf46b99f 100644
--- a/gcc/config/s390/fixdfdi.h
+++ b/gcc/config/s390/fixdfdi.h
@@ -77,13 +77,15 @@ __fixunstfdi (long double a1)
     if ((EXPD(dl1) == 0x7fff) && !FRACD_ZERO_P (dl1))
       return 0x0ULL;
 
-    /* If the upper ll part of the mantissa isn't
-       zeroed out after shifting the number would be to large.  */
-    if (exp >= -HIGH_LL_FRAC_BITS)
-      return 0xFFFFFFFFFFFFFFFFULL;
-
+    /* One extra bit is needed for the unit bit which is appended by
+       MANTD_HIGH_LL on the left of the matissa.  */
     exp += HIGH_LL_FRAC_BITS + 1;
 
+    /* If the result would still need a left shift it will be too large
+       to be represented.  */
+    if (exp > 0)
+      return 0xFFFFFFFFFFFFFFFFULL;
+
     l = MANTD_LOW_LL (dl1) >> (HIGH_LL_FRAC_BITS + 1)
         | MANTD_HIGH_LL (dl1) << (64 - (HIGH_LL_FRAC_BITS + 1));
 
@@ -117,7 +119,7 @@ union double_long {
   struct {
       SItype_x i[4]; /* 32 bit parts: 0 upper ... 3 lowest */
     } l;
-  DItype_x ll[2];   /* 64 bit parts: 0 upper, 1 lower */
+  UDItype_x ll[2];   /* 64 bit parts: 0 upper, 1 lower */
 };
 
 DItype_x __fixtfdi (long double a1);
@@ -136,7 +138,7 @@ __fixtfdi (long double a1)
     if (!EXPD (dl1))
       return 0;
 
-    /* The exponent - considered the binary point at the right end of 
+    /* The exponent - considered the binary point at the right end of
        the mantissa.  */
     exp = EXPD (dl1) - EXPONENT_BIAS - MANTISSA_BITS;
 
@@ -149,17 +151,21 @@ __fixtfdi (long double a1)
     if ((EXPD(dl1) == 0x7fff) && !FRACD_ZERO_P (dl1))
       return 0x8000000000000000ULL;
 
-    /* If the upper ll part of the mantissa isn't
-       zeroed out after shifting the number would be to large.  */
-    if (exp >= -HIGH_LL_FRAC_BITS)
+    /* One extra bit is needed for the unit bit which is appended by
+       MANTD_HIGH_LL on the left of the matissa.  */
+    exp += HIGH_LL_FRAC_BITS + 1;
+
+    /* If the result would still need a left shift it will be too large
+       to be represented.  Compared to the unsigned variant we have to
+       take care that there is still space for the sign bit to be
+       applied.  So we can only go on if there is a right-shift by one
+       or more.  */
+    if (exp >= 0)
       {
-	l = (long long)1 << 63; /* long int min */
+	l = 1ULL << 63; /* long long min */
 	return SIGND (dl1) ? l : l - 1;
       }
 
-    /* The extra bit is needed for the sign bit.  */
-    exp += HIGH_LL_FRAC_BITS + 1;
-
     l = MANTD_LOW_LL (dl1) >> (HIGH_LL_FRAC_BITS + 1)
         | MANTD_HIGH_LL (dl1) << (64 - (HIGH_LL_FRAC_BITS + 1));