[SystemZ] Optimize sign-extends of vector setccs

[oota-llvm.git] / lib / Support / APInt.cpp

diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index 71c509592c1f18f73e07f7f33a8effaaa1e986ff..89f96bd5774002b3956d409e244bf4467c795e73 100644 (file)
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -2304,24 +2304,7 @@ namespace {
   static unsigned int
   partMSB(integerPart value)
   {
-    unsigned int n, msb;
-
-    if (value == 0)
-      return -1U;
-
-    n = integerPartWidth / 2;
-
-    msb = 0;
-    do {
-      if (value >> n) {
-        value >>= n;
-        msb += n;
-      }
-
-      n >>= 1;
-    } while (n);
-
-    return msb;
+    return findLastSet(value, ZB_Max);
   }
 
   /* Returns the bit number of the least significant set bit of a
@@ -2329,24 +2312,7 @@ namespace {
   static unsigned int
   partLSB(integerPart value)
   {
-    unsigned int n, lsb;
-
-    if (value == 0)
-      return -1U;
-
-    lsb = integerPartWidth - 1;
-    n = integerPartWidth / 2;
-
-    do {
-      if (value << n) {
-        value <<= n;
-        lsb -= n;
-      }
-
-      n >>= 1;
-    } while (n);
-
-    return lsb;
+    return findFirstSet(value, ZB_Max);
   }
 }
 
@@ -2888,6 +2854,20 @@ APInt::tcIncrement(integerPart *dst, unsigned int parts)
   return i == parts;
 }
 
+/* Decrement a bignum in-place, return the borrow flag.  */
+integerPart
+APInt::tcDecrement(integerPart *dst, unsigned int parts) {
+  for (unsigned int i = 0; i < parts; i++) {
+    // If the current word is non-zero, then the decrement has no effect on the
+    // higher-order words of the integer and no borrow can occur. Exit early.
+    if (dst[i]--)
+      return 0;
+  }
+  // If every word was zero, then there is a borrow.
+  return 1;
+}
+
+
 /* Set the least significant BITS bits of a bignum, clear the
    rest.  */
 void