Fix APInt::operator*= so that it computes the correct result for large integers where there is unsigned overflow.  Fix APFloat::toString so that it doesn't depend on the incorrect behavior in common cases (and computes the correct result in some rare cases).  Fixes PR11086.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141441 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index 6eadaaf..3774c52 100644
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -386,6 +386,7 @@
   clearAllBits();
   unsigned wordsToCopy = destWords >= getNumWords() ? getNumWords() : destWords;
   memcpy(pVal, dest, wordsToCopy * APINT_WORD_SIZE);
+  clearUnusedBits();
 
   // delete dest array and return
   delete[] dest;
@@ -471,7 +472,7 @@
     return APInt(BitWidth, VAL * RHS.VAL);
   APInt Result(*this);
   Result *= RHS;
-  return Result.clearUnusedBits();
+  return Result;
 }
 
 APInt APInt::operator+(const APInt& RHS) const {