[llvm] r236326 - Fix infinite recursion in ScaledNumber::toInt.

[Diego Novillo]

Author: dnovillo
Date: Fri May  1 12:59:15 2015
New Revision: 236326

URL: http://llvm.org/viewvc/llvm-project?rev=236326&view=rev
Log:
Fix infinite recursion in ScaledNumber::toInt.

Patch from dexonsmith. The call to toInt() was calling compareTo() which
in some cases would call back to toInt(), creating an infinite loop.

Fixed by simplifying the logic in compareTo() to avoid the co-recursion.

Modified:
    llvm/trunk/include/llvm/Support/ScaledNumber.h
    llvm/trunk/unittests/Support/ScaledNumberTest.cpp

Modified: llvm/trunk/include/llvm/Support/ScaledNumber.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/ScaledNumber.h?rev=236326&r1=236325&r2=236326&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/ScaledNumber.h (original)
+++ llvm/trunk/include/llvm/Support/ScaledNumber.h Fri May  1 12:59:15 2015
@@ -670,14 +670,7 @@ public:
     return ScaledNumbers::compare(Digits, Scale, X.Digits, X.Scale);
   }
   int compareTo(uint64_t N) const {
-    ScaledNumber Scaled = get(N);
-    int Compare = compare(Scaled);
-    if (Width == 64 || Compare != 0)
-      return Compare;
-
-    // Check for precision loss.  We know *this == RoundTrip.
-    uint64_t RoundTrip = Scaled.template toInt<uint64_t>();
-    return N == RoundTrip ? 0 : RoundTrip < N ? -1 : 1;
+    return ScaledNumbers::compare<uint64_t>(Digits, Scale, N, 0);
   }
   int compareTo(int64_t N) const { return N < 0 ? 1 : compareTo(uint64_t(N)); }
 

Modified: llvm/trunk/unittests/Support/ScaledNumberTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ScaledNumberTest.cpp?rev=236326&r1=236325&r2=236326&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/ScaledNumberTest.cpp (original)
+++ llvm/trunk/unittests/Support/ScaledNumberTest.cpp Fri May  1 12:59:15 2015
@@ -556,4 +556,9 @@ TEST(ScaledNumberHelpersTest, arithmetic
   EXPECT_EQ(ScaledNumber<uint64_t>(1, 4), ScaledNumber<uint64_t>(1, 3) << 1);
 }
 
+TEST(ScaledNumberHelpersTest, toIntBug) {
+  ScaledNumber<uint32_t> n(1, 0);
+  EXPECT_EQ(1u, (n * n).toInt<uint32_t>());
+}
+
 } // end namespace