From: Diego Novillo <dnovillo@google.com>
Date: Fri, 1 May 2015 17:59:15 +0000 (+0000)
Subject: Fix infinite recursion in ScaledNumber::toInt.
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=3c178d82ce6c24cf25232f194142a5b30c6f20c2;p=oota-llvm.git

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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236326 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/Support/ScaledNumber.h b/include/llvm/Support/ScaledNumber.h
index dbe88f2e96f..0a4262b7eec 100644
--- a/include/llvm/Support/ScaledNumber.h
+++ b/include/llvm/Support/ScaledNumber.h
@@ -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)); }
 
diff --git a/unittests/Support/ScaledNumberTest.cpp b/unittests/Support/ScaledNumberTest.cpp
index 38721552ec9..2f38b2a40fb 100644
--- a/unittests/Support/ScaledNumberTest.cpp
+++ b/unittests/Support/ScaledNumberTest.cpp
@@ -556,4 +556,9 @@ TEST(ScaledNumberHelpersTest, arithmeticOperators) {
   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