[ADT] Update PointerIntPair to handle pointer types with more than 31 bits free.

Previously, the assertions in PointerIntPair would try to calculate the value
(1 << NumLowBitsAvailable); the inferred type here is 'int', so if there were
more than 31 bits available we'd get a shift overflow.

Also, add a rudimentary unit test file for PointerIntPair.

llvm-svn: 203273

1 files changed, 74 insertions, 0 deletions

diff --git a/llvm/unittests/ADT/PointerIntPairTest.cpp b/llvm/unittests/ADT/PointerIntPairTest.cpp
new file mode 100644
index 00000000000..3da31e7dfe7
--- /dev/null
+++ b/llvm/unittests/ADT/PointerIntPairTest.cpp
@@ -0,0 +1,74 @@
+//===- llvm/unittest/ADT/PointerIntPairTest.cpp - Unit tests --------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "gtest/gtest.h"
+#include "llvm/ADT/PointerIntPair.h"
+#include <limits>
+using namespace llvm;
+
+namespace {
+
+// Test fixture
+class PointerIntPairTest : public testing::Test {
+};
+
+TEST_F(PointerIntPairTest, GetSet) {
+  PointerIntPair<PointerIntPairTest *, 2> Pair{this, 1U};
+  EXPECT_EQ(this, Pair.getPointer());
+  EXPECT_EQ(1U, Pair.getInt());
+
+  Pair.setInt(2);
+  EXPECT_EQ(this, Pair.getPointer());
+  EXPECT_EQ(2U, Pair.getInt());
+
+  Pair.setPointer(nullptr);
+  EXPECT_EQ(nullptr, Pair.getPointer());
+  EXPECT_EQ(2U, Pair.getInt());
+
+  Pair.setPointerAndInt(this, 3U);
+  EXPECT_EQ(this, Pair.getPointer());
+  EXPECT_EQ(3U, Pair.getInt());
+}
+
+TEST_F(PointerIntPairTest, DefaultInitialize) {
+  PointerIntPair<PointerIntPairTest *, 2> Pair;
+  EXPECT_EQ(nullptr, Pair.getPointer());
+  EXPECT_EQ(0U, Pair.getInt());
+}
+
+TEST_F(PointerIntPairTest, ManyUnusedBits) {
+  // In real code this would be a word-sized integer limited to 31 bits.
+  struct Fixnum31 {
+    uintptr_t Value;
+  };
+  class FixnumPointerTraits {
+  public:
+    static inline void *getAsVoidPointer(Fixnum31 Num) {
+      return reinterpret_cast<void *>(Num.Value << NumLowBitsAvailable);
+    }
+    static inline Fixnum31 getFromVoidPointer(void *P) {
+      // In real code this would assert that the value is in range.
+      return { reinterpret_cast<uintptr_t>(P) >> NumLowBitsAvailable };
+    }
+    enum { NumLowBitsAvailable = std::numeric_limits<uintptr_t>::digits - 31 };
+  };
+
+  PointerIntPair<Fixnum31, 1, bool, FixnumPointerTraits> pair;
+  EXPECT_EQ((uintptr_t)0, pair.getPointer().Value);
+  EXPECT_EQ(false, pair.getInt());
+
+  pair.setPointerAndInt({ 0x7FFFFFFF }, true );
+  EXPECT_EQ((uintptr_t)0x7FFFFFFF, pair.getPointer().Value);
+  EXPECT_EQ(true, pair.getInt());
+
+  EXPECT_EQ(FixnumPointerTraits::NumLowBitsAvailable - 1,
+            PointerLikeTypeTraits<decltype(pair)>::NumLowBitsAvailable);
+}
+
+} // end anonymous namespace