Fix float to int conversion in base/numerics

base/numerics/safe_numerics_unittest.cc

Index: base/numerics/safe_numerics_unittest.cc
diff --git a/base/numerics/safe_numerics_unittest.cc b/base/numerics/safe_numerics_unittest.cc
index 6f9a966c0156431e654e71d483d81083fe555690..0df4c2d7ff7587344c031a9a07b130772726a5bb 100644
--- a/base/numerics/safe_numerics_unittest.cc
+++ b/base/numerics/safe_numerics_unittest.cc
@@ -18,6 +18,7 @@
 using std::numeric_limits;
 using base::CheckedNumeric;
 using base::checked_cast;
+using base::IsValueInRangeForNumericType;
 using base::SizeT;
 using base::StrictNumeric;
 using base::saturated_cast;
@@ -370,6 +371,15 @@ struct TestNumericConversion<Dst, Src, SIGN_PRESERVING_NARROW> {
       TEST_EXPECTED_RANGE(RANGE_OVERFLOW, SrcLimits::infinity());
       TEST_EXPECTED_RANGE(RANGE_UNDERFLOW, SrcLimits::infinity() * -1);
       TEST_EXPECTED_RANGE(RANGE_INVALID, SrcLimits::quiet_NaN());
+      if (!DstLimits::is_iec559) {
+        if (SrcLimits::digits < DstLimits::digits) {
+          TEST_EXPECTED_RANGE(RANGE_OVERFLOW,
+                              static_cast<Src>(DstLimits::max()));
+        } else {
+          TEST_EXPECTED_RANGE(RANGE_VALID, static_cast<Src>(DstLimits::max()));
+        }
+        TEST_EXPECTED_RANGE(RANGE_VALID, static_cast<Src>(DstLimits::min()));
+      }
     } else if (SrcLimits::is_signed) {
       TEST_EXPECTED_VALUE(-1, checked_dst - static_cast<Src>(1));
       TEST_EXPECTED_RANGE(RANGE_UNDERFLOW, SrcLimits::min());
@@ -428,6 +438,15 @@ struct TestNumericConversion<Dst, Src, SIGN_TO_UNSIGN_NARROW> {
       TEST_EXPECTED_RANGE(RANGE_OVERFLOW, SrcLimits::infinity());
       TEST_EXPECTED_RANGE(RANGE_UNDERFLOW, SrcLimits::infinity() * -1);
       TEST_EXPECTED_RANGE(RANGE_INVALID, SrcLimits::quiet_NaN());
+      if (!DstLimits::is_iec559) {
+        if (SrcLimits::digits < DstLimits::digits) {
+          TEST_EXPECTED_RANGE(RANGE_OVERFLOW,
+                              static_cast<Src>(DstLimits::max()));
+        } else {
+          TEST_EXPECTED_RANGE(RANGE_VALID, static_cast<Src>(DstLimits::max()));
+        }
+        TEST_EXPECTED_RANGE(RANGE_VALID, static_cast<Src>(DstLimits::min()));
+      }
     } else {
       TEST_EXPECTED_RANGE(RANGE_UNDERFLOW, SrcLimits::min());
     }
@@ -600,3 +619,77 @@ TEST(SafeNumerics, CastTests) {
   EXPECT_EQ(numeric_limits<int>::max(), saturated_cast<int>(double_large_int));
 }
 
+TEST(SafeNumerics, IsValueInRangeForNumericType) {

[brucedawson, 2015/09/11 23:23:27]

An additional class of tests would be to generate the various maximums and
confirm that that value converts to float without rounding. This could be done
by going int->float->double and int->double and confirming that the results are
the same, or round-tripping, or doing the conversion and then checking
EM_INEXACT with controlfp to validate that the conversion is exact (eg. can
enable FP exceptions for EM_INEXACT so that we crash if the conversion rounds).

Unfortunately the fiddly IEEE exception stuff is probably all non-portable.

[jschuh, 2015/09/12 00:43:12]

Yup. In a previous iteration I had to add some platform-specific FP handling due
to compiler quirks. Now that I was able to remove it I have no intention of
bringing it back.

+  EXPECT_TRUE(IsValueInRangeForNumericType<uint32_t>(0));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint32_t>(1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint32_t>(2));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint32_t>(-1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint32_t>(0xffffffffu));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint32_t>(UINT64_C(0xffffffff)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint32_t>(UINT64_C(0x100000000)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint32_t>(UINT64_C(0x100000001)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint32_t>(
+      std::numeric_limits<int32_t>::min()));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint32_t>(
+      std::numeric_limits<int64_t>::min()));
+
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(0));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(2));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(-1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(0x7fffffff));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(0x7fffffffu));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(0x80000000u));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(0xffffffffu));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(INT64_C(0x80000000)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(INT64_C(0xffffffff)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(INT64_C(0x100000000)));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(
+      std::numeric_limits<int32_t>::min()));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int32_t>(
+      implicit_cast<int64_t>(std::numeric_limits<int32_t>::min())));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(
+      implicit_cast<int64_t>(std::numeric_limits<int32_t>::min()) - 1));
+  EXPECT_FALSE(IsValueInRangeForNumericType<int32_t>(
+      std::numeric_limits<int64_t>::min()));
+
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(0));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(2));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint64_t>(-1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(0xffffffffu));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(UINT64_C(0xffffffff)));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(UINT64_C(0x100000000)));
+  EXPECT_TRUE(IsValueInRangeForNumericType<uint64_t>(UINT64_C(0x100000001)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint64_t>(
+      std::numeric_limits<int32_t>::min()));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint64_t>(INT64_C(-1)));
+  EXPECT_FALSE(IsValueInRangeForNumericType<uint64_t>(
+      std::numeric_limits<int64_t>::min()));
+
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(0));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(2));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(-1));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(0x7fffffff));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(0x7fffffffu));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(0x80000000u));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(0xffffffffu));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(INT64_C(0x80000000)));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(INT64_C(0xffffffff)));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(INT64_C(0x100000000)));
+  EXPECT_TRUE(
+      IsValueInRangeForNumericType<int64_t>(INT64_C(0x7fffffffffffffff)));
+  EXPECT_TRUE(
+      IsValueInRangeForNumericType<int64_t>(UINT64_C(0x7fffffffffffffff)));
+  EXPECT_FALSE(
+      IsValueInRangeForNumericType<int64_t>(UINT64_C(0x8000000000000000)));
+  EXPECT_FALSE(
+      IsValueInRangeForNumericType<int64_t>(UINT64_C(0xffffffffffffffff)));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(
+      std::numeric_limits<int32_t>::min()));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(
+      implicit_cast<int64_t>(std::numeric_limits<int32_t>::min())));
+  EXPECT_TRUE(IsValueInRangeForNumericType<int64_t>(
+      std::numeric_limits<int64_t>::min()));
+}