[llvm-commits] [llvm] r173459 - in /llvm/trunk: lib/Support/APFloat.cpp unittests/ADT/APFloatTest.cpp

[Benjamin Kramer]

Author: d0k
Date: Fri Jan 25 11:01:00 2013
New Revision: 173459

URL: http://llvm.org/viewvc/llvm-project?rev=173459&view=rev
Log:
APFloat: Make sure that we get a well-formed x87 NaN when converting from a smaller type.

Fixes PR15054.

Modified:
    llvm/trunk/lib/Support/APFloat.cpp
    llvm/trunk/unittests/ADT/APFloatTest.cpp

Modified: llvm/trunk/lib/Support/APFloat.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/APFloat.cpp?rev=173459&r1=173458&r2=173459&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APFloat.cpp (original)
+++ llvm/trunk/lib/Support/APFloat.cpp Fri Jan 25 11:01:00 2013
@@ -1913,6 +1913,12 @@
     *losesInfo = (fs != opOK);
   } else if (category == fcNaN) {
     *losesInfo = lostFraction != lfExactlyZero || X86SpecialNan;
+
+    // For x87 extended precision, we want to make a NaN, not a special NaN if
+    // the input wasn't special either.
+    if (!X86SpecialNan && semantics == &APFloat::x87DoubleExtended)
+      APInt::tcSetBit(significandParts(), semantics->precision - 1);
+
     // gcc forces the Quiet bit on, which means (float)(double)(float_sNan)
     // does not give you back the same bits.  This is dubious, and we
     // don't currently do it.  You're really supposed to get

Modified: llvm/trunk/unittests/ADT/APFloatTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/APFloatTest.cpp?rev=173459&r1=173458&r2=173459&view=diff
==============================================================================
--- llvm/trunk/unittests/ADT/APFloatTest.cpp (original)
+++ llvm/trunk/unittests/ADT/APFloatTest.cpp Fri Jan 25 11:01:00 2013
@@ -794,6 +794,32 @@
   test.convert(APFloat::IEEEdouble, APFloat::rmNearestTiesToEven, &losesInfo);
   EXPECT_EQ(4294967295.0, test.convertToDouble());
   EXPECT_FALSE(losesInfo);
+
+  test = APFloat::getSNaN(APFloat::IEEEsingle);
+  APFloat X87SNaN = APFloat::getSNaN(APFloat::x87DoubleExtended);
+  test.convert(APFloat::x87DoubleExtended, APFloat::rmNearestTiesToEven,
+               &losesInfo);
+  EXPECT_TRUE(test.bitwiseIsEqual(X87SNaN));
+  EXPECT_FALSE(losesInfo);
+
+  test = APFloat::getQNaN(APFloat::IEEEsingle);
+  APFloat X87QNaN = APFloat::getQNaN(APFloat::x87DoubleExtended);
+  test.convert(APFloat::x87DoubleExtended, APFloat::rmNearestTiesToEven,
+               &losesInfo);
+  EXPECT_TRUE(test.bitwiseIsEqual(X87QNaN));
+  EXPECT_FALSE(losesInfo);
+
+  test = APFloat::getSNaN(APFloat::x87DoubleExtended);
+  test.convert(APFloat::x87DoubleExtended, APFloat::rmNearestTiesToEven,
+               &losesInfo);
+  EXPECT_TRUE(test.bitwiseIsEqual(X87SNaN));
+  EXPECT_FALSE(losesInfo);
+
+  test = APFloat::getQNaN(APFloat::x87DoubleExtended);
+  test.convert(APFloat::x87DoubleExtended, APFloat::rmNearestTiesToEven,
+               &losesInfo);
+  EXPECT_TRUE(test.bitwiseIsEqual(X87QNaN));
+  EXPECT_FALSE(losesInfo);
 }
 
 TEST(APFloatTest, PPCDoubleDouble) {