[llvm] r264219 - APFloat: Fix signalling nans for scalbn

[Matt Arsenault via llvm-commits]

Author: arsenm
Date: Wed Mar 23 18:51:45 2016
New Revision: 264219

URL: http://llvm.org/viewvc/llvm-project?rev=264219&view=rev
Log:
APFloat: Fix signalling nans for scalbn

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=264219&r1=264218&r2=264219&view=diff
==============================================================================
--- llvm/trunk/lib/Support/APFloat.cpp (original)
+++ llvm/trunk/lib/Support/APFloat.cpp Wed Mar 23 18:51:45 2016
@@ -3984,6 +3984,8 @@ APFloat llvm::scalbn(APFloat X, int Exp,
   // Clamp to one past the range ends to let normalize handle overlflow.
   X.exponent += std::min(std::max(Exp, -MaxIncrement - 1), MaxIncrement);
   X.normalize(RoundingMode, lfExactlyZero);
+  if (X.isNaN())
+    X.makeQuiet();
   return X;
 }
 

Modified: llvm/trunk/unittests/ADT/APFloatTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/ADT/APFloatTest.cpp?rev=264219&r1=264218&r2=264219&view=diff
==============================================================================
--- llvm/trunk/unittests/ADT/APFloatTest.cpp (original)
+++ llvm/trunk/unittests/ADT/APFloatTest.cpp Wed Mar 23 18:51:45 2016
@@ -2890,7 +2890,22 @@ TEST(APFloatTest, scalbn) {
   EXPECT_TRUE(MZero.bitwiseIsEqual(scalbn(MZero, 0, RM)));
   EXPECT_TRUE(QPNaN.bitwiseIsEqual(scalbn(QPNaN, 0, RM)));
   EXPECT_TRUE(QMNaN.bitwiseIsEqual(scalbn(QMNaN, 0, RM)));
-  EXPECT_TRUE(SNaN.bitwiseIsEqual(scalbn(SNaN, 0, RM)));
+  EXPECT_FALSE(scalbn(SNaN, 0, RM).isSignaling());
+
+  APFloat ScalbnSNaN = scalbn(SNaN, 1, RM);
+  EXPECT_TRUE(ScalbnSNaN.isNaN() && !ScalbnSNaN.isSignaling());
+
+  // Make sure highest bit of payload is preserved.
+  const APInt Payload(64, (UINT64_C(1) << 50) |
+                      (UINT64_C(1) << 49) |
+                      (UINT64_C(1234) << 32) |
+                      1);
+
+  APFloat SNaNWithPayload = APFloat::getSNaN(APFloat::IEEEdouble, false,
+                                             &Payload);
+  APFloat QuietPayload = scalbn(SNaNWithPayload, 1, RM);
+  EXPECT_TRUE(QuietPayload.isNaN() && !QuietPayload.isSignaling());
+  EXPECT_EQ(Payload, QuietPayload.bitcastToAPInt().getLoBits(51));
 
   EXPECT_TRUE(PInf.bitwiseIsEqual(
                 scalbn(APFloat(APFloat::IEEEsingle, "0x1p+0"), 128, RM)));