commit ca4d2e60ea36bd4f532ab5d52f5b4394a33be819
author Michael Gottesman <mgottesman@apple.com> Sat Jul 27 21:49:25 2013 +0000
committer Michael Gottesman <mgottesman@apple.com> Sat Jul 27 21:49:25 2013 +0000
tree 73ef5bba6021cf78f8b7149eb5219108d4b214b6
parent 060d34b1cf9a1185b24db95925f23d9fbadce078

[APFloat] Make all arithmetic operations with NaN produce positive NaNs.

IEEE-754R 1.4 Exclusions states that IEEE-754R does not specify the
interpretation of the sign of NaNs. In order to remove an irrelevant
variable that most floating point implementations do not use,
standardize add, sub, mul, div, mod so that operating anything with
NaN always yields a positive NaN.

In a later commit I am going to update the APIs for creating NaNs so
that one can not even create a negative NaN.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187314 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Support/APFloat.cpp

diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index bc8e1d0..34bc6b6 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -1354,6 +1354,7 @@
   case PackCategoriesIntoKey(fcZero, fcNaN):
   case PackCategoriesIntoKey(fcNormal, fcNaN):
   case PackCategoriesIntoKey(fcInfinity, fcNaN):
+    sign = false;
     category = fcNaN;
     copySignificand(rhs);
     return opOK;
@@ -1472,11 +1473,13 @@
   case PackCategoriesIntoKey(fcNaN, fcNormal):
   case PackCategoriesIntoKey(fcNaN, fcInfinity):
   case PackCategoriesIntoKey(fcNaN, fcNaN):
+    sign = false;
     return opOK;
 
   case PackCategoriesIntoKey(fcZero, fcNaN):
   case PackCategoriesIntoKey(fcNormal, fcNaN):
   case PackCategoriesIntoKey(fcInfinity, fcNaN):
+    sign = false;
     category = fcNaN;
     copySignificand(rhs);
     return opOK;
@@ -1510,21 +1513,20 @@
   default:
     llvm_unreachable(0);
 
-  case PackCategoriesIntoKey(fcNaN, fcZero):
-  case PackCategoriesIntoKey(fcNaN, fcNormal):
-  case PackCategoriesIntoKey(fcNaN, fcInfinity):
-  case PackCategoriesIntoKey(fcNaN, fcNaN):
-  case PackCategoriesIntoKey(fcInfinity, fcZero):
-  case PackCategoriesIntoKey(fcInfinity, fcNormal):
-  case PackCategoriesIntoKey(fcZero, fcInfinity):
-  case PackCategoriesIntoKey(fcZero, fcNormal):
-    return opOK;
-
   case PackCategoriesIntoKey(fcZero, fcNaN):
   case PackCategoriesIntoKey(fcNormal, fcNaN):
   case PackCategoriesIntoKey(fcInfinity, fcNaN):
     category = fcNaN;
     copySignificand(rhs);
+  case PackCategoriesIntoKey(fcNaN, fcZero):
+  case PackCategoriesIntoKey(fcNaN, fcNormal):
+  case PackCategoriesIntoKey(fcNaN, fcInfinity):
+  case PackCategoriesIntoKey(fcNaN, fcNaN):
+    sign = false;
+  case PackCategoriesIntoKey(fcInfinity, fcZero):
+  case PackCategoriesIntoKey(fcInfinity, fcNormal):
+  case PackCategoriesIntoKey(fcZero, fcInfinity):
+  case PackCategoriesIntoKey(fcZero, fcNormal):
     return opOK;
 
   case PackCategoriesIntoKey(fcNormal, fcInfinity):
@@ -1564,6 +1566,7 @@
   case PackCategoriesIntoKey(fcZero, fcNaN):
   case PackCategoriesIntoKey(fcNormal, fcNaN):
   case PackCategoriesIntoKey(fcInfinity, fcNaN):
+    sign = false;
     category = fcNaN;
     copySignificand(rhs);
     return opOK;