[APFloat] Add support for operations on Signaling NaN

Fix PR30781

Differential Revision: https://reviews.llvm.org/D69774

Author: ekatz

llvm/lib/Support/APFloat.cpp

@@ -1439,25 +1439,26 @@ IEEEFloat::opStatus IEEEFloat::addOrSubtractSpecials(const IEEEFloat &rhs,
   default:
     llvm_unreachable(nullptr);
 
+  case PackCategoriesIntoKey(fcZero, fcNaN):
+  case PackCategoriesIntoKey(fcNormal, fcNaN):
+  case PackCategoriesIntoKey(fcInfinity, fcNaN):
+    assign(rhs);
+    LLVM_FALLTHROUGH;
   case PackCategoriesIntoKey(fcNaN, fcZero):
   case PackCategoriesIntoKey(fcNaN, fcNormal):
   case PackCategoriesIntoKey(fcNaN, fcInfinity):
   case PackCategoriesIntoKey(fcNaN, fcNaN):
+    if (isSignaling()) {
+      makeQuiet();
+      return opInvalidOp;
+    }
+    return rhs.isSignaling() ? opInvalidOp : opOK;
+
   case PackCategoriesIntoKey(fcNormal, fcZero):
   case PackCategoriesIntoKey(fcInfinity, fcNormal):
   case PackCategoriesIntoKey(fcInfinity, fcZero):
     return opOK;
 
-  case PackCategoriesIntoKey(fcZero, fcNaN):
-  case PackCategoriesIntoKey(fcNormal, fcNaN):
-  case PackCategoriesIntoKey(fcInfinity, fcNaN):
-    // We need to be sure to flip the sign here for subtraction because we
-    // don't have a separate negate operation so -NaN becomes 0 - NaN here.
-    sign = rhs.sign ^ subtract;
-    category = fcNaN;
-    copySignificand(rhs);
-    return opOK;
-
   case PackCategoriesIntoKey(fcNormal, fcInfinity):
   case PackCategoriesIntoKey(fcZero, fcInfinity):
     category = fcInfinity;
@@ -1562,20 +1563,22 @@ IEEEFloat::opStatus IEEEFloat::multiplySpecials(const IEEEFloat &rhs) {
   default:
     llvm_unreachable(nullptr);
 
-  case PackCategoriesIntoKey(fcNaN, fcZero):
-  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):
+    assign(rhs);
     sign = false;
-    category = fcNaN;
-    copySignificand(rhs);
-    return opOK;
+    LLVM_FALLTHROUGH;
+  case PackCategoriesIntoKey(fcNaN, fcZero):
+  case PackCategoriesIntoKey(fcNaN, fcNormal):
+  case PackCategoriesIntoKey(fcNaN, fcInfinity):
+  case PackCategoriesIntoKey(fcNaN, fcNaN):
+    sign ^= rhs.sign; // restore the original sign
+    if (isSignaling()) {
+      makeQuiet();
+      return opInvalidOp;
+    }
+    return rhs.isSignaling() ? opInvalidOp : opOK;
 
   case PackCategoriesIntoKey(fcNormal, fcInfinity):
   case PackCategoriesIntoKey(fcInfinity, fcNormal):
@@ -1607,15 +1610,20 @@ IEEEFloat::opStatus IEEEFloat::divideSpecials(const IEEEFloat &rhs) {
   case PackCategoriesIntoKey(fcZero, fcNaN):
   case PackCategoriesIntoKey(fcNormal, fcNaN):
   case PackCategoriesIntoKey(fcInfinity, fcNaN):
-    category = fcNaN;
-    copySignificand(rhs);
+    assign(rhs);
+    sign = false;
     LLVM_FALLTHROUGH;
   case PackCategoriesIntoKey(fcNaN, fcZero):
   case PackCategoriesIntoKey(fcNaN, fcNormal):
   case PackCategoriesIntoKey(fcNaN, fcInfinity):
   case PackCategoriesIntoKey(fcNaN, fcNaN):
-    sign = false;
-    LLVM_FALLTHROUGH;
+    sign ^= rhs.sign; // restore the original sign
+    if (isSignaling()) {
+      makeQuiet();
+      return opInvalidOp;
+    }
+    return rhs.isSignaling() ? opInvalidOp : opOK;
+
   case PackCategoriesIntoKey(fcInfinity, fcZero):
   case PackCategoriesIntoKey(fcInfinity, fcNormal):
   case PackCategoriesIntoKey(fcZero, fcInfinity):
@@ -1645,23 +1653,26 @@ IEEEFloat::opStatus IEEEFloat::modSpecials(const IEEEFloat &rhs) {
   default:
     llvm_unreachable(nullptr);
 
+  case PackCategoriesIntoKey(fcZero, fcNaN):
+  case PackCategoriesIntoKey(fcNormal, fcNaN):
+  case PackCategoriesIntoKey(fcInfinity, fcNaN):
+    assign(rhs);
+    LLVM_FALLTHROUGH;
   case PackCategoriesIntoKey(fcNaN, fcZero):
   case PackCategoriesIntoKey(fcNaN, fcNormal):
   case PackCategoriesIntoKey(fcNaN, fcInfinity):
   case PackCategoriesIntoKey(fcNaN, fcNaN):
+    if (isSignaling()) {
+      makeQuiet();
+      return opInvalidOp;
+    }
+    return rhs.isSignaling() ? opInvalidOp : opOK;
+
   case PackCategoriesIntoKey(fcZero, fcInfinity):
   case PackCategoriesIntoKey(fcZero, fcNormal):
   case PackCategoriesIntoKey(fcNormal, fcInfinity):
     return opOK;
 
-  case PackCategoriesIntoKey(fcZero, fcNaN):
-  case PackCategoriesIntoKey(fcNormal, fcNaN):
-  case PackCategoriesIntoKey(fcInfinity, fcNaN):
-    sign = false;
-    category = fcNaN;
-    copySignificand(rhs);
-    return opOK;
-
   case PackCategoriesIntoKey(fcNormal, fcZero):
   case PackCategoriesIntoKey(fcInfinity, fcZero):
   case PackCategoriesIntoKey(fcInfinity, fcNormal):