Add support for generating MIPS legacy NaN
Currently, the NaN values emitted for MIPS architectures do not cover
non-IEEE754-2008 compliant case. This change fixes the issue.
Patch by Vladimir Radosavljevic.
Differential Revision: http://reviews.llvm.org/D7882
llvm-svn: 230653
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 6569626..083572b 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -7590,10 +7590,23 @@
else if (S->getString().getAsInteger(0, fill))
return false;
- if (SNaN)
- Result = llvm::APFloat::getSNaN(Sem, false, &fill);
- else
- Result = llvm::APFloat::getQNaN(Sem, false, &fill);
+ if (Context.getTargetInfo().isNan2008()) {
+ if (SNaN)
+ Result = llvm::APFloat::getSNaN(Sem, false, &fill);
+ else
+ Result = llvm::APFloat::getQNaN(Sem, false, &fill);
+ } else {
+ // Prior to IEEE 754-2008, architectures were allowed to choose whether
+ // the first bit of their significand was set for qNaN or sNaN. MIPS chose
+ // a different encoding to what became a standard in 2008, and for pre-
+ // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
+ // sNaN. This is now known as "legacy NaN" encoding.
+ if (SNaN)
+ Result = llvm::APFloat::getQNaN(Sem, false, &fill);
+ else
+ Result = llvm::APFloat::getSNaN(Sem, false, &fill);
+ }
+
return true;
}