Fix IEEE 754 NaN comparisons in constant folding (#7721)

* Fix IEEE 754 NaN comparisons in constant folding

Added proper NaN handling in SCCP optimization pass to follow IEEE 754 standard:
- NaN \!= any value returns true
- All other NaN comparisons return false
- Added double precision NaN detection support
- Fixed type detection to check operands instead of result type

* Avoid differentiating NaN and non-NaN cases

* format code (#76)

---------

Co-authored-by: slangbot <ellieh+slangbot@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/source/core/slang-math.h b/source/core/slang-math.h
index e977dc37d..c7e77fce5 100644
--- a/source/core/slang-math.h
+++ b/source/core/slang-math.h
@@ -106,8 +106,10 @@ public:
     }
 
     static inline int IsNaN(float x) { return std::isnan(x); }
+    static inline int IsNaN(double x) { return std::isnan(x); }
 
     static inline int IsInf(float x) { return std::isinf(x); }
+    static inline int IsInf(double x) { return std::isinf(x); }
 
     static inline unsigned int Ones32(unsigned int x)
     {