Fix Cast Float to Int overflows

- For Casting from Float to Integers, if the input float is greater
than INT_MAX, an overflow will happen when calling rint which causes the
clipplings to be ineffectives
- Moved all the range checks and clippings before rint to avoid this
  issue

Signed-off-by: Jerry Ge <jerry.ge@arm.com>
Change-Id: Ic189d59685b6d36464e3ef26766665148a660a14

1 files changed, 23 insertions, 10 deletions

diff --git a/reference_model/src/ops/type_conversion.cc b/reference_model/src/ops/type_conversion.cc
index 17abaf7..484f768 100644
--- a/reference_model/src/ops/type_conversion.cc
+++ b/reference_model/src/ops/type_conversion.cc
@@ -1,5 +1,5 @@
 
-// Copyright (c) 2020-2023, ARM Limited.
+// Copyright (c) 2020-2024, ARM Limited.
 //
 //    Licensed under the Apache License, Version 2.0 (the "License");
 //    you may not use this file except in compliance with the License.
@@ -459,10 +459,15 @@ CastHelper<TOSA_REF_TYPE_FP16, OutDtype>::CastHelper()
     fcn = [](float in) -> OutEigenType {
         // Cast from float representation back to half_float before rounding
         half_float::half h = half_float::half(in);
-        h                  = std::rint(h);
-        OutEigenType out   = half_float::half_cast<OutEigenType, half_float::half>(h);
-        out                = std::max<OutEigenType>(out, OutMin);
-        out                = std::min<OutEigenType>(out, OutMax);
+        if (h >= half_float::half(float(OutMax)))
+            return OutMax;
+
+        if (h <= half_float::half(float(OutMin)))
+            return OutMin;
+
+        h                = std::rint(h);
+        OutEigenType out = half_float::half_cast<OutEigenType, half_float::half>(h);
+
         return out;
     };
 }
@@ -478,9 +483,13 @@ CastHelper<TOSA_REF_TYPE_BF16, OutDtype>::CastHelper()
 {
     // bf16 data (stored as fp32) converted to integer
     fcn = [](float in) -> OutEigenType {
-        OutEigenType out = std::round(in);
-        out              = std::max<OutEigenType>(out, OutMin);
-        out              = std::min<OutEigenType>(out, OutMax);
+        if (in >= float(OutMax))
+            return OutMax;
+
+        if (in <= float(OutMin))
+            return OutMin;
+
+        OutEigenType out = std::rint(in);
         return out;
     };
 }
@@ -527,9 +536,13 @@ CastHelper<TOSA_REF_TYPE_FP64, OutDtype>::CastHelper()
         case TOSA_REF_TYPE_INT32:
             // fp64 data converted to integer
             fcn = [](InEigenType in) -> OutEigenType {
+                if (in >= double(OutMax))
+                    return OutMax;
+
+                if (in <= double(OutMin))
+                    return OutMin;
+
                 OutEigenType out = std::rint(in);
-                out              = std::max<OutEigenType>(out, OutMin);
-                out              = std::min<OutEigenType>(out, OutMax);
                 return out;
             };
             break;