FP16 improvements

* Update FP16 resize to newest spec version
* Correct casting to fp16 for graphs of >1 ops

Change-Id: Iedff9a71eb7f72948b3c00a635bb0fd07d414bcd
Signed-off-by: James Ward <james.ward@arm.com>

4 files changed, 27 insertions, 19 deletions

diff --git a/reference_model/src/arith_util.h b/reference_model/src/arith_util.h
index 33bdeed..a75d7a3 100644
--- a/reference_model/src/arith_util.h
+++ b/reference_model/src/arith_util.h
@@ -30,17 +30,18 @@
 #include <fenv.h>
 #include <math.h>
 #define __STDC_LIMIT_MACROS    //enable min/max of plain data type
-#include "func_debug.h"
 #include "func_config.h"
+#include "func_debug.h"
+#include "half.hpp"
 #include "inttypes.h"
 #include "tosa_generated.h"
+#include <Eigen/Core>
+#include <bitset>
 #include <cassert>
 #include <iostream>
 #include <limits>
 #include <stdint.h>
 #include <typeinfo>
-#include <Eigen/Core>
-#include <bitset>
 
 using namespace tosa;
 using namespace std;
@@ -269,8 +270,12 @@ float fpTrunc(float f_in)
             truncateFloatToBFloat(&f_in, 1);
             break;
         case DType_FP16:
-            // TODO(jw): implement FP16 truncate function (no-op placeholder for now)
-            break;
+            // Cast to temporary float16 value before casting back to float32
+            {
+                half_float::half h = half_float::half_cast<half_float::half, float>(f_in);
+                f_in               = half_float::half_cast<float, half_float::half>(h);
+                break;
+            }
         case DType_FP32:
             // No-op for fp32
             break;
diff --git a/reference_model/src/ops/image.cc b/reference_model/src/ops/image.cc
index 66efee0..a1a4474 100644
--- a/reference_model/src/ops/image.cc
+++ b/reference_model/src/ops/image.cc
@@ -15,6 +15,7 @@
 
 #include "image.h"
 #include "arith_util.h"
+#include "half.hpp"
 
 #include <type_traits>
 
@@ -159,7 +160,8 @@ int OpResize<InDtype, OutDtype, resize_t>::eval()
 
                     resize_t dy;
                     resize_t dx;
-                    if (std::is_floating_point<resize_t>::value || (typeid(resize_t) == typeid(Eigen::bfloat16)))
+                    if (std::is_floating_point<resize_t>::value || (typeid(resize_t) == typeid(Eigen::bfloat16)) ||
+                        (typeid(resize_t) == typeid(half_float::half)))
                     {
                         dy = (resize_t)(fy - iy);
                         dx = (resize_t)(fx - ix);
@@ -190,14 +192,15 @@ int OpResize<InDtype, OutDtype, resize_t>::eval()
                             acc += (OutEigenType)v10 * dy * (1.0 - dx);
                             acc += (OutEigenType)v11 * dy * dx;
                         }
-                        else if ((typeid(resize_t) == typeid(Eigen::bfloat16)))
+                        else if ((typeid(resize_t) == typeid(Eigen::bfloat16)) ||
+                                 (typeid(resize_t) == typeid(half_float::half)))
                         {
-                            Eigen::bfloat16 bf16_acc;
-                            bf16_acc = (Eigen::bfloat16)v00 * (Eigen::bfloat16)(1.0 - dy) * (Eigen::bfloat16)(1.0 - dx);
-                            bf16_acc += (Eigen::bfloat16)v01 * (Eigen::bfloat16)(1.0 - dy) * (Eigen::bfloat16)dx;
-                            bf16_acc += (Eigen::bfloat16)v10 * (Eigen::bfloat16)dy * (Eigen::bfloat16)(1.0 - dx);
-                            bf16_acc += (Eigen::bfloat16)v11 * (Eigen::bfloat16)dy * (Eigen::bfloat16)dx;
-                            acc = (float)bf16_acc;
+                            resize_t f16_acc;
+                            f16_acc = (resize_t)v00 * (resize_t)(1.0 - dy) * (resize_t)(1.0 - dx);
+                            f16_acc += (resize_t)v01 * (resize_t)(1.0 - dy) * (resize_t)dx;
+                            f16_acc += (resize_t)v10 * (resize_t)dy * (resize_t)(1.0 - dx);
+                            f16_acc += (resize_t)v11 * (resize_t)dy * (resize_t)dx;
+                            acc = (float)f16_acc;
                         }
                         else
                         {
@@ -210,7 +213,8 @@ int OpResize<InDtype, OutDtype, resize_t>::eval()
                     else
                     {
                         ASSERT_MSG(mode == ResizeMode_NEAREST, "OpResize: invalid mode");
-                        if (std::is_floating_point<resize_t>::value || (typeid(resize_t) == typeid(Eigen::bfloat16)))
+                        if (std::is_floating_point<resize_t>::value || (typeid(resize_t) == typeid(Eigen::bfloat16)) ||
+                            (typeid(resize_t) == typeid(half_float::half)))
                         {
                             iy = (dy >= 0.5) ? iy1 : iy0;
                             ix = (dx >= 0.5) ? ix1 : ix0;
@@ -236,6 +240,6 @@ DEF_INSTANTIATE_THREE_TYPE(OpResize, INT8, INT32, int16_t);
 DEF_INSTANTIATE_THREE_TYPE(OpResize, INT8, INT8, int16_t);
 DEF_INSTANTIATE_THREE_TYPE(OpResize, INT16, INT48, int16_t);
 DEF_INSTANTIATE_THREE_TYPE(OpResize, INT16, INT16, int16_t);
-DEF_INSTANTIATE_THREE_TYPE(OpResize, FP16, FP16, float);
+DEF_INSTANTIATE_THREE_TYPE(OpResize, FP16, FP16, half_float::half);
 DEF_INSTANTIATE_THREE_TYPE(OpResize, BF16, BF16, Eigen::bfloat16);
 DEF_INSTANTIATE_THREE_TYPE(OpResize, FP32, FP32, float);
diff --git a/reference_model/src/ops/op_factory.h b/reference_model/src/ops/op_factory.h
index f399bd1..f4177db 100644
--- a/reference_model/src/ops/op_factory.h
+++ b/reference_model/src/ops/op_factory.h
@@ -108,7 +108,7 @@
 #define DEF_FACTORY_TWO_TYPE_RESIZE_FP16(OP, DTYPE1, DTYPE2)                                                           \
     if (inputDType == DType_##DTYPE1 && outputDType == DType_##DTYPE2)                                                 \
     {                                                                                                                  \
-        return new OP<DType_##DTYPE1, DType_##DTYPE2, float>(sgt, attribute, id);                                      \
+        return new OP<DType_##DTYPE1, DType_##DTYPE2, half_float::half>(sgt, attribute, id);                           \
     }
 
 #define DEF_FACTORY_TWO_TYPE_RESIZE_BF16(OP, DTYPE1, DTYPE2)                                                           \
diff --git a/reference_model/src/tensor.cc b/reference_model/src/tensor.cc
index 4eaf21d..e9598c4 100644
--- a/reference_model/src/tensor.cc
+++ b/reference_model/src/tensor.cc
@@ -159,8 +159,7 @@ int TosaReference::Tensor::readFromNpyFile(const char* filename)
     switch (dtype)
     {
         case DType_FP16:
-            // Convert from fp16 to fp32
-            //TODO(jw): remove this once we cast to fp16 in register_fcn/eval
+            // Convert from fp16 to fp32 so that fp16 values can be manipulated as float
             for (uint32_t i=0; i < elements; i++) {
                 fdatabuf[i] = half_float::half_cast<float, half_float::half>(f16databuf[i]);
             }
@@ -277,7 +276,7 @@ int TosaReference::Tensor::writeToNpyFile(const char* filename) const
                 free(f16databuf);
                 return 1;
             }
-            // Convert fp32 to fp16
+            // Convert fp32 to fp16 so that output file contains valid fp16 data
             for (uint32_t i=0; i < elements; i++) {
                 f16databuf[i] = half_float::half_cast<half_float::half, float>(fdatabuf[i]);
             }