From 574eb984df50f8d6850df20b02ad7c36ad13fda5 Mon Sep 17 00:00:00 2001
From: Oliver Simons <osimons@nvidia.com>
Date: Thu, 1 Oct 2026 17:51:48 +0200
Subject: [PATCH] Add supported for strided copies to/from FP8 in CPU

---
 ggml/src/ggml-cpu/common.h | 14 ++++++++++++++
 ggml/src/ggml-cpu/ops.cpp  | 10 +++++++++-
 tests/test-backend-ops.cpp | 10 ++++++++++
 3 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/ggml/src/ggml-cpu/common.h b/ggml/src/ggml-cpu/common.h
index abbadc359c..2c62e6976f 100644
--- a/ggml/src/ggml-cpu/common.h
+++ b/ggml/src/ggml-cpu/common.h
@@ -43,6 +43,14 @@ static inline float f32_to_f32(float x) {
     return x;
 }
 
+static inline float f8_e4m3_to_f32(ggml_fp8_e4m3_t x) {
+    return ggml_f8_e4m3_to_fp32(x.bits);
+}
+
+static inline ggml_fp8_e4m3_t f32_to_f8_e4m3(float x) {
+    return { ggml_fp32_to_f8_e4m3(x) };
+}
+
 // TODO - merge this into the traits table, after using row-based conversions
 template <class T>
 struct type_conversion_table;
@@ -65,6 +73,12 @@ struct type_conversion_table<ggml_bf16_t> {
     static constexpr ggml_bf16_t (*from_f32)(float) = f32_to_bf16;
 };
 
+template <>
+struct type_conversion_table<ggml_fp8_e4m3_t> {
+    static constexpr float (*to_f32)(ggml_fp8_e4m3_t) = f8_e4m3_to_f32;
+    static constexpr ggml_fp8_e4m3_t (*from_f32)(float) = f32_to_f8_e4m3;
+};
+
 template <>
 struct type_conversion_table<int32_t> {
     static constexpr float (*to_f32)(int32_t) = i32_to_f32;
diff --git a/ggml/src/ggml-cpu/ops.cpp b/ggml/src/ggml-cpu/ops.cpp
index 69b7e02878..69cb3a5f6f 100644
--- a/ggml/src/ggml-cpu/ops.cpp
+++ b/ggml/src/ggml-cpu/ops.cpp
@@ -540,6 +540,7 @@ void ggml_compute_forward_dup(
                 /**/ if (dst->type == GGML_TYPE_F16)  ggml_compute_forward_dup_flt<ggml_fp16_t, ggml_fp16_t>(params, dst);
                 else if (dst->type == GGML_TYPE_BF16) ggml_compute_forward_dup_flt<ggml_fp16_t, ggml_bf16_t>(params, dst);
                 else if (dst->type == GGML_TYPE_F32)  ggml_compute_forward_dup_flt<ggml_fp16_t, float      >(params, dst);
+                else if (dst->type == GGML_TYPE_F8_E4M3) ggml_compute_forward_dup_flt<ggml_fp16_t, ggml_fp8_e4m3_t>(params, dst);
                 else ggml_compute_forward_dup_to_q<ggml_fp16_t>(params, dst);
             } break;
         case GGML_TYPE_BF16:
@@ -547,6 +548,7 @@ void ggml_compute_forward_dup(
                 /**/ if (dst->type == GGML_TYPE_F16)  ggml_compute_forward_dup_flt<ggml_bf16_t, ggml_fp16_t>(params, dst);
                 else if (dst->type == GGML_TYPE_BF16) ggml_compute_forward_dup_flt<ggml_bf16_t, ggml_bf16_t>(params, dst);
                 else if (dst->type == GGML_TYPE_F32)  ggml_compute_forward_dup_flt<ggml_bf16_t, float      >(params, dst);
+                else if (dst->type == GGML_TYPE_F8_E4M3) ggml_compute_forward_dup_flt<ggml_bf16_t, ggml_fp8_e4m3_t>(params, dst);
                 else ggml_compute_forward_dup_to_q<ggml_bf16_t>(params, dst);
             } break;
         case GGML_TYPE_F32:
@@ -554,9 +556,15 @@ void ggml_compute_forward_dup(
                 /**/ if (dst->type == GGML_TYPE_F16)  ggml_compute_forward_dup_flt<float, ggml_fp16_t>(params, dst);
                 else if (dst->type == GGML_TYPE_BF16) ggml_compute_forward_dup_flt<float, ggml_bf16_t>(params, dst);
                 else if (dst->type == GGML_TYPE_F32)  ggml_compute_forward_dup_flt<float, float      >(params, dst);
+                else if (dst->type == GGML_TYPE_F8_E4M3) ggml_compute_forward_dup_flt<float, ggml_fp8_e4m3_t>(params, dst);
                 else if (dst->type == GGML_TYPE_I32)  ggml_compute_forward_dup_flt<float, int32_t    >(params, dst);
                 else ggml_compute_forward_dup_to_q<float>(params, dst);
             } break;
+        case GGML_TYPE_F8_E4M3:
+            {
+                if (dst->type == GGML_TYPE_F32) ggml_compute_forward_dup_flt<ggml_fp8_e4m3_t, float>(params, dst);
+                else GGML_ABORT("not implemented");
+            } break;
         case GGML_TYPE_I32:
             {
                 if (dst->type == GGML_TYPE_F32) ggml_compute_forward_dup_flt<int32_t, float>(params, dst);
@@ -564,7 +572,7 @@ void ggml_compute_forward_dup(
             } break;
         default:
             {
-                if ((ggml_is_quantized(src0->type) || src0->type == GGML_TYPE_F8_E4M3) && dst->type == GGML_TYPE_F32) {
+                if (ggml_is_quantized(src0->type) && dst->type == GGML_TYPE_F32) {
                     ggml_compute_forward_dup_from_q(params, dst);
                     break;
                 }
diff --git a/tests/test-backend-ops.cpp b/tests/test-backend-ops.cpp
index 889e28881f..e21f817e4c 100644
--- a/tests/test-backend-ops.cpp
+++ b/tests/test-backend-ops.cpp
@@ -9804,6 +9804,16 @@ static std::vector<std::unique_ptr<test_case>> make_test_cases_eval() {
             test_cases.emplace_back(new test_cpy(type_src, type_dst, {256, 2, 3, 4}, {-1,-1,-1,-1}, {1, 0, 2, 3})); // cpy not-contiguous
         }
     }
+    for (ggml_type type_src : {GGML_TYPE_F32, GGML_TYPE_F16, GGML_TYPE_BF16}) {
+        test_cases.emplace_back(new test_cpy(type_src, GGML_TYPE_F8_E4M3, {32, 2, 3, 4}, {-1,-1,-1,-1}, {0, 0, 0, 0}, {0, 0, 0, 0}, false, {64, 2, 3, 4}));
+        test_cases.emplace_back(new test_cpy(type_src, GGML_TYPE_F8_E4M3, {32, 2, 3, 4}, {-1,-1,-1,-1}, {1, 0, 2, 3}, {1, 0, 2, 3}));
+        test_cases.emplace_back(new test_cpy(type_src, GGML_TYPE_F8_E4M3, {32, 2, 3, 4}, {16, 4, 3, 4}, {1, 0, 2, 3}, {0, 2, 1, 3}));
+    }
+
+    test_cases.emplace_back(new test_cpy(GGML_TYPE_F8_E4M3, GGML_TYPE_F32, {32, 2, 3, 4}, {-1,-1,-1,-1}, {0, 0, 0, 0}, {0, 0, 0, 0}, false, {64, 2, 3, 4}));
+    test_cases.emplace_back(new test_cpy(GGML_TYPE_F8_E4M3, GGML_TYPE_F32, {32, 2, 3, 4}, {-1,-1,-1,-1}, {1, 0, 2, 3}, {1, 0, 2, 3}));
+    test_cases.emplace_back(new test_cpy(GGML_TYPE_F8_E4M3, GGML_TYPE_F32, {32, 2, 3, 4}, {16, 4, 3, 4}, {1, 0, 2, 3}, {0, 2, 1, 3}));
+
     // quant block count not a multiple of the kernel block size
     test_cases.emplace_back(new test_cpy(GGML_TYPE_F32, GGML_TYPE_Q4_0, {96, 1, 1, 1}));
     test_cases.emplace_back(new test_cpy(GGML_TYPE_Q4_0, GGML_TYPE_F32, {96, 1, 1, 1}));