vulkan: add 1.1 shader compatibility mode

if GGML_VULKAN_MIN_1_1 is defined:

 - rte shaders will be built with 1.1 API and "SPV_KHR_float_controls"
   spirv extension.
 - all no _cm2 shaders will be built with 1.1 API

No changes if GGML_VULKAN_MIN_1_1 is not defined (default).

ggml/CMakeLists.txt

@@ -222,6 +222,7 @@ option(GGML_VULKAN_MEMORY_DEBUG             "ggml: enable Vulkan memory debug ou
 option(GGML_VULKAN_SHADER_DEBUG_INFO        "ggml: enable Vulkan shader debug info"           OFF)
 option(GGML_VULKAN_VALIDATE                 "ggml: enable Vulkan validation"                  OFF)
 option(GGML_VULKAN_RUN_TESTS                "ggml: run Vulkan tests"                          OFF)
+option(GGML_VULKAN_MIN_1_1                  "ggml: target Vulkan 1.1 minimum (SPIR-V 1.3)"    OFF)
 option(GGML_WEBGPU                          "ggml: use WebGPU"                                OFF)
 option(GGML_WEBGPU_DEBUG                    "ggml: enable WebGPU debug output"                OFF)
 option(GGML_WEBGPU_CPU_PROFILE              "ggml: enable WebGPU profiling (CPU)"             OFF)

ggml/src/ggml-vulkan/CMakeLists.txt

@@ -112,6 +112,11 @@ if (Vulkan_FOUND)
         list(APPEND VULKAN_SHADER_GEN_CMAKE_ARGS -DGGML_VULKAN_SHADER_DEBUG_INFO=ON)
     endif()
 
+    if (GGML_VULKAN_MIN_1_1)
+        add_compile_definitions(GGML_VULKAN_MIN_1_1)
+        list(APPEND VULKAN_SHADER_GEN_CMAKE_ARGS -DGGML_VULKAN_MIN_1_1=ON)
+    endif()
+
     if (GGML_VULKAN_VALIDATE)
         add_compile_definitions(GGML_VULKAN_VALIDATE)
     endif()

ggml/src/ggml-vulkan/vulkan-shaders/CMakeLists.txt

@@ -23,6 +23,9 @@ if (GGML_VULKAN_SHADER_DEBUG_INFO)
     add_compile_definitions(GGML_VULKAN_SHADER_DEBUG_INFO)
     message(STATUS "Enabling shader debug info")
 endif()
+if (GGML_VULKAN_MIN_1_1)
+    add_compile_definitions(GGML_VULKAN_MIN_1_1)
+endif()
 
 set(TARGET vulkan-shaders-gen)
 add_executable(${TARGET} vulkan-shaders-gen.cpp)

ggml/src/ggml-vulkan/vulkan-shaders/rte.glsl

@@ -1,5 +1,9 @@
 
 #if RTE16
 #extension GL_EXT_spirv_intrinsics : enable
-spirv_execution_mode(capabilities = [4467], 4462, 16); // RoundingModeRTE, 16 bits
+spirv_execution_mode(
+#ifdef VULKAN11_RTE
+    extensions = ["SPV_KHR_float_controls"],
+#endif
+    capabilities = [4467], 4462, 16); // RoundingModeRTE, 16 bits
 #endif // RTE16

ggml/src/ggml-vulkan/vulkan-shaders/vulkan-shaders-gen.cpp

@@ -322,7 +322,21 @@ compile_count_guard acquire_compile_slot() {
 }
 
 void string_to_spv_func(std::string name, std::string in_path, std::string out_path, std::map<std::string, std::string> defines, bool coopmat, bool dep_file, compile_count_guard slot) {
-    std::string target_env = (name.find("_cm2") != std::string::npos) ? "--target-env=vulkan1.3" : "--target-env=vulkan1.2";
+    std::string target_env;
+    bool is_vulkan11;
+#ifdef GGML_VULKAN_MIN_1_1
+    // Vulkan 1.1 compatibility mode
+    if (name.find("_cm2") != std::string::npos) {
+        target_env = "--target-env=vulkan1.3";
+        is_vulkan11 = false;
+    } else {
+        target_env = "--target-env=vulkan1.1";
+        is_vulkan11 = true;
+    }
+#else
+    target_env = (name.find("_cm2") != std::string::npos) ? "--target-env=vulkan1.3" : "--target-env=vulkan1.2";
+    is_vulkan11 = false;
+#endif
 
     #ifdef _WIN32
         std::vector<std::string> cmd = {GLSLC, "-fshader-stage=compute", target_env, "\"" + in_path + "\"", "-o", "\"" + out_path + "\""};
@@ -333,7 +347,13 @@ void string_to_spv_func(std::string name, std::string in_path, std::string out_p
     // disable spirv-opt for coopmat shaders for https://github.com/ggerganov/llama.cpp/issues/10734
     // disable spirv-opt for bf16 shaders for https://github.com/ggml-org/llama.cpp/issues/15344
     // disable spirv-opt for rope shaders for https://github.com/ggml-org/llama.cpp/issues/16860
-    if (!coopmat && name.find("bf16") == std::string::npos && name.find("rope") == std::string::npos) {
+    // disable spirv-opt for RTE shaders with vulkan1.1: spirv-opt rejects RoundingModeRTE with vulkan1.1 target
+    bool has_rte = (name.find("_rte") != std::string::npos) ||
+                   (defines.find("RTE16") != defines.end() && defines.at("RTE16") == "1");
+    if (!coopmat &&
+        name.find("bf16") == std::string::npos &&
+        name.find("rope") == std::string::npos &&
+        !(has_rte && is_vulkan11)) {
         cmd.push_back("-O");
     }
 
@@ -351,6 +371,11 @@ void string_to_spv_func(std::string name, std::string in_path, std::string out_p
         cmd.push_back("-g");
     #endif
 
+    // Need SPV_KHR_float_controls extension for Vulkan 1.1 RTE shaders
+    if (is_vulkan11 && has_rte) {
+        cmd.push_back("-DVULKAN11_RTE=1");
+    }
+
     for (const auto& define : defines) {
         cmd.push_back("-D" + define.first + "=" + define.second);
     }