issue/1033 add flash-attn compile target

include/infinicore/adaptor/aten_adaptor.hpp

+#ifdef ENABLE_ATEN
 #pragma once
 #include "../context/context.hpp"
 #include "../tensor.hpp"
 
 #include <ATen/ATen.h>
 
+#ifdef ENABLE_NVIDIA_API
 #include <ATen/cuda/CUDAContext.h>
 #include <c10/cuda/CUDAGuard.h>
+#endif
 
 namespace infinicore::adaptor {
 inline at::ScalarType to_at_dtype(DataType dtype) {
@@ -37,5 +40,9 @@ inline at::Device to_at_device(const Device &device) {
 
 at::Tensor to_aten_tensor(const infinicore::Tensor &t);
 
+#ifdef ENABLE_NVIDIA_API
 c10::cuda::CUDAStream get_cuda_stream();
-} // namespace infinicore::adaptor
\ No newline at end of file
+#endif
+} // namespace infinicore::adaptor
+
+#endif // ENABLE_ATEN

include/infinicore/adaptor/flash_attention_adaptor.hpp

+#ifdef ENABLE_FLASH_ATTN
 #pragma once
 #include "aten_adaptor.hpp"
 
@@ -109,4 +110,5 @@ mha_fwd_kvcache(at::Tensor &q,                                     // batch_size
                 bool is_rotary_interleaved, // if true, rotary combines indices 0 & 1, else indices 0 & rotary_dim / 2
                 int num_splits);
 
-} // namespace flash
\ No newline at end of file
+} // namespace flash
+#endif // ENABLE_FLASH_ATTN

src/infinicore/adaptor/aten_adaptor.cc

+#ifdef ENABLE_ATEN
 #include "infinicore/adaptor/aten_adaptor.hpp"
 
 namespace infinicore::adaptor {
@@ -31,8 +32,13 @@ at::Tensor to_aten_tensor(const infinicore::Tensor &t) {
         options);
 }
 
+#ifdef ENABLE_NVIDIA_API
 c10::cuda::CUDAStream get_cuda_stream() {
     return c10::cuda::getStreamFromExternal(
         cudaStream_t(infinicore::context::getStream()), infinicore::context::getDevice().getIndex());
 }
-} // namespace infinicore::adaptor
\ No newline at end of file
+#endif
+
+} // namespace infinicore::adaptor
+
+#endif // ENABLE_ATEN

src/infinicore/ops/multi_head_attention_varlen/mha_varlen_flashattn.cc

@@ -2,6 +2,8 @@
 
 #include "infinicore/adaptor/flash_attention_adaptor.hpp"
 
+#include <stdexcept>
+
 namespace infinicore::op::mha_varlen_impl::flashattn {
 
 struct PlannedMeta {
@@ -38,6 +40,7 @@ void *plan(Tensor out,
 }
 
 void run(void *planned_meta) {
+#ifdef ENABLE_FLASH_ATTN
     c10::cuda::CUDAStreamGuard guard(infinicore::adaptor::get_cuda_stream());
     auto *p = reinterpret_cast<PlannedMeta *>(planned_meta);
 
@@ -77,6 +80,9 @@ void run(void *planned_meta) {
         0.0,
         false,
         std::nullopt);
+#else
+    throw std::runtime_error("FlashAttention is not enabled in this build");
+#endif
 }
 
 void cleanup(void **planned_meta_ptr) {

src/infinicore/pybind11/ops.hpp

@@ -12,8 +12,8 @@
 #include "ops/linear.hpp"
 #include "ops/linear_w8a8i8.hpp"
 #include "ops/matmul.hpp"
-#include "ops/mul.hpp"
 #include "ops/mha_varlen.hpp"
+#include "ops/mul.hpp"
 #include "ops/paged_attention.hpp"
 #include "ops/paged_attention_prefill.hpp"
 #include "ops/paged_caching.hpp"

xmake.lua

@@ -226,6 +226,28 @@ if has_config("ninetoothed") then
     add_defines("ENABLE_NINETOOTHED")
 end
 
+-- ATen
+option("aten")
+    set_default(false)
+    set_showmenu(true)
+    set_description("Wether to link aten and torch libraries")
+option_end()
+
+-- Flash-Attn
+option("flash-attn")
+    set_default(nil)
+    set_showmenu(true)
+    set_description("Path to flash-attention repo. If not set, flash-attention will not used.")
+option_end()
+
+if has_config("aten") then
+    add_defines("ENABLE_ATEN")
+    if get_config("flash-attn") ~= nil then
+        add_defines("ENABLE_FLASH_ATTN")
+    end
+end
+
+
 -- cuda graph
 option("graph")
     set_default(false)
@@ -439,31 +461,40 @@ target("infinicore_cpp_api")
     add_linkdirs(INFINI_ROOT.."/lib")
     add_links("infiniop", "infinirt", "infiniccl")
 
-    -- ==============================
-    -- LibTorch integration
-    -- ==============================
-    local LIBTORCH_ROOT = ("/home/panzezhong/.conda/envs/myenv/lib/python3.13/site-packages/torch")
-
-    -- headers
-    add_includedirs(
-        path.join(LIBTORCH_ROOT, "include"),
-        path.join(LIBTORCH_ROOT, "include/torch/csrc/api/include"),
-        { public = true }
-    )
-
-    -- libraries
-    add_linkdirs(path.join(LIBTORCH_ROOT, "lib"))
-
-    -- core ATen / Torch libs
-    add_links(
-        "torch",
-        "c10",
-        "torch_cuda",
-        "c10_cuda"
-    )
-    -- Flash attention lib
-    add_linkdirs("/home/panzezhong/Projects/InfiniCore/third_party/flash-attention/csrc/build")
-    add_links("flash_attn")
+    if get_config("flash-attn") ~= nil then
+        add_installfiles("(builddir)/$(plat)/$(arch)/$(mode)/flash-attn*.so", {prefixdir = "lib"})
+        if has_config("nv-gpu") then
+            add_deps("flash-attn-nvidia")
+        end
+    end
+
+    before_build(function (target)
+        if has_config("aten") then
+            local outdata = os.iorunv("python", {"-c", "import torch, os; print(os.path.dirname(torch.__file__))"}):trim()
+            local TORCH_DIR = outdata
+
+            target:add(
+                "includedirs", 
+                path.join(TORCH_DIR, "include"), 
+                path.join(TORCH_DIR, "include/torch/csrc/api/include"),
+                { public = true })
+            
+            target:add(
+                "linkdirs",
+                path.join(TORCH_DIR, "lib"),
+                { public = true }
+            )
+            target:add(
+                "links",
+                "torch",
+                "c10",
+                "torch_cuda",
+                "c10_cuda",
+                { public = true }
+            )
+        end
+
+    end)
 
     -- Add InfiniCore C++ source files (needed for RoPE and other nn modules)
     add_files("src/infinicore/*.cc")

xmake/nvidia.lua

@@ -9,6 +9,10 @@ if CUTLASS_ROOT ~= nil then
     add_includedirs(CUTLASS_ROOT)
 end
 
+local FLASH_ATTN_ROOT = get_config("flash-attn")
+
+local INFINI_ROOT = os.getenv("INFINI_ROOT") or (os.getenv(is_host("windows") and "HOMEPATH" or "HOME") .. "/.infini")
+
 target("infiniop-nvidia")
     set_kind("static")
     add_deps("infini-utils")
@@ -132,3 +136,53 @@ target("infiniccl-nvidia")
     set_languages("cxx17")
 
 target_end()
+
+target("flash-attn-nvidia")
+    set_kind("shared")
+    set_default(false)
+    set_policy("build.cuda.devlink", true)
+    set_toolchains("cuda")
+    add_links("cudart")
+    add_cugencodes("native")
+
+    before_build(function (target)
+        if FLASH_ATTN_ROOT ~= nil then
+            local outdata = os.iorunv("python", {"-c", "import torch, os; print(os.path.dirname(torch.__file__))"}):trim()
+            local TORCH_DIR = outdata
+
+            local outdata = os.iorunv("python", {"-c", "import sysconfig; print(sysconfig.get_paths()['include'])"}):trim()
+            local PYTHON_INCLUDE = outdata
+
+            local outdata = os.iorunv("python", {"-c", "import sysconfig; print(sysconfig.get_config_var('LIBDIR'))"}):trim()
+            local PYTHON_LIB_DIR = outdata
+            -- Include dirs
+            target:add("includedirs", FLASH_ATTN_ROOT .. "/csrc/flash_attn/src", {public = false})
+            target:add("includedirs", TORCH_DIR .. "/include/torch/csrc/api/include", {public = false})
+            target:add("includedirs", TORCH_DIR .. "/include", {public = false})
+            target:add("includedirs", PYTHON_INCLUDE, {public = false})
+            target:add("includedirs", CUTLASS_ROOT .. "/include", {public = false})
+            target:add("includedirs", FLASH_ATTN_ROOT .. "/csrc/flash_attn", {public = false})
+
+            -- Link libraries
+            target:add("linkdirs", TORCH_DIR .. "/lib", PYTHON_LIB_DIR)
+            target:add("links", "torch", "torch_cuda", "torch_cpu", "c10", "c10_cuda", "torch_python", "python3")
+
+        end
+
+    end)
+
+    if FLASH_ATTN_ROOT ~= nil then
+        add_files(FLASH_ATTN_ROOT .. "/csrc/flash_attn/flash_api.cpp")
+        add_files(FLASH_ATTN_ROOT .. "/csrc/flash_attn/src/*.cu")
+        -- Link options
+        add_ldflags("-Wl,--no-undefined", {force = true})
+        -- Compile options
+        add_cxflags("-fPIC", {force = true})
+        add_cuflags("-Xcompiler=-fPIC")
+        add_cuflags("--forward-unknown-to-host-compiler --expt-relaxed-constexpr --use_fast_math", {force = true})
+        set_values("cuda.rdc", false)
+    end
+
+    on_install(function (target) end)
+
+target_end()