Meaningful support for raw array creation.

CHANGELOG.md

@@ -16,6 +16,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
   `futhark_context_config_set_unified_memory`, also available on
   executables as ``--unified-memory``.
 
+* The "raw" API functions now do something potentially useful, but are
+  still considered experimental.
+
 ### Removed
 
 ### Changed

cabal.project

@@ -1,5 +1,5 @@
 packages: futhark.cabal
-index-state: 2024-02-25T13:57:21Z
+index-state: 2024-03-04T18:26:54Z
 
 package futhark
   ghc-options: -j -fwrite-ide-info -hiedir=.hie

docs/c-api.rst

@@ -258,16 +258,16 @@ will not result in a double free.
    call :c:func:`futhark_free_i32_1d`.  Multi-dimensional arrays are
    assumed to be in row-major form.  Returns ``NULL`` on failure.
 
-.. c:function:: struct futhark_i32_1d *futhark_new_raw_i32_1d(struct futhark_context *ctx, char *data, int64_t offset, int64_t dim0)
+.. c:function:: struct futhark_i32_1d *futhark_new_raw_i32_1d(struct futhark_context *ctx, char *data, int64_t dim0)
 
-   Create an array based on *raw* data, as well as an offset into it.
-   This differs little from :c:func:`futhark_i32_1d` when using the
-   ``c`` backend, but when using e.g. the ``opencl`` backend, the
-   ``data`` parameter will be a ``cl_mem``.  It is the caller's
-   responsibility to eventually call :c:func:`futhark_free_i32_1d`.
-   The ``data`` pointer must remain valid for the lifetime of the
-   array.  Unless you are very careful, this basically means for the
-   lifetime of the context.  Returns ``NULL`` on failure.
+   Create an array based on *raw* data, which is used for the
+   representation of the array. The ``data`` pointer must remain valid
+   for the lifetime of the array and will not be freed by Futhark.
+   Returns ``NULL`` on failure. The type of the ``data`` argument
+   depends on the backend, and is for example ``cl_mem`` when using
+   the OpenCL backend.
+
+   **This is an experimental and unstable interface.**
 
 .. c:function:: int futhark_free_i32_1d(struct futhark_context *ctx, struct futhark_i32_1d *arr)
 
@@ -289,6 +289,16 @@ will not result in a double free.
    must *not* be manually freed.  Assuming ``arr`` is a valid
    object, this function cannot fail.
 
+.. c:function:: char* futhark_values_raw_i32_1d(struct futhark_context *ctx, struct futhark_i32_1d *arr)
+
+   Return a pointer to the underlying storage of the array. The return
+   type depends on the backend, and is for example ``cl_mem`` when
+   using the OpenCL backend. If using unified memory with the ``hip``
+   or ``cuda`` backends, the pointer can be accessed directly from CPU
+   code.
+
+   **This is an experimental and unstable interface.**
+
 .. _opaques:
 
 Opaque Values

docs/manifest.schema.json

@@ -123,7 +123,9 @@
                                   "free": {"type": "string"},
                                   "shape": {"type": "string"},
                                   "values": {"type": "string"},
-                                  "new": {"type": "string"}
+                                  "values_raw": {"type": "string"},
+                                  "new": {"type": "string"},
+                                  "new_raw": {"type": "string"}
                               },
                               "additionalProperties": false
                           }

futhark.cabal

@@ -455,7 +455,7 @@ library
     , free >=5.1.10
     , futhark-data >= 1.1.0.0
     , futhark-server >= 1.2.2.1
-    , futhark-manifest >= 1.3.0.0
+    , futhark-manifest >= 1.4.0.0
     , githash >=0.1.6.1
     , half >= 0.3
     , haskeline

nix/futhark-manifest.nix

@@ -4,8 +4,8 @@
 }:
 mkDerivation {
   pname = "futhark-manifest";
-  version = "1.3.0.0";
-  sha256 = "778996f0086e35fe0c36fd2dd66cc6db0704053845ba44cfcee0d5d4c2a4df54";
+  version = "1.4.0.0";
+  sha256 = "c626568b5298abc4d1083ec9d6044962a6c4b1fc5599f6c793714ed4c3300fbb";
   libraryHaskellDepends = [ aeson base bytestring containers text ];
   testHaskellDepends = [
     base QuickCheck quickcheck-instances tasty tasty-hunit

src/Futhark/CodeGen/Backends/GenericC/Types.hs

@@ -89,16 +89,11 @@ arrayLibraryFunctions pub space pt signed rank = do
       [C.cexp|((size_t)$exp:arr_size) * $int:(primByteSize pt::Int)|]
 
   new_raw_body <- collect $ do
-    prepare_new
-    copy
-      CopyNoBarrier
-      [C.cexp|arr->mem.mem|]
-      [C.cexp|0|]
-      space
-      [C.cexp|data|]
-      [C.cexp|offset|]
-      space
-      [C.cexp|((size_t)$exp:arr_size) * $int:(primByteSize pt::Int)|]
+    resetMem [C.cexp|arr->mem|] space
+    stm [C.cstm|arr->mem.mem = data;|]
+    forM_ [0 .. rank - 1] $ \i ->
+      let dim_s = "dim" ++ show i
+       in stm [C.cstm|arr->shape[$int:i] = $id:dim_s;|]
 
   free_body <- collect $ unRefMem [C.cexp|arr->mem|] space
 
@@ -126,7 +121,7 @@ arrayLibraryFunctions pub space pt signed rank = do
   proto
     [C.cedecl|$ty:array_type* $id:new_array($ty:ctx_ty *ctx, const $ty:pt' *data, $params:shape_params);|]
   proto
-    [C.cedecl|$ty:array_type* $id:new_raw_array($ty:ctx_ty *ctx, $ty:memty data, typename int64_t offset, $params:shape_params);|]
+    [C.cedecl|$ty:array_type* $id:new_raw_array($ty:ctx_ty *ctx, $ty:memty data, $params:shape_params);|]
   proto
     [C.cedecl|int $id:free_array($ty:ctx_ty *ctx, $ty:array_type *arr);|]
   proto
@@ -154,7 +149,7 @@ arrayLibraryFunctions pub space pt signed rank = do
             return arr;
           }
 
-          $ty:array_type* $id:new_raw_array($ty:ctx_ty *ctx, $ty:memty data, typename int64_t offset, $params:shape_params) {
+          $ty:array_type* $id:new_raw_array($ty:ctx_ty *ctx, $ty:memty data, $params:shape_params) {
             int err = 0;
             $ty:array_type* bad = NULL;
             $ty:array_type *arr = ($ty:array_type*) malloc(sizeof($ty:array_type));
@@ -193,7 +188,9 @@ arrayLibraryFunctions pub space pt signed rank = do
       { Manifest.arrayFree = free_array,
         Manifest.arrayShape = shape_array,
         Manifest.arrayValues = values_array,
-        Manifest.arrayNew = new_array
+        Manifest.arrayNew = new_array,
+        Manifest.arrayNewRaw = new_raw_array,
+        Manifest.arrayValuesRaw = values_raw_array
       }
 
 lookupOpaqueType :: Name -> OpaqueTypes -> OpaqueType

tests_lib/c/raw.fut

@@ -0,0 +1 @@
+entry main (xs: []i32) = map (+2) xs

tests_lib/c/test_raw.c

@@ -0,0 +1,37 @@
+// Fiddling around with the raw arrays API.
+
+#include "raw.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+
+int main() {
+  struct futhark_context_config *cfg = futhark_context_config_new();
+  struct futhark_context *ctx = futhark_context_new(cfg);
+
+#ifdef FUTHARK_BACKEND_c
+
+  int32_t data[3] = {1,2,3};
+
+  struct futhark_i32_1d *in = futhark_new_raw_i32_1d(ctx, (unsigned char*)&data, 3);
+  assert(in != NULL);
+  struct futhark_i32_1d *out;
+
+  assert(futhark_entry_main(ctx, &out, in) == FUTHARK_SUCCESS);
+
+  int32_t *out_ptr = (int32_t*)futhark_values_raw_i32_1d(ctx, out);
+
+  assert(futhark_context_sync(ctx) == FUTHARK_SUCCESS);
+
+  assert(out_ptr[0] == 3);
+  assert(out_ptr[1] == 4);
+  assert(out_ptr[2] == 5);
+
+  futhark_free_i32_1d(ctx, in);
+  futhark_free_i32_1d(ctx, out);
+
+#endif
+
+  futhark_context_free(ctx);
+  futhark_context_config_free(cfg);
+}