Re: [PATCH v6 08/26] tcg: Build ffi data structures for helpers

[Richard Henderson]

On 5/31/21 11:55 AM, Philippe Mathieu-Daudé wrote:

Hi Richard,

On 5/3/21 1:57 AM, Richard Henderson wrote:

Add libffi as a build requirement for TCI.
Add libffi to the dockerfiles to satisfy that requirement.

Construct an ffi_cif structure for each unique typemask.
Record the result in a separate hash table for later lookup;
this allows helper_table to stay const.

Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
  meson.build                                   |  9 ++-
  tcg/tcg.c                                     | 58 +++++++++++++++++++
  tests/docker/dockerfiles/alpine.docker        |  1 +
  tests/docker/dockerfiles/centos7.docker       |  1 +
  tests/docker/dockerfiles/centos8.docker       |  1 +
  tests/docker/dockerfiles/debian10.docker      |  1 +
  .../dockerfiles/fedora-i386-cross.docker      |  1 +
  .../dockerfiles/fedora-win32-cross.docker     |  1 +
  .../dockerfiles/fedora-win64-cross.docker     |  1 +
  tests/docker/dockerfiles/fedora.docker        |  1 +
  tests/docker/dockerfiles/ubuntu.docker        |  1 +
  tests/docker/dockerfiles/ubuntu1804.docker    |  1 +
  tests/docker/dockerfiles/ubuntu2004.docker    |  1 +
  13 files changed, 77 insertions(+), 1 deletion(-)

@@ -1135,6 +1152,47 @@ void tcg_context_init(TCGContext *s)
                              (gpointer)&all_helpers[i]);
      }

+#ifdef CONFIG_TCG_INTERPRETER

+    /* g_direct_hash/equal for direct comparisons on uint32_t.  */

Why not use g_int_hash() then?

g_int_hash takes a pointer to an int; this stores the int directly as the hash 
key.


r~

Otherwise,
Reviewed-by: Philippe Mathieu-Daudé <f4...@amsat.org>

+    ffi_table = g_hash_table_new(NULL, NULL);
+    for (i = 0; i < ARRAY_SIZE(all_helpers); ++i) {
+        struct {
+            ffi_cif cif;
+            ffi_type *args[];
+        } *ca;
+        uint32_t typemask = all_helpers[i].typemask;
+        gpointer hash = (gpointer)(uintptr_t)typemask;
+        ffi_status status;
+        int nargs;
+
+        if (g_hash_table_lookup(ffi_table, hash)) {
+            continue;
+        }
+
+        /* Ignoring the return type, find the last non-zero field. */
+        nargs = 32 - clz32(typemask >> 3);
+        nargs = DIV_ROUND_UP(nargs, 3);
+
+        ca = g_malloc0(sizeof(*ca) + nargs * sizeof(ffi_type *));
+        ca->cif.rtype = typecode_to_ffi[typemask & 7];
+        ca->cif.nargs = nargs;
+
+        if (nargs != 0) {
+            ca->cif.arg_types = ca->args;
+            for (i = 0; i < nargs; ++i) {
+                int typecode = extract32(typemask, (i + 1) * 3, 3);
+                ca->args[i] = typecode_to_ffi[typecode];
+            }
+        }
+
+        status = ffi_prep_cif(&ca->cif, FFI_DEFAULT_ABI, nargs,
+                              ca->cif.rtype, ca->cif.arg_types);
+        assert(status == FFI_OK);
+
+        g_hash_table_insert(ffi_table, hash, (gpointer)&ca->cif);
+    }
+#endif
+
      tcg_target_init(s);
      process_op_defs(s);