radeonsi: add a way to override the disk cache key with radeonsi-build-id

This is similar to radv-build-id which is mainly used on SteamOS for
shaders pre-compilation.

For RadeonSI, it also useful to have this option to force the disk
cache key to be uniq for redistributed shaders accross machines when
it's safe.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35629>

meson.options

@@ -750,6 +750,14 @@ option(
                 'Can be extracted with readelf -x .note.gnu.build-id'
 )
 
+option(
+  'radeonsi-build-id',
+  type : 'string',
+  value : '',
+  description : 'Override build id for shader cache keys (hex string). ' +
+                'Can be extracted with readelf -x .note.gnu.build-id'
+)
+
 option(
   'min-windows-version',
   type : 'integer',

src/gallium/drivers/radeonsi/meson.build

@@ -154,6 +154,11 @@ if with_amdgpu_virtio
   libradeonsi_cflags += ['-DHAVE_AMDGPU_VIRTIO']
 endif
 
+radeonsi_build_id = get_option('radeonsi-build-id')
+if radeonsi_build_id != ''
+  libradeonsi_cflags += '-DRADEONSI_BUILD_ID_OVERRIDE="' + radeonsi_build_id + '"'
+endif
+
 libradeonsi = static_library(
   'radeonsi',
   [files_libradeonsi, sid_tables_h],

src/gallium/drivers/radeonsi/si_pipe.c

@@ -1108,6 +1108,18 @@ static void si_test_vmfault(struct si_screen *sscreen, uint64_t test_flags)
    exit(0);
 }
 
+static void
+parse_hex(char *out, const char *in, unsigned length)
+{
+   for (unsigned i = 0; i < length; ++i)
+      out[i] = 0;
+
+   for (unsigned i = 0; i < 2 * length; ++i) {
+      unsigned v = in[i] <= '9' ? in[i] - '0' : (in[i] >= 'a' ? (in[i] - 'a' + 10) : (in[i] - 'A' + 10));
+      out[i / 2] |= v << (4 * (1 - i % 2));
+   }
+}
+
 static void si_disk_cache_create(struct si_screen *sscreen)
 {
    /* Don't use the cache if shader dumping is enabled. */
@@ -1120,8 +1132,17 @@ static void si_disk_cache_create(struct si_screen *sscreen)
 
    _mesa_sha1_init(&ctx);
 
+#ifdef RADEONSI_BUILD_ID_OVERRIDE
+   {
+      unsigned size = strlen(RADEONSI_BUILD_ID_OVERRIDE) / 2;
+      char *data = alloca(size);
+      parse_hex(data, RADEONSI_BUILD_ID_OVERRIDE, size);
+      _mesa_sha1_update(&ctx, data, size);
+   }
+#else
    if (!disk_cache_get_function_identifier(si_disk_cache_create, &ctx))
       return;
+#endif
 
 #if AMD_LLVM_AVAILABLE
    if (!disk_cache_get_function_identifier(LLVMInitializeAMDGPUTargetInfo, &ctx))