m143: Generate Dawn version as array instead of string

This can reduce the device key's length further.

Bug: 439845637
Fixed: 461363158
Change-Id: I10812ad74cc7f4e8ee727f283374ea46cbb5d2e6
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/272236
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Quyen Le <lehoangquyen@chromium.org>
(cherry picked from commit c650c2e0cfb08afb0d40ddb6f8c05d1af8ba2e92)
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/274237

generator/dawn_version_generator.py

diff --git a/generator/dawn_version_generator.py b/generator/dawn_version_generator.py
index 7e2bc8c..71a6fb7 100644
--- a/generator/dawn_version_generator.py
+++ b/generator/dawn_version_generator.py
@@ -106,9 +106,24 @@
     return get_git_hash(os.path.abspath(args.dawn_dir))
 
 
+def get_version_byte_array(version_str):
+    version_str = version_str.strip()
+    if not version_str:
+        # If the version string is empty, generate an array of 20 zero bytes.
+        return ", ".join(["0x00"] * 20)
+    assert len(
+        version_str
+    ) == 40, "Version string must be a 40-character git hash if not empty."
+    byte_values = [
+        f"0x{version_str[i:i+2]}" for i in range(0, len(version_str), 2)
+    ]
+    return ", ".join(byte_values)
+
+
 def compute_params(args):
+    version = get_version(args)
     return {
-        "get_version": lambda: get_version(args),
+        "get_version_byte_array": lambda: get_version_byte_array(version),
     }
 
 

generator/templates/dawn/common/Version.h

diff --git a/generator/templates/dawn/common/Version.h b/generator/templates/dawn/common/Version.h
index fbfd493..ca540d6 100644
--- a/generator/templates/dawn/common/Version.h
+++ b/generator/templates/dawn/common/Version.h
@@ -28,14 +28,14 @@
 #ifndef COMMON_VERISON_AUTOGEN_H_
 #define COMMON_VERISON_AUTOGEN_H_
 
-#include <string_view>
+#include <array>
+#include <cstdint>
 
 namespace dawn {
 
-// The version string should either be a valid git hash or empty.
-static constexpr std::string_view kDawnVersion("{{get_version()}}");
-static_assert(kDawnVersion.size() == 40 || kDawnVersion.size() == 0);
+// The version is a 20-byte SHA1 hash. If the hash is not available, it is all zeros.
+static constexpr std::array<uint8_t, 20> kDawnVersion = { {{get_version_byte_array()}} };
 
-} // namespace dawn
+}  // namespace dawn
 
 #endif  // COMMON_VERISON_AUTOGEN_H_