From bd71304a100cbd4987983d08167724fb06230492 Mon Sep 17 00:00:00 2001
From: Xeonacid <h.dwwwwww@gmail.com>
Date: Wed, 19 Aug 2026 10:13:58 +0200
Subject: [PATCH] [build] Fall back to scalar zlib on CPUs without SIMD ports

build/BUILD.zlib overlays Chromium zlib with ISA-specific SIMD
defines and deps, but several select()s only list x86_64 and
aarch64. Bazel analysis then fails on any other CPU because those
configurable attributes have no matching condition.

The SIMD libraries already no-op when their ADLER32_SIMD_*,
INFLATE_CHUNK_SIMD_*, CRC32_* and DEFLATE_SLIDE_HASH_* defines are
unset: the corresponding C files are empty translation units or the
generic zlib sources are used instead. Add "//conditions:default": []
so those selects resolve, and skip the x86/ARM-only CRC SIMD deps
on other CPUs.

This does not enable RISC-V Vector (or other) zlib optimizations; it
only unblocks a portable scalar build.
---
 build/BUILD.zlib | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/build/BUILD.zlib b/build/BUILD.zlib
index 65b292eb76e..d14f2e721ec 100644
--- a/build/BUILD.zlib
+++ b/build/BUILD.zlib
@@ -92,6 +92,7 @@ cc_library(
     local_defines = ["ZLIB_IMPLEMENTATION"] + select({
         "@platforms//cpu:x86_64": ["ADLER32_SIMD_SSSE3"],
         "@platforms//cpu:aarch64": ["ADLER32_SIMD_NEON"],
+        "//conditions:default": [],
     }) + select({
         ":x86_linux": ["X86_NOT_WINDOWS"],
         ":x86_macos": ["X86_NOT_WINDOWS"],
@@ -149,6 +150,7 @@ cc_library(
         "@platforms//cpu:aarch64": [
             "INFLATE_CHUNK_SIMD_NEON",
         ],
+        "//conditions:default": [],
     }),
     deps = [":zlib_common_headers"],
 )
@@ -185,6 +187,7 @@ cc_library(
     local_defines = ["ZLIB_IMPLEMENTATION"] + select({
         "@platforms//cpu:x86_64": ["DEFLATE_SLIDE_HASH_SSE2"],
         "@platforms//cpu:aarch64": ["DEFLATE_SLIDE_HASH_NEON"],
+        "//conditions:default": [],
     }),
     deps = [":zlib_common_headers"],
 )
@@ -242,6 +245,7 @@ cc_library(
             "CRC32_ARMV8_CRC32",
             "DEFLATE_SLIDE_HASH_NEON",
         ],
+        "//conditions:default": [],
     }) + select({
         ":x86_linux": ["X86_NOT_WINDOWS"],
         ":x86_macos": ["X86_NOT_WINDOWS"],
@@ -259,6 +263,7 @@ cc_library(
     ] + select({
         "@platforms//cpu:x86_64": [":zlib_crc32_simd"],
         "@platforms//cpu:aarch64": [":zlib_arm_crc32"],
+        "//conditions:default": [],
     }),
 )