Add a CI step with simd disabled

Author: byroot

.github/workflows/ci.yml

@@ -26,6 +26,7 @@ jobs:
         ruby: ${{ fromJson(needs.ruby-versions.outputs.versions) }}
         include:
         - { os: ubuntu-24.04-arm, ruby: 3.4 }
+        - { os: ubuntu-latest  , ruby: 3.4, env: "JSON_DISABLE_SIMD=1" }
         - { os: macos-13, ruby: 3.4 }
         - { os: windows-latest , ruby: mswin     } # ruby/ruby windows CI
         - { os: ubuntu-latest  , ruby: jruby-9.4 } # Ruby 3.1
@@ -49,9 +50,9 @@ jobs:
           bundle config --without benchmark
           bundle install
 
-      - run: rake compile
+      - run: rake compile ${{ matrix.env }}
 
-      - run: rake test JSON_COMPACT=1
+      - run: rake test JSON_COMPACT=1 ${{ matrix.env }}
 
       - run: rake build
 

ext/json/ext/generator/extconf.rb

@@ -7,7 +7,7 @@
   append_cflags("-std=c99")
   $defs << "-DJSON_GENERATOR"
 
-  if enable_config('generator-use-simd', default=true)
+  if enable_config('generator-use-simd', default=!ENV["JSON_DISABLE_SIMD"])
     if RbConfig::CONFIG['host_cpu'] =~ /^(arm.*|aarch64.*)/
       # Try to compile a small program using NEON instructions
       if have_header('arm_neon.h')
@@ -31,7 +31,7 @@
       SRC
         $defs.push("-DENABLE_SIMD")
     end
-    
+
     have_header('cpuid.h')
   end