Continues Latin-1 support. All tests pass with ENABLE_LATIN_1 flag.

src/x64/regexp-macro-assembler-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 375 matching lines @@
 
     // Mismatch, try case-insensitive match (converting letters to lower-case).
     // I.e., if or-ing with 0x20 makes values equal and in range 'a'-'z', it's
     // a match.
     __ or_(rax, Immediate(0x20));  // Convert match character to lower-case.
     __ or_(rdx, Immediate(0x20));  // Convert capture character to lower-case.
     __ cmpb(rax, rdx);
     __ j(not_equal, on_no_match);  // Definitely not equal.
     __ subb(rax, Immediate('a'));
     __ cmpb(rax, Immediate('z' - 'a'));
+#ifndef ENABLE_LATIN_1
     __ j(above, on_no_match);  // Weren't letters anyway.
-
+#else
+    __ j(below_equal, &loop_increment);  // In range 'a'-'z'.
+    // Latin-1: Check for values in range [224,254] but not 247.
+    __ subb(rax, Immediate(224 - 'a'));
+    __ cmpb(rax, Immediate(254 - 224));
+    __ j(above, on_no_match);  // Weren't Latin-1 letters.
+    __ cmpb(rax, Immediate(247 - 224));  // Check for 247.
+    __ j(equal, on_no_match);
+#endif
     __ bind(&loop_increment);
     // Increment pointers into match and capture strings.
     __ addq(r11, Immediate(1));
     __ addq(r9, Immediate(1));
     // Compare to end of capture, and loop if not done.
     __ cmpq(r9, rbx);
     __ j(below, &loop);
 
     // Compute new value of character position after the matched part.
     __ movq(rdi, r11);
@@ skipping 1127 matching lines @@
   }
 }
 
 #undef __
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64