ARM64: always restore regexp register cache after a C function call.

src/arm64/regexp-macro-assembler-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/code-stubs.h"
 #include "src/cpu-profiler.h"
@@ skipping 379 matching lines @@
     __ Mov(x3, ExternalReference::isolate_address(isolate()));
 
     {
       AllowExternalCallThatCantCauseGC scope(masm_);
       ExternalReference function =
           ExternalReference::re_case_insensitive_compare_uc16(isolate());
       __ CallCFunction(function, argument_count);
     }
 
     // Check if function returned non-zero for success or zero for failure.
-    CompareAndBranchOrBacktrack(x0, 0, eq, on_no_match);
+    // x0 is one of the registers used as a cache so it must be tested before
+    // the cache is restored.
+    __ Cmp(x0, 0);
+    __ PopCPURegList(cached_registers);
+    BranchOrBacktrack(eq, on_no_match);
+
     // On success, increment position by length of capture.
     __ Add(current_input_offset(), current_input_offset(), capture_length);
-    // Reset the cached registers.
-    __ PopCPURegList(cached_registers);
   }
 
   __ Bind(&fallthrough);
 }
 
 void RegExpMacroAssemblerARM64::CheckNotBackReference(
     int start_reg,
     Label* on_no_match) {
   Label fallthrough;
 
@@ skipping 1275 matching lines @@
       __ Ldrh(current_character(), MemOperand(input_end(), offset, SXTW));
     }
   }
 }
 
 #endif  // V8_INTERPRETED_REGEXP
 
 }}  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM64