Issue #1677 - Part 5: "Simplify" regexp re-import process (and re-import from later revision)

I am going on record to say Mozilla are utter fucking assholes for pulling this as part of their progression.

1 files changed, 12 insertions, 35 deletions

diff --git a/js/src/regexp/regexp-macro-assembler.cc b/js/src/regexp/regexp-macro-assembler.cc
index 4a8dcd3ce8..7f8de25437 100644
--- a/js/src/regexp/regexp-macro-assembler.cc
+++ b/js/src/regexp/regexp-macro-assembler.cc
@@ -110,34 +110,7 @@ bool NativeRegExpMacroAssembler::CanReadUnaligned() {
   return FLAG_enable_regexp_unaligned_accesses && !slow_safe();
 }
 
-const byte* NativeRegExpMacroAssembler::StringCharacterPosition(
-    String subject, int start_index, const DisallowHeapAllocation& no_gc) {
-  if (subject.IsConsString()) {
-    subject = ConsString::cast(subject).first();
-  } else if (subject.IsSlicedString()) {
-    start_index += SlicedString::cast(subject).offset();
-    subject = SlicedString::cast(subject).parent();
-  }
-  if (subject.IsThinString()) {
-    subject = ThinString::cast(subject).actual();
-  }
-  DCHECK_LE(0, start_index);
-  DCHECK_LE(start_index, subject.length());
-  if (subject.IsSeqOneByteString()) {
-    return reinterpret_cast<const byte*>(
-        SeqOneByteString::cast(subject).GetChars(no_gc) + start_index);
-  } else if (subject.IsSeqTwoByteString()) {
-    return reinterpret_cast<const byte*>(
-        SeqTwoByteString::cast(subject).GetChars(no_gc) + start_index);
-  } else if (subject.IsExternalOneByteString()) {
-    return reinterpret_cast<const byte*>(
-        ExternalOneByteString::cast(subject).GetChars() + start_index);
-  } else {
-    DCHECK(subject.IsExternalTwoByteString());
-    return reinterpret_cast<const byte*>(
-        ExternalTwoByteString::cast(subject).GetChars() + start_index);
-  }
-}
+#ifndef COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
 
 // This method may only be called after an interrupt.
 int NativeRegExpMacroAssembler::CheckStackGuardState(
@@ -145,9 +118,10 @@ int NativeRegExpMacroAssembler::CheckStackGuardState(
     Address* return_address, Code re_code, Address* subject,
     const byte** input_start, const byte** input_end) {
   DisallowHeapAllocation no_gc;
+  Address old_pc = PointerAuthentication::AuthenticatePC(return_address, 0);
+  DCHECK_LE(re_code.raw_instruction_start(), old_pc);
+  DCHECK_LE(old_pc, re_code.raw_instruction_end());
 
-  DCHECK(re_code.raw_instruction_start() <= *return_address);
-  DCHECK(*return_address <= re_code.raw_instruction_end());
   StackLimitCheck check(isolate);
   bool js_has_overflowed = check.JsHasOverflowed();
 
@@ -189,9 +163,11 @@ int NativeRegExpMacroAssembler::CheckStackGuardState(
   }
 
   if (*code_handle != re_code) {  // Return address no longer valid
-    intptr_t delta = code_handle->address() - re_code.address();
     // Overwrite the return address on the stack.
-    *return_address += delta;
+    intptr_t delta = code_handle->address() - re_code.address();
+    Address new_pc = old_pc + delta;
+    // TODO(v8:10026): avoid replacing a signed pointer.
+    PointerAuthentication::ReplacePC(return_address, new_pc, 0);
   }
 
   // If we continue, we need to update the subject string addresses.
@@ -206,8 +182,7 @@ int NativeRegExpMacroAssembler::CheckStackGuardState(
     } else {
       *subject = subject_handle->ptr();
       intptr_t byte_length = *input_end - *input_start;
-      *input_start =
-          StringCharacterPosition(*subject_handle, start_index, no_gc);
+      *input_start = subject_handle->AddressOfCharacterAt(start_index, no_gc);
       *input_end = *input_start + byte_length;
     }
   }
@@ -255,7 +230,7 @@ int NativeRegExpMacroAssembler::Match(Handle<JSRegExp> regexp,
 
   DisallowHeapAllocation no_gc;
   const byte* input_start =
-      StringCharacterPosition(subject_ptr, start_offset + slice_offset, no_gc);
+      subject_ptr.AddressOfCharacterAt(start_offset + slice_offset, no_gc);
   int byte_length = char_length << char_size_shift;
   const byte* input_end = input_start + byte_length;
   return Execute(*subject, start_offset, input_start, input_end, offsets_vector,
@@ -301,6 +276,8 @@ int NativeRegExpMacroAssembler::Execute(
   return result;
 }
 
+#endif  // !COMPILING_IRREGEXP_FOR_EXTERNAL_EMBEDDER
+
 // clang-format off
 const byte NativeRegExpMacroAssembler::word_character_map[] = {
     0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u, 0x00u,