.rodata from embedded.S should be read only

.rodata usually hosts read only data. MSVC link.exe complains mismatch when
merging this read/write .rodata from embedded.S with .rodata from other object
file.

Bug: chromium:919180
Change-Id: I7789e42afe116cc4bf772e2cbb312d19e4ce7fe5
Reviewed-on: https://chromium-review.googlesource.com/c/1396361
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58653}

src/snapshot/embedded-file-writer.cc

@@ -346,7 +346,12 @@ void PlatformDependentEmbeddedFileWriter::SectionData() {
 }
 
 void PlatformDependentEmbeddedFileWriter::SectionRoData() {
+#if defined(V8_OS_WIN)
+  // .rodata defaults to r/w in COFF, but read only in ELF.
+  fprintf(fp_, ".section .rodata,\"r\"\n");
+#else
   fprintf(fp_, ".section .rodata\n");
+#endif
 }
 
 void PlatformDependentEmbeddedFileWriter::DeclareUint32(const char* name,

tools/snapshot/asm_to_inline_asm.py

@@ -17,6 +17,8 @@ def asm_to_inl_asm(in_filename, out_filename):
   with open(in_filename, 'r') as infile, open(out_filename, 'wb') as outfile:
     outfile.write('__asm__(\n')
     for line in infile:
+      # Escape " in .S file before output it to inline asm file.
+      line = line.replace('"', '\\"')
       outfile.write('  "%s\\n"\n' % line.rstrip())
     outfile.write(');\n')
   return 0