[aarch64-port-dev ] RFR: aarch64: jdk8: large code cache support

[Edward Nevill]

Hi,

The following webrev

http://cr.openjdk.java.net/~enevill/jdk8_largecode/webrev

backports large code cache support from JDK 9 to JDK 8

This incorporates the fix to pd_call_destination

http://cr.openjdk.java.net/~enevill/8144498/webrev.2

I have also updated the jdk8 patch to reflect the setting of CODE_CACHE_SIZE_LIMIT in jdk9, so that jdk8 and jdk9 are the same.

One change I am not so sure about is the following in jdk9

@@ -868,7 +867,7 @@ 
   //   blrt rscratch1
   CodeBlob *cb = CodeCache::find_blob(_entry_point); 
   if (cb) {
-    return NativeInstruction::instruction_size; 
+    return MacroAssembler::far_branch_size();
   } else { 
     return 6 * NativeInstruction::instruction_size;

whereas in jdk8 we have

-    return 4;
+    return MacroAssembler::far_branch_size();
   } else {
     // A 48-bit address.  See movptr().
-    return 16;
+    // then a blrt
+    // return 16;
+    return 4 * NativeInstruction::instruction_size;


IE. 4 * instruction_size instead of 6 * instruction_size

This is because in jdk9, aarch64_enc_java_to_runtime does

      __ adr(rscratch2, retaddr);
      __ lea(rscratch1, RuntimeAddress(entry));
      // Leave a breadcrumb for JavaThread::pd_last_frame().
      __ stp(zr, rscratch2, Address(__ pre(sp, -2 * wordSize)));
      __ blrt(rscratch1, gpcnt, fpcnt, rtype);
      __ bind(retaddr);
      __ add(sp, sp, 2 * wordSize);

whereas in jdk8 it just does

      __ lea(rscratch1, RuntimeAddress(entry));
      __ blrt(rscratch1, gpcnt, fpcnt, rtype);

For the moment I have left this unchanged.

Is this necessary and should I include it in the backport?

I have tested the large code support in jdk8 with jtreg hotspot and langtools with the following results.

Hotspot (original - 128M code cache): Test results: passed: 674; failed: 17; error: 3
Hotspot (patched - 128M code cache): Test results: passed: 674; failed: 17; error: 3
Hotspot (patched- 256M code cache): Test results: passed: 674; failed: 17; error: 3

Langtools (original - 128M code cache): Test results: passed: 3,091
Langtools (patched - 128M code cache): Test results: passed: 3,090
Langtools (patched - 256M code cache): Test results: passed: 3,091

OK to push?

Ed.