[aarch64-port-dev ] RFR: aarch64: Fix vm crash with CDS on

[Andrew Haley]

On 21/06/16 07:51, Ningsheng Jian wrote:
> Hi,
> 
> I found that the following hotspot jtreg test failures in aarch64
> openjdk9 are caused by the same issue:
> 
> runtime/CDSCompressedKPtrs/CDSCompressedKPtrs.java
> runtime/CDSCompressedKPtrs/XShareAuto.java
> runtime/CompressedOops/CompressedClassPointers.java
> runtime/NMT/NMTWithCDS.java
> runtime/SharedArchiveFile/CdsSameObjectAlignment.java
> runtime/SharedArchiveFile/SASymbolTableTest.java
> runtime/SharedArchiveFile/SharedArchiveFile.java
> runtime/SharedArchiveFile/SharedBaseAddress.java
> runtime/SharedArchiveFile/SharedStrings.java
> runtime/SharedArchiveFile/SharedStringsRunAuto.java
> 
> 
> It is caused by incorrectly patching un-patchable bytecodes in CDS
> image. Refer to [1] for details.
> 
> The crash can be reproduced by a simple hello-world case:
> 
> $ java -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=1.jsa
> -Xshare:dump Hello
> $ java -XX:+UnlockDiagnosticVMOptions -XX:SharedArchiveFile=1.jsa
> -Xshare:on Hello
> 
> 
> The following patch can fix that crash and the jtreg tests above (and
> no new failure found):
> 
> http://people.linaro.org/~ningsheng.jian/cds-fix/webrev.01/
> 
> 
> Could someone please help to review and process this patch?

I am concerned that your patch may be incomplete.  The x86 and sparc
versions of this code use

@@ -2661,7 +2684,7 @@

   __ load_signed_byte(rax, field);
   __ push(btos);
   // Rewrite bytecode to be faster
-  if (!is_static) {
+  if (!is_static && rc == may_rewrite) {
     patch_bytecode(Bytecodes::_fast_bgetfield, bc, rbx);
   }
   __ jmp(Done);

But you use

@@ -2434,7 +2434,7 @@
   __ ldrsb(r0, field);
   __ push(ztos);
   // Rewrite bytecode to be faster
-  if (!is_static) {
+  if (rc == may_rewrite) {
     // use btos rewriting, no truncating to t/f bit is needed for getfield.
     patch_bytecode(Bytecodes::_fast_bgetfield, bc, r1);
   }

The patch is at

http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/0b0b09a60061

Please make sure that AArch64 is not missing anything else.

Andrew.