RFR: 8228604: StackMapFrames are missing from redefined class bytes of retransformed classes

[Chris Plummer]

On Tue, 24 Jan 2023 00:16:10 GMT, Alex Menkov <amenkov at openjdk.org> wrote:

> classFileParser drops stack map frames for JDK classes (when verification is not required).
> As a result JvmtiClassFileReconstituter cannot restore the attribute for class redefinition.
> Note that if the class is in CDS archive, the frames are restored from CDS, so this issue affects only JDK classes which are not in CDS.
> This code is old (from "initial load") and I don't understand the reason it was implemented this way.
> 
> Testing: tier1-tier6

Copyright needs updating.

test/hotspot/jtreg/serviceability/jvmti/RedefineClasses/MissedStackMapFrames/MissedStackMapFrames.java line 91:

> 89:         int frameCount = getStackMapFrameCount(classfileBuffer);
> 90:         log("  Has stack map frames: " + frameCount);
> 91:         if (frameCount == 0) {

Shouldn't the check also be that the number of frames is the same in the "load" and "retransform" cases?

test/hotspot/jtreg/serviceability/jvmti/RedefineClasses/MissedStackMapFrames/MissedStackMapFrames.java line 107:

> 105:             byte[] retransformBytes = retransformBytes(i);
> 106:             checkStackMapFrames(cls + "(load)", loadBytes);
> 107:             checkStackMapFrames(cls + "(retranform)", retransformBytes);

"retransform"

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Changes requested by cjplummer (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12155