Enabling Full Info Points on AArch64 causes compile failures

[adinn]

** Describe the Problem**

The latest patch for debug info (PR #4505) modifies the GraphBuilderConfiguration to enable full info point generation.

class SVMHost {
  ...
@Override
public GraphBuilderConfiguration updateGraphBuilderConfiguration(GraphBuilderConfiguration config, AnalysisMethod method) {
    return config.withRetainLocalVariables(retainLocalVariables())
                    .withUnresolvedIsError(linkAtBuildTimeSupport.linkAtBuildTime(method.getDeclaringClass()))
                    .withFullInfopoints(SubstrateOptions.GenerateDebugInfo.getValue() > 0);
...

This is not a problem on x86_64. However, it leads to multiple compile failures on AArch64. They all occur because LocationMarkerPhase.processState() has been passed a FullInfopointNode referencing a live value in the link register lr aka r30.

java.lang.NullPointerException
at com.oracle.svm.core.CalleeSavedRegisters.getOffsetInFrame(CalleeSavedRegisters.java:108)
at com.oracle.svm.core.heap.SubstrateReferenceMapBuilder.addLiveValue(SubstrateReferenceMapBuilder.java:65)
at jdk.internal.vm.compiler/org.graalvm.compiler.lir.dfa.RegStackValueSet$1.visitValue(RegStackValueSet.java:155)
at jdk.internal.vm.compiler/org.graalvm.compiler.lir.ValueConsumer.visitValue(ValueConsumer.java:51)
at jdk.internal.vm.compiler/org.graalvm.compiler.lir.util.IndexedValueMap.visitEach(IndexedValueMap.java:455)
at jdk.internal.vm.compiler/org.graalvm.compiler.lir.dfa.RegStackValueSet.addLiveValues(RegStackValueSet.java:158)
at jdk.internal.vm.compiler/org.graalvm.compiler.lir.dfa.LocationMarkerPhase$Marker.processState(LocationMarkerPhase.java:97)
    ...

The reference map builder assumes that lr is a callee saved register which is why it ends up calling CalleeSavedRegisters.getOffsetInFrame. Unfortunately, when the call to getOffsetInFrame looks up lr in the map stored in field offsetsInSaveArea the result is null leading to a NPE.

Steps to reproduce the issue

Path 1:
1 Clone the repo from #4505
git clone git://github.com/adinn/graal debug_location_info
2 Build on Linux/AArch64
mx build
3 Run the debug info test
mx debuginfotest

Path 2:
1 Clone the Oracle master
2) Modify class SVMHost.updateGraphBuilderConfiguration to always enable full infopoints

  public GraphBuilderConfiguration updateGraphBuilderConfiguration(GraphBuilderConfiguration config, AnalysisMethod method) {
      return config.withRetainLocalVariables(retainLocalVariables())
                    .withUnresolvedIsError(linkAtBuildTimeSupport.linkAtBuildTime(method.getDeclaringClass()))
                    .withFullInfopoints(true);
  ...

3. Build on Linux/AArch64
   mx build
   4 Run the debug info test
   mx debuginfotest

Describe GraalVM and your environment:

• GraalVM version: Manifests with latest GraalVM head or with version in PR [GR-38416] Implement debug location info #4505
• JDK major version: 17 or 11
• OS: Linux
• Architecture: AArch64

[olpaw]

The reference map builder assumes that lr is a callee saved register which is why it ends up calling CalleeSavedRegisters.getOffsetInFrame. Unfortunately, when the call to getOffsetInFrame looks up lr in the map stored in field offsetsInSaveArea the result is null leading to a NPE.

@teshull, sounds like SubstrateReferenceMapBuilder#addLiveValue needs to handle AArch64 differently. Do you have any hints / ideas on how to fix this?

[teshull]

hmm. I'm off the rest of this week, but I'll look into it the beginning of next week

[olpaw]

hmm. I'm off the rest of this week, but I'll look into it the beginning of next week

Thanks a lot!

[adinn]

Hi Tom, Thanks for taking a look at this.

[adinn]

@teshull I discussed a possible fix here #4505 (comment)

[teshull]

fixed by #4565