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8315771: [JVMCI] Resolution of bootstrap methods with int[] static arguments #15588

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8315771: [JVMCI] Resolution of bootstrap methods with int[] static arguments #15588

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b0940de
Implement lookup of bootstrap methods with static arguments of type i…
Zeavee Sep 6, 2023
2cdc0b4
Rewrite doc for bootstrapArgumentIndexAt and add second argument to a…
Zeavee Sep 6, 2023
b33ffed
Add more details to the documentation and add a pseudo code example f…
Zeavee Sep 7, 2023
093d0ce
Add missing line of pseudo code and applied modification suggestion
Zeavee Sep 7, 2023
4ec0a7b
Add CachedBSMArgs to resolve arguments lazily instead of letting the …
Zeavee Sep 7, 2023
079969c
Fix BootstrapMethodInvocation.getStaticArguments documentation and ad…
Zeavee Sep 8, 2023
d6aa593
Use lookupConstant instead of lookupConstantInPool in CachedBSMArgs.get
Zeavee Sep 13, 2023
d75e092
Add undefined behavior documentation for bootstrapArgumentIndexAt and…
Zeavee Sep 13, 2023
f4377fc
Update getStaticArguments documentation example and update TestDynami…
Zeavee Sep 14, 2023
9e0627a
Add -XX:UseBootstrapCallInfo=3 to TestDynamicConstant
Zeavee Sep 19, 2023
ea4aa98
Add an extra run configuration for TestDynamicConstant instead of rep…
Zeavee Sep 19, 2023
7c27481
Update BootstrapMethodInvocation.getStaticArguments documentation
Zeavee Sep 20, 2023
7a8d9f2
Iterate over all static arguments in TestDynamicConstant
Zeavee Sep 21, 2023
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6 changes: 3 additions & 3 deletions src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/CompilerToVM.java
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Expand Up @@ -477,14 +477,14 @@ Object[] resolveBootstrapMethod(HotSpotConstantPool constantPool, int cpi) {
private native Object[] resolveBootstrapMethod(HotSpotConstantPool constantPool, long constantPoolPointer, int cpi);

/**
* Gets the constant pool index of a static argument of a bootstrap specifier (a constant pool entry
* containing information about a bootstrap method). Used when the list of static arguments in the
* Gets the constant pool index of a static argument of a {@code CONSTANT_Dynamic_info} or
* @{code CONSTANT_InvokeDynamic_info} entry. Used when the list of static arguments in the
* {@link BootstrapMethodInvocation} is a {@code List<PrimitiveConstant>} of the form
* {{@code arg_count}, {@code pool_index}}, meaning the arguments are not already resolved and that
* the JDK has to lookup the arguments when they are needed. The {@code cpi} corresponds to
* {@code pool_index} and the {@code index} has to be smaller than {@code arg_count}.
*
* @param cpi the index of a bootstrap specifier in the constant pool
* @param cpi the index of a {@code CONSTANT_Dynamic_info} or @{code CONSTANT_InvokeDynamic_info} entry
* @param index the index of the static argument in the list of static arguments
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What happens when index is out of bounds?

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Currently, it returns another constant pool index or a random number. I can add a check in the CachedBSMArgs.get method to prevent this.

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Yes please. We should opt for exceptions over undefined behavior whenever possible.

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After double checking, there is in fact already an assert for checking if the index is out of bounds. Should I change it to an exception?

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Is the assertion in code that can throw exceptions?

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The assertion is here. I don't think we can throw exception there. I could check the size in jvmciCompilerToVM.bootstrapArgumentIndexAt, but it would require a bit of code duplication to obtain it.

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Ok. You should just add a note in the javadoc that the result is undefined if index is out of bounds. This is all internal API so I assume we can guarantee the value is correct?

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Yes, it is only used in CachedBSMArgs.get, which will throw an ArrayIndexOutOfBoundsException before we arrive there.

* @return the constant pool index associated with the static argument
*/
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11 changes: 6 additions & 5 deletions src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/meta/ConstantPool.java
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Expand Up @@ -136,13 +136,14 @@ default JavaMethod lookupMethod(int cpi, int opcode) {
* The procedure to obtain and use a {@link BootstrapMethodInvocation} is the following:
*
* <pre>
* bsmInvocation = lookupBootstrapMethodInvocation(index, opcode);
* bsmInvocation = constantpool.lookupBootstrapMethodInvocation(index, opcode);
* staticArguments = bsmInvocation.getStaticArguments();
* if staticArguments are PrimitiveConstant {
* argCount = staticArguments.get(0).asInt();
* cpi = staticArguments.get(1).asInt();
* for (int i = 0; i < argCount; ++i) {
* arguments[i] = lookupConstant(cpi, i);
* argCpi = constantpool.bootstrapArgumentIndexAt(cpi, i);
* arguments[i] = constantpool.lookupConstant(argCpi, resolve);
* }
* call bootstrap method with newly resolved arguments
* } else {
Expand Down Expand Up @@ -188,14 +189,14 @@ interface BootstrapMethodInvocation {
}

/**
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This is very confusing documentation. It's not clear what index or entry you are referring to each time you say "index". Please provide a concrete example.

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I have rewritten the documentation, I hope it is clearer. I also added a second argument to be able to access different different static arguments on the same bootstrap specifier.

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It still needs an example showing how this API should be used. Please add a complete (pseudo-code) example to the javadoc of BootstrapMethodInvocation.

* Gets the constant pool index of a static argument of a bootstrap specifier (a constant pool entry
* containing information about a bootstrap method). Used when the list of static arguments in the
* Gets the constant pool index of a static argument of a {@code CONSTANT_Dynamic_info} or
* @{code CONSTANT_InvokeDynamic_info} entry. Used when the list of static arguments in the
* {@link BootstrapMethodInvocation} is a {@code List<PrimitiveConstant>} of the form
* {{@code arg_count}, {@code pool_index}}, meaning the arguments are not already resolved and that
* the JDK has to lookup the arguments when they are needed. The {@code cpi} corresponds to
* {@code pool_index} and the {@code index} has to be smaller than {@code arg_count}.
*
* @param cpi the index of a bootstrap specifier in the constant pool
* @param cpi the index of a {@code CONSTANT_Dynamic_info} or @{code CONSTANT_InvokeDynamic_info} entry
* @param index the index of the static argument in the list of static arguments
* @return the constant pool index associated with the static argument
*/
Expand Down