[code-reflection] RFR: 8373576: BytecodeGenerator fails with AssertionError on InvokeOp with varargs

[Adam Sotona]

The first operand of a static vararg method invocation is wrongly identified as the first operand on stack for the following bytecode instruction.
However several bytecode instructions prepend the operand use, so the operand presence on the stack must be deferred.

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Commit messages:
 - 8373576: BytecodeGenerator fails with AssertionError on InvokeOp with varargs

Changes: https://git.openjdk.org/babylon/pull/747/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=747&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8373576
  Stats: 8 lines in 2 files changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/babylon/pull/747.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/747/head:pull/747

PR: https://git.openjdk.org/babylon/pull/747