Fix StackMapFrame.CopyTo misrouting frame types 64-65 - #3
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The encode dispatch in StackMapFrame.CopyTo routed FrameType <= 65 to SameStackMapFrame, but per JVMS 4.7.4 same_frame is only frame_type 0-63; 64-127 is same_locals_1_stack_item_frame. Frame types 64 and 65 therefore hit the (SameStackMapFrame)this cast, which itself asserts FrameType <= 63 and throws, making those frames impossible to re-encode. Correct the boundary to <= 63 so 64-65 fall through to the same_locals_1_stack_item_frame branch, matching the decode/measure paths which already use the correct boundary. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Summary
StackMapFrame.CopyTo(the encode dispatch) routesFrameType <= 65toSameStackMapFrame. Per JVMS §4.7.4,same_frameis onlyframe_type0–63; 64–127 issame_locals_1_stack_item_frame.As a result, frame types 64 and 65 hit the
(SameStackMapFrame)thiscast, which itself assertsFrameType <= 63and throws — so any method whose StackMapTable contains asame_locals_1_stack_item_framewith offset delta 0 or 1 (frame types 64/65) cannot be re-encoded.Verification
Confirmed the boundaries against the JVMS (Java SE 25, §4.7.4):
same_framesame_locals_1_stack_item_framesame_locals_1_stack_item_frame_extendedchop_framesame_frame_extendedappend_framefull_frameThe decode/measure paths (
TryMeasureData,AsSameStackMap) already use the correct<= 63boundary — only this one encode dispatch had the typo.Change
One line:
FrameType is <= 65→FrameType is <= 63, so 64–65 fall through to thesame_locals_1_stack_item_framebranch.Builds clean (0 errors). Independent of #2 (the Java 25 version bump); branched from
main.🤖 Generated with Claude Code
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