cleavir: a local mv-call's phi must name the block its arguments end in

[dg1sbg]

DIRECT-MV-LOCAL-CALL-VAS gives MERGE one phi per optional parameter, then in each switch case builds that case's argument values and records the case's own block as the phi predecessor.

Building a value can emit an invoke — the checked unbox a generated type-checker performs, whenever a landing pad is in scope — and IRC-CREATE-INVOKE-WFT ends the block and continues in a fresh normal-dest. The phi is then told about a block that no longer branches to MERGE:

PHI node entries do not match predecessors!
  %phi263 = phi float [ undef, %lmvc-optional-0 ], [ %single-float276, %lmvc-optional-1 ], ...
label %lmvc-optional-3
label %normal-dest295

Broken module → the image dies.

• both loops now read the insert block after the values are built, and use that
• optional cases and the more-than-enough case alike
• values computed before an invoke still dominate: their block dominates the invoke's normal destination

Repro (no minimal case yet — see below): a CLIM toolkit compiled natively, FiveAM compiling test bodies at run time; died at test 1582/2101 in a MULTIPLE-VALUE-BIND of three single-floats from a typed function inside an UNWIND-PROTECT. With this change the same run completes all 2101.

• full ninja test: exit 0, 2070 successes, no new failure
• 34 826 such block splits recorded in one instrumented run; callees are all generated …-CHECKER local functions
• no regression test: 26 standalone shapes, including that source form, compile cleanly — the trigger needs type information the running image accumulates. Happy to keep hunting if you want the small case before merging.