Handling unresolved calls in PML

[alexjordan]

Different parts of platin currently fail to process functions with unresolved calls (e.g. flowfact transformation, visualization). @dlp proposed trace analysis to identify some call targets, but this cannot handle calls in parts of the program not executed during the trace. (Platin testcase created here: https://github.com/t-crest/patmos-benchmarks/blob/master/tests/platin/22-call-any.c)

To manually resolve the calls (or ignore them), we could ultimately use

1. source code annotations
2. external annotations

Both should update a programs PML file in some way. 5a6cc5e adds an experimental platin tool to modify program information in a PML file. Program elements are selected by matching an XPath-inspired PMLPath. The only modification action supported right now is --clear-callees (clears the callee list in selected instructions), removing or replacing modifications could be added as well.

Proposed PMLPath (by example):

The first segment of the path selects the set of bitcode bc or machine code mc functions; the following segments represent function, basic block, instruction, respectively. Matching predicates are of the form [@property=name], all elements are selected using *.

The bitcode and the machine code function 'main':
/*/[@label=main]

All blocks in bitcode function 'main':
/bc/[@label=main]/*

All instructions in bitcode function 'main' that call function 'foo':
/bc/[@label=main]/*/[@callees=foo]

[alexjordan]

The command to "fix" the unresolved call in main of 22-call-any.c is:
platin pmlmod --match "/*/[@label=main]/*/*" --clear-callees -i 22-call-any.pml -o 22-call-any.pml

[Emoun]

Closing as this issue seems solved.