Now that we've started printing the targets of `Call` instructions in the IR dumps, I figured I might as well print the names of the variable being loaded or stored as well. We could potentially extend this to match fields, array elements, etc., but that's quite a bit more work.
I've added one more property to the annotations provided by `PrintIRLocalFlow.qll`: The `pflow` property will now be emitted for any operand or instruction for which `configuration.hasPartialFlow` determines that there is partial flow to that node. This requires that partial flow be enabled via overriding `Configuration::explorationLimit()` in order to display. Otherwise, you'll still just get the local flow info as before.
This change adds a new module, `PrintIRLocalFlow.qll`, which can be imported into any query that uses both `PrintIR.qll` and the IR dataflow library. The IR dump printed by `PrintIR.qll` will be annotated with information about how each operand and instruction participates in dataflow.
For each operand and instruction, the following propeties are displayed:
- `flow`: Which local operands/instructions have flow to this node, and which local operands/instruction this node has flow to.
- `source`: `true` if this node is a source
- `sink`: `true` if this node is a sink
- `barrier`: Lists which kinds of barrier this node is. Can be zero or more of `full`, `in`, `out`, and `guard`. If the node is a guard barrier, the IR of the guarding instruction is also printed.
We already had a way to print additional properties for instructions and blocks, but not for operands. I added support for operand properties to `IRPropertyProvider`. These are now printed in a curly-brace-enclosed list immediately after the corresponding operand.
When printing flow, instructions are identified by their result ID (e.g., `m128`). Operands are identified by both the result ID of their instruction and their kind (e.g., `r145.left`). For flow from an operand to its use instruction, it just prints `result` at the operand, and prints only the operand kind on the instruction.
Example output:
```
# 344| m344_34(vector<int, allocator<int>>) = Chi : total:m344_20{flow:def->@, @->result}, partial:m344_33{flow:def->@, @->result}
# 344| flow = total->@, partial->@, +m344_33->@, @->+r347_3, @->v347_7.side_effect, @->m347_9.total, @->m344_20.1
```
The `+` annotations indicate when the flow came from `isAdditionalFlowStep()`, rather than built-in local flow.
