This change is in the core generator monad and applied in the PowerPC backend.
This change includes some macaw updates (which required a new elf-edit version).
Now test to ensure that no blocks end in a classification failure (or a
disassembly failure). Before, many blocks were not classified, which causes
problems downstream. This required some changes in macaw core in two places:
1. The simplifier needed some additional rules to remove some redundant
constructions that threw off the abstract interpretation of values. This was
particularly an issue while reading return values off of the stack in
PowerPC.
2. Extending the abstract interpretation to be able to handle more operations (shiftl)
We need special treatment of the return, as the low two bits are cleared on
PowerPC, so we can't just rely on pattern matching against the ReturnAddr in the
IP register.
The Macaw Discovery now calls the identifyReturn to identify return
statements. Supply this for ARM, but at present this simply
replicates the original inline code which does not properly detect ARM
return operations because the low bit(s) of the address are always
cleared when writing to the instruction pointer in ARM.
The identifyReturn was previously unused because the Macaw Discovery
performed this test inline, but some architectures have different
semantics so the identifyReturn is now used by the Discovery process.
This implements the return discovery that should be sufficient for the
PPC.
Recent changes in macaw(-base) mean that we split blocks more aggressively. The
old expected outputs were conservative - these new values are much more in line
with intuitive expectation (with more aggressive splitting of blocks and less
code duplication between blocks).
Original version was pushing error into generated TH, which was
generating the error statement into the SSA formula; this breaks
formula interpretation at compile time but hides the error. Instead,
this changes it so that the error is thrown during TH evaluation.
