This commit reorders the argument passed to various `printDeclaration`
and `printDefinition` helper functions, to make them more uniform across
each other, and to accept the same arguments in the same order.
This commit:
* Introduces `_` as a prefix for all non-user entities we emit in
decompiled code.
Also, some names have been changed to be more concise.
Specifically, the following entities have changed:
`_ENUM_UNDERLYING`, `_ABI`, `_REG`, `_padding_at_`,
`_artificial_struct_`, `_artificial_wrapper_`, `_stack`,
`_break_from_loop_`, `_var_`, `_stack_arguments`,
`_artificial_struct_returned_`, `_enum_max_value_`.
* Introduce _PACKED for `__attribute__((packed))`.
* `EnumEntry` name: drop the `EnumType` name prefix.
Before this commit, we used to decomple UndefValue to the literal 0.
This was causing problems in some cases, such as switch(0 /*undef*/)
where clang was issuing a warning that was impossible do disable without
turning off -Wall alltogether, which is undesirable.
This commit introduces a set of helper functions in
revng-primitive-types.h, that are now used to avoid emitting undef as
constant.
This is more semantically meaningful when looking at the decompiled
code, and it has the nice side effect that it silences the clang
warnings mentioned above.
Now extractvalue instruction are replaced by dedicated
OpaqueExtractValue custom opcode, that prevents LLVM from doing strange
things with extractvalues during optimizations (such as e.g. sinking).
This is important since extractvalue instructions and struct-typed
values in general in our LLVM IR are not real first-class citizens, but
only a byproduct of the binary lifting process, and they actually
represent bundles of registers that are returned from isolated
functions.
This commit enables to emit accesses with the square bracket array
access operator on pointers.
This is accomplished by adding an additional mandatory argument to
ModelGEP (AND NOT to ModelGEPRef) to represent this case.
MakeModelGEPPass is updated to take this into account, together with all
the other passes that handle ModelGEPs.
Not equal is handled separatedly during the decompilation process in
order to add the appropriate cast.
Currently, the code only triggers when the not equal is the outermost
operation in the expression - case for which there are no tests in the
test suite.
In ModelToHeader generate Inline Types in PTML by handling
Structs, Unions and Enums.
In addition, during the ModelToHeader we avoid producing
Structs that describe stacks, and in the DecompileFunction we
produce the definition of it inline if it is safe (referenced
only once).
This commit refactors the C Backend as follows.
- The emission of basic blocks is now statement based.
There are some instructions that are handled as statements.
Those instructions are the points where the codegen starts from when
emitting C.
Conversely, all the other instructions are initially ignored when
iterating on instructions in a basic block, and are only reached when
traversing the dataflow that originates from statements.
- The TokenMap, that originally included all the string representing all
the instructions, is now used only to store the names of funciton
arguments and instructions representing local variables.
- Starting from each statement-like instruction, the C codegen is driven
by a traversal of the dataflow of the operands. The dataflow is
traversed recursively with the `getToken` method, materializing
strings on the fly until the visit reaches "leaves" i.e. instruction
that represent local variables, constants, or function arguments.
Adopting this approach allowed to reduce the peak memory consumption of
the backend, as well as making it faster on our benchmarks.
Since when we added the -exit-ssa pass, loads and stores are never
supposed to reach the C backend anymore.
This commit drops the code that supports them, that was effectively dead
code since a quite long time.
Pietro Fezzardi