The collection points of several ABI analyses where incorrect. Several
analyses that should have collected data only from entry points were
collecting data from any node in the graph.
Up until now, we did not need different !dbg/DISubprogram
attached to each isolated llvm::Function, but for the
purpose of MLIR lowering, we need it.
On the LLVM IR level, we used to reuse root's DISubpgram,
and we have not being attaching !dbg/DISubprogram to the
isolated functions at all (just to llvm::Instructions),
but that was an hack in order to avoid some LLVM verify
checks, since LLVM IR expects !dbg attachments to calls of
functions that could be inlined, but by avoid !dbg on the
Function itself, it won't verify !dbg attachments on the
instructions, since it will assume it has no debug info in
it. When it comes to MLIR, it expects different !dbg
attached to each function, in order to process debug info
in it, so that is the reason we cannot rely on the root
DISubprogram only anymore.
getJumpTargetBlock takes llvm::BasicBlock * as argument, but doesn't
need to modify it, so const it adds const to it and other functions that
are used by getJumpTargetBlock: findJumpTarget, isTranslated, getType,
isJumpTarget.
The goal of this update is to propagate prototypes of functions called
in wrappers to this wrappers.
When some function hasn't it's own prototype, but the only thing it does
is calling another function, DetectABI pass sets callee prototype as
caller prototype also.
This behaviour is limited to callers that:
1. have only one basic block
2. end with call
3. don't write arguments of callee
4. don't modify stack pointer
5. don't write to memory.
`ValueMaterializer` is a rewrite of what was called `AdvancedValueInfo`
which follows the same principles.
The main benefits over the old version is:
* We materialize the data-flow graph and the CFG of the relevant part of
root. This makes debugging significantly easier.
* We drop the old MonotoneFramework infrastructure in favor of
getMaximalFixedPoint.
* We significantly reduce the amount of queries we make to
AdvancedValueInfo.
We used to ignore CFEPs that matched the starting address of a basic
block of a previously detect function.
We now also exclude such CFEPs even if the candidate is *part* of an
existing block.
This is done mainly so that downstream passes do not need to run
`CollectCFG` to store information that has already been computed but not
serialized.
This come at the cost of computing the CFG also of functions we don't
want to analyze in `DetectABI`.
We used to only color instructions in the same BasicBlock as the call to
`newpc`. However, an instruction in the original binary can span
multiple BasicBlocks.
This commit introduces `BasicBlockID` as the unique identifier for a
`efa::BasicBlock` into the CFG. A `BasicBlockID` is defined by a
`MetaAddress` plus an incremental integer. This enables us to have
multiple instances of the same block in a single function, which is
particularly useful when inlining multiple times the same function.
Apart from this, the commit also does the following:
* It drops representing `MetaAddress`es a `structs` in the IR. This created
several issues related to ABI. We now represent them as strings.
* It defines more functions in `support.h`, instead of defining prototypes
by hand in `CodeGenerator.cpp` and the like. Specifically, `unknownPC`
and `raise_exception_helper`. We also introduce a C "constructor" for
`PlainMetaAddress`.
* It significantly reduces the API of `GeneratedCodeBasicInfo`, which
was supposed to be put on a diet since a long time. Specifically,
many jump target related methods have been moved to free functions in
`IRHelpers.h`. Also `GCBI::getSuccessors` has been pushed into its
only user, `PruneRetSuccessors`, to prevent further usage of a
deprecated API. In the future, it would be nice to drop it entirely.
* It introduces `efa::BasicBlock::InlinedFrom`.
* Introduce an enum to represent named argument indices for `newpc`.
This enables us to more effectively manipulate its argument list.
* It improves the verification and error reporting for
`efa::FunctionMetadata`.
* Update tests.
This commit is preliminary to another piece of work to improve the
generality of inlining beyond the simple "fake function" scenario, for
which the feature was originally conceived.
FunctionMetadata was being deserialized every time they were
inspected. This commit introduces a cache structure to prevent this
excessive deserializations.
Alessandro Di Federico