ymandel marked 10 inline comments as done.
ymandel added a comment.
Thanks for the review!
================
Comment at:
clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp:39-45
+ using dataflow::ControlFlowContext;
+ using dataflow::DataflowAnalysisContext;
+ using dataflow::DataflowAnalysisState;
+ using dataflow::Environment;
+ using dataflow::UncheckedOptionalAccessModel;
+ using dataflow::WatchedLiteralsSolver;
+ using llvm::Expected;
----------------
sgatev wrote:
> Do we really need all these using declarations? There seems to be one
> reference for each of these types. I think we can simply qualify the
> references.
No, we don't need them, but IMO they clarify the code. We're really heavy with
the types, given that `auto` is discouraged, so I think pulling these out
improves readability in some critical places (lines 56 and 63). I figured I'd
do all for consistency. I've removed those not related to lines 56 and 63, or
used more than once. WDYT?
================
Comment at:
clang-tools-extra/clang-tidy/bugprone/UncheckedOptionalAccessCheck.cpp:84
+ if (!BlockToOutputState ||
+ BlockToOutputState->size() <= Context->getCFG().getExit().getBlockID())
+ return;
----------------
sgatev wrote:
> xazax.hun wrote:
> > ymandel wrote:
> > > xazax.hun wrote:
> > > > xazax.hun wrote:
> > > > > ymandel wrote:
> > > > > > xazax.hun wrote:
> > > > > > > xazax.hun wrote:
> > > > > > > > Could the size of the vector ever be wrong? Should this be an
> > > > > > > > assert instead?
> > > > > > > Whoops, after the update this comment is out of place, now it
> > > > > > > supposed to be on line 60.
> > > > > > Based on my reading, it is a rare, but possible condition.
> > > > > > Basically, we need code where the exit block is unreachable, which
> > > > > > I believe can happen in weird cases like:
> > > > > >
> > > > > > ```
> > > > > > while(true) {...}
> > > > > > ```
> > > > > > https://godbolt.org/z/rfEnfaWTv -- notice the lack of predecessors
> > > > > > for the exit block.
> > > > > >
> > > > > > See the code here, which follows the ordering of the blocks and
> > > > > > doesn't force blocks to be processed:
> > > > > >
> > > > > > https://github.com/llvm/llvm-project/blob/main/clang/lib/Analysis/FlowSensitive/TypeErasedDataflowAnalysis.cpp#L337-L364
> > > > > Interesting. Since we already have optionals in the vector, I assumed
> > > > > we will always have matching size. I think we might want to change
> > > > > this so there is only one way for the analysis to not provide a state
> > > > > for a basic block to make this a bit less confusing,
> > > > Actually, in the linked code I see `
> > > > BlockStates.resize(CFCtx.getCFG().size(), llvm::None);`. So I would
> > > > expect the size to be always right with possibly some `None`s for the
> > > > nodes that were not processed.
> > > > Actually, in the linked code I see `
> > > > BlockStates.resize(CFCtx.getCFG().size(), llvm::None);`. So I would
> > > > expect the size to be always right with possibly some `None`s for the
> > > > nodes that were not processed.
> > > Ah, my mistake! I thought `resize` only allocated the space. #TIL
> > >
> > > Changed to an assert. Thanks.
> > >
> > But this discussion shed light on an interesting detail. If the exit block
> > is unreachable, we will not diagnose the unsafe accesses. I wonder if this
> > worth a FIXME.
> The documentation of `runDataflowAnalysis` already hints that the size of the
> vector matches the size of the CFG. Do you think we should make this more
> clear?
> But this discussion shed light on an interesting detail. If the exit block is
> unreachable, we will not diagnose the unsafe accesses. I wonder if this worth
> a FIXME.
> The documentation of runDataflowAnalysis already hints that the size of the
> vector matches the size of the CFG. Do you think we should make this more
> clear?
Yes to both. I'll send a separate patch on that header with the doc changes.
Repository:
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https://reviews.llvm.org/D121120/new/
https://reviews.llvm.org/D121120
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