analyze: memcpy/memset, void* rewrites, and other fixes for algo_md5 #1043
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… by inner adjustment
aneksteind
reviewed
Nov 8, 2023
| mutbl: hir::Mutability, | ||
| ) -> bool { | ||
| let adjusts = self.typeck_results.expr_adjustments(ex); | ||
| if adjusts.len() < 2 { |
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a comment for the magic numbers would be helpful
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Refactored slightly in 6eca040 to make it clear we're inspecting the last two elements of adjusts.
aneksteind
reviewed
Nov 8, 2023
| ex.span, ref_expr.span, mutbl | ||
| ); | ||
| // Check whether the `&x` / `&mut x` expr got the expected adjustments. | ||
| if self.expr_has_address_of_adjustments(ref_expr, mutbl) { |
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this is the part that extracts &x from the cast?
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Added a small comment in 6eca040
aneksteind
approved these changes
Nov 8, 2023
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&x as *const Tthat don't get lowered to an actual MIRRvalue::Castassignmentunlower_maphas no origin" errors in algo_md5dataflowchanges for memcpy/memset. Specifically, this detects whether the memcpy/memset is affecting exactly one item (byte count ==mem::size_of::<T>(), whereTis the pointee type) or possibly more than one item. Multi-item memcpy/memset requires the OFFSET permission on the input pointers. The check formem::size_of::<T>()uses the newrecent_writesanalysis to find the instruction that was used to compute the byte length argument.rewrite::expr::convertto fold certain rewrites together. Specifically, when applying a MIR rewrite and there is already a HIR rewrite on the current node, in some cases it will edit the current rewrite instead of wrapping it. For example,mir_op::RewriteKind::MutToImmapplied toRewrite::Ref(rw, Mutability::Mut)(&mut _) will produceRewrite::Ref(rw, Mutability::Not)(&_) rather thanRef(Deref(Ref(rw, Mut)), Not)(&*(&mut _)). This fixes an issue with the removal of array.as_mut_ptr()calls in cases where we're rewriting the resulting pointer type to a non-mut slice.input: *mut c_voidtoinput: &[u8]in certain algo_md5 function signatures.CVoidCastsmachinery, which is now superseded by pointee analysis and cast removal.