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upcall_call_shim_on_rust_stack has redundant call to record stack limit? #2680
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This is necessary. When switching to the c stack sp_limit is set to 0, so it must be restored before going back to rust. The sp_limit needs to be 0 when running on the C stack, so that when crust functions get called, their wrappers don't inadvertently trigger while on the C stack (which can corrupt the "state machine" of saving prev_c_sp and prev_rust_sp, frighteningly). By the way, I am moving these to rust_task.h as part of the tls push. (#1857) |
… also include ZSTs (rust-lang#2794) This change considers another case for the code generation of scalar data. In particular, when the expected type is an ADT, we previously considered two cases: either there is no field or there is one. But in cases where the ADT includes a ZST, the ADT will contain multiple fields: one associated to the scalar data, and other fields associated to the ZSTs. In those cases, we ended up crashing as in rust-lang#2680: ```rust error: internal compiler error: Kani unexpectedly panicked at panicked at cprover_bindings/src/goto_program/expr.rs:804:9: assertion failed: `(left == right)` left: `2`, right: `1`: Error in struct_expr; mismatch in number of fields and values. StructTag("tag-_161424092592971241517604180463813633314") [Expr { value: IntConstant(0), typ: Unsignedbv { width: 8 }, location: None, size_of_annotation: None }]. thread 'rustc' panicked at cprover_bindings/src/goto_program/expr.rs:804:9: assertion failed: `(left == right)` left: `2`, right: `1`: Error in struct_expr; mismatch in number of fields and values. StructTag("tag-_161424092592971241517604180463813633314") [Expr { value: IntConstant(0), typ: Unsignedbv { width: 8 }, location: None, size_of_annotation: None }] ``` With the changes in this PR, that's no longer the case. Resolves rust-lang#2364 Resolves rust-lang#2680
Unclear comment in this function in rust_upcall.cpp, but appears to be saying function does some redundant work. Clarify?
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