Remove support for sending pointers to GenMC.

Author: Patrick-6

genmc-sys/src/lib.rs

@@ -14,11 +14,11 @@ pub struct GenmcThreadId(pub i32);
 pub const GENMC_MAIN_THREAD_ID: GenmcThreadId = GenmcThreadId(0);
 
 impl GenmcScalar {
-    pub const UNINIT: Self = Self { value: 0, extra: 0, is_init: false };
+    pub const UNINIT: Self = Self { value: 0, is_init: false };
     pub const DUMMY: Self = Self::from_u64(0xDEADBEEF);
 
     pub const fn from_u64(value: u64) -> Self {
-        Self { value, extra: 0, is_init: true }
+        Self { value, is_init: true }
     }
 }
 
@@ -87,7 +87,6 @@ mod ffi {
     #[derive(Debug, Clone, Copy)]
     struct GenmcScalar {
         value: u64,
-        extra: u64,
         is_init: bool,
     }
 

src/concurrency/genmc/helper.rs

@@ -4,8 +4,7 @@ use rustc_middle::ty::ScalarInt;
 use tracing::info;
 
 use super::GenmcScalar;
-use crate::alloc_addresses::EvalContextExt as _;
-use crate::{BorTag, MiriInterpCx, Pointer, Provenance, Scalar, throw_unsup_format};
+use crate::{MiriInterpCx, Scalar, throw_unsup_format};
 
 pub fn split_access(address: Size, size: Size) -> impl Iterator<Item = (u64, u64)> {
     /// Maximum size memory access in bytes that GenMC supports.
@@ -70,66 +69,28 @@ pub fn option_scalar_to_genmc_scalar<'tcx>(
 }
 
 pub fn scalar_to_genmc_scalar<'tcx>(
-    ecx: &MiriInterpCx<'tcx>,
+    _ecx: &MiriInterpCx<'tcx>,
     scalar: Scalar,
 ) -> InterpResult<'tcx, GenmcScalar> {
     interp_ok(match scalar {
         rustc_const_eval::interpret::Scalar::Int(scalar_int) => {
             // TODO GENMC: u128 support
             let value: u64 = scalar_int.to_uint(scalar_int.size()).try_into().unwrap(); // TODO GENMC: doesn't work for size != 8
-            GenmcScalar { value, extra: 0, is_init: true }
-        }
-        rustc_const_eval::interpret::Scalar::Ptr(pointer, size) => {
-            let addr = Pointer::from(pointer).addr();
-            if let Provenance::Wildcard = pointer.provenance {
-                throw_unsup_format!("Pointers with wildcard provenance not allowed in GenMC mode");
-            }
-            let (alloc_id, _size, _prov_extra) =
-                rustc_const_eval::interpret::Machine::ptr_get_alloc(ecx, pointer, size.into())
-                    .unwrap();
-            let base_addr = ecx.addr_from_alloc_id(alloc_id, None)?;
-            GenmcScalar { value: addr.bytes(), extra: base_addr, is_init: true }
+            GenmcScalar { value, is_init: true }
         }
+        rustc_const_eval::interpret::Scalar::Ptr(_pointer, _size) =>
+            throw_unsup_format!(
+                "FIXME(genmc): Implement sending pointers (with provenance) to GenMC."
+            ),
     })
 }
 
 pub fn genmc_scalar_to_scalar<'tcx>(
-    ecx: &MiriInterpCx<'tcx>,
+    _ecx: &MiriInterpCx<'tcx>,
     scalar: GenmcScalar,
     size: Size,
 ) -> InterpResult<'tcx, Scalar> {
-    // TODO GENMC: proper handling of large integers
-    // TODO GENMC: proper handling of pointers (currently assumes all integers)
-
-    if scalar.extra != 0 {
-        // We have a pointer!
-
-        let addr = Size::from_bytes(scalar.value);
-        let base_addr = scalar.extra;
-
-        let alloc_size = 0; // TODO GENMC: what is the correct size here? Is 0 ok?
-        let only_exposed_allocations = false;
-        let Some(alloc_id) =
-            ecx.alloc_id_from_addr(base_addr, alloc_size, only_exposed_allocations)
-        else {
-            // TODO GENMC: what is the correct error in this case?
-            throw_unsup_format!(
-                "Cannot get allocation id of pointer received from GenMC (base address: 0x{base_addr:x}, pointer address: 0x{:x})",
-                addr.bytes()
-            );
-        };
-
-        // TODO GENMC: is using `size: Size` ok here? Can we ever have `size != sizeof pointer`?
-
-        // FIXME: Currently GenMC mode incompatible with aliasing model checking
-        let tag = BorTag::default();
-        let provenance = crate::machine::Provenance::Concrete { alloc_id, tag };
-        let offset = addr;
-        let ptr = rustc_middle::mir::interpret::Pointer::new(provenance, offset);
-
-        let size = size.bytes().try_into().unwrap();
-        return interp_ok(Scalar::Ptr(ptr, size));
-    }
+    // FIXME(genmc): Add GencmScalar to Miri Pointer conversion.
 
     // NOTE: GenMC always returns 64 bit values, and the upper bits are not yet truncated.
     // FIXME(genmc): Rework if 128bit support is added to GenMC.