Merge pull request #50 from oli-obk/casts

implement more casts

Author: solson

src/error.rs

@@ -28,7 +28,7 @@ pub enum EvalError<'tcx> {
     ExecuteMemory,
     ArrayIndexOutOfBounds(Span, u64, u64),
     Math(Span, ConstMathErr),
-    InvalidChar(u32),
+    InvalidChar(u64),
     OutOfMemory {
         allocation_size: usize,
         memory_size: usize,

src/interpreter/cast.rs

@@ -0,0 +1,96 @@
+
+use super::{
+    EvalContext,
+};
+use error::{EvalResult, EvalError};
+use rustc::ty;
+use primval::PrimVal;
+use memory::Pointer;
+
+use rustc::ty::Ty;
+use syntax::ast;
+
+impl<'a, 'tcx> EvalContext<'a, 'tcx> {
+    pub(super) fn cast_primval(&self, val: PrimVal, ty: Ty<'tcx>) -> EvalResult<'tcx, PrimVal> {
+        use primval::PrimVal::*;
+        match val {
+            Bool(b) => self.cast_const_int(b as u64, ty, false),
+            F32(f) => self.cast_const_float(f as f64, ty),
+            F64(f) => self.cast_const_float(f, ty),
+            I8(i) => self.cast_signed_int(i as i64, ty),
+            I16(i) => self.cast_signed_int(i as i64, ty),
+            I32(i) => self.cast_signed_int(i as i64, ty),
+            I64(i) => self.cast_signed_int(i, ty),
+            U8(u) => self.cast_const_int(u as u64, ty, false),
+            U16(u) => self.cast_const_int(u as u64, ty, false),
+            U32(u) => self.cast_const_int(u as u64, ty, false),
+            Char(c) => self.cast_const_int(c as u64, ty, false),
+            U64(u) |
+            IntegerPtr(u) => self.cast_const_int(u, ty, false),
+            FnPtr(ptr) |
+            AbstractPtr(ptr) => self.cast_ptr(ptr, ty),
+        }
+    }
+
+    fn cast_ptr(&self, ptr: Pointer, ty: Ty<'tcx>) -> EvalResult<'tcx, PrimVal> {
+        use primval::PrimVal::*;
+        match ty.sty {
+            ty::TyRef(..) |
+            ty::TyRawPtr(_) => Ok(AbstractPtr(ptr)),
+            ty::TyFnPtr(_) => Ok(FnPtr(ptr)),
+            _ => Err(EvalError::Unimplemented(format!("ptr to {:?} cast", ty))),
+        }
+    }
+
+    fn cast_signed_int(&self, val: i64, ty: ty::Ty<'tcx>) -> EvalResult<'tcx, PrimVal> {
+        self.cast_const_int(val as u64, ty, val < 0)
+    }
+
+    fn cast_const_int(&self, v: u64, ty: ty::Ty<'tcx>, negative: bool) -> EvalResult<'tcx, PrimVal> {
+        use primval::PrimVal::*;
+        match ty.sty {
+            ty::TyBool if v == 0 => Ok(Bool(false)),
+            ty::TyBool if v == 1 => Ok(Bool(true)),
+            ty::TyBool => Err(EvalError::InvalidBool),
+            ty::TyInt(ast::IntTy::I8) => Ok(I8(v as i64 as i8)),
+            ty::TyInt(ast::IntTy::I16) => Ok(I16(v as i64 as i16)),
+            ty::TyInt(ast::IntTy::I32) => Ok(I32(v as i64 as i32)),
+            ty::TyInt(ast::IntTy::I64) => Ok(I64(v as i64)),
+            ty::TyInt(ast::IntTy::Is) => {
+                let int_ty = self.tcx.sess.target.int_type;
+                let ty = self.tcx.mk_mach_int(int_ty);
+                self.cast_const_int(v, ty, negative)
+            },
+            ty::TyUint(ast::UintTy::U8) => Ok(U8(v as u8)),
+            ty::TyUint(ast::UintTy::U16) => Ok(U16(v as u16)),
+            ty::TyUint(ast::UintTy::U32) => Ok(U32(v as u32)),
+            ty::TyUint(ast::UintTy::U64) => Ok(U64(v)),
+            ty::TyUint(ast::UintTy::Us) => {
+                let uint_ty = self.tcx.sess.target.uint_type;
+                let ty = self.tcx.mk_mach_uint(uint_ty);
+                self.cast_const_int(v, ty, negative)
+            },
+            ty::TyFloat(ast::FloatTy::F64) if negative => Ok(F64(v as i64 as f64)),
+            ty::TyFloat(ast::FloatTy::F64) => Ok(F64(v as f64)),
+            ty::TyFloat(ast::FloatTy::F32) if negative => Ok(F32(v as i64 as f32)),
+            ty::TyFloat(ast::FloatTy::F32) => Ok(F32(v as f32)),
+            ty::TyRawPtr(_) => Ok(IntegerPtr(v)),
+            ty::TyChar if v as u8 as u64 == v => Ok(Char(v as u8 as char)),
+            ty::TyChar => Err(EvalError::InvalidChar(v)),
+            _ => Err(EvalError::Unimplemented(format!("int to {:?} cast", ty))),
+        }
+    }
+
+    fn cast_const_float(&self, val: f64, ty: Ty<'tcx>) -> EvalResult<'tcx, PrimVal> {
+        use primval::PrimVal::*;
+        match ty.sty {
+            // casting negative floats to unsigned integers yields zero
+            ty::TyUint(_) if val < 0.0 => self.cast_const_int(0, ty, false),
+            ty::TyInt(_) if val < 0.0 => self.cast_const_int(val as i64 as u64, ty, true),
+            ty::TyInt(_) | ty::TyUint(_) => self.cast_const_int(val as u64, ty, false),
+            ty::TyFloat(ast::FloatTy::F64) => Ok(F64(val)),
+            ty::TyFloat(ast::FloatTy::F32) => Ok(F32(val as f32)),
+            _ => Err(EvalError::Unimplemented(format!("float to {:?} cast", ty))),
+        }
+    }
+}

src/interpreter/mod.rs

@@ -5,7 +5,7 @@ use rustc::mir::repr as mir;
 use rustc::traits::Reveal;
 use rustc::ty::layout::{self, Layout, Size};
 use rustc::ty::subst::{self, Subst, Substs};
-use rustc::ty::{self, Ty, TyCtxt};
+use rustc::ty::{self, Ty, TyCtxt, TypeFoldable};
 use rustc::util::nodemap::DefIdMap;
 use rustc_data_structures::indexed_vec::Idx;
 use std::cell::RefCell;
@@ -22,6 +22,7 @@ use std::collections::HashMap;
 
 mod step;
 mod terminator;
+mod cast;
 
 pub struct EvalContext<'a, 'tcx: 'a> {
     /// The results of the type checker, from rustc.
@@ -211,9 +212,10 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                 let psize = self.memory.pointer_size();
                 let static_ptr = self.memory.allocate(s.len(), 1)?;
                 let ptr = self.memory.allocate(psize * 2, psize)?;
+                let (ptr, extra) = self.get_fat_ptr(ptr);
                 self.memory.write_bytes(static_ptr, s.as_bytes())?;
                 self.memory.write_ptr(ptr, static_ptr)?;
-                self.memory.write_usize(ptr.offset(psize as isize), s.len() as u64)?;
+                self.memory.write_usize(extra, s.len() as u64)?;
                 Ok(ptr)
             }
             ByteStr(ref bs) => {
@@ -244,6 +246,8 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
     }
 
     fn type_is_sized(&self, ty: Ty<'tcx>) -> bool {
+        // generics are weird, don't run this function on a generic
+        assert!(!ty.needs_subst());
         ty.is_sized(self.tcx, &self.tcx.empty_parameter_environment(), DUMMY_SP)
     }
 
@@ -558,12 +562,12 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
 
             Ref(_, _, ref lvalue) => {
                 let lv = self.eval_lvalue(lvalue)?;
-                self.memory.write_ptr(dest, lv.ptr)?;
+                let (ptr, extra) = self.get_fat_ptr(dest);
+                self.memory.write_ptr(ptr, lv.ptr)?;
                 match lv.extra {
                     LvalueExtra::None => {},
                     LvalueExtra::Length(len) => {
-                        let len_ptr = dest.offset(self.memory.pointer_size() as isize);
-                        self.memory.write_usize(len_ptr, len)?;
+                        self.memory.write_usize(extra, len)?;
                     }
                     LvalueExtra::DowncastVariant(..) =>
                         bug!("attempted to take a reference to an enum downcast lvalue"),
@@ -583,14 +587,14 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                     Unsize => {
                         let src = self.eval_operand(operand)?;
                         let src_ty = self.operand_ty(operand);
-                        self.move_(src, dest, src_ty)?;
+                        let (ptr, extra) = self.get_fat_ptr(dest);
+                        self.move_(src, ptr, src_ty)?;
                         let src_pointee_ty = pointee_type(src_ty).unwrap();
                         let dest_pointee_ty = pointee_type(dest_ty).unwrap();
 
                         match (&src_pointee_ty.sty, &dest_pointee_ty.sty) {
                             (&ty::TyArray(_, length), &ty::TySlice(_)) => {
-                                let len_ptr = dest.offset(self.memory.pointer_size() as isize);
-                                self.memory.write_usize(len_ptr, length as u64)?;
+                                self.memory.write_usize(extra, length as u64)?;
                             }
 
                             _ => return Err(EvalError::Unimplemented(format!("can't handle cast: {:?}", rvalue))),
@@ -600,20 +604,25 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                     Misc => {
                         let src = self.eval_operand(operand)?;
                         let src_ty = self.operand_ty(operand);
-                        // FIXME(solson): Wrong for almost everything.
-                        warn!("misc cast from {:?} to {:?}", src_ty, dest_ty);
-                        let dest_size = self.type_size(dest_ty);
-                        let src_size = self.type_size(src_ty);
-                        let dest_align = self.type_align(dest_ty);
-
-                        // Hack to support fat pointer -> thin pointer casts to keep tests for
-                        // other things passing for now.
-                        let is_fat_ptr_cast = pointee_type(src_ty).map_or(false, |ty| !self.type_is_sized(ty));
-
-                        if dest_size == src_size || is_fat_ptr_cast {
-                            self.memory.copy(src, dest, dest_size, dest_align)?;
+                        if self.type_is_fat_ptr(src_ty) {
+                            let (data_ptr, _meta_ptr) = self.get_fat_ptr(src);
+                            let ptr_size = self.memory.pointer_size();
+                            let dest_ty = self.monomorphize(dest_ty, self.substs());
+                            if self.type_is_fat_ptr(dest_ty) {
+                                // FIXME: add assertion that the extra part of the src_ty and
+                                // dest_ty is of the same type
+                                self.memory.copy(data_ptr, dest, ptr_size * 2, ptr_size)?;
+                            } else { // cast to thin-ptr
+                                // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
+                                // pointer-cast of that pointer to desired pointer type.
+                                self.memory.copy(data_ptr, dest, ptr_size, ptr_size)?;
+                            }
                         } else {
-                            return Err(EvalError::Unimplemented(format!("can't handle cast: {:?}", rvalue)));
+                            // FIXME: dest_ty should already be monomorphized
+                            let dest_ty = self.monomorphize(dest_ty, self.substs());
+                            let src_val = self.read_primval(src, src_ty)?;
+                            let dest_val = self.cast_primval(src_val, dest_ty)?;
+                            self.memory.write_primval(dest, dest_val)?;
                         }
                     }
 
@@ -644,6 +653,15 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
         Ok(())
     }
 
+    fn type_is_fat_ptr(&self, ty: Ty<'tcx>) -> bool {
+        match ty.sty {
+            ty::TyRawPtr(ty::TypeAndMut{ty, ..}) |
+            ty::TyRef(_, ty::TypeAndMut{ty, ..}) |
+            ty::TyBox(ty) => !self.type_is_sized(ty),
+            _ => false,
+        }
+    }
+
     fn nonnull_offset(&self, ty: Ty<'tcx>, nndiscr: u64, discrfield: &[u32]) -> EvalResult<'tcx, Size> {
         // Skip the constant 0 at the start meant for LLVM GEP.
         let mut path = discrfield.iter().skip(1).map(|&i| i as usize);
@@ -809,11 +827,12 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
 
                     Deref => {
                         let pointee_ty = pointee_type(base_ty).expect("Deref of non-pointer");
+                        self.memory.dump(base.ptr.alloc_id);
                         let ptr = self.memory.read_ptr(base.ptr)?;
                         let extra = match pointee_ty.sty {
                             ty::TySlice(_) | ty::TyStr => {
-                                let len_ptr = base.ptr.offset(self.memory.pointer_size() as isize);
-                                let len = self.memory.read_usize(len_ptr)?;
+                                let (_, extra) = self.get_fat_ptr(base.ptr);
+                                let len = self.memory.read_usize(extra)?;
                                 LvalueExtra::Length(len)
                             }
                             ty::TyTrait(_) => unimplemented!(),
@@ -842,6 +861,12 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
         Ok(Lvalue { ptr: ptr, extra: LvalueExtra::None })
     }
 
+    fn get_fat_ptr(&self, ptr: Pointer) -> (Pointer, Pointer) {
+        assert_eq!(layout::FAT_PTR_ADDR, 0);
+        assert_eq!(layout::FAT_PTR_EXTRA, 1);
+        (ptr, ptr.offset(self.memory.pointer_size() as isize))
+    }
+
     fn lvalue_ty(&self, lvalue: &mir::Lvalue<'tcx>) -> Ty<'tcx> {
         self.monomorphize(lvalue.ty(&self.mir(), self.tcx).to_ty(self.tcx), self.substs())
     }
@@ -865,7 +890,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                 let c = self.memory.read_uint(ptr, 4)? as u32;
                 match ::std::char::from_u32(c) {
                     Some(ch) => PrimVal::Char(ch),
-                    None => return Err(EvalError::InvalidChar(c)),
+                    None => return Err(EvalError::InvalidChar(c as u64)),
                 }
             }
             (_, &ty::TyInt(IntTy::I8))    => PrimVal::I8(self.memory.read_int(ptr, 1)? as i8),
@@ -905,6 +930,25 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                 }
             }
 
+            (_, &ty::TyEnum(..)) => {
+                use rustc::ty::layout::Layout::*;
+                if let CEnum { discr, signed, .. } = *self.type_layout(ty) {
+                    match (discr.size().bytes(), signed) {
+                        (1, true)  => PrimVal::I8(self.memory.read_int(ptr, 1)? as i8),
+                        (2, true)  => PrimVal::I16(self.memory.read_int(ptr, 2)? as i16),
+                        (4, true)  => PrimVal::I32(self.memory.read_int(ptr, 4)? as i32),
+                        (8, true)  => PrimVal::I64(self.memory.read_int(ptr, 8)? as i64),
+                        (1, false) => PrimVal::U8(self.memory.read_uint(ptr, 1)? as u8),
+                        (2, false) => PrimVal::U16(self.memory.read_uint(ptr, 2)? as u16),
+                        (4, false) => PrimVal::U32(self.memory.read_uint(ptr, 4)? as u32),
+                        (8, false) => PrimVal::U64(self.memory.read_uint(ptr, 8)? as u64),
+                        (size, _) => bug!("CEnum discr size {}", size),
+                    }
+                } else {
+                    bug!("primitive read of non-clike enum: {:?}", ty);
+                }
+            },
+
             _ => bug!("primitive read of non-primitive type: {:?}", ty),
         };
         Ok(val)

src/interpreter/terminator.rs

@@ -47,7 +47,7 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                 let discr_val = self.memory.read_uint(discr_ptr, discr_size)?;
                 if let ty::TyChar = discr_ty.sty {
                     if ::std::char::from_u32(discr_val as u32).is_none() {
-                        return Err(EvalError::InvalidChar(discr_val as u32));
+                        return Err(EvalError::InvalidChar(discr_val as u64));
                     }
                 }
 

src/memory.rs

@@ -455,8 +455,8 @@ impl<'a, 'tcx> Memory<'a, 'tcx> {
             PrimVal::IntegerPtr(n) => self.write_uint(ptr, n as u64, pointer_size),
             PrimVal::F32(f) => self.write_f32(ptr, f),
             PrimVal::F64(f) => self.write_f64(ptr, f),
-            PrimVal::FnPtr(_p) |
-            PrimVal::AbstractPtr(_p) => unimplemented!(),
+            PrimVal::FnPtr(p) |
+            PrimVal::AbstractPtr(p) => self.write_ptr(ptr, p),
         }
     }