Implement int extension

Author: sapir

src/builder.rs

@@ -1219,7 +1219,8 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
             // TODO(antoyo): nothing to do as it is only for LLVM?
             return value;
         }
-        self.context.new_cast(self.location, value, dest_ty)
+
+        self.extend_int(value, dest_ty, true)
     }
 
     fn fptoui(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
@@ -1700,9 +1701,8 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         call
     }
 
-    fn zext(&mut self, value: RValue<'gcc>, dest_typ: Type<'gcc>) -> RValue<'gcc> {
-        // FIXME(antoyo): this does not zero-extend.
-        self.gcc_int_cast(value, dest_typ)
+    fn zext(&mut self, value: RValue<'gcc>, dest_ty: Type<'gcc>) -> RValue<'gcc> {
+        self.extend_int(value, dest_ty, false)
     }
 
     fn cx(&self) -> &CodegenCx<'gcc, 'tcx> {

src/context.rs

@@ -10,12 +10,12 @@ use rustc_data_structures::base_n::ToBaseN;
 use rustc_data_structures::base_n::ALPHANUMERIC_ONLY;
 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
 use rustc_middle::mir::mono::CodegenUnit;
-use rustc_middle::span_bug;
 use rustc_middle::ty::layout::{
     FnAbiError, FnAbiOf, FnAbiOfHelpers, FnAbiRequest, HasParamEnv, HasTyCtxt, LayoutError,
     LayoutOfHelpers, TyAndLayout,
 };
 use rustc_middle::ty::{self, Instance, ParamEnv, PolyExistentialTraitRef, Ty, TyCtxt};
+use rustc_middle::{bug, span_bug};
 use rustc_session::Session;
 use rustc_span::{source_map::respan, Span};
 use rustc_target::abi::{
@@ -360,6 +360,31 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         function
     }
 
+    pub fn get_matching_int_type(&self, typ: Type<'gcc>, signed: bool) -> Type<'gcc> {
+        let size = if typ.is_compatible_with(self.bool_type) {
+            // For booleans, return an 8-bit integer instead.
+            1
+        } else {
+            typ.get_size()
+        };
+
+        match (size, signed) {
+            (1, false) => self.u8_type,
+            (2, false) => self.u16_type,
+            (4, false) => self.u32_type,
+            (8, false) => self.u64_type,
+            (16, false) => self.u128_type,
+            (1, true) => self.i8_type,
+            (2, true) => self.i16_type,
+            (4, true) => self.i32_type,
+            (8, true) => self.i64_type,
+            (16, true) => self.i128_type,
+            _ => {
+                bug!("attempt to get bad int type {}{}", if signed { 'i' } else { 'u' }, size * 8);
+            }
+        }
+    }
+
     pub fn is_native_int_type(&self, typ: Type<'gcc>) -> bool {
         let types = [
             self.u8_type,

src/int.rs

@@ -5,6 +5,7 @@
 use gccjit::{BinaryOp, ComparisonOp, FunctionType, Location, RValue, ToRValue, Type, UnaryOp};
 use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
 use rustc_codegen_ssa::traits::{BackendTypes, BaseTypeMethods, BuilderMethods, OverflowOp};
+use rustc_middle::bug;
 use rustc_middle::ty::{ParamEnv, Ty};
 use rustc_target::abi::{
     call::{ArgAbi, ArgAttributes, Conv, FnAbi, PassMode},
@@ -866,6 +867,21 @@ impl<'gcc, 'tcx> CodegenCx<'gcc, 'tcx> {
         self.bitwise_operation(BinaryOp::BitwiseOr, a, b, loc)
     }
 
+    pub fn extend_int(
+        &self,
+        value: RValue<'gcc>,
+        dest_ty: Type<'gcc>,
+        signed: bool,
+    ) -> RValue<'gcc> {
+        let src_ty = value.get_type();
+        if !self.is_native_int_type_or_bool(src_ty) || !self.is_native_int_type_or_bool(dest_ty) {
+            bug!("got extend_int for non-int type {:?} -> {:?}", src_ty, dest_ty);
+        }
+
+        let intermediate_ty = self.get_matching_int_type(src_ty, signed);
+        self.gcc_int_cast(self.gcc_int_cast(value, intermediate_ty), dest_ty)
+    }
+
     // TODO(antoyo): can we use https://github.com/rust-lang/compiler-builtins/blob/master/src/int/mod.rs#L379 instead?
     pub fn gcc_int_cast(&self, value: RValue<'gcc>, dest_typ: Type<'gcc>) -> RValue<'gcc> {
         let value_type = value.get_type();