Merge pull request #2698 from rtfeldman/i/2696

Make sure casting to unsigned types performs zero-extension

compiler/gen_llvm/src/llvm/bitcode.rs

@@ -240,8 +240,12 @@ fn build_has_tag_id_help<'a, 'ctx, 'env>(
                     tag_value.into(),
                 );
 
-                env.builder
-                    .build_int_cast(tag_id_i64, env.context.i16_type(), "to_i16")
+                env.builder.build_int_cast_sign_flag(
+                    tag_id_i64,
+                    env.context.i16_type(),
+                    true,
+                    "to_i16",
+                )
             };
 
             let answer = env.builder.build_int_compare(

compiler/gen_llvm/src/llvm/build.rs

@@ -1850,7 +1850,7 @@ pub fn tag_pointer_read_tag_id<'a, 'ctx, 'env>(
     let masked = env.builder.build_and(as_int, mask_intval, "mask");
 
     env.builder
-        .build_int_cast(masked, env.context.i8_type(), "to_u8")
+        .build_int_cast_sign_flag(masked, env.context.i8_type(), false, "to_u8")
 }
 
 pub fn tag_pointer_clear_tag_id<'a, 'ctx, 'env>(
@@ -5943,8 +5943,11 @@ fn run_low_level<'a, 'ctx, 'env>(
             let arg = load_symbol(scope, &args[0]).into_int_value();
 
             let to = basic_type_from_layout(env, layout).into_int_type();
+            let to_signed = intwidth_from_layout(*layout).is_signed();
 
-            env.builder.build_int_cast(arg, to, "inc_cast").into()
+            env.builder
+                .build_int_cast_sign_flag(arg, to, to_signed, "inc_cast")
+                .into()
         }
         Eq => {
             debug_assert_eq!(args.len(), 2);
@@ -7052,7 +7055,12 @@ fn build_int_unary_op<'a, 'ctx, 'env>(
                 let target_int_type = convert::int_type_from_int_width(env, target_int_width);
                 let target_int_val: BasicValueEnum<'ctx> = env
                     .builder
-                    .build_int_cast(arg, target_int_type, "int_cast")
+                    .build_int_cast_sign_flag(
+                        arg,
+                        target_int_type,
+                        target_int_width.is_signed(),
+                        "int_cast",
+                    )
                     .into();
 
                 let return_type =

compiler/gen_llvm/src/llvm/build_dict.rs

@@ -65,7 +65,12 @@ pub fn dict_len<'a, 'ctx, 'env>(
             );
 
             env.builder
-                .build_int_cast(length_i64.into_int_value(), env.ptr_int(), "to_usize")
+                .build_int_cast_sign_flag(
+                    length_i64.into_int_value(),
+                    env.ptr_int(),
+                    false,
+                    "to_usize",
+                )
                 .into()
         }
         _ => unreachable!("Invalid layout given to Dict.len : {:?}", dict_layout),

compiler/gen_llvm/src/llvm/build_str.rs

@@ -179,7 +179,7 @@ pub fn str_number_of_bytes<'a, 'ctx, 'env>(
 
     // cast to the appropriate usize of the current build
     env.builder
-        .build_int_cast(length, env.ptr_int(), "len_as_usize")
+        .build_int_cast_sign_flag(length, env.ptr_int(), false, "len_as_usize")
 }
 
 /// Str.startsWith : Str, Str -> Bool

compiler/gen_llvm/src/llvm/compare.rs

@@ -1127,8 +1127,10 @@ fn build_tag_eq_help<'a, 'ctx, 'env>(
             let i8_type = env.context.i8_type();
 
             let sum = env.builder.build_int_add(
-                env.builder.build_int_cast(is_null_1, i8_type, "to_u8"),
-                env.builder.build_int_cast(is_null_2, i8_type, "to_u8"),
+                env.builder
+                    .build_int_cast_sign_flag(is_null_1, i8_type, false, "to_u8"),
+                env.builder
+                    .build_int_cast_sign_flag(is_null_2, i8_type, false, "to_u8"),
                 "sum_is_null",
             );
 

compiler/gen_llvm/src/llvm/refcounting.rs

@@ -1778,9 +1778,9 @@ fn modify_refcount_union_help<'a, 'ctx, 'env>(
         .build_load(tag_id_ptr, "load_tag_id")
         .into_int_value();
 
-    let tag_id_u8 = env
-        .builder
-        .build_int_cast(tag_id, env.context.i8_type(), "tag_id_u8");
+    let tag_id_u8 =
+        env.builder
+            .build_int_cast_sign_flag(tag_id, env.context.i8_type(), false, "tag_id_u8");
 
     // next, make a jump table for all possible values of the tag_id
     let mut cases = Vec::with_capacity_in(tags.len(), env.arena);