Ensure sizeof returns correctly for isbits Union arrays. Fixes #23321

Author: quinnj

src/builtins.c

@@ -270,8 +270,15 @@ JL_CALLABLE(jl_f_sizeof)
             jl_error("type does not have a fixed size");
         return jl_box_long(jl_datatype_size(x));
     }
-    if (jl_is_array(x))
-        return jl_box_long(jl_array_len(x) * ((jl_array_t*)x)->elsize);
+    if (jl_is_array(x)) {
+        jl_value_t *ety = jl_tparam0(jl_typeof(x));
+        size_t elsize = 0, al = 0;
+        int isboxed = !jl_islayout_inline(ety, &elsize, &al);
+        if (isboxed)
+            elsize = sizeof(void*);
+        size_t len = jl_array_len(x);
+        return jl_box_long((!isboxed && jl_is_uniontype(ety)) ? len * elsize + len : len * elsize);
+    }
     if (jl_is_string(x))
         return jl_box_long(jl_string_len(x));
     if (jl_is_symbol(x))

src/codegen.cpp

@@ -2718,18 +2718,24 @@ static bool emit_builtin_call(jl_codectx_t &ctx, jl_cgval_t *ret, jl_value_t *f,
             auto len = emit_arraylen(ctx, obj, ary_ex);
             jl_value_t *ety = jl_tparam0(sty);
             Value *elsize;
+            size_t elsz = 0, al = 0;
+            bool isboxed = !jl_islayout_inline(ety, &elsz, &al);
             if (!jl_has_free_typevars(ety)) {
-                if (!jl_array_store_unboxed(ety)) {
+                if (isboxed) {
                     elsize = ConstantInt::get(T_size, sizeof(void*));
                 }
                 else {
-                    elsize = ConstantInt::get(T_size, jl_datatype_size(ety));
+                    elsize = ConstantInt::get(T_size, elsz);
                 }
             }
             else {
                 elsize = ctx.builder.CreateZExt(emit_arrayelsize(ctx, obj), T_size);
             }
-            *ret = mark_julia_type(ctx, ctx.builder.CreateMul(len, elsize), false, jl_long_type);
+            Value *sz = ctx.builder.CreateMul(len, elsize);
+            if (!isboxed && jl_is_uniontype(ety)) {
+                sz = ctx.builder.CreateAdd(sz, len);
+            }
+            *ret = mark_julia_type(ctx, sz, false, jl_long_type);
             return true;
         }
         if (jl_is_type_type((jl_value_t*)sty) && !jl_is_typevar(jl_tparam0(sty))) {

test/core.jl

@@ -5284,7 +5284,7 @@ for U in unboxedunions
         mxsz = maximum(sizeof, Base.uniontypes(U))
         A = Array{U}(len)
         @test length(A) == prod(len)
-        @test Core.sizeof(A) == prod(len) * mxsz
+        @test Core.sizeof(A) == prod(len) * mxsz + prod(len)
         @test isassigned(A, 1)
         @test isassigned(A, length(A))
 
@@ -5312,7 +5312,7 @@ for U in unboxedunions
 
         # reshape
         A3 = reshape(A, (div(prod(len), 2), 2))
-        @test Core.sizeof(A) == prod(len) * mxsz
+        @test Core.sizeof(A) == prod(len) * mxsz + prod(len)
         @test isassigned(A, 1)
         @test A[1] === initvalue2(F)