sparse-llvm incorrect type when ealing with union type

[Dibyendu Majumdar <mobile@xxxxxxxxxxxxxxx>]

Hi,

I am investigating a type error in LLVM. Here is the snippet of code:

typedef union GCObject GCObject;
typedef unsigned char lu_byte;
typedef double lua_Number;
typedef union {
 GCObject *gc;
 void *p;
 lua_Number n;
 int b;
} Value;
typedef struct lua_TValue {
 Value value;
 int tt;
} TValue;
typedef struct UpVal {
 GCObject *next;
 lu_byte tt;
 lu_byte marked;
 TValue *v;
 union {
  TValue value;
  struct {
   struct UpVal *prev;
   struct UpVal *next;
  } l;
 } u;
} UpVal;
static void close(UpVal *uv)
{
 uv->v = &uv->u.value;
}

The linearized output is:

close:
.L0:
        <entry-point>
        add.64      %r2 <- %arg1, $24
        store.64    %r2 -> 16[%arg1]
        ret

The result of the add operation ends up the same type as arg1 which is
UpVal*. But this is then assigned to uv->v which is expected to be
TValue*. So LLVM doesn't like it.

While in this case we could cast to the expected value before the
store - I am worried that in other cases where the value is read and
used somewhere it will have the wrong type.

I see that the add instruction's type is 'void *'.

Any suggestions on how to solve this issue?

Thanks and Regards
Dibyendu
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