don't use opty args in create_thread

Author: beepster4096

src/shims/unix/thread.rs

@@ -13,11 +13,17 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        let thread_info_place = this.deref_operand(thread)?;
+
+        let start_routine = this.read_pointer(start_routine)?;
+
+        let func_arg = this.read_immediate(arg)?;
+
         this.start_thread(
-            Some(thread),
+            Some(thread_info_place),
             start_routine,
             Abi::C { unwind: false },
-            arg,
+            func_arg,
             this.layout_of(this.tcx.types.usize)?,
         )?;
 

src/shims/windows/thread.rs

@@ -19,30 +19,40 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     ) -> InterpResult<'tcx, ThreadId> {
         let this = self.eval_context_mut();
 
-        if !this.ptr_is_null(this.read_pointer(security_op)?)? {
-            throw_unsup_format!("non-null `lpThreadAttributes` in `CreateThread`")
-        }
+        let security = this.read_pointer(security_op)?;
 
         // stacksize is ignored, but still needs to be a valid usize
         let _ = this.read_scalar(stacksize_op)?.to_machine_usize(this)?;
 
+        let start_routine = this.read_pointer(start_op)?;
+
+        let func_arg = this.read_immediate(arg_op)?;
+
         let flags = this.read_scalar(flags_op)?.to_u32()?;
 
+        let thread = if this.ptr_is_null(this.read_pointer(thread_op)?)? {
+            None
+        } else {
+            let thread_info_place = this.deref_operand(thread_op)?;
+            Some(thread_info_place)
+        };
+
         let stack_size_param_is_a_reservation =
             this.eval_windows("c", "STACK_SIZE_PARAM_IS_A_RESERVATION")?.to_u32()?;
 
         if flags != 0 && flags != stack_size_param_is_a_reservation {
             throw_unsup_format!("unsupported `dwCreationFlags` {} in `CreateThread`", flags)
         }
 
-        let thread =
-            if this.ptr_is_null(this.read_pointer(thread_op)?)? { None } else { Some(thread_op) };
+        if !this.ptr_is_null(security)? {
+            throw_unsup_format!("non-null `lpThreadAttributes` in `CreateThread`")
+        }
 
         this.start_thread(
             thread,
-            start_op,
+            start_routine,
             Abi::System { unwind: false },
-            arg_op,
+            func_arg,
             this.layout_of(this.tcx.types.u32)?,
         )
     }