Fix potential assertion failure if GC was invoked while enabling profiling

basis/tools/profiler/profiler-tests.factor

@@ -64,3 +64,11 @@ IN: tools.profiler.tests
 : crash-bug-2 ( -- ) 100000 [ crash-bug-1 drop ] times ;
 
 [ ] [ [ crash-bug-2 ] profile ] unit-test
+
+[ 1 ] [
+    [
+        [ [ ] (( -- )) define-temp ] with-compilation-unit
+        dup execute( -- )
+    ] profile
+    counter>>
+] unit-test

vm/profiler.cpp

@@ -37,8 +37,21 @@ void factor_vm::set_profiling(bool profiling)
 	for(cell i = 0; i < length; i++)
 	{
 		tagged<word> word(array_nth(words.untagged(),i));
+
+		/* Note: can't do w->profiling = ... since LHS evaluates
+		before RHS, and if RHS does a GC, we will have an
+		invalid pointer on the LHS */
 		if(profiling)
+		{
+			if(!word->profiling)
+			{
+				code_block *profiling_block = compile_profiling_stub(word.value());
+				word->profiling = profiling_block;
+			}
+
 			word->counter = tag_fixnum(0);
+		}
+
 		update_word_xt(word.untagged());
 	}
 

vm/words.cpp

@@ -23,10 +23,14 @@ word *factor_vm::allot_word(cell name_, cell vocab_, cell hashcode_)
 	new_word->code = NULL;
 
 	jit_compile_word(new_word.value(),new_word->def,true);
-	update_word_xt(new_word.untagged());
-
 	if(profiling_p)
+	{
+		code_block *profiling_block = compile_profiling_stub(new_word.value());
+		new_word->profiling = profiling_block;
 		relocate_code_block(new_word->profiling);
+	}
+
+	update_word_xt(new_word.untagged());
 
 	return new_word.untagged();
 }
@@ -58,24 +62,10 @@ void factor_vm::primitive_word_xt()
 	}
 }
 
-/* Allocates memory */
+void factor_vm::update_word_xt(word *w)
-void factor_vm::update_word_xt(word *w_)
 {
-	data_root<word> w(w_,this);
+	if(profiling_p && w->profiling)
-
-	if(profiling_p)
-	{
-		if(!w->profiling)
-		{
-			/* Note: can't do w->profiling = ... since LHS evaluates
-			before RHS, and if RHS does a GC, we will have an
-			invalid pointer on the LHS */
-			code_block *profiling = compile_profiling_stub(w.value());
-			w->profiling = profiling;
-		}
-
 		w->xt = w->profiling->xt();
-	}
 	else
 		w->xt = w->code->xt();
 }