From 6be2d8ccf2aee1600c10fb0afc6b01a52ecc319e Mon Sep 17 00:00:00 2001
From: Mark Thom <markjordanthom@gmail.com>
Date: Sun, 19 Jan 2020 20:56:11 -0700
Subject: [PATCH] correct bug in bb_b_put, correct stack truncation bug
 resulting in erroneous failures (affecting issue #255 and the in-progress
 tabling library)

---
 src/prolog/lib/non_iso.pl                  |  2 +-
 src/prolog/machine/attributed_variables.rs |  6 ++++--
 src/prolog/machine/machine_state.rs        | 10 ++++------
 src/prolog/machine/machine_state_impl.rs   |  2 --
 src/prolog/machine/system_calls.rs         |  1 -
 5 files changed, 9 insertions(+), 12 deletions(-)

diff --git a/src/prolog/lib/non_iso.pl b/src/prolog/lib/non_iso.pl
index 22f0001e..136e1e3a 100644
--- a/src/prolog/lib/non_iso.pl
+++ b/src/prolog/lib/non_iso.pl
@@ -21,7 +21,7 @@ bb_b_put(Key, NewValue) :-
     (  '$bb_get_with_offset'(Key, OldValue, OldOffset) ->
        call_cleanup((store_global_var_with_offset(Key, NewValue) ; false),
 		    reset_global_var_at_offset(Key, OldValue, OldOffset))
-    ;  call_cleanup((store_global_var(Key, NewValue, _) ; false),
+    ;  call_cleanup((store_global_var_with_offset(Key, NewValue) ; false),
 		    reset_global_var_at_key(Key))
     ).
 
diff --git a/src/prolog/machine/attributed_variables.rs b/src/prolog/machine/attributed_variables.rs
index eb0fbbb5..6c2dc4c1 100644
--- a/src/prolog/machine/attributed_variables.rs
+++ b/src/prolog/machine/attributed_variables.rs
@@ -117,8 +117,10 @@ impl MachineState {
             self.stack.index_and_frame_mut(e)[i] = self[RegType::Temp(i)].clone();
         }
 
-        self.stack.index_and_frame_mut(e)[self.num_of_args + 1] = Addr::Con(Constant::CutPoint(self.b0));
-        self.stack.index_and_frame_mut(e)[self.num_of_args + 2] = Addr::Con(Constant::Usize(self.num_of_args));
+        self.stack.index_and_frame_mut(e)[self.num_of_args + 1] =
+            Addr::Con(Constant::CutPoint(self.b0));
+        self.stack.index_and_frame_mut(e)[self.num_of_args + 2] =
+            Addr::Con(Constant::Usize(self.num_of_args));
 
         self.verify_attributes();
 
diff --git a/src/prolog/machine/machine_state.rs b/src/prolog/machine/machine_state.rs
index 84af7ccb..134b2924 100644
--- a/src/prolog/machine/machine_state.rs
+++ b/src/prolog/machine/machine_state.rs
@@ -552,8 +552,8 @@ pub(crate) trait CallPolicy: Any {
             attr_var_init_queue_b,
             attr_var_init_bindings_b);
 
-        machine_st.b = machine_st.stack.index_or_frame(b).prelude.b;
         machine_st.truncate_stack();
+        machine_st.b = machine_st.stack.index_or_frame(b).prelude.b;
 
         machine_st.hb = machine_st.heap.h;
         machine_st.p += offset;
@@ -597,11 +597,11 @@ pub(crate) trait CallPolicy: Any {
 
         machine_st.attr_var_init.backtrack(
             attr_var_init_queue_b,
-            attr_var_init_bindings_b
+            attr_var_init_bindings_b,
         );
 
-        machine_st.b = machine_st.stack.index_or_frame(b).prelude.b;
         machine_st.truncate_stack();
+        machine_st.b = machine_st.stack.index_or_frame(b).prelude.b;
 
         machine_st.hb = machine_st.heap.h;
         machine_st.p += 1;
@@ -881,7 +881,7 @@ pub(crate) trait CallPolicy: Any {
                     if machine_st.fail {
                         return Ok(());
                     }
-                    
+
                     machine_st.p = CodePtr::CallN(arity, machine_st.p.local(), machine_st.last_call);
                 }
                 ClauseType::Inlined(inlined) => {
@@ -1069,7 +1069,6 @@ fn cut_body(machine_st: &mut MachineState, addr: Addr) -> bool {
                 machine_st.b = b0;
                 machine_st.tidy_trail();
                 machine_st.tidy_pstr_trail();
-                machine_st.truncate_stack();
             }
         }
         _ => {
@@ -1157,7 +1156,6 @@ impl CutPolicy for SCCCutPolicy {
                     machine_st.b = b0;
                     machine_st.tidy_trail();
                     machine_st.tidy_pstr_trail();
-                    machine_st.truncate_stack();
                 }
             }
             _ => {
diff --git a/src/prolog/machine/machine_state_impl.rs b/src/prolog/machine/machine_state_impl.rs
index d56cd17b..11894901 100644
--- a/src/prolog/machine/machine_state_impl.rs
+++ b/src/prolog/machine/machine_state_impl.rs
@@ -2074,7 +2074,6 @@ impl MachineState {
 
     pub(super) fn unwind_stack(&mut self) {
         self.b = self.block;
-        self.truncate_stack();
         self.fail = true;
     }
 
@@ -3329,7 +3328,6 @@ impl MachineState {
                     self.b = b0;
                     self.tidy_trail();
                     self.tidy_pstr_trail();
-                    self.truncate_stack();
                 }
 
                 self.p += 1;
diff --git a/src/prolog/machine/system_calls.rs b/src/prolog/machine/system_calls.rs
index 13138be8..4aae067c 100644
--- a/src/prolog/machine/system_calls.rs
+++ b/src/prolog/machine/system_calls.rs
@@ -2025,7 +2025,6 @@ impl MachineState {
 
                         if nb > 0 && self.stack.index_or_frame(b).prelude.b == nb {
                             self.b = self.stack.index_or_frame(nb).prelude.b;
-                            self.truncate_stack();
                         }
                     }
                     _ => self.fail = true,
-- 
2.54.0