From 37e34c5209e48624d5e272c5b1dcf2bea7fdc1d3 Mon Sep 17 00:00:00 2001
From: Mark Thom <markjordanthom@gmail.com>
Date: Mon, 31 Jan 2022 21:24:19 -0700
Subject: [PATCH] reset instruction pointers with calls, make
 HCPrinter::range_from safe (#1233)

---
 src/heap_print.rs            | 2 +-
 src/machine/dispatch.rs      | 4 ++++
 src/machine/machine_state.rs | 6 +++++-
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/heap_print.rs b/src/heap_print.rs
index af9503df..40afdbfc 100644
--- a/src/heap_print.rs
+++ b/src/heap_print.rs
@@ -376,7 +376,7 @@ impl HCValueOutputter for PrinterOutputter {
     }
 
     fn range_from(&self, index: RangeFrom<usize>) -> &str {
-        &self.contents.as_str()[index]
+        &self.contents.as_str().get(index).unwrap_or("")
     }
 }
 
diff --git a/src/machine/dispatch.rs b/src/machine/dispatch.rs
index 4c02ea8b..8663a407 100644
--- a/src/machine/dispatch.rs
+++ b/src/machine/dispatch.rs
@@ -962,6 +962,8 @@ impl Machine {
                     match self.find_living_dynamic_else(p) {
                         Some((p, next_i)) => {
                             self.machine_st.p = p;
+                            self.machine_st.oip = 0;
+                            self.machine_st.iip = 0;
 
                             match self.machine_st.dynamic_mode {
                                 FirstOrNext::First if next_i == 0 => {
@@ -1044,6 +1046,8 @@ impl Machine {
                     match self.find_living_dynamic_else(p) {
                         Some((p, next_i)) => {
                             self.machine_st.p = p;
+                            self.machine_st.oip = 0;
+                            self.machine_st.iip = 0;
 
                             match self.machine_st.dynamic_mode {
                                 FirstOrNext::First if next_i == 0 => {
diff --git a/src/machine/machine_state.rs b/src/machine/machine_state.rs
index 27a35884..5d8e591d 100644
--- a/src/machine/machine_state.rs
+++ b/src/machine/machine_state.rs
@@ -439,15 +439,19 @@ impl MachineState {
     pub(super) fn call_at_index(&mut self, arity: usize, p: usize) {
         self.cp = self.p + 1;
         self.p = p;
+        self.oip = 0;
+        self.iip = 0;
         self.num_of_args = arity;
         self.b0 = self.b;
     }
 
     #[inline(always)]
     pub(super) fn execute_at_index(&mut self, arity: usize, p: usize) {
+        self.p = p;
+        self.oip = 0;
+        self.iip = 0;
         self.num_of_args = arity;
         self.b0 = self.b;
-        self.p = p;
     }
 
     pub fn read_term(&mut self, stream: Stream, indices: &mut IndexStore) -> CallResult {
-- 
2.54.0