From 67711f53da3d236cb17b59a67011110480218268 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Sat, 3 Nov 2012 07:10:33 -0600
Subject: [PATCH] fix problem with prompts, call/cc, and tail-buffer allocation

Merge to v5.3.1
(cherry picked from commit 8079ff6c4f7a1deb0d7b5779cf6b2fd44cebb4d6)
---
 src/racket/gc2/newgc.c | 21 +++++++++++++++++++++
 src/racket/src/eval.c  |  2 ++
 src/racket/src/fun.c   | 13 +++++++++++++
 3 files changed, 36 insertions(+)

diff --git a/src/racket/gc2/newgc.c b/src/racket/gc2/newgc.c
index 3246bca34a..8f59726af8 100644
--- a/src/racket/gc2/newgc.c
+++ b/src/racket/gc2/newgc.c
@@ -1280,6 +1280,21 @@ inline static uintptr_t allocate_slowpath(NewGC *gc, size_t allocate_size, uintp
   return newptr;
 }
 
+static void check_allocation_time_invariants()
+{
+#if 0
+  Scheme_Thread *p = scheme_current_thread;
+  if (p) {
+    if (p->values_buffer) { 
+      memset(p->values_buffer, 0, sizeof(Scheme_Object*) * p->values_buffer_size);
+    }
+    if (p->tail_buffer && (p->tail_buffer != p->runstack_tmp_keep)) {
+      memset(p->tail_buffer, 0, sizeof(Scheme_Object*) * p->tail_buffer_size);
+    }
+  }
+#endif
+}
+
 inline static void *allocate(const size_t request_size, const int type)
 {
   size_t allocate_size;
@@ -1287,6 +1302,8 @@ inline static void *allocate(const size_t request_size, const int type)
 
   if(request_size == 0) return (void *) zero_sized;
 
+  check_allocation_time_invariants();
+
   allocate_size = COMPUTE_ALLOC_SIZE_FOR_OBJECT_SIZE(request_size);
   if(allocate_size > MAX_OBJECT_SIZE)  return allocate_big(request_size, type);
 
@@ -1338,6 +1355,8 @@ inline static void *fast_malloc_one_small_tagged(size_t request_size, int dirty)
   uintptr_t newptr;
   const size_t allocate_size = COMPUTE_ALLOC_SIZE_FOR_OBJECT_SIZE(request_size);
 
+  check_allocation_time_invariants();
+
   newptr = GC_gen0_alloc_page_ptr + allocate_size;
 
   if(OVERFLOWS_GEN0(newptr)) {
@@ -1371,6 +1390,8 @@ void *GC_malloc_pair(void *car, void *cdr)
   void *pair;
   const size_t allocate_size = PAIR_SIZE_IN_BYTES;
 
+  check_allocation_time_invariants();
+
   newptr = GC_gen0_alloc_page_ptr + allocate_size;
 
   if(OVERFLOWS_GEN0(newptr)) {
diff --git a/src/racket/src/eval.c b/src/racket/src/eval.c
index 14c2b22409..21c5a19428 100644
--- a/src/racket/src/eval.c
+++ b/src/racket/src/eval.c
@@ -1580,6 +1580,8 @@ Scheme_Object *scheme_jump_to_continuation(Scheme_Object *obj, int num_rands, Sc
     else {
       GC_CAN_IGNORE Scheme_Object *vals;
       vals = scheme_values(num_rands, (Scheme_Object **)value);
+      if (SAME_OBJ(p->ku.multiple.array, p->values_buffer))
+        p->values_buffer = NULL;
       c->value = vals;
     }
 
diff --git a/src/racket/src/fun.c b/src/racket/src/fun.c
index a453aae645..d3ba7a5d3e 100644
--- a/src/racket/src/fun.c
+++ b/src/racket/src/fun.c
@@ -6368,6 +6368,11 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
 
     p = scheme_current_thread;
 
+    if (v == SCHEME_MULTIPLE_VALUES) {
+      if (SAME_OBJ(p->ku.multiple.array, p->values_buffer))
+        p->values_buffer = NULL;
+    }
+
     restore_from_prompt(prompt);
 
     p->suspend_break = 0;
@@ -6392,6 +6397,10 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
         
           if (v) {
             /* Got a result: */
+            if (v == SCHEME_MULTIPLE_VALUES) {
+              if (SAME_OBJ(p->ku.multiple.array, p->values_buffer))
+                p->values_buffer = NULL;
+            }
             prompt_unwind_one_dw(prompt_tag);
             handler = NULL;
           } else {
@@ -6456,6 +6465,10 @@ static Scheme_Object *call_with_prompt (int in_argc, Scheme_Object *in_argv[])
 
           if (SAME_OBJ(handler, scheme_values_func)) {
             v = scheme_values(argc, argv);
+            if (v == SCHEME_MULTIPLE_VALUES) {
+              if (SAME_OBJ(p->ku.multiple.array, p->values_buffer))
+                p->values_buffer = NULL;
+            }
             handler = NULL;
           } else if (SCHEME_FALSEP(handler)) {
             if (argc == 1) {