From a9e6baccec3c32fba2de37fd40836e173e2b8f15 Mon Sep 17 00:00:00 2001
From: "Kim F. Storm" <storm@cua.dk>
Date: Mon, 21 Jun 2004 22:35:29 +0000
Subject: [PATCH] (SAFE_ALLOCA_LISP): New macro to allocate Lisp_Objects.
 Temporarily inhibits GC if memory is xmalloc'ed, as the Lisp_Objects in that
 memory area are unknown to GC.  Add comments.

---
 src/lisp.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/lisp.h b/src/lisp.h
index dc78e524213..c6e585e0863 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -3256,6 +3256,8 @@ extern Lisp_Object safe_alloca_unwind (Lisp_Object);
 #define USE_SAFE_ALLOCA			\
   int sa_count = SPECPDL_INDEX ()
 
+/* SAFE_ALLOCA allocates a simple buffer.  */
+
 #define SAFE_ALLOCA(buf, type, size)			  \
   do {							  \
     if ((size) < MAX_ALLOCA)				  \
@@ -3268,6 +3270,24 @@ extern Lisp_Object safe_alloca_unwind (Lisp_Object);
       }							  \
   } while (0)
 
+/* SAFE_ALLOCA_LISP allocates an array of Lisp_Objects.
+   Temporarily inhibits GC since that array is unknow to GC.  */
+
+#define SAFE_ALLOCA_LISP(buf, size)			  \
+  do {							  \
+    if ((size) < MAX_ALLOCA)				  \
+      buf = (Lisp_Object *) alloca (size);		  \
+    else						  \
+      {							  \
+	buf = (Lisp_Object *) xmalloc (size);		  \
+	inhibit_garbage_collection();			  \
+	record_unwind_protect (safe_alloca_unwind,	  \
+			       make_save_value (buf, 0)); \
+      }							  \
+  } while (0)
+
+/* SAFE_FREE frees xmalloced memory and enables GC as needed.  */
+
 #define SAFE_FREE(size)			\
   do {					\
     if ((size) >= MAX_ALLOCA)		\
-- 
2.39.2