From d81e077cbea3864fddbce2f49858a8b3e0406d73 Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Sat, 10 Dec 2016 01:04:37 -0600
Subject: [PATCH] try to avoid unneeded malloc

---
 C/text.c                      | 27 +++++++++++++++++
 H/YapText.h                   | 55 ++++++++++++++++++-----------------
 library/dialect/swi/fli/swi.c |  9 +++++-
 3 files changed, 64 insertions(+), 27 deletions(-)

diff --git a/C/text.c b/C/text.c
index e67a6a27d..648ca6c2a 100644
--- a/C/text.c
+++ b/C/text.c
@@ -70,6 +70,33 @@ int pop_text_stack(int i) {
   return lvl;
 }
 
+void *protected_pop_text_stack(int i, void *protected, bool tmp,
+                               size_t sz USES_REGS) {
+  void *out = protected;
+  int lvl = LOCAL_TextBuffer->lvl;
+  while (lvl > i) {
+    struct mblock *p = LOCAL_TextBuffer->first[lvl];
+    while (p) {
+      struct mblock *np = p->next;
+      if (p + 1 == protected) {
+        if (tmp)
+          out = LOCAL_FileNameBuf;
+        else
+          out = p;
+        memcpy(out, protected, sz);
+      } else {
+        free(p);
+      }
+      p = np;
+    }
+    LOCAL_TextBuffer->first[lvl] = NULL;
+    LOCAL_TextBuffer->last[lvl] = NULL;
+    lvl--;
+  }
+  LOCAL_TextBuffer->lvl = lvl;
+  return out;
+}
+
 //	void pop_text_stack(int i) { LOCAL_TextBuffer->lvl = i; }
 
 void *Malloc(size_t sz USES_REGS) {
diff --git a/H/YapText.h b/H/YapText.h
index 57f16f969..267667df0 100644
--- a/H/YapText.h
+++ b/H/YapText.h
@@ -35,16 +35,18 @@
 ///
 extern void *Malloc(size_t sz USES_REGS);
 extern void *Realloc(void *buf, size_t sz USES_REGS);
-extern void  Free(void *buf USES_REGS);
+extern void Free(void *buf USES_REGS);
 
-extern int push_text_stack( USES_REGS1 );
-extern int pop_text_stack( int lvl USES_REGS );
+extern int push_text_stack(USES_REGS1);
+extern int pop_text_stack(int lvl USES_REGS);
+extern void *protected_pop_text_stack(int lvl, void *safe, bool tmp,
+                                      size_t sz USES_REGS);
 
 #ifndef min
-#define min(x,y) (x<y ? x : y)
+#define min(x, y) (x < y ? x : y)
 #endif
 
-#define MBYTE (1024*1024)
+#define MBYTE (1024 * 1024)
 
 /* Character types for tokenizer and write.c */
 
@@ -156,24 +158,26 @@ INLINE_ONLY EXTERN inline char_kind_t chtype(Int ch) {
 #define __android_log_print(...)
 #endif
 
-INLINE_ONLY inline EXTERN utf8proc_ssize_t get_utf8(const utf8proc_uint8_t *ptr, size_t n,
+INLINE_ONLY inline EXTERN utf8proc_ssize_t get_utf8(const utf8proc_uint8_t *ptr,
+                                                    size_t n,
                                                     utf8proc_int32_t *valp);
 
-INLINE_ONLY inline EXTERN utf8proc_ssize_t get_utf8(const utf8proc_uint8_t *ptr, size_t n,
-                                        utf8proc_int32_t *valp) {
+INLINE_ONLY inline EXTERN utf8proc_ssize_t get_utf8(const utf8proc_uint8_t *ptr,
+                                                    size_t n,
+                                                    utf8proc_int32_t *valp) {
   return utf8proc_iterate(ptr, n, valp);
 }
 
-INLINE_ONLY inline EXTERN  utf8proc_ssize_t put_utf8(utf8proc_uint8_t *ptr,
-                                                     utf8proc_int32_t val);
+INLINE_ONLY inline EXTERN utf8proc_ssize_t put_utf8(utf8proc_uint8_t *ptr,
+                                                    utf8proc_int32_t val);
 
-INLINE_ONLY inline EXTERN  utf8proc_ssize_t put_utf8(utf8proc_uint8_t *ptr,
-utf8proc_int32_t val) {
+INLINE_ONLY inline EXTERN utf8proc_ssize_t put_utf8(utf8proc_uint8_t *ptr,
+                                                    utf8proc_int32_t val) {
   return utf8proc_encode_char(val, ptr);
 }
 
 inline static const utf8proc_uint8_t *skip_utf8(const utf8proc_uint8_t *pt,
-utf8proc_ssize_t n) {
+                                                utf8proc_ssize_t n) {
   utf8proc_ssize_t i;
   utf8proc_int32_t b;
   for (i = 0; i < n; i++) {
@@ -198,7 +202,7 @@ inline static utf8proc_ssize_t strlen_utf8(const utf8proc_uint8_t *pt) {
       return rc;
     else if (b > 0) {
       pt += l;
-      rc ++;
+      rc++;
     } else {
       pt++;
     }
@@ -294,8 +298,8 @@ inline static int cmpn_utf8(const utf8proc_uint8_t *pt1,
 #define SURROGATE_OFFSET                                                       \
   ((uint32_t)0x10000 - (uint32_t)(0xD800 << 10) - (uint32_t)0xDC00)
 
-extern const char *Yap_tokText(void*tokptr);
-extern Term Yap_tokRep(void*tokptr);
+extern const char *Yap_tokText(void *tokptr);
+extern Term Yap_tokRep(void *tokptr);
 
 // standard strings
 
@@ -1383,17 +1387,16 @@ static inline Term Yap_UTF8ToString(const char *s USES_REGS) {
 }
 
 static inline Atom UTF32ToAtom(const wchar_t *s USES_REGS) {
-    seq_tv_t inp, out;
-    
-    inp.val.w0 = s;
-    inp.type = YAP_STRING_WCHARS ;
-    out.type = YAP_STRING_ATOM;
-    out.max = -1;
-    if (!Yap_CVT_Text(&inp, &out PASS_REGS))
-        return 0L;
-    return out.val.a;
-}
+  seq_tv_t inp, out;
 
+  inp.val.w0 = s;
+  inp.type = YAP_STRING_WCHARS;
+  out.type = YAP_STRING_ATOM;
+  out.max = -1;
+  if (!Yap_CVT_Text(&inp, &out PASS_REGS))
+    return 0L;
+  return out.val.a;
+}
 
 static inline Term Yap_WCharsToListOfCodes(const wchar_t *s USES_REGS) {
   seq_tv_t inp, out;
diff --git a/library/dialect/swi/fli/swi.c b/library/dialect/swi/fli/swi.c
index 07dfcacb1..ea3318708 100755
--- a/library/dialect/swi/fli/swi.c
+++ b/library/dialect/swi/fli/swi.c
@@ -203,6 +203,7 @@ X_API int PL_get_nchars(term_t l, size_t *lengthp, char **s, unsigned flags) {
   CACHE_REGS
   seq_tv_t inp, out;
 
+  int lvl = push_text_stack();
   inp.val.t = Yap_GetFromSlot(l);
   inp.type = cvtFlags(flags);
   out.type = YAP_STRING_CHARS;
@@ -220,8 +221,14 @@ X_API int PL_get_nchars(term_t l, size_t *lengthp, char **s, unsigned flags) {
     out.type |= YAP_STRING_NCHARS;
     out.max = *lengthp;
   }
-  if (!Yap_CVT_Text(&inp, &out PASS_REGS))
+  const char *buf;
+  if (!Yap_CVT_Text(&inp, &out PASS_REGS)) {
+    pop_text_stack(lvl);
     return false;
+  }
+  out.val.c = protected_pop_text_stack(lvl, out.val.c,
+                                       flags & (BUF_RING | BUF_DISCARDABLE),
+                                       strlen(out.val.c) + 1 PASS_REGS);
   *s = out.val.c;
   return true;
 }