Add 'scm_c_make_char' and use it where appropriate.

This reverts the change to SCM_MAKE_CHAR made in the previous commit
63818453ad226cd3c2d1fd8ade12e3d7c1d43c05, which used an arithmetic trick
to avoid evaluating its argument more than once.

Here, we restore the previous implementation of SCM_MAKE_CHAR, which
evaluates its argument twice.  Instead, we introduce a new inlinable
function 'scm_c_make_char' and replace uses of SCM_MAKE_CHAR with calls
to 'scm_c_make_char' where appropriate.

* libguile/chars.h (scm_c_make_char): New inline function.
* libguile/inline.c: Include chars.h.
* libguile/srfi-13.c (REF_IN_CHARSET, scm_string_any, scm_string_every)
(scm_string_trim, scm_string_trim_right, scm_string_trim_both)
(scm_string_index, scm_string_index_right, scm_string_skip)
(scm_string_skip_right, scm_string_count, string_titlecase_x)
(string_reverse_x, scm_string_fold, scm_string_fold_right)
(scm_string_for_each, scm_string_filter, scm_string_delete):
Use 'scm_c_make_char' instead of 'SCM_MAKE_CHAR' in cases where the
argument calls a function.
* libguile/chars.c (scm_char_upcase, scm_char_downcase, scm_char_titlecase),
libguile/ports.c (scm_port_decode_char),
libguile/print.c (scm_simple_format),
libguile/read.c (scm_read_character),
libguile/strings.c (scm_string_ref, scm_c_string_ref),
libguile/vm-engine.c ("string-ref"): Ditto.

9 files changed, 59 insertions, 47 deletions

diff --git a/libguile/chars.c b/libguile/chars.c
index 064fca40a..408b23996 100644
--- a/libguile/chars.c
+++ b/libguile/chars.c
@@ -1,5 +1,5 @@
-/* Copyright (C) 1995,1996,1998, 2000, 2001, 2004, 2006, 2008, 2009,
- *   2010, 2011, 2014 Free Software Foundation, Inc.
+/* Copyright (C) 1995, 1996, 1998, 2000, 2001, 2004, 2006, 2008-2011,
+ *   2014, 2019 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -454,7 +454,7 @@ SCM_DEFINE (scm_char_upcase, "char-upcase", 1, 0, 0,
 #define FUNC_NAME s_scm_char_upcase
 {
   SCM_VALIDATE_CHAR (1, chr);
-  return SCM_MAKE_CHAR (scm_c_upcase (SCM_CHAR (chr)));
+  return scm_c_make_char (scm_c_upcase (SCM_CHAR (chr)));
 }
 #undef FUNC_NAME
 
@@ -465,7 +465,7 @@ SCM_DEFINE (scm_char_downcase, "char-downcase", 1, 0, 0,
 #define FUNC_NAME s_scm_char_downcase
 {
   SCM_VALIDATE_CHAR (1, chr);
-  return SCM_MAKE_CHAR (scm_c_downcase (SCM_CHAR(chr)));
+  return scm_c_make_char (scm_c_downcase (SCM_CHAR(chr)));
 }
 #undef FUNC_NAME
 
@@ -475,7 +475,7 @@ SCM_DEFINE (scm_char_titlecase, "char-titlecase", 1, 0, 0,
 #define FUNC_NAME s_scm_char_titlecase
 {
   SCM_VALIDATE_CHAR (1, chr);
-  return SCM_MAKE_CHAR (scm_c_titlecase (SCM_CHAR(chr)));
+  return scm_c_make_char (scm_c_titlecase (SCM_CHAR(chr)));
 }
 #undef FUNC_NAME
 
diff --git a/libguile/chars.h b/libguile/chars.h
index 505a7f9c8..fea747f1d 100644
--- a/libguile/chars.h
+++ b/libguile/chars.h
@@ -41,14 +41,13 @@ typedef scm_t_int32 scm_t_wchar;
    (0 to 255) to Latin-1 codepoints (0 to 255) while allowing higher
    codepoints (256 to 1114111) to pass through unchanged.
 
-   To avoid evaluating X more than once, we use an arithmetic trick: we
-   compute (X mod 2^N) mod (2^N - 256), which is equal to the required
-   mapping in the range -256 .. (2^N - 257).  Here, N is the number of
-   bits in scm_t_bits.  Note that (scm_t_bits) (x) implicitly computes
-   (X mod 2^N), and (scm_t_bits) -256 equals (2^N - 256).  GCC is able
-   to optimize away these operations in practice.  */
-#define SCM_MAKE_CHAR(x) \
-  (SCM_MAKE_ITAG8 ((scm_t_bits) (x) % (scm_t_bits) -256, scm_tc8_char))
+   This macro evaluates X twice, which may lead to side effects if used
+   incorrectly.  It's also likely to be inefficient if X calls a
+   procedure.  Use 'scm_c_make_char' in those cases.  */
+#define SCM_MAKE_CHAR(x)                                                \
+  ((x) <= 1                                                             \
+   ? SCM_MAKE_ITAG8 ((scm_t_bits) (unsigned char) (x), scm_tc8_char)    \
+   : SCM_MAKE_ITAG8 ((scm_t_bits) (x), scm_tc8_char))
 
 #define SCM_CODEPOINT_DOTTED_CIRCLE (0x25cc)
 #define SCM_CODEPOINT_SURROGATE_START (0xd800)
@@ -85,14 +84,25 @@ SCM_API SCM scm_char_upcase (SCM chr);
 SCM_API SCM scm_char_downcase (SCM chr);
 SCM_API SCM scm_char_titlecase (SCM chr);
 SCM_API SCM scm_char_general_category (SCM chr);
+
+SCM_INLINE SCM scm_c_make_char (scm_t_wchar c);
 SCM_API scm_t_wchar scm_c_upcase (scm_t_wchar c);
 SCM_API scm_t_wchar scm_c_downcase (scm_t_wchar c);
 SCM_API scm_t_wchar scm_c_titlecase (scm_t_wchar c);
+
 SCM_INTERNAL const char *scm_i_charname (SCM chr);
 SCM_INTERNAL SCM scm_i_charname_to_char (const char *charname, 
                                          size_t charname_len);
 SCM_INTERNAL void scm_init_chars (void);
 
+#if SCM_CAN_INLINE || defined SCM_INLINE_C_IMPLEMENTING_INLINES
+SCM_INLINE_IMPLEMENTATION SCM
+scm_c_make_char (scm_t_wchar c)
+{
+  return SCM_MAKE_CHAR(c);
+}
+#endif
+
 #endif  /* SCM_CHARS_H */
 
 /*
diff --git a/libguile/inline.c b/libguile/inline.c
index 6e7688c37..3ad55269e 100644
--- a/libguile/inline.c
+++ b/libguile/inline.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 2001, 2006, 2008, 2011, 2012, 2013 Free Software Foundation, Inc.
+/* Copyright (C) 2001, 2006, 2008, 2011-2013, 2019
+ *   Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -24,6 +25,7 @@
 #define SCM_INLINE_C_IMPLEMENTING_INLINES 1
 #include "libguile/inline.h"
 #include "libguile/array-handle.h"
+#include "libguile/chars.h"
 #include "libguile/gc.h"
 #include "libguile/smob.h"
 #include "libguile/pairs.h"
diff --git a/libguile/ports.c b/libguile/ports.c
index 72bb73a01..bb257041a 100644
--- a/libguile/ports.c
+++ b/libguile/ports.c
@@ -1914,7 +1914,7 @@ SCM_DEFINE (scm_port_decode_char, "port-decode-char", 4, 0, 0,
          output.  */
       return SCM_BOOL_F;
 
-    return SCM_MAKE_CHAR (utf8_to_codepoint (utf8_buf, output_size));
+    return scm_c_make_char (utf8_to_codepoint (utf8_buf, output_size));
   }
 }
 #undef FUNC_NAME
diff --git a/libguile/print.c b/libguile/print.c
index 6b5b16b61..722caf593 100644
--- a/libguile/print.c
+++ b/libguile/print.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1995-2004, 2006, 2008-2018 Free Software Foundation, Inc.
+/* Copyright (C) 1995-2004, 2006, 2008-2019 Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -1160,14 +1160,14 @@ SCM_DEFINE (scm_simple_format, "simple-format", 2, 0, 1,
 	    continue;
 	  default:
 	    SCM_MISC_ERROR ("FORMAT: Unsupported format option ~~~A - use (ice-9 format) instead",
-			    scm_list_1 (SCM_MAKE_CHAR (scm_i_string_ref (message, p))));
+			    scm_list_1 (scm_c_make_char (scm_i_string_ref (message, p))));
 	    
 	  }
 
 
 	if (!scm_is_pair (args))
 	  SCM_MISC_ERROR ("FORMAT: Missing argument for ~~~A",
-			  scm_list_1 (SCM_MAKE_CHAR (scm_i_string_ref (message, p))));
+			  scm_list_1 (scm_c_make_char (scm_i_string_ref (message, p))));
 			  		
 	scm_lfwrite_substr (message, start, p - 1, port);
 	/* we pass destination here */
diff --git a/libguile/read.c b/libguile/read.c
index 45bb6a799..63d67210e 100644
--- a/libguile/read.c
+++ b/libguile/read.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1995-1997, 1999-2001, 2003, 2004, 2006-2012, 2014-2018
+/* Copyright (C) 1995-1997, 1999-2001, 2003, 2004, 2006-2012, 2014-2019
  *   Free Software Foundation, Inc.
  * 
  * This library is free software; you can redistribute it and/or
@@ -1092,7 +1092,7 @@ scm_read_character (scm_t_wchar chr, SCM port, scm_t_read_opts *opts)
   /* Ignore dotted circles, which may be used to keep combining characters from
      combining with the backslash in #\charname.  */
   if (cp == SCM_CODEPOINT_DOTTED_CIRCLE && charname_len == 2)
-    return SCM_MAKE_CHAR (scm_i_string_ref (charname, 1));
+    return scm_c_make_char (scm_i_string_ref (charname, 1));
 
   if (cp >= '0' && cp < '8')
     {
diff --git a/libguile/srfi-13.c b/libguile/srfi-13.c
index 3ff44fb6c..4a9719173 100644
--- a/libguile/srfi-13.c
+++ b/libguile/srfi-13.c
@@ -1,6 +1,6 @@
 /* srfi-13.c --- SRFI-13 procedures for Guile
  *
- * Copyright (C) 2001, 2004-2006, 2008-2013, 2017, 2018
+ * Copyright (C) 2001, 2004-2006, 2008-2013, 2017-2019
  *   Free Software Foundation, Inc.
  *
  * This library is free software; you can redistribute it and/or
@@ -53,7 +53,7 @@
   } while (0)
 
 #define REF_IN_CHARSET(s, i, cs)					\
-  (scm_is_true (scm_char_set_contains_p ((cs), SCM_MAKE_CHAR (scm_i_string_ref (s, i)))))
+  (scm_is_true (scm_char_set_contains_p ((cs), scm_c_make_char (scm_i_string_ref (s, i)))))
 
 SCM_DEFINE (scm_string_null_p, "string-null?", 1, 0, 0,
            (SCM str),
@@ -133,7 +133,7 @@ SCM_DEFINE (scm_string_any, "string-any-c-code", 2, 2, 0,
       while (cstart < cend)
         {
           res = scm_call_1 (char_pred, 
-                            SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+                            scm_c_make_char (scm_i_string_ref (s, cstart)));
           if (scm_is_true (res))
             break;
           cstart++;
@@ -200,7 +200,7 @@ SCM_DEFINE (scm_string_every, "string-every-c-code", 2, 2, 0,
       while (cstart < cend)
         {
           res = scm_call_1 (char_pred, 
-                            SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+                            scm_c_make_char (scm_i_string_ref (s, cstart)));
           if (scm_is_false (res))
             break;
           cstart++;
@@ -758,7 +758,7 @@ SCM_DEFINE (scm_string_trim, "string-trim", 1, 3, 0,
 	{
 	  SCM res;
 
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cstart)));
 	  if (scm_is_false (res))
 	    break;
 	  cstart++;
@@ -834,7 +834,7 @@ SCM_DEFINE (scm_string_trim_right, "string-trim-right", 1, 3, 0,
 	{
 	  SCM res;
 
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cend - 1)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cend - 1)));
 	  if (scm_is_false (res))
 	    break;
 	  cend--;
@@ -928,7 +928,7 @@ SCM_DEFINE (scm_string_trim_both, "string-trim-both", 1, 3, 0,
 	{
 	  SCM res;
 
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cstart)));
 	  if (scm_is_false (res))
 	    break;
 	  cstart++;
@@ -937,7 +937,7 @@ SCM_DEFINE (scm_string_trim_both, "string-trim-both", 1, 3, 0,
 	{
 	  SCM res;
 
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cend - 1)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cend - 1)));
 	  if (scm_is_false (res))
 	    break;
 	  cend--;
@@ -1698,7 +1698,7 @@ SCM_DEFINE (scm_string_index, "string-index", 2, 2, 0,
       while (cstart < cend)
 	{
 	  SCM res;
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cstart)));
 	  if (scm_is_true (res))
 	    goto found;
 	  cstart++;
@@ -1764,7 +1764,7 @@ SCM_DEFINE (scm_string_index_right, "string-index-right", 2, 2, 0,
 	{
 	  SCM res;
 	  cend--;
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cend)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cend)));
 	  if (scm_is_true (res))
 	    goto found;
 	}
@@ -1850,7 +1850,7 @@ SCM_DEFINE (scm_string_skip, "string-skip", 2, 2, 0,
       while (cstart < cend)
 	{
 	  SCM res;
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cstart)));
 	  if (scm_is_false (res))
 	    goto found;
 	  cstart++;
@@ -1917,7 +1917,7 @@ SCM_DEFINE (scm_string_skip_right, "string-skip-right", 2, 2, 0,
 	{
 	  SCM res;
 	  cend--;
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cend)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cend)));
 	  if (scm_is_false (res))
 	    goto found;
 	}
@@ -1983,7 +1983,7 @@ SCM_DEFINE (scm_string_count, "string-count", 2, 2, 0,
       while (cstart < cend)
 	{
 	  SCM res;
-	  res = scm_call_1 (char_pred, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+	  res = scm_call_1 (char_pred, scm_c_make_char (scm_i_string_ref (s, cstart)));
 	  if (scm_is_true (res))
 	    count++;
 	  cstart++;
@@ -2240,7 +2240,7 @@ string_titlecase_x (SCM str, size_t start, size_t end)
       str = scm_i_string_start_writing (str);
       for(i = start; i < end;  i++)
         {
-          ch = SCM_MAKE_CHAR (scm_i_string_ref (str, i));
+          ch = scm_c_make_char (scm_i_string_ref (str, i));
           if (scm_is_true (scm_char_alphabetic_p (ch)))
             {
               if (!in_word)
@@ -2338,7 +2338,7 @@ string_reverse_x (SCM str, size_t cstart, size_t cend)
           cend--;
           while (cstart < cend)
             {
-              tmp = SCM_MAKE_CHAR (scm_i_string_ref (str, cstart));
+              tmp = scm_c_make_char (scm_i_string_ref (str, cstart));
               scm_i_string_set_x (str, cstart, scm_i_string_ref (str, cend));
               scm_i_string_set_x (str, cend, SCM_CHAR (tmp));
               cstart++;
@@ -2575,7 +2575,7 @@ SCM_DEFINE (scm_string_fold, "string-fold", 3, 2, 0,
   result = knil;
   while (cstart < cend)
     {
-      result = scm_call_2 (kons, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)), result);
+      result = scm_call_2 (kons, scm_c_make_char (scm_i_string_ref (s, cstart)), result);
       cstart++;
     }
 
@@ -2603,7 +2603,7 @@ SCM_DEFINE (scm_string_fold_right, "string-fold-right", 3, 2, 0,
   result = knil;
   while (cstart < cend)
     {
-      result = scm_call_2 (kons, SCM_MAKE_CHAR (scm_i_string_ref (s, cend-1)), result);
+      result = scm_call_2 (kons, scm_c_make_char (scm_i_string_ref (s, cend-1)), result);
       cend--;
     }
 
@@ -2760,7 +2760,7 @@ SCM_DEFINE (scm_string_for_each, "string-for-each", 2, 2, 0,
 			      4, end, cend);
   while (cstart < cend)
     {
-      scm_call_1 (proc, SCM_MAKE_CHAR (scm_i_string_ref (s, cstart)));
+      scm_call_1 (proc, scm_c_make_char (scm_i_string_ref (s, cstart)));
       cstart++;
     }
 
@@ -3217,7 +3217,7 @@ SCM_DEFINE (scm_string_filter, "string-filter", 2, 2, 0,
       while (idx < cend)
 	{
 	  SCM res, ch;
-	  ch = SCM_MAKE_CHAR (scm_i_string_ref (s, idx));
+	  ch = scm_c_make_char (scm_i_string_ref (s, idx));
 	  res = scm_call_1 (char_pred, ch);
 	  if (scm_is_true (res))
 	    ls = scm_cons (ch, ls);
@@ -3368,7 +3368,7 @@ SCM_DEFINE (scm_string_delete, "string-delete", 2, 2, 0,
       idx = cstart;
       while (idx < cend)
 	{
-	  SCM res, ch = SCM_MAKE_CHAR (scm_i_string_ref (s, idx));
+	  SCM res, ch = scm_c_make_char (scm_i_string_ref (s, idx));
 	  res = scm_call_1 (char_pred, ch);
 	  if (scm_is_false (res))
 	    ls = scm_cons (ch, ls);
diff --git a/libguile/strings.c b/libguile/strings.c
index 62ff2e303..5a150278d 100644
--- a/libguile/strings.c
+++ b/libguile/strings.c
@@ -1209,9 +1209,9 @@ SCM_DEFINE (scm_string_ref, "string-ref", 2, 0, 0,
     scm_out_of_range (NULL, k);
 
   if (scm_i_is_narrow_string (str))
-    return SCM_MAKE_CHAR (scm_i_string_chars (str)[idx]);
+    return scm_c_make_char (scm_i_string_chars (str)[idx]);
   else
-    return SCM_MAKE_CHAR (scm_i_string_wide_chars (str)[idx]);
+    return scm_c_make_char (scm_i_string_wide_chars (str)[idx]);
 }
 #undef FUNC_NAME
 
@@ -1221,9 +1221,9 @@ scm_c_string_ref (SCM str, size_t p)
   if (p >= scm_i_string_length (str))
     scm_out_of_range (NULL, scm_from_size_t (p));
   if (scm_i_is_narrow_string (str))
-    return SCM_MAKE_CHAR (scm_i_string_chars (str)[p]);
+    return scm_c_make_char (scm_i_string_chars (str)[p]);
   else
-    return SCM_MAKE_CHAR (scm_i_string_wide_chars (str)[p]);
+    return scm_c_make_char (scm_i_string_wide_chars (str)[p]);
 
 }
 
diff --git a/libguile/vm-engine.c b/libguile/vm-engine.c
index 53d7f3522..931017e2d 100644
--- a/libguile/vm-engine.c
+++ b/libguile/vm-engine.c
@@ -1,5 +1,5 @@
-/* Copyright (C) 2001, 2009, 2010, 2011, 2012, 2013,
- *   2014, 2015, 2018 Free Software Foundation, Inc.
+/* Copyright (C) 2001, 2009-2015, 2018, 2019
+ *   Free Software Foundation, Inc.
  * 
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public License
@@ -2269,7 +2269,7 @@ VM_NAME (scm_i_thread *thread, struct scm_vm *vp,
       VM_VALIDATE_STRING (str, "string-ref");
       VM_VALIDATE_INDEX (c_idx, scm_i_string_length (str), "string-ref");
 
-      RETURN (SCM_MAKE_CHAR (scm_i_string_ref (str, c_idx)));
+      RETURN (scm_c_make_char (scm_i_string_ref (str, c_idx)));
     }
 
   /* string-set! instruction is currently number 192.  Probably need to