Make data for OP_REVERSE use IMM2_SIZE instead of LINK_SIZE, for cons…

…istency with OP_VREVERSE

ChangeLog

@@ -153,6 +153,9 @@ the pattern /|a(?0)/ matched against "aaaa".
 39. Add a test for ridiculous ovector offset values to the substring extraction 
 functions.
 
+40. Make OP_REVERSE use IMM2_SIZE for its data instead of LINK_SIZE, for 
+consistency with OP_VREVERSE.
+
 
 Version 10.42 11-December-2022
 ------------------------------

HACKING

@@ -735,15 +735,16 @@ OP_ASSERT_NOT.
 Backward assertions use the opcodes OP_ASSERTBACK, OP_ASSERTBACK_NA, and
 OP_ASSERTBACK_NOT. If all the branches of a backward assertion are of fixed
 length (not necessarily the same), the first opcode inside each branch is
-OP_REVERSE, followed by a LINK_SIZE count of the number of characters to move
+OP_REVERSE, followed by an IMM2_SIZE count of the number of characters to move
 back the pointer in the subject string, thus allowing each branch to have a
 different (but fixed) length.
 
 Variable-length backward assertions whose maximum matching length is limited
 are also supported. For such assertions, the first opcode inside each branch is
 OP_VREVERSE, followed by the minimum and maximum lengths for that branch,
-unless these happen to be equal, in which case OP_REVERSE is used. These values
-occupy two code units each in 8-bit mode, and 1 code unit in 16/32 bit modes.
+unless these happen to be equal, in which case OP_REVERSE is used. These 
+IMM2_SIZE values occupy two code units each in 8-bit mode, and 1 code unit in
+16/32 bit modes.
 
 In ASCII or UTF-32 mode, the character counts in OP_REVERSE and OP_VREVERSE are
 also the number of code units, but in UTF-8/16 mode each character may occupy
@@ -849,4 +850,4 @@ not a real opcode, but is used to check at compile time that tables indexed by
 opcode are the correct length, in order to catch updating errors.
 
 Philip Hazel
-July 2023
+November 2023

src/pcre2_compile.c

@@ -8450,8 +8450,8 @@ for (;;)
         lookbehindminlength == lookbehindlength)
       {
       *code++ = OP_REVERSE;
-      PUTINC(code, 0, lookbehindlength);
-      length += 1 + LINK_SIZE;
+      PUT2INC(code, 0, lookbehindlength);
+      length += 1 + IMM2_SIZE;
       }
     else
       {

src/pcre2_dfa_match.c

@@ -635,8 +635,8 @@ if (*this_start_code == OP_ASSERTBACK || *this_start_code == OP_ASSERTBACK_NOT)
   end_code = this_start_code;
   do
     {
-    uint32_t revlen = (end_code[1+LINK_SIZE] == OP_REVERSE)? 1 + LINK_SIZE : 0;
-    size_t back = (revlen == 0)? 0 : (size_t)GET(end_code, 2+LINK_SIZE);
+    uint32_t revlen = (end_code[1+LINK_SIZE] == OP_REVERSE)? 1 + IMM2_SIZE : 0;
+    size_t back = (revlen == 0)? 0 : (size_t)GET2(end_code, 2+LINK_SIZE);
     if (back <= gone_back)
       {
       int bstate = (int)(end_code - start_code + 1 + LINK_SIZE + revlen);

src/pcre2_internal.h

@@ -1778,7 +1778,7 @@ in UTF-8 mode. The code that uses this table must know about such things. */
   1+LINK_SIZE,                   /* KetRmax                                */ \
   1+LINK_SIZE,                   /* KetRmin                                */ \
   1+LINK_SIZE,                   /* KetRpos                                */ \
-  1+LINK_SIZE,                   /* Reverse                                */ \
+  1+IMM2_SIZE,                   /* Reverse                                */ \
   1+2*IMM2_SIZE,                 /* VReverse                               */ \
   1+LINK_SIZE,                   /* Assert                                 */ \
   1+LINK_SIZE,                   /* Assert not                             */ \

src/pcre2_match.c

@@ -5718,7 +5718,7 @@ fprintf(stderr, "++ op=%d\n", *Fecode);
     we move back a number of characters, not bytes. */
 
     case OP_REVERSE:
-    number = GET(Fecode, 1);
+    number = GET2(Fecode, 1);
 #ifdef SUPPORT_UNICODE
     if (utf)
       {
@@ -5742,7 +5742,7 @@ fprintf(stderr, "++ op=%d\n", *Fecode);
     /* Save the earliest consulted character, then skip to next opcode */
 
     if (Feptr < mb->start_used_ptr) mb->start_used_ptr = Feptr;
-    Fecode += 1 + LINK_SIZE;
+    Fecode += 1 + IMM2_SIZE;
     break;
 
 

src/pcre2_printint.c

@@ -429,7 +429,7 @@ for(;;)
     case OP_COND:
     case OP_SCOND:
     case OP_REVERSE:
-    if (print_lengths) fprintf(f, "%3d ", GET(code, 1));
+    if (print_lengths) fprintf(f, "%3d ", GET2(code, 1));
       else fprintf(f, "    ");
     fprintf(f, "%s", OP_names[*code]);
     break;