Fix GH-11956: PCRE regular expressions with JIT enabled gives different result

The code in the attached test used to work correctly in PHP 8.0, but not
in 8.1+. This is because PHP 8.1+ uses a more modern version of pcre2
than PHP 8.0, and that pcre2 versions has a regression.

While upgrading pcre2lib seems to be only done for the master branch, it
is possible to backport upstream fixes to stable branches. This has been
already done in the past in for JIT regressions [1], so it is not
unprecedented.

We backport the upstream pcre2 fix [2].

[1] 788a701e222
[2] PCRE2Project/pcre2#135

Closes GH-12108.

Author: ndossche

NEWS

@@ -13,6 +13,10 @@ PHP                                                                        NEWS
   . Fixed bug GH-12186 (segfault copying/cloning a finalized HashContext).
     (MaxSem)
 
+- PCRE:
+  . Fixed bug GH-11956 (Backport upstream fix, PCRE regular expressions with
+    JIT enabled gives different result). (nielsdos)
+
 - SimpleXML:
   . Fixed bug GH-12170 (Can't use xpath with comments in SimpleXML). (nielsdos)
   . Fixed bug GH-12192 (SimpleXML infinite loop when getName() is called

ext/pcre/pcre2lib/pcre2_jit_compile.c

@@ -11286,19 +11286,19 @@ if (exact > 1)
     }
   }
 else if (exact == 1)
-  {
   compile_char1_matchingpath(common, type, cc, &backtrack->topbacktracks, TRUE);
 
-  if (early_fail_type == type_fail_range)
-    {
-    OP1(SLJIT_MOV, TMP1, 0, SLJIT_MEM1(SLJIT_SP), early_fail_ptr);
-    OP1(SLJIT_MOV, TMP2, 0, SLJIT_MEM1(SLJIT_SP), early_fail_ptr + (int)sizeof(sljit_sw));
-    OP2(SLJIT_SUB, TMP1, 0, TMP1, 0, TMP2, 0);
-    OP2(SLJIT_SUB, TMP2, 0, STR_PTR, 0, TMP2, 0);
-    add_jump(compiler, &backtrack->topbacktracks, CMP(SLJIT_LESS_EQUAL, TMP2, 0, TMP1, 0));
+if (early_fail_type == type_fail_range)
+  {
+  /* Range end first, followed by range start. */
+  OP1(SLJIT_MOV, TMP1, 0, SLJIT_MEM1(SLJIT_SP), early_fail_ptr);
+  OP1(SLJIT_MOV, TMP2, 0, SLJIT_MEM1(SLJIT_SP), early_fail_ptr + (int)sizeof(sljit_sw));
+  OP2(SLJIT_SUB, TMP1, 0, TMP1, 0, TMP2, 0);
+  OP2(SLJIT_SUB, TMP2, 0, STR_PTR, 0, TMP2, 0);
+  add_jump(compiler, &backtrack->topbacktracks, CMP(SLJIT_LESS_EQUAL, TMP2, 0, TMP1, 0));
 
-    OP1(SLJIT_MOV, SLJIT_MEM1(SLJIT_SP), early_fail_ptr + (int)sizeof(sljit_sw), STR_PTR, 0);
-    }
+  OP1(SLJIT_MOV, SLJIT_MEM1(SLJIT_SP), early_fail_ptr, STR_PTR, 0);
+  OP1(SLJIT_MOV, SLJIT_MEM1(SLJIT_SP), early_fail_ptr + (int)sizeof(sljit_sw), STR_PTR, 0);
   }
 
 switch(opcode)

ext/pcre/tests/gh11956.phpt

@@ -0,0 +1,16 @@
+--TEST--
+GH-11956 (PCRE regular expressions with JIT enabled gives different result)
+--INI--
+pcre.jit=1
+--FILE--
+<?php
+preg_match( '/<(\w+)[\s\w\-]+ id="S44_i89ew">/', '<br><div id="S44_i89ew">', $matches );
+var_dump($matches);
+?>
+--EXPECT--
+array(2) {
+  [0]=>
+  string(20) "<div id="S44_i89ew">"
+  [1]=>
+  string(2) "di"
+}