[sql] Import reference version of SQLite 3.17..

third_party/sqlite/sqlite-src-3170000/tool/vdbe-compress.tcl

+#!/usr/bin/tcl
+#
+# This script makes modifications to the vdbe.c source file which reduce
+# the amount of stack space required by the sqlite3VdbeExec() routine.
+#
+# The modifications performed by this script are optional.  The vdbe.c
+# source file will compile correctly with and without the modifications
+# performed by this script.  And all routines within vdbe.c will compute
+# the same result.  The modifications made by this script merely help
+# the C compiler to generate code for sqlite3VdbeExec() that uses less
+# stack space.
+#
+# Script usage:
+#
+#          mv vdbe.c vdbe.c.template
+#          tclsh vdbe-compress.tcl $CFLAGS <vdbe.c.template >vdbe.c
+#
+# Modifications made:
+#
+# All modifications are within the sqlite3VdbeExec() function.  The
+# modifications seek to reduce the amount of stack space allocated by
+# this routine by moving local variable declarations out of individual
+# opcode implementations and into a single large union.  The union contains
+# a separate structure for each opcode and that structure contains the
+# local variables used by that opcode.  In this way, the total amount
+# of stack space required by sqlite3VdbeExec() is reduced from the
+# sum of all local variables to the maximum of the local variable space
+# required for any single opcode.
+#
+# In order to be recognized by this script, local variables must appear
+# on the first line after the open curly-brace that begins a new opcode
+# implementation.  Local variables must not have initializers, though they
+# may be commented.
+#
+# The union definition is inserted in place of a special marker comment
+# in the preamble to the sqlite3VdbeExec() implementation.
+#
+#############################################################################
+#
+set beforeUnion {}   ;# C code before union
+set unionDef {}      ;# C code of the union
+set afterUnion {}    ;# C code after the union
+set sCtr 0           ;# Context counter
+
+# If the SQLITE_SMALL_STACK compile-time option is missing, then
+# this transformation becomes a no-op.
+#
+if {![regexp {SQLITE_SMALL_STACK} $argv]} {
+  while {![eof stdin]} {
+    puts [gets stdin]
+  }
+  exit
+}
+
+# Read program text up to the spot where the union should be
+# inserted.
+#
+while {![eof stdin]} {
+  set line [gets stdin]
+  if {[regexp {INSERT STACK UNION HERE} $line]} break
+  append beforeUnion $line\n
+}
+
+# Process the remaining text.  Build up the union definition as we go.
+#
+set vlist {}
+set seenDecl 0
+set namechars {abcdefghijklmnopqrstuvwxyz}
+set nnc [string length $namechars]
+while {![eof stdin]} {
+  set line [gets stdin]
+  if {[regexp "^case (OP_\\w+): \173" $line all operator]} {
+    append afterUnion $line\n
+    set vlist {}
+    while {![eof stdin]} {
+      set line [gets stdin]
+      if {[regexp {^ +(const )?\w+ \**(\w+)(\[.*\])?;} $line \
+           all constKeyword vname notused1]} {
+        if {!$seenDecl} {
+          set sname {}
+          append sname [string index $namechars [expr {$sCtr/$nnc}]]
+          append sname [string index $namechars [expr {$sCtr%$nnc}]]
+          incr sCtr
+          append unionDef "    struct ${operator}_stack_vars \173\n"
+          append afterUnion \
+             "#if 0  /* local variables moved into u.$sname */\n"
+          set seenDecl 1
+        }
+        append unionDef "    $line\n"
+        append afterUnion $line\n
+        lappend vlist $vname
+      } elseif {[regexp {^#(if|endif)} $line] && [llength $vlist]>0} {
+        append unionDef "$line\n"
+        append afterUnion $line\n
+      } else {
+        break
+      }
+    }
+    if {$seenDecl} {
+      append unionDef   "    \175 $sname;\n"
+      append afterUnion "#endif /* local variables moved into u.$sname */\n"
+    }
+    set seenDecl 0
+  }
+  if {[regexp "^\175" $line]} {
+    append afterUnion $line\n
+    set vlist {}
+  } elseif {[llength $vlist]>0} {
+    append line " "
+    foreach v $vlist {
+      regsub -all "(\[^a-zA-Z0-9>.\])${v}(\\W)" $line "\\1u.$sname.$v\\2" line
+      regsub -all "(\[^a-zA-Z0-9>.\])${v}(\\W)" $line "\\1u.$sname.$v\\2" line
+
+      # The expressions above fail to catch instance of variable "abc" in
+      # expressions like (32>abc). The following expression makes those
+      # substitutions.
+      regsub -all "(\[^-\])>${v}(\\W)" $line "\\1>u.$sname.$v\\2" line
+    }
+    append afterUnion [string trimright $line]\n
+  } elseif {$line=="" && [eof stdin]} {
+    # no-op
+  } else {
+    append afterUnion $line\n
+  }
+}
+
+# Output the resulting text.
+#
+puts -nonewline $beforeUnion
+puts "  /********************************************************************"
+puts "  ** Automatically generated code"
+puts "  **"
+puts "  ** The following union is automatically generated by the"
+puts "  ** vdbe-compress.tcl script.  The purpose of this union is to"
+puts "  ** reduce the amount of stack space required by this function."
+puts "  ** See comments in the vdbe-compress.tcl script for details."
+puts "  */"
+puts "  union vdbeExecUnion \173"
+puts -nonewline $unionDef
+puts "  \175 u;"
+puts "  /* End automatically generated code"
+puts "  ********************************************************************/"
+puts -nonewline $afterUnion