sqlcipher/tool/vdbe-compress.tcl at master · CoderXL/sqlcipher · GitHub

History

138 lines (134 loc) · 4.76 KB

Raw

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

#!/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

}

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

sqlcipher/tool/vdbe-compress.tcl at master · CoderXL/sqlcipher · GitHub

Expand file tree

Breadcrumbs

vdbe-compress.tcl

Latest commit

History

Breadcrumbs

vdbe-compress.tcl

File metadata and controls