mirror of
git://git.musl-libc.org/musl
synced 2024-12-25 08:02:28 +00:00
0650a05947
There is a lot which could be common between i386 and x86_64, but none of it will be useful for any other arch. These should be useful for all archs, however.
201 lines
5.8 KiB
Awk
201 lines
5.8 KiB
Awk
# Insert GAS CFI directives ("control frame information") into x86-32 asm input
|
|
#
|
|
# CFI directives tell the assembler how to generate "stack frame" debug info
|
|
# This information can tell a debugger (like gdb) how to find the current stack
|
|
# frame at any point in the program code, and how to find the values which
|
|
# various registers had at higher points in the call stack
|
|
# With this information, the debugger can show a backtrace, and you can move up
|
|
# and down the call stack and examine the values of local variables
|
|
|
|
BEGIN {
|
|
# don't put CFI data in the .eh_frame ELF section (which we don't keep)
|
|
print ".cfi_sections .debug_frame"
|
|
|
|
# only emit CFI directives inside a function
|
|
in_function = 0
|
|
|
|
# emit .loc directives with line numbers from original source
|
|
printf ".file 1 \"%s\"\n", ARGV[1]
|
|
line_number = 0
|
|
|
|
# used to detect "call label; label:" trick
|
|
called = ""
|
|
}
|
|
|
|
function get_const1() {
|
|
# for instructions with 2 operands, get 1st operand (assuming it is constant)
|
|
match($0, /-?(0x[0-9a-fA-F]+|[0-9]+),/)
|
|
return parse_const(substr($0, RSTART, RLENGTH-1))
|
|
}
|
|
function get_reg() {
|
|
# only use if you already know there is 1 and only 1 register
|
|
match($0, /%e(ax|bx|cx|dx|si|di|bp)/)
|
|
return substr($0, RSTART+1, 3)
|
|
}
|
|
function get_reg1() {
|
|
# for instructions with 2 operands, get 1st operand (assuming it is register)
|
|
match($0, /%e(ax|bx|cx|dx|si|di|bp),/)
|
|
return substr($0, RSTART+1, 3)
|
|
}
|
|
function get_reg2() {
|
|
# for instructions with 2 operands, get 2nd operand (assuming it is register)
|
|
match($0, /,%e(ax|bx|cx|dx|si|di|bp)/)
|
|
return substr($0, RSTART+RLENGTH-3, 3)
|
|
}
|
|
|
|
function adjust_sp_offset(delta) {
|
|
if (in_function)
|
|
printf ".cfi_adjust_cfa_offset %d\n", delta
|
|
}
|
|
|
|
{
|
|
line_number = line_number + 1
|
|
|
|
# clean the input up before doing anything else
|
|
# delete comments
|
|
gsub(/(#|\/\/).*/, "")
|
|
|
|
# canonicalize whitespace
|
|
gsub(/[ \t]+/, " ") # mawk doesn't understand \s
|
|
gsub(/ *, */, ",")
|
|
gsub(/ *: */, ": ")
|
|
gsub(/ $/, "")
|
|
gsub(/^ /, "")
|
|
}
|
|
|
|
# check for assembler directives which we care about
|
|
/^\.(section|data|text)/ {
|
|
# a .cfi_startproc/.cfi_endproc pair should be within the same section
|
|
# otherwise, clang will choke when generating ELF output
|
|
if (in_function) {
|
|
print ".cfi_endproc"
|
|
in_function = 0
|
|
}
|
|
}
|
|
/^\.type [a-zA-Z0-9_]+,\@function/ {
|
|
functions[substr($2, 1, length($2)-10)] = 1
|
|
}
|
|
# not interested in assembler directives beyond this, just pass them through
|
|
/^\./ {
|
|
print
|
|
next
|
|
}
|
|
|
|
/^[a-zA-Z0-9_]+:/ {
|
|
label = substr($1, 1, length($1)-1) # drop trailing :
|
|
|
|
if (called == label) {
|
|
# note adjustment of stack pointer from "call label; label:"
|
|
adjust_sp_offset(4)
|
|
}
|
|
|
|
if (functions[label]) {
|
|
if (in_function)
|
|
print ".cfi_endproc"
|
|
|
|
in_function = 1
|
|
print ".cfi_startproc"
|
|
|
|
for (register in saved)
|
|
delete saved[register]
|
|
for (register in dirty)
|
|
delete dirty[register]
|
|
}
|
|
|
|
# an instruction may follow on the same line, so continue processing
|
|
}
|
|
|
|
/^$/ { next }
|
|
|
|
{
|
|
called = ""
|
|
printf ".loc 1 %d\n", line_number
|
|
print
|
|
}
|
|
|
|
# KEEPING UP WITH THE STACK POINTER
|
|
# We do NOT attempt to understand foolish and ridiculous tricks like stashing
|
|
# the stack pointer and then using %esp as a scratch register, or bitshifting
|
|
# it or taking its square root or anything stupid like that.
|
|
# %esp should only be adjusted by pushing/popping or adding/subtracting constants
|
|
#
|
|
/pushl?/ {
|
|
if (match($0, / %(ax|bx|cx|dx|di|si|bp|sp)/))
|
|
adjust_sp_offset(2)
|
|
else
|
|
adjust_sp_offset(4)
|
|
}
|
|
/popl?/ {
|
|
if (match($0, / %(ax|bx|cx|dx|di|si|bp|sp)/))
|
|
adjust_sp_offset(-2)
|
|
else
|
|
adjust_sp_offset(-4)
|
|
}
|
|
/addl? \$-?(0x[0-9a-fA-F]+|[0-9]+),%esp/ { adjust_sp_offset(-get_const1()) }
|
|
/subl? \$-?(0x[0-9a-fA-F]+|[0-9]+),%esp/ { adjust_sp_offset(get_const1()) }
|
|
|
|
/call/ {
|
|
if (match($0, /call [0-9]+f/)) # "forward" label
|
|
called = substr($0, RSTART+5, RLENGTH-6)
|
|
else if (match($0, /call [0-9a-zA-Z_]+/))
|
|
called = substr($0, RSTART+5, RLENGTH-5)
|
|
}
|
|
|
|
# TRACKING REGISTER VALUES FROM THE PREVIOUS STACK FRAME
|
|
#
|
|
/pushl? %e(ax|bx|cx|dx|si|di|bp)/ { # don't match "push (%reg)"
|
|
# if a register is being pushed, and its value has not changed since the
|
|
# beginning of this function, the pushed value can be used when printing
|
|
# local variables at the next level up the stack
|
|
# emit '.cfi_rel_offset' for that
|
|
|
|
if (in_function) {
|
|
register = get_reg()
|
|
if (!saved[register] && !dirty[register]) {
|
|
printf ".cfi_rel_offset %s,0\n", register
|
|
saved[register] = 1
|
|
}
|
|
}
|
|
}
|
|
|
|
/movl? %e(ax|bx|cx|dx|si|di|bp),-?(0x[0-9a-fA-F]+|[0-9]+)?\(%esp\)/ {
|
|
if (in_function) {
|
|
register = get_reg()
|
|
if (match($0, /-?(0x[0-9a-fA-F]+|[0-9]+)\(%esp\)/)) {
|
|
offset = parse_const(substr($0, RSTART, RLENGTH-6))
|
|
} else {
|
|
offset = 0
|
|
}
|
|
if (!saved[register] && !dirty[register]) {
|
|
printf ".cfi_rel_offset %s,%d\n", register, offset
|
|
saved[register] = 1
|
|
}
|
|
}
|
|
}
|
|
|
|
# IF REGISTER VALUES ARE UNCEREMONIOUSLY TRASHED
|
|
# ...then we want to know about it.
|
|
#
|
|
function trashed(register) {
|
|
if (in_function && !saved[register] && !dirty[register]) {
|
|
printf ".cfi_undefined %s\n", register
|
|
}
|
|
dirty[register] = 1
|
|
}
|
|
# this does NOT exhaustively check for all possible instructions which could
|
|
# overwrite a register value inherited from the caller (just the common ones)
|
|
/mov.*,%e(ax|bx|cx|dx|si|di|bp)/ { trashed(get_reg2()) }
|
|
/(add|addl|sub|subl|and|or|xor|lea|sal|sar|shl|shr) %e(ax|bx|cx|dx|si|di|bp),/ {
|
|
trashed(get_reg1())
|
|
}
|
|
/i?mul [^,]*$/ { trashed("eax"); trashed("edx") }
|
|
/i?mul %e(ax|bx|cx|dx|si|di|bp),/ { trashed(get_reg1()) }
|
|
/i?div/ { trashed("eax"); trashed("edx") }
|
|
/(dec|inc|not|neg|pop) %e(ax|bx|cx|dx|si|di|bp)/ { trashed(get_reg()) }
|
|
/cpuid/ { trashed("eax"); trashed("ebx"); trashed("ecx"); trashed("edx") }
|
|
|
|
END {
|
|
if (in_function)
|
|
print ".cfi_endproc"
|
|
}
|