Alex Dowad | 4e6b8ee | 2015-10-13 13:28:52 +0200 | [diff] [blame] | 1 | # Insert GAS CFI directives ("control frame information") into x86-64 asm input |
| 2 | |
| 3 | BEGIN { |
| 4 | # don't put CFI data in the .eh_frame ELF section (which we don't keep) |
| 5 | print ".cfi_sections .debug_frame" |
| 6 | |
| 7 | # only emit CFI directives inside a function |
| 8 | in_function = 0 |
| 9 | |
| 10 | # emit .loc directives with line numbers from original source |
| 11 | printf ".file 1 \"%s\"\n", ARGV[1] |
| 12 | line_number = 0 |
| 13 | |
| 14 | # used to detect "call label; label:" trick |
| 15 | called = "" |
| 16 | } |
| 17 | |
| 18 | function get_const1() { |
| 19 | # for instructions with 2 operands, get 1st operand (assuming it is constant) |
| 20 | match($0, /-?(0x[0-9a-fA-F]+|[0-9]+),/) |
| 21 | return parse_const(substr($0, RSTART, RLENGTH-1)) |
| 22 | } |
| 23 | |
| 24 | function canonicalize_reg(register) { |
| 25 | if (match(register, /^r/)) |
| 26 | return register |
| 27 | else if (match(register, /^e/)) |
| 28 | return "r" substr(register, 2, length(register)-1) |
| 29 | else if (match(register, /[hl]$/)) # AH, AL, BH, BL, etc |
| 30 | return "r" substr(register, 1, 1) "x" |
| 31 | else # AX, BX, CX, etc |
| 32 | return "r" register |
| 33 | } |
| 34 | function get_reg() { |
| 35 | # only use if you already know there is 1 and only 1 register |
| 36 | match($0, /%[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15)/) |
| 37 | return canonicalize_reg(substr($0, RSTART+1, RLENGTH-1)) |
| 38 | } |
| 39 | function get_reg1() { |
| 40 | # for instructions with 2 operands, get 1st operand (assuming it is register) |
| 41 | match($0, /%[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15),/) |
| 42 | return canonicalize_reg(substr($0, RSTART+1, RLENGTH-2)) |
| 43 | } |
| 44 | function get_reg2() { |
| 45 | # for instructions with 2 operands, get 2nd operand (assuming it is register) |
| 46 | match($0, /,%[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15)/) |
| 47 | return canonicalize_reg(substr($0, RSTART+2, RLENGTH-2)) |
| 48 | } |
| 49 | |
| 50 | function adjust_sp_offset(delta) { |
| 51 | if (in_function) |
| 52 | printf ".cfi_adjust_cfa_offset %d\n", delta |
| 53 | } |
| 54 | |
| 55 | { |
| 56 | line_number = line_number + 1 |
| 57 | |
| 58 | # clean the input up before doing anything else |
| 59 | # delete comments |
| 60 | gsub(/(#|\/\/).*/, "") |
| 61 | |
| 62 | # canonicalize whitespace |
| 63 | gsub(/[ \t]+/, " ") # mawk doesn't understand \s |
| 64 | gsub(/ *, */, ",") |
| 65 | gsub(/ *: */, ": ") |
| 66 | gsub(/ $/, "") |
| 67 | gsub(/^ /, "") |
| 68 | } |
| 69 | |
| 70 | # check for assembler directives which we care about |
| 71 | /^\.(section|data|text)/ { |
| 72 | # a .cfi_startproc/.cfi_endproc pair should be within the same section |
| 73 | # otherwise, clang will choke when generating ELF output |
| 74 | if (in_function) { |
| 75 | print ".cfi_endproc" |
| 76 | in_function = 0 |
| 77 | } |
| 78 | } |
| 79 | /^\.type [a-zA-Z0-9_]+,\@function/ { |
| 80 | functions[substr($2, 1, length($2)-10)] = 1 |
| 81 | } |
| 82 | # not interested in assembler directives beyond this, just pass them through |
| 83 | /^\./ { |
| 84 | print |
| 85 | next |
| 86 | } |
| 87 | |
| 88 | /^[a-zA-Z0-9_]+:/ { |
| 89 | label = substr($1, 1, length($1)-1) # drop trailing : |
| 90 | |
| 91 | if (called == label) { |
| 92 | # note adjustment of stack pointer from "call label; label:" |
| 93 | adjust_sp_offset(8) |
| 94 | } |
| 95 | |
| 96 | if (functions[label]) { |
| 97 | if (in_function) |
| 98 | print ".cfi_endproc" |
| 99 | |
| 100 | in_function = 1 |
| 101 | print ".cfi_startproc" |
| 102 | |
| 103 | for (register in saved) |
| 104 | delete saved[register] |
| 105 | for (register in dirty) |
| 106 | delete dirty[register] |
| 107 | } |
| 108 | |
| 109 | # an instruction may follow on the same line, so continue processing |
| 110 | } |
| 111 | |
| 112 | /^$/ { next } |
| 113 | |
| 114 | { |
| 115 | called = "" |
| 116 | printf ".loc 1 %d\n", line_number |
| 117 | print |
| 118 | } |
| 119 | |
| 120 | # KEEPING UP WITH THE STACK POINTER |
| 121 | # %rsp should only be adjusted by pushing/popping or adding/subtracting constants |
| 122 | # |
| 123 | /pushl?/ { |
| 124 | adjust_sp_offset(8) |
| 125 | } |
| 126 | /popl?/ { |
| 127 | adjust_sp_offset(-8) |
| 128 | } |
| 129 | /addl? \$-?(0x[0-9a-fA-F]+|[0-9]+),%rsp/ { adjust_sp_offset(-get_const1()) } |
| 130 | /subl? \$-?(0x[0-9a-fA-F]+|[0-9]+),%rsp/ { adjust_sp_offset(get_const1()) } |
| 131 | |
| 132 | /call/ { |
| 133 | if (match($0, /call [0-9]+f/)) # "forward" label |
| 134 | called = substr($0, RSTART+5, RLENGTH-6) |
| 135 | else if (match($0, /call [0-9a-zA-Z_]+/)) |
| 136 | called = substr($0, RSTART+5, RLENGTH-5) |
| 137 | } |
| 138 | |
| 139 | # TRACKING REGISTER VALUES FROM THE PREVIOUS STACK FRAME |
| 140 | # |
| 141 | /pushl? %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15)/ { # don't match "push (%reg)" |
| 142 | # if a register is being pushed, and its value has not changed since the |
| 143 | # beginning of this function, the pushed value can be used when printing |
| 144 | # local variables at the next level up the stack |
| 145 | # emit '.cfi_rel_offset' for that |
| 146 | |
| 147 | if (in_function) { |
| 148 | register = get_reg() |
| 149 | if (!saved[register] && !dirty[register]) { |
| 150 | printf ".cfi_rel_offset %s,0\n", register |
| 151 | saved[register] = 1 |
| 152 | } |
| 153 | } |
| 154 | } |
| 155 | |
| 156 | /movl? %r(ax|bx|cx|dx|si|di|bp|8|9|10|11|12|13|14|15),-?(0x[0-9a-fA-F]+|[0-9]+)?\(%rsp\)/ { |
| 157 | if (in_function) { |
| 158 | register = get_reg() |
| 159 | if (match($0, /-?(0x[0-9a-fA-F]+|[0-9]+)\(%rsp\)/)) { |
| 160 | offset = parse_const(substr($0, RSTART, RLENGTH-6)) |
| 161 | } else { |
| 162 | offset = 0 |
| 163 | } |
| 164 | if (!saved[register] && !dirty[register]) { |
| 165 | printf ".cfi_rel_offset %s,%d\n", register, offset |
| 166 | saved[register] = 1 |
| 167 | } |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | # IF REGISTER VALUES ARE UNCEREMONIOUSLY TRASHED |
| 172 | # ...then we want to know about it. |
| 173 | # |
| 174 | function trashed(register) { |
| 175 | if (in_function && !saved[register] && !dirty[register]) { |
| 176 | printf ".cfi_undefined %s\n", register |
| 177 | } |
| 178 | dirty[register] = 1 |
| 179 | } |
| 180 | # this does NOT exhaustively check for all possible instructions which could |
| 181 | # overwrite a register value inherited from the caller (just the common ones) |
| 182 | /mov.*,%[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15)$/ { trashed(get_reg2()) } |
| 183 | /(add|addl|sub|subl|and|or|xor|lea|sal|sar|shl|shr).*,%[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15)$/ { |
| 184 | trashed(get_reg2()) |
| 185 | } |
| 186 | /^i?mul [^,]*$/ { trashed("rax"); trashed("rdx") } |
| 187 | /^i?mul.*,%[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15)$/ { trashed(get_reg2()) } |
| 188 | /^i?div/ { trashed("rax"); trashed("rdx") } |
| 189 | |
| 190 | /(dec|inc|not|neg|pop) %[er]?([abcd][xlh]|si|di|bp|8|9|10|11|12|13|14|15)/ { trashed(get_reg()) } |
| 191 | /cpuid/ { trashed("rax"); trashed("rbx"); trashed("rcx"); trashed("rdx") } |
| 192 | |
| 193 | END { |
| 194 | if (in_function) |
| 195 | print ".cfi_endproc" |
| 196 | } |