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HBehrens / puncover

Analyses C/C++ build output for code size, static variables, and stack usage

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Support xc16 (pic) disassembler output

sarfata opened this issue · comments

commented

The disassembly generated by the xc16 toolchain (microchip) generates symbols for every label in the source code. For example, this is one function that gets transformed into multiple symbols: SetUsbChannel, .L3, .L4, .L6, .L2.

00007270 <_SetUsbChannel>:
SetUsbChannel():
/project/bootload.X/usb_switch.c:21
    7270:	88 1f 78    	mov.w     w8, [w15++]
    7272:	00 04 78    	mov.w     w0, w8
/project/bootload.X/usb_switch.c:25
    7274:	e1 0f 54    	sub.w     w8, #0x1, [w15]
    7276:	09 00 32    	bra       Z, 0x728a <.L4>
    7278:	03 00 39    	bra       NC, 0x7280 <.L3>
    727a:	e2 0f 54    	sub.w     w8, #0x2, [w15]
    727c:	0f 00 3a    	bra       NZ, 0x729c <.L2>
    727e:	0a 00 37    	bra       0x7294 <.L6>

00007280 <.L3>:
/project/bootload.X/usb_switch.c:28
    7280:	e0 00 20    	mov.w     #0xe, w0
    7282:	a0 ff 07    	rcall     0x71c4 <_output_high> <.LFB8> <.LFE7>
/project/bootload.X/usb_switch.c:29
    7284:	f0 00 20    	mov.w     #0xf, w0
    7286:	a8 ff 07    	rcall     0x71d8 <_output_low> <.LFB9> <.LFE8>
/project/bootload.X/usb_switch.c:30
    7288:	09 00 37    	bra       0x729c <.L2>

0000728a <.L4>:
/project/bootload.X/usb_switch.c:33
    728a:	e0 00 20    	mov.w     #0xe, w0
    728c:	a5 ff 07    	rcall     0x71d8 <_output_low> <.LFB9> <.LFE8>
/project/bootload.X/usb_switch.c:34
    728e:	f0 00 20    	mov.w     #0xf, w0
    7290:	a3 ff 07    	rcall     0x71d8 <_output_low> <.LFB9> <.LFE8>
/project/bootload.X/usb_switch.c:35
    7292:	04 00 37    	bra       0x729c <.L2>

00007294 <.L6>:
/project/bootload.X/usb_switch.c:38
    7294:	e0 00 20    	mov.w     #0xe, w0
    7296:	a0 ff 07    	rcall     0x71d8 <_output_low> <.LFB9> <.LFE8>
/project/bootload.X/usb_switch.c:39
    7298:	f0 00 20    	mov.w     #0xf, w0
    729a:	94 ff 07    	rcall     0x71c4 <_output_high> <.LFB8> <.LFE7>

0000729c <.L2>:
/project/bootload.X/usb_switch.c:43
    729c:	78 43 88    	mov.w     w8, 0x86e
/project/bootload.X/usb_switch.c:44
    729e:	4f 04 78    	mov.w     [--w15], w8
    72a0:	00 00 06    	return

The current result is that for a elf file disassembled with this toolset, 80% of the code size goes in <unknown>/<unknown> and looking at SetUsbChannel only shows the first few lines of the assembly. Callers/Callees counting is also broken (related to #7/#8/#20 probably).

Todo:

  • add some tests parsing this type of output
  • parse assembly all the way til the end of the function (until beginning of the next one is probably the only way to detect the end of one)
  • figure out a way to sum the size of all the symbols that make one function