http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46393
Summary: m68k code size regression
Product: gcc
Version: 4.5.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: anders.monto...@iki.fi
The following code snippet compiles to 112 bytes using GCC 4.4.0 and 154 bytes
using GCC 4.5.1.
Host is OS X 10.6, target is m68k-elf bare-metal toolchain using newlib.
The code was compiled with -m68000 -Os -c.
unpack.c:
#include <stdint.h>
uint8_t ChannelMap[32];
typedef struct
{
uint8_t note;
uint8_t instrument;
uint8_t volume;
uint8_t command;
uint8_t info;
} Channeldata_t;
Channeldata_t RowBuffer[16];
uint8_t UnpackRow(const uint8_t *pRowData)
{
uint8_t count = 0, byte, channel, mappedchannel;
Channeldata_t *pChannelData;
while ((byte = *pRowData++) != 0)
{
++count;
channel = byte & 0x1f;
mappedchannel = ChannelMap[channel];
pChannelData = &RowBuffer[mappedchannel];
if (byte & 0x20)
{
pChannelData->note = *pRowData++;
pChannelData->instrument = *pRowData++;
++count;
}
if (byte & 0x40)
{
pChannelData->volume = *pRowData++;
++count;
}
if (byte & 0x80)
{
pChannelData->command = *pRowData++;
pChannelData->info = *pRowData++;
count += 2;
}
}
return count;
}
GCC 4.4.0-produced code:
00000000 <UnpackRow>:
0: 4e56 0000 linkw %fp,#0
4: 48e7 3820 moveml %d2-%d4/%a2,%...@-
8: 206e 0008 moveal %fp@(8),%a0
c: 4200 clrb %d0
e: 45f9 0000 0000 lea 0 <UnpackRow>,%a2
14: 604e bras 64 <UnpackRow+0x64>
16: 5288 addql #1,%a0
18: 5200 addqb #1,%d0
1a: 7400 moveq #0,%d2
1c: 1401 moveb %d1,%d2
1e: 761f moveq #31,%d3
20: c682 andl %d2,%d3
22: 1632 3800 moveb %a2@(0000000000000000,%d3:l),%d3
26: 0283 0000 00ff andil #255,%d3
2c: 2803 movel %d3,%d4
2e: d883 addl %d3,%d4
30: d884 addl %d4,%d4
32: 2244 moveal %d4,%a1
34: d3c3 addal %d3,%a1
36: d3fc 0000 0000 addal #0,%a1
3c: 0802 0005 btst #5,%d2
40: 6708 beqs 4a <UnpackRow+0x4a>
42: 1298 moveb %...@+,%a1@
44: 1358 0001 moveb %...@+,%a1@(1)
48: 5200 addqb #1,%d0
4a: 0802 0006 btst #6,%d2
4e: 6706 beqs 56 <UnpackRow+0x56>
50: 1358 0002 moveb %...@+,%a1@(2)
54: 5200 addqb #1,%d0
56: 4a01 tstb %d1
58: 6c0a bges 64 <UnpackRow+0x64>
5a: 1358 0003 moveb %...@+,%a1@(3)
5e: 1358 0004 moveb %...@+,%a1@(4)
62: 5400 addqb #2,%d0
64: 1210 moveb %a0@,%d1
66: 66ae bnes 16 <UnpackRow+0x16>
68: 4cdf 041c moveml %...@+,%d2-%d4/%a2
6c: 4e5e unlk %fp
6e: 4e75 rts
GCC 4.5.1-produced code:
00000000 <UnpackRow>:
0: 4e56 0000 linkw %fp,#0
4: 48e7 383c moveml %d2-%d4/%a2-%a5,%...@-
8: 206e 0008 moveal %fp@(8),%a0
c: 4200 clrb %d0
e: 49f9 0000 0000 lea 0 <UnpackRow>,%a4
14: 47f9 0000 0000 lea 0 <UnpackRow>,%a3
1a: 45f9 0000 0000 lea 0 <UnpackRow>,%a2
20: 606c bras 8e <UnpackRow+0x8e>
22: 5288 addql #1,%a0
24: 5200 addqb #1,%d0
26: 721f moveq #31,%d1
28: c282 andl %d2,%d1
2a: 1234 1800 moveb %a4@(0000000000000000,%d1:l),%d1
2e: 0281 0000 00ff andil #255,%d1
34: 7600 moveq #0,%d3
36: 1602 moveb %d2,%d3
38: 0803 0005 btst #5,%d3
3c: 6714 beqs 52 <UnpackRow+0x52>
3e: 2801 movel %d1,%d4
40: d881 addl %d1,%d4
42: d884 addl %d4,%d4
44: 2244 moveal %d4,%a1
46: d3c1 addal %d1,%a1
48: 1398 b800 moveb %...@+,%a1@(0000000000000000,%a3:l)
4c: 1398 a800 moveb %...@+,%a1@(0000000000000000,%a2:l)
50: 5200 addqb #1,%d0
52: 0803 0006 btst #6,%d3
56: 6714 beqs 6c <UnpackRow+0x6c>
58: 2601 movel %d1,%d3
5a: d681 addl %d1,%d3
5c: d683 addl %d3,%d3
5e: 2243 moveal %d3,%a1
60: d3c1 addal %d1,%a1
62: d3fc 0000 0000 addal #0,%a1
68: 1298 moveb %...@+,%a1@
6a: 5200 addqb #1,%d0
6c: 4a02 tstb %d2
6e: 6c1e bges 8e <UnpackRow+0x8e>
70: 2401 movel %d1,%d2
72: d481 addl %d1,%d2
74: d482 addl %d2,%d2
76: 2242 moveal %d2,%a1
78: d3c1 addal %d1,%a1
7a: 2a49 moveal %a1,%a5
7c: dbfc 0000 0000 addal #0,%a5
82: 1a98 moveb %...@+,%a5@
84: d3fc 0000 0000 addal #0,%a1
8a: 1298 moveb %...@+,%a1@
8c: 5400 addqb #2,%d0
8e: 1410 moveb %a0@,%d2
90: 6690 bnes 22 <UnpackRow+0x22>
92: 4cdf 3c1c moveml %...@+,%d2-%d4/%a2-%a5
96: 4e5e unlk %fp
98: 4e75 rts
