diff options
| author | Kirill Smelkov <kirr@navytux.spb.ru> | 2012-11-16 00:04:56 +0400 |
|---|---|---|
| committer | Kirill Smelkov <kirr@navytux.spb.ru> | 2012-11-16 10:22:45 +0400 |
| commit | ab24aaeca303abadd987c2a4ab3a56efe755c37c (patch) | |
| tree | e7b682064790846ebc4203a6d7c54bdf0a2f5428 | |
| parent | b2a02961b4407ca76db5a66ca5ae855cbfba4e8e (diff) | |
| download | tinycc-ab24aaeca303abadd987c2a4ab3a56efe755c37c.tar.gz tinycc-ab24aaeca303abadd987c2a4ab3a56efe755c37c.tar.bz2 | |
i386: We can change 'lea 0(%ebp),r' to 'mov %ebp,r'
Because that mov is 1 byte shorter, look:
int *func()
{
return __builtin_frame_address(0);
}
before patch:
00000000 <func>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 81 ec 00 00 00 00 sub $0x0,%esp
9: 8d 45 00 lea 0x0(%ebp),%eax // <- here
c: e9 00 00 00 00 jmp 11 <func+0x11>
11: c9 leave
12: c3 ret
after patch:
00000000 <func>:
0: 55 push %ebp
1: 89 e5 mov %esp,%ebp
3: 81 ec 00 00 00 00 sub $0x0,%esp
9: 89 e8 mov %ebp,%eax // <- here
b: e9 00 00 00 00 jmp 10 <func+0x10>
10: c9 leave
11: c3 ret
| -rw-r--r-- | i386-gen.c | 9 |
1 files changed, 7 insertions, 2 deletions
@@ -260,8 +260,13 @@ ST_FUNC void load(int r, SValue *sv) o(0xb8 + r); /* mov $xx, r */ gen_addr32(fr, sv->sym, fc); } else if (v == VT_LOCAL) { - o(0x8d); /* lea xxx(%ebp), r */ - gen_modrm(r, VT_LOCAL, sv->sym, fc); + if (fc) { + o(0x8d); /* lea xxx(%ebp), r */ + gen_modrm(r, VT_LOCAL, sv->sym, fc); + } else { + o(0x89); + o(0xe8 + r); /* mov %ebp, r */ + } } else if (v == VT_CMP) { oad(0xb8 + r, 0); /* mov $0, r */ o(0x0f); /* setxx %br */ |
