diff options
| author | cinap_lenrek <cinap_lenrek@felloff.net> | 2014-03-29 19:44:04 +0100 |
|---|---|---|
| committer | cinap_lenrek <cinap_lenrek@felloff.net> | 2014-03-29 19:44:04 +0100 |
| commit | cde97a4d5f17fe597cc55aa4653082bf2c01598c (patch) | |
| tree | 449fdbe028b01b9d21031c0696ba125edebc3ebe /sys/src/cmd/8c | |
| parent | 91bed257fa7382c90fdd9d99089442b453090bba (diff) | |
6c, 8c: optimize away CMPL/CMPQ reg, $0 instruction in peephole pass
when the previous instruction sets the zero flag,
we can remove the CMPL/CMPQ instruction.
this removes compares for zero/non zero tests only.
it only looks at the previous non-nop instruction
to see if it sets our compare value register.
Diffstat (limited to 'sys/src/cmd/8c')
| -rw-r--r-- | sys/src/cmd/8c/peep.c | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/sys/src/cmd/8c/peep.c b/sys/src/cmd/8c/peep.c index 5f61925d7..b0f639dd7 100644 --- a/sys/src/cmd/8c/peep.c +++ b/sys/src/cmd/8c/peep.c @@ -137,6 +137,36 @@ loop1: p->from = zprog.from; } break; + + case ACMPL: + if(p->to.type != D_CONST || p->to.offset != 0 || regtyp(&p->from) == 0) + break; + if(p->link == P || (p->link->as != AJEQ && p->link->as != AJNE)) + break; + r1 = uniqp(r); + while(r1 != R && r1->prog->as == ANOP) + r1 = uniqp(r1); + if(r1 == R || r1->prog->to.type != p->from.type) + break; + p1 = r1->prog; + switch(p1->as){ + case AANDL: + case AORL: + case AXORL: + case ANEGL: + case AADDL: + case AADCL: + case ASUBL: + case ASBBL: + case ASHLL: + case ASHRL: + case ASALL: + case ASARL: + case AINCL: + case ADECL: + excise(r); + } + break; } } if(t) |