/* * shortprop eliminates redundant zero/sign extensions. * * MOVBS x, R * <no use R> * MOVBS R, R' * * changed to * * MOVBS x, R * ... * MOVB R, R' (compiled to mov) * * MOVBS above can be a MOVBS, MOVBU, MOVHS or MOVHU. */ static int shortprop(Flow *r) { Prog *p, *p1; Flow *r1; p = r->prog; r1 = findpre(r, &p->from); if(r1 == nil) return 0; p1 = r1->prog; if(p1->as == p->as) { // Two consecutive extensions. goto gotit; } if(p1->as == AMOVW && isdconst(&p1->from) && p1->from.offset >= 0 && p1->from.offset < 128) { // Loaded an immediate. goto gotit; } return 0; gotit: if(debug['P']) print("shortprop\n%P\n%P", p1, p); switch(p->as) { case AMOVBS: case AMOVBU: p->as = AMOVB; break; case AMOVHS: case AMOVHU: p->as = AMOVH; break; } if(debug['P']) print(" => %A\n", p->as); return 1; }
int xtramodes(Reg *r, Adr *a) { Reg *r1, *r2, *r3; Prog *p, *p1; Adr v; p = r->prog; if(debug['h'] && p->as == AMOVB && p->from.type == D_OREG) /* byte load */ return 0; v = *a; v.type = D_REG; r1 = findpre(r, &v); if(r1 != R) { p1 = r1->prog; if(p1->to.type == D_REG && p1->to.reg == v.reg) switch(p1->as) { case AADD: if(p1->from.type == D_REG || (p1->from.type == D_SHIFT && (p1->from.offset&(1<<4)) == 0 && (p->as != AMOVB || (a == &p->from && (p1->from.offset&~0xf) == 0))) || (p1->from.type == D_CONST && p1->from.offset > -4096 && p1->from.offset < 4096)) if(nochange(uniqs(r1), r, p1)) { if(a != &p->from || v.reg != p->to.reg) if (finduse(r->s1, &v)) { if(p1->reg == NREG || p1->reg == v.reg) /* pre-indexing */ p->scond |= C_WBIT; else return 0; } switch (p1->from.type) { case D_REG: /* register offset */ a->type = D_SHIFT; a->offset = p1->from.reg; break; case D_SHIFT: /* scaled register offset */ a->type = D_SHIFT; case D_CONST: /* immediate offset */ a->offset = p1->from.offset; break; } if(p1->reg != NREG) a->reg = p1->reg; excise(r1); return 1; } break; case AMOVW: if(p1->from.type == D_REG) if((r2 = findinc(r1, r, &p1->from)) != R) { for(r3=uniqs(r2); r3->prog->as==ANOP; r3=uniqs(r3)) ; if(r3 == r) { /* post-indexing */ p1 = r2->prog; a->reg = p1->to.reg; a->offset = p1->from.offset; p->scond |= C_PBIT; if(!finduse(r, &r1->prog->to)) excise(r1); excise(r2); return 1; } } break; } } if(a != &p->from || a->reg != p->to.reg) if((r1 = findinc(r, R, &v)) != R) { /* post-indexing */ p1 = r1->prog; a->offset = p1->from.offset; p->scond |= C_PBIT; excise(r1); return 1; } return 0; }