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Diffstat (limited to 'src/cmd/9g/ggen.c')
| -rw-r--r-- | src/cmd/9g/ggen.c | 1034 |
1 files changed, 1034 insertions, 0 deletions
diff --git a/src/cmd/9g/ggen.c b/src/cmd/9g/ggen.c new file mode 100644 index 000000000..c41d8eb41 --- /dev/null +++ b/src/cmd/9g/ggen.c @@ -0,0 +1,1034 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +#undef EXTERN +#define EXTERN +#include <u.h> +#include <libc.h> +#include "gg.h" +#include "opt.h" + +static Prog *appendpp(Prog *p, int as, int ftype, int freg, vlong foffset, int ttype, int treg, vlong toffset); +static Prog *zerorange(Prog *p, vlong frame, vlong lo, vlong hi); + +void +defframe(Prog *ptxt) +{ + uint32 frame; + Prog *p; + vlong hi, lo; + NodeList *l; + Node *n; + + // fill in argument size + ptxt->to.offset = rnd(curfn->type->argwid, widthptr); + + // fill in final stack size + ptxt->to.offset <<= 32; + frame = rnd(stksize+maxarg, widthreg); + ptxt->to.offset |= frame; + + // insert code to zero ambiguously live variables + // so that the garbage collector only sees initialized values + // when it looks for pointers. + p = ptxt; + lo = hi = 0; + // iterate through declarations - they are sorted in decreasing xoffset order. + for(l=curfn->dcl; l != nil; l = l->next) { + n = l->n; + if(!n->needzero) + continue; + if(n->class != PAUTO) + fatal("needzero class %d", n->class); + if(n->type->width % widthptr != 0 || n->xoffset % widthptr != 0 || n->type->width == 0) + fatal("var %lN has size %d offset %d", n, (int)n->type->width, (int)n->xoffset); + + if(lo != hi && n->xoffset + n->type->width >= lo - 2*widthreg) { + // merge with range we already have + lo = n->xoffset; + continue; + } + // zero old range + p = zerorange(p, frame, lo, hi); + + // set new range + hi = n->xoffset + n->type->width; + lo = n->xoffset; + } + // zero final range + zerorange(p, frame, lo, hi); +} + +static Prog* +zerorange(Prog *p, vlong frame, vlong lo, vlong hi) +{ + vlong cnt, i; + Prog *p1; + Node *f; + + cnt = hi - lo; + if(cnt == 0) + return p; + if(cnt < 4*widthptr) { + for(i = 0; i < cnt; i += widthptr) + p = appendpp(p, AMOVD, D_REG, REGZERO, 0, D_OREG, REGSP, 8+frame+lo+i); + } else if(cnt <= 128*widthptr) { + p = appendpp(p, AADD, D_CONST, NREG, 8+frame+lo-8, D_REG, REGRT1, 0); + p->reg = REGSP; + p = appendpp(p, ADUFFZERO, D_NONE, NREG, 0, D_OREG, NREG, 0); + f = sysfunc("duffzero"); + naddr(f, &p->to, 1); + afunclit(&p->to, f); + p->to.offset = 4*(128-cnt/widthptr); + } else { + p = appendpp(p, AMOVD, D_CONST, NREG, 8+frame+lo-8, D_REG, REGTMP, 0); + p = appendpp(p, AADD, D_REG, REGTMP, 0, D_REG, REGRT1, 0); + p->reg = REGSP; + p = appendpp(p, AMOVD, D_CONST, NREG, cnt, D_REG, REGTMP, 0); + p = appendpp(p, AADD, D_REG, REGTMP, 0, D_REG, REGRT2, 0); + p->reg = REGRT1; + p1 = p = appendpp(p, AMOVDU, D_REG, REGZERO, 0, D_OREG, REGRT1, widthptr); + p = appendpp(p, ACMP, D_REG, REGRT1, 0, D_REG, REGRT2, 0); + p = appendpp(p, ABNE, D_NONE, NREG, 0, D_BRANCH, NREG, 0); + patch(p, p1); + } + return p; +} + +static Prog* +appendpp(Prog *p, int as, int ftype, int freg, vlong foffset, int ttype, int treg, vlong toffset) +{ + Prog *q; + q = mal(sizeof(*q)); + clearp(q); + q->as = as; + q->lineno = p->lineno; + q->from.type = ftype; + q->from.reg = freg; + q->from.offset = foffset; + q->to.type = ttype; + q->to.reg = treg; + q->to.offset = toffset; + q->link = p->link; + p->link = q; + return q; +} + +// Sweep the prog list to mark any used nodes. +void +markautoused(Prog *p) +{ + for (; p; p = p->link) { + if (p->as == ATYPE || p->as == AVARDEF || p->as == AVARKILL) + continue; + + if (p->from.node) + p->from.node->used = 1; + + if (p->to.node) + p->to.node->used = 1; + } +} + +// Fixup instructions after allocauto (formerly compactframe) has moved all autos around. +void +fixautoused(Prog *p) +{ + Prog **lp; + + for (lp=&p; (p=*lp) != P; ) { + if (p->as == ATYPE && p->from.node && p->from.name == D_AUTO && !p->from.node->used) { + *lp = p->link; + continue; + } + if ((p->as == AVARDEF || p->as == AVARKILL) && p->to.node && !p->to.node->used) { + // Cannot remove VARDEF instruction, because - unlike TYPE handled above - + // VARDEFs are interspersed with other code, and a jump might be using the + // VARDEF as a target. Replace with a no-op instead. A later pass will remove + // the no-ops. + p->to.type = D_NONE; + p->to.node = N; + p->as = ANOP; + continue; + } + if (p->from.name == D_AUTO && p->from.node) + p->from.offset += p->from.node->stkdelta; + + if (p->to.name == D_AUTO && p->to.node) + p->to.offset += p->to.node->stkdelta; + + lp = &p->link; + } +} + +/* + * generate: BL reg, f + * where both reg and f are registers. + * On power, f must be moved to CTR first. + */ +static void +ginsBL(Node *reg, Node *f) +{ + Prog *p; + p = gins(AMOVD, f, N); + p->to.type = D_SPR; + p->to.offset = D_CTR; + p = gins(ABL, reg, N); + p->to.type = D_SPR; + p->to.offset = D_CTR; +} + +/* + * generate: + * call f + * proc=-1 normal call but no return + * proc=0 normal call + * proc=1 goroutine run in new proc + * proc=2 defer call save away stack + * proc=3 normal call to C pointer (not Go func value) + */ +void +ginscall(Node *f, int proc) +{ + Prog *p; + Node reg, con, reg2; + Node r1; + + if(f->type != T) + setmaxarg(f->type); + + switch(proc) { + default: + fatal("ginscall: bad proc %d", proc); + break; + + case 0: // normal call + case -1: // normal call but no return + if(f->op == ONAME && f->class == PFUNC) { + if(f == deferreturn) { + // Deferred calls will appear to be returning to + // the CALL deferreturn(SB) that we are about to emit. + // However, the stack trace code will show the line + // of the instruction byte before the return PC. + // To avoid that being an unrelated instruction, + // insert a Power64 NOP that we will have the right line number. + // Power64 NOP is really or r0, r0, r0; use that description + // because the NOP pseudo-instruction would be removed by + // the linker. + nodreg(®, types[TINT], D_R0); + gins(AOR, ®, ®); + } + p = gins(ABL, N, f); + afunclit(&p->to, f); + if(proc == -1 || noreturn(p)) + gins(AUNDEF, N, N); + break; + } + nodreg(®, types[tptr], D_R0+REGENV); + nodreg(&r1, types[tptr], D_R0+3); + gmove(f, ®); + reg.op = OINDREG; + gmove(®, &r1); + reg.op = OREGISTER; + ginsBL(®, &r1); + break; + + case 3: // normal call of c function pointer + ginsBL(N, f); + break; + + case 1: // call in new proc (go) + case 2: // deferred call (defer) + nodconst(&con, types[TINT64], argsize(f->type)); + nodreg(®, types[TINT64], D_R0+3); + nodreg(®2, types[TINT64], D_R0+4); + gmove(f, ®); + + p = gins(ASUB, N, N); + p->from.type = D_CONST; + p->from.offset = 3 * 8; + p->to.type = D_REG; + p->to.reg = REGSP; + + gmove(&con, ®2); + p = gins(AMOVW, ®2, N); + p->to.type = D_OREG; + p->to.reg = REGSP; + p->to.offset = 8; + + p = gins(AMOVD, ®, N); + p->to.type = D_OREG; + p->to.reg = REGSP; + p->to.offset = 16; + + if(proc == 1) + ginscall(newproc, 0); + else { + if(!hasdefer) + fatal("hasdefer=0 but has defer"); + ginscall(deferproc, 0); + } + + p = gins(AADD, N, N); + p->from.type = D_CONST; + p->from.offset = 3 * 8; + p->to.type = D_REG; + p->to.reg = REGSP; + + if(proc == 2) { + nodreg(®, types[TINT64], D_R0+3); + p = gins(ACMP, ®, N); + p->to.type = D_REG; + p->to.reg = D_R0; + p = gbranch(ABEQ, T, +1); + cgen_ret(N); + patch(p, pc); + } + break; + } +} + +/* + * n is call to interface method. + * generate res = n. + */ +void +cgen_callinter(Node *n, Node *res, int proc) +{ + Node *i, *f; + Node tmpi, nodi, nodo, nodr, nodsp; + Prog *p; + + i = n->left; + if(i->op != ODOTINTER) + fatal("cgen_callinter: not ODOTINTER %O", i->op); + + f = i->right; // field + if(f->op != ONAME) + fatal("cgen_callinter: not ONAME %O", f->op); + + i = i->left; // interface + + if(!i->addable) { + tempname(&tmpi, i->type); + cgen(i, &tmpi); + i = &tmpi; + } + + genlist(n->list); // assign the args + + // i is now addable, prepare an indirected + // register to hold its address. + igen(i, &nodi, res); // REG = &inter + + nodindreg(&nodsp, types[tptr], D_R0+REGSP); + nodsp.xoffset = widthptr; + nodi.type = types[tptr]; + nodi.xoffset += widthptr; + cgen(&nodi, &nodsp); // 0(SP) = 8(REG) -- i.data + + regalloc(&nodo, types[tptr], res); + nodi.type = types[tptr]; + nodi.xoffset -= widthptr; + cgen(&nodi, &nodo); // REG = 0(REG) -- i.tab + regfree(&nodi); + + regalloc(&nodr, types[tptr], &nodo); + if(n->left->xoffset == BADWIDTH) + fatal("cgen_callinter: badwidth"); + cgen_checknil(&nodo); // in case offset is huge + nodo.op = OINDREG; + nodo.xoffset = n->left->xoffset + 3*widthptr + 8; + if(proc == 0) { + // plain call: use direct c function pointer - more efficient + cgen(&nodo, &nodr); // REG = 32+offset(REG) -- i.tab->fun[f] + proc = 3; + } else { + // go/defer. generate go func value. + p = gins(AMOVD, &nodo, &nodr); // REG = &(32+offset(REG)) -- i.tab->fun[f] + p->from.type = D_CONST; + } + + nodr.type = n->left->type; + ginscall(&nodr, proc); + + regfree(&nodr); + regfree(&nodo); +} + +/* + * generate function call; + * proc=0 normal call + * proc=1 goroutine run in new proc + * proc=2 defer call save away stack + */ +void +cgen_call(Node *n, int proc) +{ + Type *t; + Node nod, afun; + + if(n == N) + return; + + if(n->left->ullman >= UINF) { + // if name involves a fn call + // precompute the address of the fn + tempname(&afun, types[tptr]); + cgen(n->left, &afun); + } + + genlist(n->list); // assign the args + t = n->left->type; + + // call tempname pointer + if(n->left->ullman >= UINF) { + regalloc(&nod, types[tptr], N); + cgen_as(&nod, &afun); + nod.type = t; + ginscall(&nod, proc); + regfree(&nod); + return; + } + + // call pointer + if(n->left->op != ONAME || n->left->class != PFUNC) { + regalloc(&nod, types[tptr], N); + cgen_as(&nod, n->left); + nod.type = t; + ginscall(&nod, proc); + regfree(&nod); + return; + } + + // call direct + n->left->method = 1; + ginscall(n->left, proc); +} + +/* + * call to n has already been generated. + * generate: + * res = return value from call. + */ +void +cgen_callret(Node *n, Node *res) +{ + Node nod; + Type *fp, *t; + Iter flist; + + t = n->left->type; + if(t->etype == TPTR32 || t->etype == TPTR64) + t = t->type; + + fp = structfirst(&flist, getoutarg(t)); + if(fp == T) + fatal("cgen_callret: nil"); + + memset(&nod, 0, sizeof(nod)); + nod.op = OINDREG; + nod.val.u.reg = D_R0+REGSP; + nod.addable = 1; + + nod.xoffset = fp->width + widthptr; // +widthptr: saved LR at 0(R1) + nod.type = fp->type; + cgen_as(res, &nod); +} + +/* + * call to n has already been generated. + * generate: + * res = &return value from call. + */ +void +cgen_aret(Node *n, Node *res) +{ + Node nod1, nod2; + Type *fp, *t; + Iter flist; + + t = n->left->type; + if(isptr[t->etype]) + t = t->type; + + fp = structfirst(&flist, getoutarg(t)); + if(fp == T) + fatal("cgen_aret: nil"); + + memset(&nod1, 0, sizeof(nod1)); + nod1.op = OINDREG; + nod1.val.u.reg = D_R0 + REGSP; + nod1.addable = 1; + + nod1.xoffset = fp->width + widthptr; // +widthptr: saved lr at 0(SP) + nod1.type = fp->type; + + if(res->op != OREGISTER) { + regalloc(&nod2, types[tptr], res); + agen(&nod1, &nod2); + gins(AMOVD, &nod2, res); + regfree(&nod2); + } else + agen(&nod1, res); +} + +/* + * generate return. + * n->left is assignments to return values. + */ +void +cgen_ret(Node *n) +{ + Prog *p; + + if(n != N) + genlist(n->list); // copy out args + if(hasdefer) + ginscall(deferreturn, 0); + genlist(curfn->exit); + p = gins(ARET, N, N); + if(n != N && n->op == ORETJMP) { + p->to.name = D_EXTERN; + p->to.type = D_CONST; + p->to.sym = linksym(n->left->sym); + } +} + +void +cgen_asop(Node *n) +{ + USED(n); + fatal("cgen_asop"); // no longer used +} + +int +samereg(Node *a, Node *b) +{ + if(a == N || b == N) + return 0; + if(a->op != OREGISTER) + return 0; + if(b->op != OREGISTER) + return 0; + if(a->val.u.reg != b->val.u.reg) + return 0; + return 1; +} + +/* + * generate division. + * generates one of: + * res = nl / nr + * res = nl % nr + * according to op. + */ +void +dodiv(int op, Node *nl, Node *nr, Node *res) +{ + int a, check; + Type *t, *t0; + Node tl, tr, tl2, tr2, nm1, nz, tm; + Prog *p1, *p2; + + // Have to be careful about handling + // most negative int divided by -1 correctly. + // The hardware will generate undefined result. + // Also need to explicitly trap on division on zero, + // the hardware will silently generate undefined result. + // DIVW will leave unpredicable result in higher 32-bit, + // so always use DIVD/DIVDU. + t = nl->type; + t0 = t; + check = 0; + if(issigned[t->etype]) { + check = 1; + if(isconst(nl, CTINT) && mpgetfix(nl->val.u.xval) != -(1ULL<<(t->width*8-1))) + check = 0; + else if(isconst(nr, CTINT) && mpgetfix(nr->val.u.xval) != -1) + check = 0; + } + if(t->width < 8) { + if(issigned[t->etype]) + t = types[TINT64]; + else + t = types[TUINT64]; + check = 0; + } + + a = optoas(ODIV, t); + + regalloc(&tl, t0, N); + regalloc(&tr, t0, N); + if(nl->ullman >= nr->ullman) { + cgen(nl, &tl); + cgen(nr, &tr); + } else { + cgen(nr, &tr); + cgen(nl, &tl); + } + if(t != t0) { + // Convert + tl2 = tl; + tr2 = tr; + tl.type = t; + tr.type = t; + gmove(&tl2, &tl); + gmove(&tr2, &tr); + } + + // Handle divide-by-zero panic. + p1 = gins(optoas(OCMP, t), &tr, N); + p1->to.type = D_REG; + p1->to.reg = REGZERO; + p1 = gbranch(optoas(ONE, t), T, +1); + if(panicdiv == N) + panicdiv = sysfunc("panicdivide"); + ginscall(panicdiv, -1); + patch(p1, pc); + + if(check) { + nodconst(&nm1, t, -1); + gins(optoas(OCMP, t), &tr, &nm1); + p1 = gbranch(optoas(ONE, t), T, +1); + if(op == ODIV) { + // a / (-1) is -a. + gins(optoas(OMINUS, t), N, &tl); + gmove(&tl, res); + } else { + // a % (-1) is 0. + nodconst(&nz, t, 0); + gmove(&nz, res); + } + p2 = gbranch(AJMP, T, 0); + patch(p1, pc); + } + p1 = gins(a, &tr, &tl); + if(op == ODIV) { + regfree(&tr); + gmove(&tl, res); + } else { + // A%B = A-(A/B*B) + regalloc(&tm, t, N); + // patch div to use the 3 register form + // TODO(minux): add gins3? + p1->reg = p1->to.reg; + p1->to.reg = tm.val.u.reg; + gins(optoas(OMUL, t), &tr, &tm); + regfree(&tr); + gins(optoas(OSUB, t), &tm, &tl); + regfree(&tm); + gmove(&tl, res); + } + regfree(&tl); + if(check) + patch(p2, pc); +} + +/* + * generate division according to op, one of: + * res = nl / nr + * res = nl % nr + */ +void +cgen_div(int op, Node *nl, Node *nr, Node *res) +{ + Node n1, n2, n3; + int w, a; + Magic m; + + // TODO(minux): enable division by magic multiply (also need to fix longmod below) + //if(nr->op != OLITERAL) + goto longdiv; + w = nl->type->width*8; + + // Front end handled 32-bit division. We only need to handle 64-bit. + // try to do division by multiply by (2^w)/d + // see hacker's delight chapter 10 + switch(simtype[nl->type->etype]) { + default: + goto longdiv; + + case TUINT64: + m.w = w; + m.ud = mpgetfix(nr->val.u.xval); + umagic(&m); + if(m.bad) + break; + if(op == OMOD) + goto longmod; + + cgenr(nl, &n1, N); + nodconst(&n2, nl->type, m.um); + regalloc(&n3, nl->type, res); + cgen_hmul(&n1, &n2, &n3); + + if(m.ua) { + // need to add numerator accounting for overflow + gins(optoas(OADD, nl->type), &n1, &n3); + nodconst(&n2, nl->type, 1); + gins(optoas(ORROTC, nl->type), &n2, &n3); + nodconst(&n2, nl->type, m.s-1); + gins(optoas(ORSH, nl->type), &n2, &n3); + } else { + nodconst(&n2, nl->type, m.s); + gins(optoas(ORSH, nl->type), &n2, &n3); // shift dx + } + + gmove(&n3, res); + regfree(&n1); + regfree(&n3); + return; + + case TINT64: + m.w = w; + m.sd = mpgetfix(nr->val.u.xval); + smagic(&m); + if(m.bad) + break; + if(op == OMOD) + goto longmod; + + cgenr(nl, &n1, res); + nodconst(&n2, nl->type, m.sm); + regalloc(&n3, nl->type, N); + cgen_hmul(&n1, &n2, &n3); + + if(m.sm < 0) { + // need to add numerator + gins(optoas(OADD, nl->type), &n1, &n3); + } + + nodconst(&n2, nl->type, m.s); + gins(optoas(ORSH, nl->type), &n2, &n3); // shift n3 + + nodconst(&n2, nl->type, w-1); + gins(optoas(ORSH, nl->type), &n2, &n1); // -1 iff num is neg + gins(optoas(OSUB, nl->type), &n1, &n3); // added + + if(m.sd < 0) { + // this could probably be removed + // by factoring it into the multiplier + gins(optoas(OMINUS, nl->type), N, &n3); + } + + gmove(&n3, res); + regfree(&n1); + regfree(&n3); + return; + } + goto longdiv; + +longdiv: + // division and mod using (slow) hardware instruction + dodiv(op, nl, nr, res); + return; + +longmod: + // mod using formula A%B = A-(A/B*B) but + // we know that there is a fast algorithm for A/B + regalloc(&n1, nl->type, res); + cgen(nl, &n1); + regalloc(&n2, nl->type, N); + cgen_div(ODIV, &n1, nr, &n2); + a = optoas(OMUL, nl->type); + if(w == 8) { + // use 2-operand 16-bit multiply + // because there is no 2-operand 8-bit multiply + //a = AIMULW; + } + if(!smallintconst(nr)) { + regalloc(&n3, nl->type, N); + cgen(nr, &n3); + gins(a, &n3, &n2); + regfree(&n3); + } else + gins(a, nr, &n2); + gins(optoas(OSUB, nl->type), &n2, &n1); + gmove(&n1, res); + regfree(&n1); + regfree(&n2); +} + +/* + * generate high multiply: + * res = (nl*nr) >> width + */ +void +cgen_hmul(Node *nl, Node *nr, Node *res) +{ + int w; + Node n1, n2, *tmp; + Type *t; + Prog *p; + + // largest ullman on left. + if(nl->ullman < nr->ullman) { + tmp = nl; + nl = nr; + nr = tmp; + } + t = nl->type; + w = t->width * 8; + cgenr(nl, &n1, res); + cgenr(nr, &n2, N); + switch(simtype[t->etype]) { + case TINT8: + case TINT16: + case TINT32: + gins(optoas(OMUL, t), &n2, &n1); + p = gins(ASRAD, N, &n1); + p->from.type = D_CONST; + p->from.offset = w; + break; + case TUINT8: + case TUINT16: + case TUINT32: + gins(optoas(OMUL, t), &n2, &n1); + p = gins(ASRD, N, &n1); + p->from.type = D_CONST; + p->from.offset = w; + break; + case TINT64: + case TUINT64: + if(issigned[t->etype]) + p = gins(AMULHD, &n2, &n1); + else + p = gins(AMULHDU, &n2, &n1); + break; + default: + fatal("cgen_hmul %T", t); + break; + } + cgen(&n1, res); + regfree(&n1); + regfree(&n2); +} + +/* + * generate shift according to op, one of: + * res = nl << nr + * res = nl >> nr + */ +void +cgen_shift(int op, int bounded, Node *nl, Node *nr, Node *res) +{ + Node n1, n2, n3, n4, n5; + int a; + Prog *p1; + uvlong sc; + Type *tcount; + + a = optoas(op, nl->type); + + if(nr->op == OLITERAL) { + regalloc(&n1, nl->type, res); + cgen(nl, &n1); + sc = mpgetfix(nr->val.u.xval); + if(sc >= nl->type->width*8) { + // large shift gets 2 shifts by width-1 + nodconst(&n3, types[TUINT32], nl->type->width*8-1); + gins(a, &n3, &n1); + gins(a, &n3, &n1); + } else + gins(a, nr, &n1); + gmove(&n1, res); + regfree(&n1); + goto ret; + } + + if(nl->ullman >= UINF) { + tempname(&n4, nl->type); + cgen(nl, &n4); + nl = &n4; + } + if(nr->ullman >= UINF) { + tempname(&n5, nr->type); + cgen(nr, &n5); + nr = &n5; + } + + // Allow either uint32 or uint64 as shift type, + // to avoid unnecessary conversion from uint32 to uint64 + // just to do the comparison. + tcount = types[simtype[nr->type->etype]]; + if(tcount->etype < TUINT32) + tcount = types[TUINT32]; + + regalloc(&n1, nr->type, N); // to hold the shift type in CX + regalloc(&n3, tcount, &n1); // to clear high bits of CX + + regalloc(&n2, nl->type, res); + if(nl->ullman >= nr->ullman) { + cgen(nl, &n2); + cgen(nr, &n1); + gmove(&n1, &n3); + } else { + cgen(nr, &n1); + gmove(&n1, &n3); + cgen(nl, &n2); + } + regfree(&n3); + + // test and fix up large shifts + if(!bounded) { + nodconst(&n3, tcount, nl->type->width*8); + gins(optoas(OCMP, tcount), &n1, &n3); + p1 = gbranch(optoas(OLT, tcount), T, +1); + if(op == ORSH && issigned[nl->type->etype]) { + nodconst(&n3, types[TUINT32], nl->type->width*8-1); + gins(a, &n3, &n2); + } else { + nodconst(&n3, nl->type, 0); + gmove(&n3, &n2); + } + patch(p1, pc); + } + + gins(a, &n1, &n2); + + gmove(&n2, res); + + regfree(&n1); + regfree(&n2); + +ret: + ; +} + +void +clearfat(Node *nl) +{ + uint64 w, c, q, t; + Node dst, end, r0, *f; + Prog *p, *pl; + + /* clear a fat object */ + if(debug['g']) { + print("clearfat %N (%T, size: %lld)\n", nl, nl->type, nl->type->width); + } + + w = nl->type->width; + // Avoid taking the address for simple enough types. + //if(componentgen(N, nl)) + // return; + + c = w % 8; // bytes + q = w / 8; // dwords + + if(reg[REGRT1] > 0) + fatal("R%d in use during clearfat", REGRT1); + + nodreg(&r0, types[TUINT64], 0); // r0 is always zero + nodreg(&dst, types[tptr], D_R0+REGRT1); + reg[REGRT1]++; + agen(nl, &dst); + + if(q > 128) { + p = gins(ASUB, N, &dst); + p->from.type = D_CONST; + p->from.offset = 8; + + regalloc(&end, types[tptr], N); + p = gins(AMOVD, &dst, &end); + p->from.type = D_CONST; + p->from.offset = q*8; + + p = gins(AMOVDU, &r0, &dst); + p->to.type = D_OREG; + p->to.offset = 8; + pl = p; + + p = gins(ACMP, &dst, &end); + patch(gbranch(ABNE, T, 0), pl); + + regfree(&end); + } else if(q >= 4) { + p = gins(ASUB, N, &dst); + p->from.type = D_CONST; + p->from.offset = 8; + f = sysfunc("duffzero"); + p = gins(ADUFFZERO, N, f); + afunclit(&p->to, f); + // 4 and 128 = magic constants: see ../../runtime/asm_power64x.s + p->to.offset = 4*(128-q); + } else + for(t = 0; t < q; t++) { + p = gins(AMOVD, &r0, &dst); + p->to.type = D_OREG; + p->to.offset = 8*t; + } + + for(t = 0; t < c; t++) { + p = gins(AMOVB, &r0, &dst); + p->to.type = D_OREG; + p->to.offset = t; + } + reg[REGRT1]--; +} + +// Called after regopt and peep have run. +// Expand CHECKNIL pseudo-op into actual nil pointer check. +void +expandchecks(Prog *firstp) +{ + Prog *p, *p1, *p2; + + for(p = firstp; p != P; p = p->link) { + if(debug_checknil && ctxt->debugvlog) + print("expandchecks: %P\n", p); + if(p->as != ACHECKNIL) + continue; + if(debug_checknil && p->lineno > 1) // p->lineno==1 in generated wrappers + warnl(p->lineno, "generated nil check"); + if(p->from.type != D_REG) + fatal("invalid nil check %P\n", p); + /* + // check is + // TD $4, R0, arg (R0 is always zero) + // eqv. to: + // tdeq r0, arg + // NOTE: this needs special runtime support to make SIGTRAP recoverable. + reg = p->from.reg; + p->as = ATD; + p->from = p->to = p->from3 = zprog.from; + p->from.type = D_CONST; + p->from.offset = 4; + p->from.reg = NREG; + p->reg = 0; + p->to.type = D_REG; + p->to.reg = reg; + */ + // check is + // CMP arg, R0 + // BNE 2(PC) [likely] + // MOVD R0, 0(R0) + p1 = mal(sizeof *p1); + p2 = mal(sizeof *p2); + clearp(p1); + clearp(p2); + p1->link = p2; + p2->link = p->link; + p->link = p1; + p1->lineno = p->lineno; + p2->lineno = p->lineno; + p1->pc = 9999; + p2->pc = 9999; + p->as = ACMP; + p->to.type = D_REG; + p->to.reg = REGZERO; + p1->as = ABNE; + //p1->from.type = D_CONST; + //p1->from.offset = 1; // likely + p1->to.type = D_BRANCH; + p1->to.u.branch = p2->link; + // crash by write to memory address 0. + p2->as = AMOVD; + p2->from.type = D_REG; + p2->from.reg = 0; + p2->to.type = D_OREG; + p2->to.reg = 0; + p2->to.offset = 0; + } +} |