// 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.
// TODO(rsc):
// assume CLD?
#include "gg.h"
void
mgen(Node *n, Node *n1, Node *rg)
{
n1->op = OEMPTY;
if(n->addable) {
*n1 = *n;
if(n1->op == OREGISTER || n1->op == OINDREG)
reg[n->val.u.reg]++;
return;
}
if(n->type->width > widthptr)
tempname(n1, n->type);
else
regalloc(n1, n->type, rg);
cgen(n, n1);
}
void
mfree(Node *n)
{
if(n->op == OREGISTER)
regfree(n);
}
/*
* generate:
* res = n;
* simplifies and calls gmove.
*
* TODO:
* sudoaddable
*/
void
cgen(Node *n, Node *res)
{
Node *nl, *nr, *r, n1, n2, nt, f0, f1;
Prog *p1, *p2, *p3;
int a;
if(debug['g']) {
dump("\ncgen-n", n);
dump("cgen-res", res);
}
if(n == N || n->type == T)
fatal("cgen: n nil");
if(res == N || res->type == T)
fatal("cgen: res nil");
// inline slices
if(cgen_inline(n, res))
return;
while(n->op == OCONVNOP)
n = n->left;
// function calls on both sides? introduce temporary
if(n->ullman >= UINF && res->ullman >= UINF) {
tempname(&n1, n->type);
cgen(n, &n1);
cgen(&n1, res);
return;
}
// structs etc get handled specially
if(isfat(n->type)) {
sgen(n, res, n->type->width);
return;
}
// update addressability for string, slice
// can't do in walk because n->left->addable
// changes if n->left is an escaping local variable.
switch(n->op) {
case OLEN:
if(isslice(n->left->type) || istype(n->left->type, TSTRING))
n->addable = n->left->addable;
break;
case OCAP:
if(isslice(n->left->type))
n->addable = n->left->addable;
break;
}
// if both are addressable, move
if(n->addable && res->addable) {
gmove(n, res);
return;
}
// if both are not addressable, use a temporary.
if(!n->addable && !res->addable) {
// could use regalloc here sometimes,
// but have to check for ullman >= UINF.
tempname(&n1, n->type);
cgen(n, &n1);
cgen(&n1, res);
return;
}
// if result is not addressable directly but n is,
// compute its address and then store via the address.
if(!res->addable) {
igen(res, &n1, N);
cgen(n, &n1);
regfree(&n1);
return;
}
// otherwise, the result is addressable but n is not.
// let's do some computation.
// use ullman to pick operand to eval first.
nl = n->left;
nr = n->right;
if(nl != N && nl->ullman >= UINF)
if(nr != N && nr->ullman >= UINF) {
// both are hard
tempname(&n1, nl->type);
cgen(nl, &n1);
n2 = *n;
n2.left = &n1;
cgen(&n2, res);
return;
}
// 64-bit ops are hard on 32-bit machine.
if(is64(n->type) || is64(res->type) || n->left != N && is64(n->left->type)) {
switch(n->op) {
// math goes to cgen64.
case OMINUS:
case OCOM:
case OADD:
case OSUB:
case OMUL:
case OLSH:
case ORSH:
case OAND:
case OOR:
case OXOR:
cgen64(n, res);
return;
}
}
if(nl != N && isfloat[n->type->etype] && isfloat[nl->type->etype])
goto flt;
switch(n->op) {
default:
dump("cgen", n);
fatal("cgen %O", n->op);
break;
// these call bgen to get a bool value
case OOROR:
case OANDAND:
case OEQ:
case ONE:
case OLT:
case OLE:
case OGE:
case OGT:
case ONOT:
p1 = gbranch(AJMP, T);
p2 = pc;
gmove(nodbool(1), res);
p3 = gbranch(AJMP, T);
patch(p1, pc);
bgen(n, 1, p2);
gmove(nodbool(0), res);
patch(p3, pc);
return;
case OPLUS:
cgen(nl, res);
return;
case OMINUS:
case OCOM:
a = optoas(n->op, nl->type);
goto uop;
// symmetric binary
case OAND:
case OOR:
case OXOR:
case OADD:
case OMUL:
a = optoas(n->op, nl->type);
if(a == AIMULB) {
cgen_bmul(n->op, nl, nr, res);
break;
}
goto sbop;
// asymmetric binary
case OSUB:
a = optoas(n->op, nl->type);
goto abop;
case OCONV:
if(eqtype(n->type, nl->type) || noconv(n->type, nl->type)) {
cgen(nl, res);
break;
}
mgen(nl, &n1, res);
gmove(&n1, res);
mfree(&n1);
break;
case ODOT:
case ODOTPTR:
case OINDEX:
case OIND:
case ONAME: // PHEAP or PPARAMREF var
igen(n, &n1, res);
gmove(&n1, res);
regfree(&n1);
break;
case OLEN:
if(istype(nl->type, TMAP) || istype(nl->type, TCHAN)) {
// map has len in the first 32-bit word.
// a zero pointer means zero length
tempname(&n1, types[tptr]);
cgen(nl, &n1);
regalloc(&n2, types[tptr], N);
gmove(&n1, &n2);
n1 = n2;
nodconst(&n2, types[tptr], 0);
gins(optoas(OCMP, types[tptr]), &n1, &n2);
p1 = gbranch(optoas(OEQ, types[tptr]), T);
n2 = n1;
n2.op = OINDREG;
n2.type = types[TINT32];
gmove(&n2, &n1);
patch(p1, pc);
gmove(&n1, res);
regfree(&n1);
break;
}
if(istype(nl->type, TSTRING) || isslice(nl->type)) {
// both slice and string have len one pointer into the struct.
igen(nl, &n1, res);
n1.op = OREGISTER; // was OINDREG
regalloc(&n2, types[TUINT32], &n1);
n1.op = OINDREG;
n1.type = types[TUINT32];
n1.xoffset = Array_nel;
gmove(&n1, &n2);
gmove(&n2, res);
regfree(&n1);
regfree(&n2);
break;
}
fatal("cgen: OLEN: unknown type %lT", nl->type);
break;
case OCAP:
if(istype(nl->type, TCHAN)) {
// chan has cap in the second 32-bit word.
// a zero pointer means zero length
regalloc(&n1, types[tptr], res);
cgen(nl, &n1);
nodconst(&n2, types[tptr], 0);
gins(optoas(OCMP, types[tptr]), &n1, &n2);
p1 = gbranch(optoas(OEQ, types[tptr]), T);
n2 = n1;
n2.op = OINDREG;
n2.xoffset = 4;
n2.type = types[TINT32];
gmove(&n2, &n1);
patch(p1, pc);
gmove(&n1, res);
regfree(&n1);
break;
}
if(isslice(nl->type)) {
igen(nl, &n1, res);
n1.op = OINDREG;
n1.type = types[TUINT32];
n1.xoffset = Array_cap;
gmove(&n1, res);
regfree(&n1);
break;
}
fatal("cgen: OCAP: unknown type %lT", nl->type);
break;
case OADDR:
agen(nl, res);
break;
case OCALLMETH:
cgen_callmeth(n, 0);
cgen_callret(n, res);
break;
case OCALLINTER:
cgen_callinter(n, res, 0);
cgen_callret(n, res);
break;
case OCALLFUNC:
cgen_call(n, 0);
cgen_callret(n, res);
break;
case OMOD:
case ODIV:
cgen_div(n->op, nl, nr, res);
break;
case OLSH:
case ORSH:
cgen_shift(n->op, nl, nr, res);
break;
}
return;
sbop: // symmetric binary
if(nl->ullman < nr->ullman) {
r = nl;
nl = nr;
nr = r;
}
abop: // asymmetric binary
if(nl->ullman >= nr->ullman) {
tempname(&nt, nl->type);
cgen(nl, &nt);
mgen(nr, &n2, N);
regalloc(&n1, nl->type, res);
gmove(&nt, &n1);
gins(a, &n2, &n1);
gmove(&n1, res);
regfree(&n1);
mfree(&n2);
} else {
regalloc(&n2, nr->type, res);
cgen(nr, &n2);
regalloc(&n1, nl->type, N);
cgen(nl, &n1);
gins(a, &n2, &n1);
regfree(&n2);
gmove(&n1, res);
regfree(&n1);
}
return;
uop: // unary
tempname(&n1, nl->type);
cgen(nl, &n1);
gins(a, N, &n1);
gmove(&n1, res);
return;
flt: // floating-point. 387 (not SSE2) to interoperate with 6c
nodreg(&f0, nl->type, D_F0);
nodreg(&f1, n->type, D_F0+1);
if(nr != N)
goto flt2;
if(n->op == OMINUS) {
nr = nodintconst(-1);
convlit(&nr, n->type);
n->op = OMUL;
goto flt2;
}
// unary
cgen(nl, &f0);
if(n->op != OCONV && n->op != OPLUS)
gins(foptoas(n->op, n->type, 0), &f0, &f0);
gmove(&f0, res);
return;
flt2: // binary
if(nl->ullman >= nr->ullman) {
cgen(nl, &f0);
if(nr->addable)
gins(foptoas(n->op, n->type, 0), nr, &f0);
else {
cgen(nr, &f0);
gins(foptoas(n->op, n->type, Fpop), &f0, &f1);
}
} else {
cgen(nr, &f0);
if(nl->addable)
gins(foptoas(n->op, n->type, Frev), nl, &f0);
else {
cgen(nl, &f0);
gins(foptoas(n->op, n->type, Frev|Fpop), &f0, &f1);
}
}
gmove(&f0, res);
return;
}
/*
* address gen
* res = &n;
*/
void
agen(Node *n, Node *res)
{
Node *nl, *nr;
Node n1, n2, n3, n4, tmp;
Type *t;
uint32 w;
uint64 v;
Prog *p1;
if(debug['g']) {
dump("\nagen-res", res);
dump("agen-r", n);
}
if(n == N || n->type == T || res == N || res->type == T)
fatal("agen");
while(n->op == OCONVNOP)
n = n->left;
// addressable var is easy
if(n->addable) {
if(n->op == OREGISTER)
fatal("agen OREGISTER");
regalloc(&n1, types[tptr], res);
gins(ALEAL, n, &n1);
gmove(&n1, res);
regfree(&n1);
return;
}
// let's compute
nl = n->left;
nr = n->right;
switch(n->op) {
default:
fatal("agen %O", n->op);
case OCALLMETH:
cgen_callmeth(n, 0);
cgen_aret(n, res);
break;
case OCALLINTER:
cgen_callinter(n, res, 0);
cgen_aret(n, res);
break;
case OCALLFUNC:
cgen_call(n, 0);
cgen_aret(n, res);
break;
case OINDEX:
// TODO(rsc): uint64 indices
w = n->type->width;
if(nr->addable) {
agenr(nl, &n3, res);
if(!isconst(nr, CTINT)) {
tempname(&tmp, types[TINT32]);
cgen(nr, &tmp);
regalloc(&n1, tmp.type, N);
gmove(&tmp, &n1);
}
} else if(nl->addable) {
if(!isconst(nr, CTINT)) {
tempname(&tmp, types[TINT32]);
cgen(nr, &tmp);
regalloc(&n1, tmp.type, N);
gmove(&tmp, &n1);
}
regalloc(&n3, types[tptr], res);
agen(nl, &n3);
} else {
tempname(&tmp, types[TINT32]);
cgen(nr, &tmp);
nr = &tmp;
agenr(nl, &n3, res);
regalloc(&n1, tmp.type, N);
gins(optoas(OAS, tmp.type), &tmp, &n1);
}
// &a is in &n3 (allocated in res)
// i is in &n1 (if not constant)
// w is width
// explicit check for nil if array is large enough
// that we might derive too big a pointer.
if(!isslice(nl->type) && nl->type->width >= unmappedzero) {
regalloc(&n4, types[tptr], &n3);
gmove(&n3, &n4);
n4.op = OINDREG;
n4.type = types[TUINT8];
n4.xoffset = 0;
gins(ATESTB, nodintconst(0), &n4);
regfree(&n4);
}
if(w == 0)
fatal("index is zero width");
// constant index
if(isconst(nr, CTINT)) {
v = mpgetfix(nr->val.u.xval);
if(isslice(nl->type)) {
if(!debug['B'] && !n->etype) {
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
n1.xoffset = Array_nel;
nodconst(&n2, types[TUINT32], v);
gins(optoas(OCMP, types[TUINT32]), &n1, &n2);
p1 = gbranch(optoas(OGT, types[TUINT32]), T);
ginscall(throwindex, 0);
patch(p1, pc);
}
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
n1.xoffset = Array_array;
gmove(&n1, &n3);
} else
if(!debug['B'] && !n->etype) {
if(v < 0)
yyerror("out of bounds on array");
else
if(v >= nl->type->bound)
yyerror("out of bounds on array");
}
nodconst(&n2, types[tptr], v*w);
gins(optoas(OADD, types[tptr]), &n2, &n3);
gmove(&n3, res);
regfree(&n3);
break;
}
// type of the index
t = types[TUINT32];
if(issigned[n1.type->etype])
t = types[TINT32];
regalloc(&n2, t, &n1); // i
gmove(&n1, &n2);
regfree(&n1);
if(!debug['B'] && !n->etype) {
// check bounds
if(isslice(nl->type)) {
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
n1.xoffset = Array_nel;
} else
nodconst(&n1, types[TUINT32], nl->type->bound);
gins(optoas(OCMP, types[TUINT32]), &n2, &n1);
p1 = gbranch(optoas(OLT, types[TUINT32]), T);
ginscall(throwindex, 0);
patch(p1, pc);
}
if(isslice(nl->type)) {
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
n1.xoffset = Array_array;
gmove(&n1, &n3);
}
if(w == 1 || w == 2 || w == 4 || w == 8) {
p1 = gins(ALEAL, &n2, &n3);
p1->from.scale = w;
p1->from.index = p1->from.type;
p1->from.type = p1->to.type + D_INDIR;
} else {
nodconst(&n1, t, w);
gins(optoas(OMUL, t), &n1, &n2);
gins(optoas(OADD, types[tptr]), &n2, &n3);
gmove(&n3, res);
}
gmove(&n3, res);
regfree(&n2);
regfree(&n3);
break;
case ONAME:
// should only get here with names in this func.
if(n->funcdepth > 0 && n->funcdepth != funcdepth) {
dump("bad agen", n);
fatal("agen: bad ONAME funcdepth %d != %d",
n->funcdepth, funcdepth);
}
// should only get here for heap vars or paramref
if(!(n->class & PHEAP) && n->class != PPARAMREF) {
dump("bad agen", n);
fatal("agen: bad ONAME class %#x", n->class);
}
cgen(n->heapaddr, res);
if(n->xoffset != 0) {
nodconst(&n1, types[tptr], n->xoffset);
gins(optoas(OADD, types[tptr]), &n1, res);
}
break;
case OIND:
cgen(nl, res);
break;
case ODOT:
t = nl->type;
agen(nl, res);
if(n->xoffset != 0) {
nodconst(&n1, types[tptr], n->xoffset);
gins(optoas(OADD, types[tptr]), &n1, res);
}
break;
case ODOTPTR:
t = nl->type;
if(!isptr[t->etype])
fatal("agen: not ptr %N", n);
cgen(nl, res);
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->type->width >= unmappedzero) {
regalloc(&n1, types[tptr], res);
gmove(res, &n1);
n1.op = OINDREG;
n1.type = types[TUINT8];
n1.xoffset = 0;
gins(ATESTB, nodintconst(0), &n1);
regfree(&n1);
}
nodconst(&n1, types[tptr], n->xoffset);
gins(optoas(OADD, types[tptr]), &n1, res);
}
break;
}
}
/*
* generate:
* newreg = &n;
* res = newreg
*
* on exit, a has been changed to be *newreg.
* caller must regfree(a).
*/
void
igen(Node *n, Node *a, Node *res)
{
Node n1;
tempname(&n1, types[tptr]);
agen(n, &n1);
regalloc(a, types[tptr], res);
gmove(&n1, a);
a->op = OINDREG;
a->type = n->type;
}
/*
* generate:
* newreg = &n;
*
* caller must regfree(a).
*/
void
agenr(Node *n, Node *a, Node *res)
{
Node n1;
tempname(&n1, types[tptr]);
agen(n, &n1);
regalloc(a, types[tptr], res);
gmove(&n1, a);
}
/*
* branch gen
* if(n == true) goto to;
*/
void
bgen(Node *n, int true, Prog *to)
{
int et, a;
Node *nl, *nr, *r;
Node n1, n2, tmp, t1, t2, ax;
Prog *p1, *p2;
if(debug['g']) {
dump("\nbgen", n);
}
if(n == N)
n = nodbool(1);
nl = n->left;
nr = n->right;
if(n->type == T) {
convlit(&n, types[TBOOL]);
if(n->type == T)
return;
}
et = n->type->etype;
if(et != TBOOL) {
yyerror("cgen: bad type %T for %O", n->type, n->op);
patch(gins(AEND, N, N), to);
return;
}
nl = N;
nr = N;
switch(n->op) {
default:
def:
regalloc(&n1, n->type, N);
cgen(n, &n1);
nodconst(&n2, n->type, 0);
gins(optoas(OCMP, n->type), &n1, &n2);
a = AJNE;
if(!true)
a = AJEQ;
patch(gbranch(a, n->type), to);
regfree(&n1);
return;
case OLITERAL:
// need to ask if it is bool?
if(!true == !n->val.u.bval)
patch(gbranch(AJMP, T), to);
return;
case ONAME:
if(!n->addable)
goto def;
nodconst(&n1, n->type, 0);
gins(optoas(OCMP, n->type), n, &n1);
a = AJNE;
if(!true)
a = AJEQ;
patch(gbranch(a, n->type), to);
return;
case OANDAND:
if(!true)
goto caseor;
caseand:
p1 = gbranch(AJMP, T);
p2 = gbranch(AJMP, T);
patch(p1, pc);
bgen(n->left, !true, p2);
bgen(n->right, !true, p2);
p1 = gbranch(AJMP, T);
patch(p1, to);
patch(p2, pc);
return;
case OOROR:
if(!true)
goto caseand;
caseor:
bgen(n->left, true, to);
bgen(n->right, true, to);
return;
case OEQ:
case ONE:
case OLT:
case OGT:
case OLE:
case OGE:
nr = n->right;
if(nr == N || nr->type == T)
return;
case ONOT: // unary
nl = n->left;
if(nl == N || nl->type == T)
return;
}
switch(n->op) {
case ONOT:
bgen(nl, !true, to);
break;
case OEQ:
case ONE:
case OLT:
case OGT:
case OLE:
case OGE:
a = n->op;
if(!true) {
if(isfloat[nl->type->etype]) {
// brcom is not valid on floats when NaN is involved.
p1 = gbranch(AJMP, T);
p2 = gbranch(AJMP, T);
patch(p1, pc);
bgen(n, 1, p2);
patch(gbranch(AJMP, T), to);
patch(p2, pc);
break;
}
a = brcom(a);
}
// make simplest on right
if(nl->op == OLITERAL || nl->ullman < nr->ullman) {
a = brrev(a);
r = nl;
nl = nr;
nr = r;
}
if(isslice(nl->type)) {
// only valid to cmp darray to literal nil
if((a != OEQ && a != ONE) || nr->op != OLITERAL) {
yyerror("illegal array comparison");
break;
}
a = optoas(a, types[tptr]);
regalloc(&n1, types[tptr], N);
agen(nl, &n1);
n2 = n1;
n2.op = OINDREG;
n2.xoffset = Array_array;
nodconst(&tmp, types[tptr], 0);
gins(optoas(OCMP, types[tptr]), &n2, &tmp);
patch(gbranch(a, types[tptr]), to);
regfree(&n1);
break;
}
if(isinter(nl->type)) {
// front end shold only leave cmp to literal nil
if((a != OEQ && a != ONE) || nr->op != OLITERAL) {
yyerror("illegal interface comparison");
break;
}
a = optoas(a, types[tptr]);
regalloc(&n1, types[tptr], N);
agen(nl, &n1);
n2 = n1;
n2.op = OINDREG;
n2.xoffset = 0;
nodconst(&tmp, types[tptr], 0);
gins(optoas(OCMP, types[tptr]), &n2, &tmp);
patch(gbranch(a, types[tptr]), to);
regfree(&n1);
break;
}
if(isfloat[nr->type->etype]) {
a = brrev(a); // because the args are stacked
if(a == OGE || a == OGT) {
// only < and <= work right with NaN; reverse if needed
r = nr;
nr = nl;
nl = r;
a = brrev(a);
}
nodreg(&tmp, nr->type, D_F0);
nodreg(&n2, nr->type, D_F0 + 1);
nodreg(&ax, types[TUINT16], D_AX);
et = simsimtype(nr->type);
if(et == TFLOAT64) {
// easy - do in FPU
cgen(nr, &tmp);
cgen(nl, &tmp);
gins(AFUCOMPP, &tmp, &n2);
} else {
// TODO(rsc): The moves back and forth to memory
// here are for truncating the value to 32 bits.
// This handles 32-bit comparison but presumably
// all the other ops have the same problem.
// We need to figure out what the right general
// solution is, besides telling people to use float64.
tempname(&t1, types[TFLOAT32]);
tempname(&t2, types[TFLOAT32]);
cgen(nr, &t1);
cgen(nl, &t2);
gmove(&t2, &tmp);
gins(AFCOMFP, &t1, &tmp);
}
gins(AFSTSW, N, &ax);
gins(ASAHF, N, N);
if(a == OEQ) {
// neither NE nor P
p1 = gbranch(AJNE, T);
p2 = gbranch(AJPS, T);
patch(gbranch(AJMP, T), to);
patch(p1, pc);
patch(p2, pc);
} else if(a == ONE) {
// either NE or P
patch(gbranch(AJNE, T), to);
patch(gbranch(AJPS, T), to);
} else
patch(gbranch(optoas(a, nr->type), T), to);
break;
}
if(is64(nr->type)) {
if(!nl->addable) {
tempname(&n1, nl->type);
cgen(nl, &n1);
nl = &n1;
}
if(!nr->addable) {
tempname(&n2, nr->type);
cgen(nr, &n2);
nr = &n2;
}
cmp64(nl, nr, a, to);
break;
}
a = optoas(a, nr->type);
if(nr->ullman >= UINF) {
tempname(&n1, nl->type);
tempname(&tmp, nr->type);
cgen(nr, &tmp);
cgen(nl, &n1);
regalloc(&n2, nr->type, N);
cgen(&tmp, &n2);
goto cmp;
}
tempname(&n1, nl->type);
cgen(nl, &n1);
if(smallintconst(nr)) {
gins(optoas(OCMP, nr->type), &n1, nr);
patch(gbranch(a, nr->type), to);
break;
}
tempname(&tmp, nr->type);
cgen(nr, &tmp);
regalloc(&n2, nr->type, N);
gmove(&tmp, &n2);
cmp:
gins(optoas(OCMP, nr->type), &n1, &n2);
patch(gbranch(a, nr->type), to);
regfree(&n2);
break;
}
}
/*
* n is on stack, either local variable
* or return value from function call.
* return n's offset from SP.
*/
int32
stkof(Node *n)
{
Type *t;
Iter flist;
switch(n->op) {
case OINDREG:
return n->xoffset;
case OCALLMETH:
case OCALLINTER:
case OCALLFUNC:
t = n->left->type;
if(isptr[t->etype])
t = t->type;
t = structfirst(&flist, getoutarg(t));
if(t != T)
return t->width;
break;
}
// botch - probably failing to recognize address
// arithmetic on the above. eg INDEX and DOT
return -1000;
}
/*
* struct gen
* memmove(&res, &n, w);
*/
void
sgen(Node *n, Node *res, int32 w)
{
Node dst, src, tdst, tsrc;
int32 c, q, odst, osrc;
if(debug['g']) {
print("\nsgen w=%d\n", w);
dump("r", n);
dump("res", res);
}
if(w == 0)
return;
if(n->ullman >= UINF && res->ullman >= UINF) {
fatal("sgen UINF");
}
if(w < 0)
fatal("sgen copy %d", w);
// offset on the stack
osrc = stkof(n);
odst = stkof(res);
nodreg(&dst, types[tptr], D_DI);
nodreg(&src, types[tptr], D_SI);
tempname(&tsrc, types[tptr]);
tempname(&tdst, types[tptr]);
if(!n->addable)
agen(n, &tsrc);
if(!res->addable)
agen(res, &tdst);
if(n->addable)
agen(n, &src);
else
gmove(&tsrc, &src);
if(res->addable)
agen(res, &dst);
else
gmove(&tdst, &dst);
c = w % 4; // bytes
q = w / 4; // doublewords
// if we are copying forward on the stack and
// the src and dst overlap, then reverse direction
if(osrc < odst && odst < osrc+w) {
// reverse direction
gins(ASTD, N, N); // set direction flag
if(c > 0) {
gconreg(AADDL, w-1, D_SI);
gconreg(AADDL, w-1, D_DI);
gconreg(AMOVL, c, D_CX);
gins(AREP, N, N); // repeat
gins(AMOVSB, N, N); // MOVB *(SI)-,*(DI)-
}
if(q > 0) {
if(c > 0) {
gconreg(AADDL, -3, D_SI);
gconreg(AADDL, -3, D_DI);
} else {
gconreg(AADDL, w-4, D_SI);
gconreg(AADDL, w-4, D_DI);
}
gconreg(AMOVL, q, D_CX);
gins(AREP, N, N); // repeat
gins(AMOVSL, N, N); // MOVL *(SI)-,*(DI)-
}
// we leave with the flag clear
gins(ACLD, N, N);
} else {
gins(ACLD, N, N); // paranoia. TODO(rsc): remove?
// normal direction
if(q >= 4) {
gconreg(AMOVL, q, D_CX);
gins(AREP, N, N); // repeat
gins(AMOVSL, N, N); // MOVL *(SI)+,*(DI)+
} else
while(q > 0) {
gins(AMOVSL, N, N); // MOVL *(SI)+,*(DI)+
q--;
}
while(c > 0) {
gins(AMOVSB, N, N); // MOVB *(SI)+,*(DI)+
c--;
}
}
}
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