cmd/gc: faster code, mainly for rotate
* Eliminate bounds check on known small shifts.
* Rewrite x<<s | x>>(32-s) as a rotate (constant s).
* More aggressive (but still minimal) range analysis.
R=ken, dave, iant
CC=golang-dev
https://golang.org/cl/6209077
diff --git a/src/cmd/5g/cgen.c b/src/cmd/5g/cgen.c
index cccef94..e0e635b 100644
--- a/src/cmd/5g/cgen.c
+++ b/src/cmd/5g/cgen.c
@@ -156,6 +156,7 @@
case OADD:
case OSUB:
case OMUL:
+ case OLROT:
case OLSH:
case ORSH:
case OAND:
@@ -241,9 +242,10 @@
a = optoas(n->op, nl->type);
goto abop;
+ case OLROT:
case OLSH:
case ORSH:
- cgen_shift(n->op, nl, nr, res);
+ cgen_shift(n->op, n->bounded, nl, nr, res);
break;
case OCONV:
@@ -620,7 +622,7 @@
fatal("constant string constant index");
v = mpgetfix(nr->val.u.xval);
if(isslice(nl->type) || nl->type->etype == TSTRING) {
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
@@ -660,7 +662,7 @@
gmove(&n1, &n2);
regfree(&n1);
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
// check bounds
regalloc(&n4, types[TUINT32], N);
if(isconst(nl, CTSTR)) {
diff --git a/src/cmd/5g/cgen64.c b/src/cmd/5g/cgen64.c
index 1235d1a..2bd5b0f 100644
--- a/src/cmd/5g/cgen64.c
+++ b/src/cmd/5g/cgen64.c
@@ -94,6 +94,7 @@
case OAND:
case OOR:
case OXOR:
+ case OLROT:
// binary operators.
// common setup below.
break;
@@ -197,6 +198,47 @@
break;
+ case OLROT:
+ // We only rotate by a constant c in [0,64).
+ // if c >= 32:
+ // lo, hi = hi, lo
+ // c -= 32
+ // if c == 0:
+ // no-op
+ // else:
+ // t = hi
+ // shld hi:lo, c
+ // shld lo:t, c
+ v = mpgetfix(r->val.u.xval);
+ regalloc(&bl, lo1.type, N);
+ regalloc(&bh, hi1.type, N);
+ if(v >= 32) {
+ // reverse during load to do the first 32 bits of rotate
+ v -= 32;
+ gins(AMOVW, &hi1, &bl);
+ gins(AMOVW, &lo1, &bh);
+ } else {
+ gins(AMOVW, &hi1, &bh);
+ gins(AMOVW, &lo1, &bl);
+ }
+ if(v == 0) {
+ gins(AMOVW, &bh, &ah);
+ gins(AMOVW, &bl, &al);
+ } else {
+ // rotate by 1 <= v <= 31
+ // MOVW bl<<v, al
+ // MOVW bh<<v, ah
+ // OR bl>>(32-v), ah
+ // OR bh>>(32-v), al
+ gshift(AMOVW, &bl, SHIFT_LL, v, &al);
+ gshift(AMOVW, &bh, SHIFT_LL, v, &ah);
+ gshift(AORR, &bl, SHIFT_LR, 32-v, &ah);
+ gshift(AORR, &bh, SHIFT_LR, 32-v, &al);
+ }
+ regfree(&bl);
+ regfree(&bh);
+ break;
+
case OLSH:
regalloc(&bl, lo1.type, N);
regalloc(&bh, hi1.type, N);
diff --git a/src/cmd/5g/gg.h b/src/cmd/5g/gg.h
index 7dbf3be..4c057cae 100644
--- a/src/cmd/5g/gg.h
+++ b/src/cmd/5g/gg.h
@@ -104,7 +104,7 @@
Prog * gregshift(int as, Node *lhs, int32 stype, Node *reg, Node *rhs);
void naddr(Node*, Addr*, int);
void cgen_aret(Node*, Node*);
-void cgen_shift(int, Node*, Node*, Node*);
+void cgen_shift(int, int, Node*, Node*, Node*);
/*
* cgen64.c
diff --git a/src/cmd/5g/ggen.c b/src/cmd/5g/ggen.c
index de10062..5ba4e61 100644
--- a/src/cmd/5g/ggen.c
+++ b/src/cmd/5g/ggen.c
@@ -469,10 +469,10 @@
* res = nl >> nr
*/
void
-cgen_shift(int op, Node *nl, Node *nr, Node *res)
+cgen_shift(int op, int bounded, Node *nl, Node *nr, Node *res)
{
Node n1, n2, n3, nt, t, lo, hi;
- int w;
+ int w, v;
Prog *p1, *p2, *p3;
Type *tr;
uvlong sc;
@@ -482,6 +482,24 @@
w = nl->type->width * 8;
+ if(op == OLROT) {
+ v = mpgetfix(nr->val.u.xval);
+ regalloc(&n1, nl->type, res);
+ if(w == 32) {
+ cgen(nl, &n1);
+ gshift(AMOVW, &n1, SHIFT_RR, w-v, &n1);
+ } else {
+ regalloc(&n2, nl->type, N);
+ cgen(nl, &n2);
+ gshift(AMOVW, &n2, SHIFT_LL, v, &n1);
+ gshift(AORR, &n2, SHIFT_LR, w-v, &n1);
+ regfree(&n2);
+ }
+ gmove(&n1, res);
+ regfree(&n1);
+ return;
+ }
+
if(nr->op == OLITERAL) {
regalloc(&n1, nl->type, res);
cgen(nl, &n1);
@@ -549,6 +567,7 @@
p3 = gbranch(ABEQ, T);
// test and fix up large shifts
+ // TODO: if(!bounded), don't emit some of this.
regalloc(&n3, tr, N);
nodconst(&t, types[TUINT32], w);
gmove(&t, &n3);
diff --git a/src/cmd/5g/gsubr.c b/src/cmd/5g/gsubr.c
index 9acf936..d559306 100644
--- a/src/cmd/5g/gsubr.c
+++ b/src/cmd/5g/gsubr.c
@@ -2032,7 +2032,7 @@
v = mpgetfix(r->val.u.xval);
if(o & ODynam) {
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
n1 = *reg;
n1.op = OINDREG;
n1.type = types[tptr];
diff --git a/src/cmd/6g/cgen.c b/src/cmd/6g/cgen.c
index 00334e7..465fc88 100644
--- a/src/cmd/6g/cgen.c
+++ b/src/cmd/6g/cgen.c
@@ -240,6 +240,25 @@
goto abop;
case OCONV:
+ if(n->type->width > nl->type->width) {
+ // If loading from memory, do conversion during load,
+ // so as to avoid use of 8-bit register in, say, int(*byteptr).
+ switch(nl->op) {
+ case ODOT:
+ case ODOTPTR:
+ case OINDEX:
+ case OIND:
+ case ONAME:
+ igen(nl, &n1, res);
+ regalloc(&n2, n->type, res);
+ gmove(&n1, &n2);
+ gmove(&n2, res);
+ regfree(&n2);
+ regfree(&n1);
+ goto ret;
+ }
+ }
+
regalloc(&n1, nl->type, res);
regalloc(&n2, n->type, &n1);
cgen(nl, &n1);
@@ -370,13 +389,14 @@
case OLSH:
case ORSH:
- cgen_shift(n->op, nl, nr, res);
+ case OLROT:
+ cgen_shift(n->op, n->bounded, nl, nr, res);
break;
}
goto ret;
sbop: // symmetric binary
- if(nl->ullman < nr->ullman) {
+ if(nl->ullman < nr->ullman || nl->op == OLITERAL) {
r = nl;
nl = nr;
nr = r;
@@ -386,7 +406,13 @@
if(nl->ullman >= nr->ullman) {
regalloc(&n1, nl->type, res);
cgen(nl, &n1);
-
+ /*
+ * This generates smaller code - it avoids a MOV - but it's
+ * easily 10% slower due to not being able to
+ * optimize/manipulate the move.
+ * To see, run: go test -bench . crypto/md5
+ * with and without.
+ *
if(sudoaddable(a, nr, &addr)) {
p1 = gins(a, N, &n1);
p1->from = addr;
@@ -395,18 +421,30 @@
regfree(&n1);
goto ret;
}
- regalloc(&n2, nr->type, N);
- cgen(nr, &n2);
+ *
+ */
+
+ if(smallintconst(nr))
+ n2 = *nr;
+ else {
+ regalloc(&n2, nr->type, N);
+ cgen(nr, &n2);
+ }
} else {
- regalloc(&n2, nr->type, res);
- cgen(nr, &n2);
+ if(smallintconst(nr))
+ n2 = *nr;
+ else {
+ regalloc(&n2, nr->type, res);
+ cgen(nr, &n2);
+ }
regalloc(&n1, nl->type, N);
cgen(nl, &n1);
}
gins(a, &n2, &n1);
gmove(&n1, res);
regfree(&n1);
- regfree(&n2);
+ if(n2.op != OLITERAL)
+ regfree(&n2);
goto ret;
uop: // unary
@@ -529,7 +567,7 @@
fatal("constant string constant index"); // front end should handle
v = mpgetfix(nr->val.u.xval);
if(isslice(nl->type) || nl->type->etype == TSTRING) {
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
@@ -564,7 +602,7 @@
gmove(&n1, &n2);
regfree(&n1);
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
// check bounds
n5.op = OXXX;
t = types[TUINT32];
@@ -692,6 +730,7 @@
{
Type *fp;
Iter flist;
+ Node n1, n2;
switch(n->op) {
case ONAME:
@@ -710,8 +749,29 @@
a->xoffset = fp->width;
a->type = n->type;
return;
+
+ case OINDEX:
+ // Index of fixed-size array by constant can
+ // put the offset in the addressing.
+ // Could do the same for slice except that we need
+ // to use the real index for the bounds checking.
+ if(isfixedarray(n->left->type) ||
+ (isptr[n->left->type->etype] && isfixedarray(n->left->left->type)))
+ if(isconst(n->right, CTINT)) {
+ nodconst(&n1, types[TINT64], 0);
+ n2 = *n;
+ n2.right = &n1;
+
+ regalloc(a, types[tptr], res);
+ agen(&n2, a);
+ a->op = OINDREG;
+ a->xoffset = mpgetfix(n->right->val.u.xval)*n->type->width;
+ a->type = n->type;
+ return;
+ }
+
}
-
+
regalloc(a, types[tptr], res);
agen(n, a);
a->op = OINDREG;
diff --git a/src/cmd/6g/gg.h b/src/cmd/6g/gg.h
index 47a5400..265230d 100644
--- a/src/cmd/6g/gg.h
+++ b/src/cmd/6g/gg.h
@@ -71,7 +71,7 @@
void cgen_callret(Node*, Node*);
void cgen_div(int, Node*, Node*, Node*);
void cgen_bmul(int, Node*, Node*, Node*);
-void cgen_shift(int, Node*, Node*, Node*);
+void cgen_shift(int, int, Node*, Node*, Node*);
void cgen_dcl(Node*);
int needconvert(Type*, Type*);
void genconv(Type*, Type*);
diff --git a/src/cmd/6g/ggen.c b/src/cmd/6g/ggen.c
index 434ee32..b861569 100644
--- a/src/cmd/6g/ggen.c
+++ b/src/cmd/6g/ggen.c
@@ -865,7 +865,7 @@
* res = nl >> nr
*/
void
-cgen_shift(int op, Node *nl, Node *nr, Node *res)
+cgen_shift(int op, int bounded, Node *nl, Node *nr, Node *res)
{
Node n1, n2, n3, n4, n5, cx, oldcx;
int a, rcx;
@@ -880,7 +880,7 @@
cgen(nl, &n1);
sc = mpgetfix(nr->val.u.xval);
if(sc >= nl->type->width*8) {
- // large shift gets 2 shifts by width
+ // 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);
@@ -939,17 +939,20 @@
regfree(&n3);
// test and fix up large shifts
- nodconst(&n3, tcount, nl->type->width*8);
- gins(optoas(OCMP, tcount), &n1, &n3);
- p1 = gbranch(optoas(OLT, tcount), T);
- 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);
+ if(!bounded) {
+ nodconst(&n3, tcount, nl->type->width*8);
+ gins(optoas(OCMP, tcount), &n1, &n3);
+ p1 = gbranch(optoas(OLT, tcount), T);
+ 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);
}
- patch(p1, pc);
+
gins(a, &n1, &n2);
if(oldcx.op != 0) {
diff --git a/src/cmd/6g/gsubr.c b/src/cmd/6g/gsubr.c
index fb31212..142bbe8 100644
--- a/src/cmd/6g/gsubr.c
+++ b/src/cmd/6g/gsubr.c
@@ -616,7 +616,7 @@
Prog *p1, *p2;
if(debug['M'])
- print("gmove %N -> %N\n", f, t);
+ print("gmove %lN -> %lN\n", f, t);
ft = simsimtype(f->type);
tt = simsimtype(t->type);
@@ -1050,7 +1050,9 @@
w = 8;
break;
}
- if(w != 0 && f != N && (af.width > w || at.width > w)) {
+ if(w != 0 && ((f != N && af.width < w) || (t != N && at.width > w))) {
+ dump("f", f);
+ dump("t", t);
fatal("bad width: %P (%d, %d)\n", p, af.width, at.width);
}
@@ -1087,9 +1089,15 @@
a->type = D_NONE;
a->gotype = S;
a->node = N;
+ a->width = 0;
if(n == N)
return;
+ if(n->type != T && n->type->etype != TIDEAL) {
+ dowidth(n->type);
+ a->width = n->type->width;
+ }
+
switch(n->op) {
default:
fatal("naddr: bad %O %D", n->op, a);
@@ -1140,10 +1148,8 @@
case ONAME:
a->etype = 0;
- a->width = 0;
if(n->type != T) {
a->etype = simtype[n->type->etype];
- a->width = n->type->width;
a->gotype = ngotype(n);
}
a->offset = n->xoffset;
@@ -1176,6 +1182,7 @@
case PFUNC:
a->index = D_EXTERN;
a->type = D_ADDR;
+ a->width = widthptr;
break;
}
break;
@@ -1213,6 +1220,7 @@
case OADDR:
naddr(n->left, a, canemitcode);
+ a->width = widthptr;
if(a->type >= D_INDIR) {
a->type -= D_INDIR;
break;
@@ -1648,6 +1656,28 @@
a = AXORQ;
break;
+ case CASE(OLROT, TINT8):
+ case CASE(OLROT, TUINT8):
+ a = AROLB;
+ break;
+
+ case CASE(OLROT, TINT16):
+ case CASE(OLROT, TUINT16):
+ a = AROLW;
+ break;
+
+ case CASE(OLROT, TINT32):
+ case CASE(OLROT, TUINT32):
+ case CASE(OLROT, TPTR32):
+ a = AROLL;
+ break;
+
+ case CASE(OLROT, TINT64):
+ case CASE(OLROT, TUINT64):
+ case CASE(OLROT, TPTR64):
+ a = AROLQ;
+ break;
+
case CASE(OLSH, TINT8):
case CASE(OLSH, TUINT8):
a = ASHLB;
@@ -2056,7 +2086,7 @@
}
// check bounds
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
// check bounds
n4.op = OXXX;
t = types[TUINT32];
@@ -2143,11 +2173,11 @@
reg->op = OEMPTY;
reg1->op = OEMPTY;
- regalloc(reg, types[tptr], N);
- agen(l, reg);
-
if(o & ODynam) {
- if(!debug['B'] && !n->etype) {
+ regalloc(reg, types[tptr], N);
+ agen(l, reg);
+
+ if(!debug['B'] && !n->bounded) {
n1 = *reg;
n1.op = OINDREG;
n1.type = types[tptr];
@@ -2165,14 +2195,24 @@
n1.xoffset = Array_array;
gmove(&n1, reg);
+ n2 = *reg;
+ n2.op = OINDREG;
+ n2.xoffset = v*w;
+ a->type = D_NONE;
+ a->index = D_NONE;
+ naddr(&n2, a, 1);
+ goto yes;
}
-
- n2 = *reg;
- n2.op = OINDREG;
- n2.xoffset = v*w;
+
+ igen(l, &n1, N);
+ if(n1.op == OINDREG) {
+ *reg = n1;
+ reg->op = OREGISTER;
+ }
+ n1.xoffset += v*w;
a->type = D_NONE;
- a->index = D_NONE;
- naddr(&n2, a, 1);
+ a->index= D_NONE;
+ naddr(&n1, a, 1);
goto yes;
oindex_const_sudo:
@@ -2183,7 +2223,7 @@
}
// slice indexed by a constant
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
a->offset += Array_nel;
nodconst(&n2, types[TUINT64], v);
p1 = gins(optoas(OCMP, types[TUINT32]), N, &n2);
diff --git a/src/cmd/8g/cgen.c b/src/cmd/8g/cgen.c
index 48619ac..541a9bf 100644
--- a/src/cmd/8g/cgen.c
+++ b/src/cmd/8g/cgen.c
@@ -160,6 +160,7 @@
case OADD:
case OSUB:
case OMUL:
+ case OLROT:
case OLSH:
case ORSH:
case OAND:
@@ -360,20 +361,27 @@
case OLSH:
case ORSH:
- cgen_shift(n->op, nl, nr, res);
+ case OLROT:
+ cgen_shift(n->op, n->bounded, nl, nr, res);
break;
}
return;
sbop: // symmetric binary
- if(nl->ullman < nr->ullman) {
+ if(nl->ullman < nr->ullman || nl->op == OLITERAL) {
r = nl;
nl = nr;
nr = r;
}
abop: // asymmetric binary
- if(nl->ullman >= nr->ullman) {
+ if(smallintconst(nr)) {
+ regalloc(&n1, nr->type, res);
+ cgen(nl, &n1);
+ gins(a, nr, &n1);
+ gmove(&n1, res);
+ regfree(&n1);
+ } else if(nl->ullman >= nr->ullman) {
tempname(&nt, nl->type);
cgen(nl, &nt);
mgen(nr, &n2, N);
@@ -580,7 +588,7 @@
fatal("constant string constant index");
v = mpgetfix(nr->val.u.xval);
if(isslice(nl->type) || nl->type->etype == TSTRING) {
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
n1 = n3;
n1.op = OINDREG;
n1.type = types[tptr];
@@ -612,7 +620,7 @@
gmove(&n1, &n2);
regfree(&n1);
- if(!debug['B'] && !n->etype) {
+ if(!debug['B'] && !n->bounded) {
// check bounds
if(isconst(nl, CTSTR))
nodconst(&n1, types[TUINT32], nl->val.u.sval->len);
diff --git a/src/cmd/8g/cgen64.c b/src/cmd/8g/cgen64.c
index 8e568a0..3a7de8a 100644
--- a/src/cmd/8g/cgen64.c
+++ b/src/cmd/8g/cgen64.c
@@ -49,6 +49,7 @@
case OADD:
case OSUB:
case OMUL:
+ case OLROT:
case OLSH:
case ORSH:
case OAND:
@@ -131,6 +132,40 @@
regfree(&ex);
regfree(&fx);
break;
+
+ case OLROT:
+ // We only rotate by a constant c in [0,64).
+ // if c >= 32:
+ // lo, hi = hi, lo
+ // c -= 32
+ // if c == 0:
+ // no-op
+ // else:
+ // t = hi
+ // shld hi:lo, c
+ // shld lo:t, c
+ v = mpgetfix(r->val.u.xval);
+ if(v >= 32) {
+ // reverse during load to do the first 32 bits of rotate
+ v -= 32;
+ gins(AMOVL, &lo1, &dx);
+ gins(AMOVL, &hi1, &ax);
+ } else {
+ gins(AMOVL, &lo1, &ax);
+ gins(AMOVL, &hi1, &dx);
+ }
+ if(v == 0) {
+ // done
+ } else {
+ gins(AMOVL, &dx, &cx);
+ p1 = gins(ASHLL, ncon(v), &dx);
+ p1->from.index = D_AX; // double-width shift
+ p1->from.scale = 0;
+ p1 = gins(ASHLL, ncon(v), &ax);
+ p1->from.index = D_CX; // double-width shift
+ p1->from.scale = 0;
+ }
+ break;
case OLSH:
if(r->op == OLITERAL) {
diff --git a/src/cmd/8g/gg.h b/src/cmd/8g/gg.h
index 0a4f0ad..27963f3 100644
--- a/src/cmd/8g/gg.h
+++ b/src/cmd/8g/gg.h
@@ -83,7 +83,7 @@
void cgen_callret(Node*, Node*);
void cgen_div(int, Node*, Node*, Node*);
void cgen_bmul(int, Node*, Node*, Node*);
-void cgen_shift(int, Node*, Node*, Node*);
+void cgen_shift(int, int, Node*, Node*, Node*);
void cgen_dcl(Node*);
int needconvert(Type*, Type*);
void genconv(Type*, Type*);
diff --git a/src/cmd/8g/ggen.c b/src/cmd/8g/ggen.c
index 6a45701..4ccf6a0 100644
--- a/src/cmd/8g/ggen.c
+++ b/src/cmd/8g/ggen.c
@@ -630,7 +630,7 @@
* res = nl >> nr
*/
void
-cgen_shift(int op, Node *nl, Node *nr, Node *res)
+cgen_shift(int op, int bounded, Node *nl, Node *nr, Node *res)
{
Node n1, n2, nt, cx, oldcx, hi, lo;
int a, w;
@@ -651,7 +651,7 @@
gmove(&n2, &n1);
sc = mpgetfix(nr->val.u.xval);
if(sc >= nl->type->width*8) {
- // large shift gets 2 shifts by width
+ // large shift gets 2 shifts by width-1
gins(a, ncon(w-1), &n1);
gins(a, ncon(w-1), &n1);
} else
@@ -689,27 +689,37 @@
}
// test and fix up large shifts
- if(nr->type->width > 4) {
- // delayed reg alloc
- nodreg(&n1, types[TUINT32], D_CX);
- regalloc(&n1, types[TUINT32], &n1); // to hold the shift type in CX
- split64(&nt, &lo, &hi);
- gmove(&lo, &n1);
- gins(optoas(OCMP, types[TUINT32]), &hi, ncon(0));
- p2 = gbranch(optoas(ONE, types[TUINT32]), T);
- gins(optoas(OCMP, types[TUINT32]), &n1, ncon(w));
- p1 = gbranch(optoas(OLT, types[TUINT32]), T);
- patch(p2, pc);
+ if(bounded) {
+ if(nr->type->width > 4) {
+ // delayed reg alloc
+ nodreg(&n1, types[TUINT32], D_CX);
+ regalloc(&n1, types[TUINT32], &n1); // to hold the shift type in CX
+ split64(&nt, &lo, &hi);
+ gmove(&lo, &n1);
+ }
} else {
- gins(optoas(OCMP, nr->type), &n1, ncon(w));
- p1 = gbranch(optoas(OLT, types[TUINT32]), T);
+ if(nr->type->width > 4) {
+ // delayed reg alloc
+ nodreg(&n1, types[TUINT32], D_CX);
+ regalloc(&n1, types[TUINT32], &n1); // to hold the shift type in CX
+ split64(&nt, &lo, &hi);
+ gmove(&lo, &n1);
+ gins(optoas(OCMP, types[TUINT32]), &hi, ncon(0));
+ p2 = gbranch(optoas(ONE, types[TUINT32]), T);
+ gins(optoas(OCMP, types[TUINT32]), &n1, ncon(w));
+ p1 = gbranch(optoas(OLT, types[TUINT32]), T);
+ patch(p2, pc);
+ } else {
+ gins(optoas(OCMP, nr->type), &n1, ncon(w));
+ p1 = gbranch(optoas(OLT, types[TUINT32]), T);
+ }
+ if(op == ORSH && issigned[nl->type->etype]) {
+ gins(a, ncon(w-1), &n2);
+ } else {
+ gmove(ncon(0), &n2);
+ }
+ patch(p1, pc);
}
- if(op == ORSH && issigned[nl->type->etype]) {
- gins(a, ncon(w-1), &n2);
- } else {
- gmove(ncon(0), &n2);
- }
- patch(p1, pc);
gins(a, &n1, &n2);
if(oldcx.op != 0)
diff --git a/src/cmd/8g/gsubr.c b/src/cmd/8g/gsubr.c
index 5e89af0..47bd897 100644
--- a/src/cmd/8g/gsubr.c
+++ b/src/cmd/8g/gsubr.c
@@ -572,6 +572,22 @@
a = AXORL;
break;
+ case CASE(OLROT, TINT8):
+ case CASE(OLROT, TUINT8):
+ a = AROLB;
+ break;
+
+ case CASE(OLROT, TINT16):
+ case CASE(OLROT, TUINT16):
+ a = AROLW;
+ break;
+
+ case CASE(OLROT, TINT32):
+ case CASE(OLROT, TUINT32):
+ case CASE(OLROT, TPTR32):
+ a = AROLL;
+ break;
+
case CASE(OLSH, TINT8):
case CASE(OLSH, TUINT8):
a = ASHLB;
diff --git a/src/cmd/gc/go.h b/src/cmd/gc/go.h
index 8c4fff1..5b7b1eb 100644
--- a/src/cmd/gc/go.h
+++ b/src/cmd/gc/go.h
@@ -234,6 +234,7 @@
uchar addable; // type of addressability - 0 is not addressable
uchar trecur; // to detect loops
uchar etype; // op for OASOP, etype for OTYPE, exclam for export
+ uchar bounded; // bounds check unnecessary
uchar class; // PPARAM, PAUTO, PEXTERN, etc
uchar method; // OCALLMETH name
uchar embedded; // ODCLFIELD embedded type
@@ -488,6 +489,7 @@
// for back ends
OCMP, ODEC, OEXTEND, OINC, OREGISTER, OINDREG,
+ OLROT,
OEND,
};
diff --git a/src/cmd/gc/range.c b/src/cmd/gc/range.c
index 9bcd833..8e9d1af 100644
--- a/src/cmd/gc/range.c
+++ b/src/cmd/gc/range.c
@@ -145,7 +145,7 @@
if(v2) {
hp = temp(ptrto(n->type->type));
tmp = nod(OINDEX, ha, nodintconst(0));
- tmp->etype = 1; // no bounds check
+ tmp->bounded = 1;
init = list(init, nod(OAS, hp, nod(OADDR, tmp, N)));
}
diff --git a/src/cmd/gc/sinit.c b/src/cmd/gc/sinit.c
index c8796f8..335d9b2 100644
--- a/src/cmd/gc/sinit.c
+++ b/src/cmd/gc/sinit.c
@@ -747,7 +747,7 @@
index = r->left;
value = r->right;
a = nod(OINDEX, var, index);
- a->etype = 1; // no bounds checking
+ a->bounded = 1;
// TODO need to check bounds?
switch(value->op) {
@@ -879,11 +879,11 @@
index = temp(types[TINT]);
a = nod(OINDEX, vstat, index);
- a->etype = 1; // no bounds checking
+ a->bounded = 1;
a = nod(ODOT, a, newname(symb));
r = nod(OINDEX, vstat, index);
- r->etype = 1; // no bounds checking
+ r->bounded = 1;
r = nod(ODOT, r, newname(syma));
r = nod(OINDEX, var, r);
diff --git a/src/cmd/gc/subr.c b/src/cmd/gc/subr.c
index 9542b2e..0fee277 100644
--- a/src/cmd/gc/subr.c
+++ b/src/cmd/gc/subr.c
@@ -2663,7 +2663,7 @@
call->list = list(call->list, nh);
call->list = list(call->list, nodintconst(t->type->width));
nx = nod(OINDEX, np, ni);
- nx->etype = 1; // no bounds check
+ nx->bounded = 1;
na = nod(OADDR, nx, N);
na->etype = 1; // no escape to heap
call->list = list(call->list, na);
@@ -2874,9 +2874,9 @@
// if p[i] != q[i] { *eq = false; return }
nx = nod(OINDEX, np, ni);
- nx->etype = 1; // no bounds check
+ nx->bounded = 1;
ny = nod(OINDEX, nq, ni);
- ny->etype = 1; // no bounds check
+ ny->bounded = 1;
nif = nod(OIF, N, N);
nif->ntest = nod(ONE, nx, ny);
diff --git a/src/cmd/gc/walk.c b/src/cmd/gc/walk.c
index a4edc90..026db25 100644
--- a/src/cmd/gc/walk.c
+++ b/src/cmd/gc/walk.c
@@ -22,6 +22,9 @@
static Node* appendslice(Node*, NodeList**);
static Node* append(Node*, NodeList**);
static void walkcompare(Node**, NodeList**);
+static void walkrotate(Node**);
+static int bounded(Node*, int64);
+static Mpint mpzero;
// can this code branch reach the end
// without an unconditional RETURN
@@ -454,8 +457,16 @@
case OLSH:
case ORSH:
+ walkexpr(&n->left, init);
+ walkexpr(&n->right, init);
+ shiftwalked:
+ t = n->left->type;
+ n->bounded = bounded(n->right, 8*t->width);
+ if(debug['m'] && n->etype && !isconst(n->right, CTINT))
+ warn("shift bounds check elided");
+ goto ret;
+
case OAND:
- case OOR:
case OXOR:
case OSUB:
case OMUL:
@@ -465,10 +476,17 @@
case OGT:
case OADD:
case OCOMPLEX:
+ case OLROT:
walkexpr(&n->left, init);
walkexpr(&n->right, init);
goto ret;
+ case OOR:
+ walkexpr(&n->left, init);
+ walkexpr(&n->right, init);
+ walkrotate(&n);
+ goto ret;
+
case OEQ:
case ONE:
walkexpr(&n->left, init);
@@ -794,7 +812,10 @@
typecheck(&r, Etop);
walkexpr(&r, init);
n = r;
+ goto ret;
}
+ if(n->etype == OLSH || n->etype == ORSH)
+ goto shiftwalked;
goto ret;
case OANDNOT:
@@ -844,40 +865,40 @@
walkexpr(&n->right, init);
// if range of type cannot exceed static array bound,
- // disable bounds check
- if(isfixedarray(n->left->type))
- if(!issigned[n->right->type->etype])
- if(n->right->type->width < 4)
- if((1<<(8*n->right->type->width)) <= n->left->type->bound)
- n->etype = 1;
-
- if(isconst(n->left, CTSTR))
- if(!issigned[n->right->type->etype])
- if(n->right->type->width < 4)
- if((1<<(8*n->right->type->width)) <= n->left->val.u.sval->len)
- n->etype = 1;
-
- // check for static out of bounds
- if(isconst(n->right, CTINT) && !n->etype) {
- v = mpgetfix(n->right->val.u.xval);
- len = 1LL<<60;
- t = n->left->type;
- if(isconst(n->left, CTSTR))
- len = n->left->val.u.sval->len;
- if(t != T && isptr[t->etype])
- t = t->type;
- if(isfixedarray(t))
- len = t->bound;
- if(v < 0 || v >= (1LL<<31) || v >= len)
+ // disable bounds check.
+ if(n->bounded)
+ goto ret;
+ t = n->left->type;
+ if(t != T && isptr[t->etype])
+ t = t->type;
+ if(isfixedarray(t)) {
+ n->bounded = bounded(n->right, t->bound);
+ if(debug['m'] && n->bounded && !isconst(n->right, CTINT))
+ warn("index bounds check elided");
+ if(smallintconst(n->right) && !n->bounded)
yyerror("index out of bounds");
- else if(isconst(n->left, CTSTR)) {
- // replace "abc"[2] with 'b'.
- // delayed until now because "abc"[2] is not
- // an ideal constant.
- nodconst(n, n->type, n->left->val.u.sval->s[v]);
- n->typecheck = 1;
+ } else if(isconst(n->left, CTSTR)) {
+ n->bounded = bounded(n->right, n->left->val.u.sval->len);
+ if(debug['m'] && n->bounded && !isconst(n->right, CTINT))
+ warn("index bounds check elided");
+ if(smallintconst(n->right)) {
+ if(!n->bounded)
+ yyerror("index out of bounds");
+ else {
+ // replace "abc"[2] with 'b'.
+ // delayed until now because "abc"[2] is not
+ // an ideal constant.
+ v = mpgetfix(n->right->val.u.xval);
+ nodconst(n, n->type, n->left->val.u.sval->s[v]);
+ n->typecheck = 1;
+ }
}
}
+
+ if(isconst(n->right, CTINT))
+ if(mpcmpfixfix(n->right->val.u.xval, &mpzero) < 0 ||
+ mpcmpfixfix(n->right->val.u.xval, maxintval[TINT]) > 0)
+ yyerror("index out of bounds");
goto ret;
case OINDEXMAP:
@@ -938,7 +959,7 @@
// sliceslice(old []any, lb uint64, hb uint64, width uint64) (ary []any)
// sliceslice1(old []any, lb uint64, width uint64) (ary []any)
t = n->type;
- et = n->etype;
+ et = n->bounded;
if(n->right->left == N)
l = nodintconst(0);
else
@@ -961,7 +982,7 @@
l,
nodintconst(t->type->width));
}
- n->etype = et; // preserve no-typecheck flag from OSLICE to the slice* call.
+ n->bounded = et; // preserve flag from OSLICE to the slice* call.
goto ret;
slicearray:
@@ -2395,12 +2416,12 @@
l = list(l, nod(OAS, nn, nod(OLEN, ns, N))); // n = len(s)
nx = nod(OSLICE, ns, nod(OKEY, N, nod(OADD, nn, na))); // ...s[:n+argc]
- nx->etype = 1; // disable bounds check
+ nx->bounded = 1;
l = list(l, nod(OAS, ns, nx)); // s = s[:n+argc]
for (a = n->list->next; a != nil; a = a->next) {
nx = nod(OINDEX, ns, nn); // s[n] ...
- nx->etype = 1; // disable bounds check
+ nx->bounded = 1;
l = list(l, nod(OAS, nx, a->n)); // s[n] = arg
if (a->next != nil)
l = list(l, nod(OAS, nn, nod(OADD, nn, nodintconst(1)))); // n = n + 1
@@ -2596,3 +2617,135 @@
*np = r;
return;
}
+
+static int
+samecheap(Node *a, Node *b)
+{
+ if(a == N || b == N || a->op != b->op)
+ return 0;
+
+ switch(a->op) {
+ case ONAME:
+ return a == b;
+ // TODO: Could do more here, but maybe this is enough.
+ // It's all cheapexpr does.
+ }
+ return 0;
+}
+
+static void
+walkrotate(Node **np)
+{
+ int w, sl, sr, s;
+ Node *l, *r;
+ Node *n;
+
+ n = *np;
+
+ // Want << | >> or >> | << on unsigned value.
+ l = n->left;
+ r = n->right;
+ if(n->op != OOR ||
+ (l->op != OLSH && l->op != ORSH) ||
+ (r->op != OLSH && r->op != ORSH) ||
+ n->type == T || issigned[n->type->etype] ||
+ l->op == r->op) {
+ return;
+ }
+
+ // Want same, side effect-free expression on lhs of both shifts.
+ if(!samecheap(l->left, r->left))
+ return;
+
+ // Constants adding to width?
+ w = l->type->width * 8;
+ if(smallintconst(l->right) && smallintconst(r->right)) {
+ if((sl=mpgetfix(l->right->val.u.xval)) >= 0 && (sr=mpgetfix(r->right->val.u.xval)) >= 0 && sl+sr == w)
+ goto yes;
+ return;
+ }
+
+ // TODO: Could allow s and 32-s if s is bounded (maybe s&31 and 32-s&31).
+ return;
+
+yes:
+ // Rewrite left shift half to left rotate.
+ if(l->op == OLSH)
+ n = l;
+ else
+ n = r;
+ n->op = OLROT;
+
+ // Remove rotate 0 and rotate w.
+ s = mpgetfix(n->right->val.u.xval);
+ if(s == 0 || s == w)
+ n = n->left;
+
+ *np = n;
+ return;
+}
+
+// return 1 if integer n must be in range [0, max), 0 otherwise
+static int
+bounded(Node *n, int64 max)
+{
+ int64 v;
+ int32 bits;
+ int sign;
+
+ if(n->type == T || !isint[n->type->etype])
+ return 0;
+
+ sign = issigned[n->type->etype];
+ bits = 8*n->type->width;
+
+ if(smallintconst(n)) {
+ v = mpgetfix(n->val.u.xval);
+ return 0 <= v && v < max;
+ }
+
+ switch(n->op) {
+ case OAND:
+ v = -1;
+ if(smallintconst(n->left)) {
+ v = mpgetfix(n->left->val.u.xval);
+ } else if(smallintconst(n->right)) {
+ v = mpgetfix(n->right->val.u.xval);
+ }
+ if(0 <= v && v < max)
+ return 1;
+ break;
+
+ case OMOD:
+ if(!sign && smallintconst(n->right)) {
+ v = mpgetfix(n->right->val.u.xval);
+ if(0 <= v && v <= max)
+ return 1;
+ }
+ break;
+
+ case ODIV:
+ if(!sign && smallintconst(n->right)) {
+ v = mpgetfix(n->right->val.u.xval);
+ while(bits > 0 && v >= 2) {
+ bits--;
+ v >>= 1;
+ }
+ }
+ break;
+
+ case ORSH:
+ if(!sign && smallintconst(n->right)) {
+ v = mpgetfix(n->right->val.u.xval);
+ if(v > bits)
+ return 1;
+ bits -= v;
+ }
+ break;
+ }
+
+ if(!sign && bits <= 62 && (1LL<<bits) <= max)
+ return 1;
+
+ return 0;
+}
diff --git a/test/bounds.go b/test/bounds.go
new file mode 100644
index 0000000..7b2b528
--- /dev/null
+++ b/test/bounds.go
@@ -0,0 +1,277 @@
+// errchk -0 $G -m -l $D/$F.go
+
+// Copyright 2012 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.
+
+// Test, using compiler diagnostic flags, that bounds check elimination
+// is eliminating the correct checks.
+
+package foo
+
+var (
+ s []int
+
+ a1 [1]int
+ a1k [1000]int
+ a100k [100000]int
+
+ p1 *[1]int
+ p1k *[1000]int
+ p100k *[100000]int
+
+ i int
+ ui uint
+ i8 int8
+ ui8 uint8
+ i16 int16
+ ui16 uint16
+ i32 int32
+ ui32 uint32
+ i64 int64
+ ui64 uint64
+)
+
+func main() {
+ // Most things need checks.
+ use(s[i])
+ use(a1[i])
+ use(a1k[i])
+ use(a100k[i])
+ use(p1[i])
+ use(p1k[i])
+ use(p100k[i])
+
+ use(s[ui])
+ use(a1[ui])
+ use(a1k[ui])
+ use(a100k[ui])
+ use(p1[ui])
+ use(p1k[ui])
+ use(p100k[ui])
+
+ use(s[i8])
+ use(a1[i8])
+ use(a1k[i8])
+ use(a100k[i8])
+ use(p1[i8])
+ use(p1k[i8])
+ use(p100k[i8])
+
+ // Unsigned 8-bit numbers don't need checks for len >= 2⁸.
+ use(s[ui8])
+ use(a1[ui8])
+ use(a1k[ui8]) // ERROR "index bounds check elided"
+ use(a100k[ui8]) // ERROR "index bounds check elided"
+ use(p1[ui8])
+ use(p1k[ui8]) // ERROR "index bounds check elided"
+ use(p100k[ui8]) // ERROR "index bounds check elided"
+
+ use(s[i16])
+ use(a1[i16])
+ use(a1k[i16])
+ use(a100k[i16])
+ use(p1[i16])
+ use(p1k[i16])
+ use(p100k[i16])
+
+ // Unsigned 16-bit numbers don't need checks for len >= 2¹⁶.
+ use(s[ui16])
+ use(a1[ui16])
+ use(a1k[ui16])
+ use(a100k[ui16]) // ERROR "index bounds check elided"
+ use(p1[ui16])
+ use(p1k[ui16])
+ use(p100k[ui16]) // ERROR "index bounds check elided"
+
+ use(s[i32])
+ use(a1[i32])
+ use(a1k[i32])
+ use(a100k[i32])
+ use(p1[i32])
+ use(p1k[i32])
+ use(p100k[i32])
+
+ use(s[ui32])
+ use(a1[ui32])
+ use(a1k[ui32])
+ use(a100k[ui32])
+ use(p1[ui32])
+ use(p1k[ui32])
+ use(p100k[ui32])
+
+ use(s[i64])
+ use(a1[i64])
+ use(a1k[i64])
+ use(a100k[i64])
+ use(p1[i64])
+ use(p1k[i64])
+ use(p100k[i64])
+
+ use(s[ui64])
+ use(a1[ui64])
+ use(a1k[ui64])
+ use(a100k[ui64])
+ use(p1[ui64])
+ use(p1k[ui64])
+ use(p100k[ui64])
+
+ // Mod truncates the maximum value to one less than the argument,
+ // but signed mod can be negative, so only unsigned mod counts.
+ use(s[i%999])
+ use(a1[i%999])
+ use(a1k[i%999])
+ use(a100k[i%999])
+ use(p1[i%999])
+ use(p1k[i%999])
+ use(p100k[i%999])
+
+ use(s[ui%999])
+ use(a1[ui%999])
+ use(a1k[ui%999]) // ERROR "index bounds check elided"
+ use(a100k[ui%999]) // ERROR "index bounds check elided"
+ use(p1[ui%999])
+ use(p1k[ui%999]) // ERROR "index bounds check elided"
+ use(p100k[ui%999]) // ERROR "index bounds check elided"
+
+ use(s[i%1000])
+ use(a1[i%1000])
+ use(a1k[i%1000])
+ use(a100k[i%1000])
+ use(p1[i%1000])
+ use(p1k[i%1000])
+ use(p100k[i%1000])
+
+ use(s[ui%1000])
+ use(a1[ui%1000])
+ use(a1k[ui%1000]) // ERROR "index bounds check elided"
+ use(a100k[ui%1000]) // ERROR "index bounds check elided"
+ use(p1[ui%1000])
+ use(p1k[ui%1000]) // ERROR "index bounds check elided"
+ use(p100k[ui%1000]) // ERROR "index bounds check elided"
+
+ use(s[i%1001])
+ use(a1[i%1001])
+ use(a1k[i%1001])
+ use(a100k[i%1001])
+ use(p1[i%1001])
+ use(p1k[i%1001])
+ use(p100k[i%1001])
+
+ use(s[ui%1001])
+ use(a1[ui%1001])
+ use(a1k[ui%1001])
+ use(a100k[ui%1001]) // ERROR "index bounds check elided"
+ use(p1[ui%1001])
+ use(p1k[ui%1001])
+ use(p100k[ui%1001]) // ERROR "index bounds check elided"
+
+ // Bitwise and truncates the maximum value to the mask value.
+ // The result (for a positive mask) cannot be negative, so elision
+ // applies to both signed and unsigned indexes.
+ use(s[i&999])
+ use(a1[i&999])
+ use(a1k[i&999]) // ERROR "index bounds check elided"
+ use(a100k[i&999]) // ERROR "index bounds check elided"
+ use(p1[i&999])
+ use(p1k[i&999]) // ERROR "index bounds check elided"
+ use(p100k[i&999]) // ERROR "index bounds check elided"
+
+ use(s[ui&999])
+ use(a1[ui&999])
+ use(a1k[ui&999]) // ERROR "index bounds check elided"
+ use(a100k[ui&999]) // ERROR "index bounds check elided"
+ use(p1[ui&999])
+ use(p1k[ui&999]) // ERROR "index bounds check elided"
+ use(p100k[ui&999]) // ERROR "index bounds check elided"
+
+ use(s[i&1000])
+ use(a1[i&1000])
+ use(a1k[i&1000])
+ use(a100k[i&1000]) // ERROR "index bounds check elided"
+ use(p1[i&1000])
+ use(p1k[i&1000])
+ use(p100k[i&1000]) // ERROR "index bounds check elided"
+
+ use(s[ui&1000])
+ use(a1[ui&1000])
+ use(a1k[ui&1000])
+ use(a100k[ui&1000]) // ERROR "index bounds check elided"
+ use(p1[ui&1000])
+ use(p1k[ui&1000])
+ use(p100k[ui&1000]) // ERROR "index bounds check elided"
+
+ // Right shift cuts the effective number of bits in the index,
+ // but only for unsigned (signed stays negative).
+ use(s[i32>>22])
+ use(a1[i32>>22])
+ use(a1k[i32>>22])
+ use(a100k[i32>>22])
+ use(p1[i32>>22])
+ use(p1k[i32>>22])
+ use(p100k[i32>>22])
+
+ use(s[ui32>>22])
+ use(a1[ui32>>22])
+ use(a1k[ui32>>22])
+ use(a100k[ui32>>22]) // ERROR "index bounds check elided"
+ use(p1[ui32>>22])
+ use(p1k[ui32>>22])
+ use(p100k[ui32>>22]) // ERROR "index bounds check elided"
+
+ use(s[i32>>23])
+ use(a1[i32>>23])
+ use(a1k[i32>>23])
+ use(a100k[i32>>23])
+ use(p1[i32>>23])
+ use(p1k[i32>>23])
+ use(p100k[i32>>23])
+
+ use(s[ui32>>23])
+ use(a1[ui32>>23])
+ use(a1k[ui32>>23]) // ERROR "index bounds check elided"
+ use(a100k[ui32>>23]) // ERROR "index bounds check elided"
+ use(p1[ui32>>23])
+ use(p1k[ui32>>23]) // ERROR "index bounds check elided"
+ use(p100k[ui32>>23]) // ERROR "index bounds check elided"
+
+ // Division cuts the range like right shift does.
+ use(s[i/1e6])
+ use(a1[i/1e6])
+ use(a1k[i/1e6])
+ use(a100k[i/1e6])
+ use(p1[i/1e6])
+ use(p1k[i/1e6])
+ use(p100k[i/1e6])
+
+ use(s[ui/1e6])
+ use(a1[ui/1e6])
+ use(a1k[ui/1e6])
+ use(a100k[ui/1e6]) // ERROR "index bounds check elided"
+ use(p1[ui/1e6])
+ use(p1k[ui/1e6])
+ use(p100k[ui/1e6]) // ERROR "index bounds check elided"
+
+ use(s[i/1e7])
+ use(a1[i/1e7])
+ use(a1k[i/1e7])
+ use(a100k[i/1e7])
+ use(p1[i/1e7])
+ use(p1k[i/1e7])
+ use(p100k[i/1e7])
+
+ use(s[ui/1e7])
+ use(a1[ui/1e7])
+ use(a1k[ui/1e7]) // ERROR "index bounds check elided"
+ use(a100k[ui/1e7]) // ERROR "index bounds check elided"
+ use(p1[ui/1e7])
+ use(p1k[ui/1e7]) // ERROR "index bounds check elided"
+ use(p100k[ui/1e7]) // ERROR "index bounds check elided"
+
+}
+
+var sum int
+
+func use(x int) {
+ sum += x
+}
diff --git a/test/rotate.go b/test/rotate.go
new file mode 100644
index 0000000..67d32d7
--- /dev/null
+++ b/test/rotate.go
@@ -0,0 +1,141 @@
+// $G $D/$F.go && $L $F.$A &&
+// ./$A.out >tmp.go && $G tmp.go && $L -o $A.out1 tmp.$A && ./$A.out1
+// rm -f tmp.go $A.out1
+
+// Copyright 2012 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.
+
+// Generate test of shift and rotate by constants.
+// The output is compiled and run.
+//
+// The output takes around a minute to compile, link, and run
+// but it is only done during ./run, not in normal builds using run.go.
+
+package main
+
+import (
+ "bufio"
+ "flag"
+ "fmt"
+ "os"
+)
+
+func main() {
+ flag.Parse()
+
+ b := bufio.NewWriter(os.Stdout)
+ defer b.Flush()
+
+ fmt.Fprintf(b, "%s\n", prolog)
+
+ for logBits := uint(3); logBits <= 6; logBits++ {
+ for mode := 0; mode < 1<<2; mode++ {
+ gentest(b, 1<<logBits, mode&1 != 0, mode&2 != 0)
+ }
+ }
+}
+
+const prolog = `
+
+package main
+
+import (
+ "fmt"
+ "os"
+)
+
+var (
+ i8 int8 = 0x12
+ i16 int16 = 0x1234
+ i32 int32 = 0x12345678
+ i64 int64 = 0x123456789abcdef0
+ ui8 uint8 = 0x12
+ ui16 uint16 = 0x1234
+ ui32 uint32 = 0x12345678
+ ui64 uint64 = 0x123456789abcdef0
+
+ ni8 = ^i8
+ ni16 = ^i16
+ ni32 = ^i32
+ ni64 = ^i64
+ nui8 = ^ui8
+ nui16 = ^ui16
+ nui32 = ^ui32
+ nui64 = ^ui64
+)
+
+var nfail = 0
+
+func check(desc string, have, want interface{}) {
+ if have != want {
+ nfail++
+ fmt.Printf("%s = %T(%#x), want %T(%#x)\n", desc, have, have, want, want)
+ if nfail >= 100 {
+ fmt.Printf("BUG: stopping after 100 failures\n")
+ os.Exit(0)
+ }
+ }
+}
+
+func main() {
+ if nfail > 0 {
+ fmt.Printf("BUG\n")
+ }
+}
+
+`
+
+func gentest(b *bufio.Writer, bits uint, unsigned, inverted bool) {
+ fmt.Fprintf(b, "func init() {\n")
+ defer fmt.Fprintf(b, "}\n")
+ n := 0
+
+ // Generate tests for left/right and right/left.
+ for l := uint(0); l <= bits; l++ {
+ for r := uint(0); r <= bits; r++ {
+ typ := fmt.Sprintf("int%d", bits)
+ v := fmt.Sprintf("i%d", bits)
+ if unsigned {
+ typ = "u" + typ
+ v = "u" + v
+ }
+ v0 := int64(0x123456789abcdef0)
+ if inverted {
+ v = "n" + v
+ v0 = ^v0
+ }
+ expr1 := fmt.Sprintf("%s<<%d | %s>>%d", v, l, v, r)
+ expr2 := fmt.Sprintf("%s>>%d | %s<<%d", v, r, v, l)
+
+ var result string
+ if unsigned {
+ v := uint64(v0) >> (64 - bits)
+ v = v<<l | v>>r
+ v <<= 64 - bits
+ v >>= 64 - bits
+ result = fmt.Sprintf("%#x", v)
+ } else {
+ v := int64(v0) >> (64 - bits)
+ v = v<<l | v>>r
+ v <<= 64 - bits
+ v >>= 64 - bits
+ result = fmt.Sprintf("%#x", v)
+ }
+
+ fmt.Fprintf(b, "\tcheck(%q, %s, %s(%s))\n", expr1, expr1, typ, result)
+ fmt.Fprintf(b, "\tcheck(%q, %s, %s(%s))\n", expr2, expr2, typ, result)
+
+ // Chop test into multiple functions so that there's not one
+ // enormous function to compile/link.
+ // All the functions are named init so we don't have to do
+ // anything special to call them. ☺
+ if n++; n >= 100 {
+ fmt.Fprintf(b, "}\n")
+ fmt.Fprintf(b, "func init() {\n")
+ n = 0
+ }
+ }
+ }
+}
+
