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gcc/libdecnumber/bid/bid2dpd_dpd2bid.c
Joseph Myers 0fad54f0a8 Fix libdecnumber handling of non-canonical BID significands (PR middle-end/91226). 
As reported in bug 91226, the libdecnumber code used on the host to
interpret DFP values in the BID encoding fails, for _Decimal64 and
_Decimal128, to check for the case where a significand is too large
and so specified in IEEE 754 to be a non-canonical encoding of the
zero significand.  This patch adds the required handling of that case,
together with tests both using -O2 (testing this host code) and -O0
(testing libgcc code, which already worked before the patch); the
tests also cover _Decimal32, which already had the required check.

In the _Decimal128 case, where the code previously completely ignored
the case where the first four bits of the combination field are 1100,
1101 or 1110, the logic for determining the correct quantum exponent
in that case is also newly added by this patch, so tests are added for
that as well (again, libgcc already handled it correctly when the
conversion was done at runtime rather than at compile time).

Bootstrapped with no regressions for x86_64-pc-linux-gnu.

	PR middle-end/91226
libdecnumber:
	* bid/bid2dpd_dpd2bid.c (_bid_to_dpd64): Handle non-canonical
	significands.
	(_bid_to_dpd128): Likewise.  Check for case where combination
	field starts 1100, 1101 or 1110.

gcc/testsuite:
	* gcc.dg/dfp/bid-non-canonical-d128-1.c,
	gcc.dg/dfp/bid-non-canonical-d128-2.c,
	gcc.dg/dfp/bid-non-canonical-d128-3.c,
	gcc.dg/dfp/bid-non-canonical-d128-4.c,
	gcc.dg/dfp/bid-non-canonical-d32-1.c,
	gcc.dg/dfp/bid-non-canonical-d32-2.c,
	gcc.dg/dfp/bid-non-canonical-d64-1.c,
	gcc.dg/dfp/bid-non-canonical-d64-2.c: New tests.

From-SVN: r279129
2019-12-09 13:59:24 +00:00

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/* Copyright (C) 2007-2019 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
#undef IN_LIBGCC2
#include "bid-dpd.h"
/* get full 64x64bit product */
#define __mul_64x64_to_128(P, CX, CY) \
{ \
UINT64 CXH, CXL, CYH,CYL,PL,PH,PM,PM2; \
CXH = (CX) >> 32; \
CXL = (UINT32)(CX); \
CYH = (CY) >> 32; \
CYL = (UINT32)(CY); \
\
PM = CXH*CYL; \
PH = CXH*CYH; \
PL = CXL*CYL; \
PM2 = CXL*CYH; \
PH += (PM>>32); \
PM = (UINT64)((UINT32)PM)+PM2+(PL>>32); \
\
(P).w[1] = PH + (PM>>32); \
(P).w[0] = (PM<<32)+(UINT32)PL; \
}
/* add 64-bit value to 128-bit */
#define __add_128_64(R128, A128, B64) \
{ \
UINT64 R64H; \
R64H = (A128).w[1]; \
(R128).w[0] = (B64) + (A128).w[0]; \
if((R128).w[0] < (B64)) R64H ++; \
(R128).w[1] = R64H; \
}
/* add 128-bit value to 128-bit (assume no carry-out) */
#define __add_128_128(R128, A128, B128) \
{ \
UINT128 Q128; \
Q128.w[1] = (A128).w[1]+(B128).w[1]; \
Q128.w[0] = (B128).w[0] + (A128).w[0]; \
if(Q128.w[0] < (B128).w[0]) Q128.w[1] ++; \
(R128).w[1] = Q128.w[1]; \
(R128).w[0] = Q128.w[0]; \
}
#define __mul_128x128_high(Q, A, B) \
{ \
UINT128 ALBL, ALBH, AHBL, AHBH, QM, QM2; \
\
__mul_64x64_to_128(ALBH, (A).w[0], (B).w[1]); \
__mul_64x64_to_128(AHBL, (B).w[0], (A).w[1]); \
__mul_64x64_to_128(ALBL, (A).w[0], (B).w[0]); \
__mul_64x64_to_128(AHBH, (A).w[1],(B).w[1]); \
\
__add_128_128(QM, ALBH, AHBL); \
__add_128_64(QM2, QM, ALBL.w[1]); \
__add_128_64((Q), AHBH, QM2.w[1]); \
}
#include "bid2dpd_dpd2bid.h"
static const unsigned int dm103[] =
{ 0, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000 };
void _bid_to_dpd32 (_Decimal32 *, _Decimal32 *);
void
_bid_to_dpd32 (_Decimal32 *pres, _Decimal32 *px) {
unsigned int sign, coefficient_x, exp, dcoeff;
unsigned int b2, b1, b0, b01, res;
_Decimal32 x = *px;
sign = (x & 0x80000000);
if ((x & 0x60000000ul) == 0x60000000ul) {
/* special encodings */
if ((x & 0x78000000ul) == 0x78000000ul) {
*pres = x; /* NaN or Infinity */
return;
}
/* coefficient */
coefficient_x = (x & 0x001ffffful) | 0x00800000ul;
if (coefficient_x >= 10000000) coefficient_x = 0;
/* get exponent */
exp = (x >> 21) & 0xff;
} else {
exp = (x >> 23) & 0xff;
coefficient_x = (x & 0x007ffffful);
}
b01 = coefficient_x / 1000;
b2 = coefficient_x - 1000 * b01;
b0 = b01 / 1000;
b1 = b01 - 1000 * b0;
dcoeff = b2d[b2] | b2d2[b1];
if (b0 >= 8) { /* is b0 8 or 9? */
res = sign | ((0x600 | ((exp >> 6) << 7) |
((b0 & 1) << 6) | (exp & 0x3f)) << 20) | dcoeff;
} else { /* else b0 is 0..7 */
res = sign | ((((exp >> 6) << 9) | (b0 << 6) |
(exp & 0x3f)) << 20) | dcoeff;
}
*pres = res;
}
void _dpd_to_bid32 (_Decimal32 *, _Decimal32 *);
void
_dpd_to_bid32 (_Decimal32 *pres, _Decimal32 *px) {
unsigned int r;
unsigned int sign, exp, bcoeff;
UINT64 trailing;
unsigned int d0, d1, d2;
_Decimal32 x = *px;
sign = (x & 0x80000000);
trailing = (x & 0x000fffff);
if ((x & 0x78000000) == 0x78000000) {
*pres = x;
return;
}
/* normal number */
if ((x & 0x60000000) == 0x60000000) { /* G0..G1 = 11 -> d0 = 8 + G4 */
d0 = d2b3[((x >> 26) & 1) | 8]; /* d0 = (comb & 0x0100 ? 9 : 8); */
exp = (x >> 27) & 3; /* exp leading bits are G2..G3 */
} else {
d0 = d2b3[(x >> 26) & 0x7];
exp = (x >> 29) & 3; /* exp loading bits are G0..G1 */
}
d1 = d2b2[(trailing >> 10) & 0x3ff];
d2 = d2b[(trailing) & 0x3ff];
bcoeff = d2 + d1 + d0;
exp = (exp << 6) + ((x >> 20) & 0x3f);
if (bcoeff < (1 << 23)) {
r = exp;
r <<= 23;
r |= (bcoeff | sign);
} else {
r = exp;
r <<= 21;
r |= (sign | 0x60000000ul);
/* add coeff, without leading bits */
r |= (((unsigned int) bcoeff) & 0x1fffff);
}
*pres = r;
}
void _bid_to_dpd64 (_Decimal64 *, _Decimal64 *);
void
_bid_to_dpd64 (_Decimal64 *pres, _Decimal64 *px) {
UINT64 res;
UINT64 sign, comb, exp, B34, B01;
UINT64 d103, D61;
UINT64 b0, b2, b3, b5;
unsigned int b1, b4;
UINT64 bcoeff;
UINT64 dcoeff;
unsigned int yhi, ylo;
_Decimal64 x = *px;
sign = (x & 0x8000000000000000ull);
comb = (x & 0x7ffc000000000000ull) >> 51;
if ((comb & 0xf00) == 0xf00) {
*pres = x;
return;
}
/* Normal number */
if ((comb & 0xc00) == 0xc00) { /* G0..G1 = 11 -> exp is G2..G11 */
exp = (comb) & 0x3ff;
bcoeff = (x & 0x0007ffffffffffffull) | 0x0020000000000000ull;
if (bcoeff >= 10000000000000000ull)
bcoeff = 0;
} else {
exp = (comb >> 2) & 0x3ff;
bcoeff = (x & 0x001fffffffffffffull);
}
D61 = 2305843009ull; /* Floor(2^61 / 10^9) */
/* Multiply the binary coefficient by ceil(2^64 / 1000), and take the upper
64-bits in order to compute a division by 1000. */
yhi = (D61 * (UINT64)(bcoeff >> (UINT64)27)) >> (UINT64)34;
ylo = bcoeff - 1000000000ull * yhi;
if (ylo >= 1000000000) {
ylo = ylo - 1000000000;
yhi = yhi + 1;
}
d103 = 0x4189374c;
B34 = ((UINT64) ylo * d103) >> (32 + 8);
B01 = ((UINT64) yhi * d103) >> (32 + 8);
b5 = ylo - B34 * 1000;
b2 = yhi - B01 * 1000;
b3 = ((UINT64) B34 * d103) >> (32 + 8);
b0 = ((UINT64) B01 * d103) >> (32 + 8);
b4 = (unsigned int) B34 - (unsigned int) b3 *1000;
b1 = (unsigned int) B01 - (unsigned int) dm103[b0];
dcoeff = b2d[b5] | b2d2[b4] | b2d3[b3] | b2d4[b2] | b2d5[b1];
if (b0 >= 8) /* is b0 8 or 9? */
res = sign | ((0x1800 | ((exp >> 8) << 9) | ((b0 & 1) << 8) |
(exp & 0xff)) << 50) | dcoeff;
else /* else b0 is 0..7 */
res = sign | ((((exp >> 8) << 11) | (b0 << 8) |
(exp & 0xff)) << 50) | dcoeff;
*pres = res;
}
void _dpd_to_bid64 (_Decimal64 *, _Decimal64 *);
void
_dpd_to_bid64 (_Decimal64 *pres, _Decimal64 *px) {
UINT64 res;
UINT64 sign, comb, exp;
UINT64 trailing;
UINT64 d0, d1, d2;
unsigned int d3, d4, d5;
UINT64 bcoeff, mask;
_Decimal64 x = *px;
sign = (x & 0x8000000000000000ull);
comb = (x & 0x7ffc000000000000ull) >> 50;
trailing = (x & 0x0003ffffffffffffull);
if ((comb & 0x1e00) == 0x1e00) {
*pres = x;
return;
}
/* normal number */
if ((comb & 0x1800) == 0x1800) { /* G0..G1 = 11 -> d0 = 8 + G4 */
d0 = d2b6[((comb >> 8) & 1) | 8]; /* d0 = (comb & 0x0100 ? 9 : 8); */
exp = (comb & 0x600) >> 1; /* exp = (comb & 0x0400 ? 1 : 0) * 0x200 +
(comb & 0x0200 ? 1 : 0) * 0x100; exp leading bits are G2..G3 */
} else {
d0 = d2b6[(comb >> 8) & 0x7];
exp = (comb & 0x1800) >> 3; /* exp = (comb & 0x1000 ? 1 : 0) * 0x200 +
(comb & 0x0800 ? 1 : 0) * 0x100; exp loading bits are G0..G1 */
}
d1 = d2b5[(trailing >> 40) & 0x3ff];
d2 = d2b4[(trailing >> 30) & 0x3ff];
d3 = d2b3[(trailing >> 20) & 0x3ff];
d4 = d2b2[(trailing >> 10) & 0x3ff];
d5 = d2b[(trailing) & 0x3ff];
bcoeff = (d5 + d4 + d3) + d2 + d1 + d0;
exp += (comb & 0xff);
mask = 1;
mask <<= 53;
if (bcoeff < mask) { /* check whether coefficient fits in 10*5+3 bits */
res = exp;
res <<= 53;
res |= (bcoeff | sign);
*pres = res;
return;
}
/* special format */
res = (exp << 51) | (sign | 0x6000000000000000ull);
/* add coeff, without leading bits */
mask = (mask >> 2) - 1;
bcoeff &= mask;
res |= bcoeff;
*pres = res;
}
void _bid_to_dpd128 (_Decimal128 *, _Decimal128 *);
void
_bid_to_dpd128 (_Decimal128 *pres, _Decimal128 *px) {
UINT128 res;
UINT128 sign;
unsigned int comb;
UINT128 bcoeff;
UINT128 dcoeff;
UINT128 BH, d1018, BT2, BT1;
UINT64 exp, BL, d109;
UINT64 d106, d103;
UINT64 k1, k2, k4, k5, k7, k8, k10, k11;
unsigned int BHH32, BLL32, BHL32, BLH32, k0, k3, k6, k9, amount;
_Decimal128 x = *px;
sign.w[1] = (x.w[1] & 0x8000000000000000ull);
sign.w[0] = 0;
comb = (x.w[1] /*& 0x7fffc00000000000ull */ ) >> 46;
exp = 0;
if ((comb & 0x1e000) == 0x1e000) {
res = x;
} else { /* normal number */
if ((comb & 0x18000) == 0x18000) {
/* Noncanonical significand (prepending 8 or 9 to any 110-bit
trailing significand field produces a value above 10^34). */
exp = (comb & 0x7fff) >> 1;
bcoeff.w[1] = 0;
bcoeff.w[0] = 0;
} else {
exp = ((x.w[1] & 0x7fff000000000000ull) >> 49) & 0x3fff;
bcoeff.w[1] = (x.w[1] & 0x0001ffffffffffffull);
bcoeff.w[0] = x.w[0];
if (bcoeff.w[1] > 0x1ed09bead87c0ull
|| (bcoeff.w[1] == 0x1ed09bead87c0ull
&& bcoeff.w[0] >= 0x378d8e6400000000ull)) {
bcoeff.w[1] = 0;
bcoeff.w[0] = 0;
}
}
d1018 = reciprocals10_128[18];
__mul_128x128_high (BH, bcoeff, d1018);
amount = recip_scale[18];
BH.w[0] = (BH.w[0] >> amount) | (BH.w[1] << (64 - amount));
BL = bcoeff.w[0] - BH.w[0] * 1000000000000000000ull;
d109 = reciprocals10_64[9];
__mul_64x64_to_128 (BT1, BH.w[0], d109);
BHH32 = (unsigned int) (BT1.w[1] >> short_recip_scale[9]);
BHL32 = (unsigned int) BH.w[0] - BHH32 * 1000000000;
__mul_64x64_to_128 (BT2, BL, d109);
BLH32 = (unsigned int) (BT2.w[1] >> short_recip_scale[9]);
BLL32 = (unsigned int) BL - BLH32 * 1000000000;
d106 = 0x431BDE83;
d103 = 0x4189374c;
k0 = ((UINT64) BHH32 * d106) >> (32 + 18);
BHH32 -= (unsigned int) k0 *1000000;
k1 = ((UINT64) BHH32 * d103) >> (32 + 8);
k2 = BHH32 - (unsigned int) k1 *1000;
k3 = ((UINT64) BHL32 * d106) >> (32 + 18);
BHL32 -= (unsigned int) k3 *1000000;
k4 = ((UINT64) BHL32 * d103) >> (32 + 8);
k5 = BHL32 - (unsigned int) k4 *1000;
k6 = ((UINT64) BLH32 * d106) >> (32 + 18);
BLH32 -= (unsigned int) k6 *1000000;
k7 = ((UINT64) BLH32 * d103) >> (32 + 8);
k8 = BLH32 - (unsigned int) k7 *1000;
k9 = ((UINT64) BLL32 * d106) >> (32 + 18);
BLL32 -= (unsigned int) k9 *1000000;
k10 = ((UINT64) BLL32 * d103) >> (32 + 8);
k11 = BLL32 - (unsigned int) k10 *1000;
dcoeff.w[1] = (b2d[k5] >> 4) | (b2d[k4] << 6) | (b2d[k3] << 16) |
(b2d[k2] << 26) | (b2d[k1] << 36);
dcoeff.w[0] = b2d[k11] | (b2d[k10] << 10) | (b2d[k9] << 20) |
(b2d[k8] << 30) | (b2d[k7] << 40) | (b2d[k6] << 50) | (b2d[k5] << 60);
res.w[0] = dcoeff.w[0];
if (k0 >= 8) {
res.w[1] = sign.w[1] | ((0x18000 | ((exp >> 12) << 13) |
((k0 & 1) << 12) | (exp & 0xfff)) << 46) | dcoeff.w[1];
} else {
res.w[1] = sign.w[1] | ((((exp >> 12) << 15) | (k0 << 12) |
(exp & 0xfff)) << 46) | dcoeff.w[1];
}
}
*pres = res;
}
void _dpd_to_bid128 (_Decimal128 *, _Decimal128 *);
void
_dpd_to_bid128 (_Decimal128 *pres, _Decimal128 *px) {
UINT128 res;
UINT128 sign;
UINT64 exp, comb;
UINT128 trailing;
UINT64 d0, d1, d2, d3, d4, d5, d6, d7, d8, d9, d10, d11;
UINT128 bcoeff;
UINT64 tl, th;
_Decimal128 x = *px;
sign.w[1] = (x.w[1] & 0x8000000000000000ull);
sign.w[0] = 0;
comb = (x.w[1] & 0x7fffc00000000000ull) >> 46;
trailing.w[1] = x.w[1];
trailing.w[0] = x.w[0];
if ((comb & 0x1e000) == 0x1e000) {
*pres = x;
return;
}
if ((comb & 0x18000) == 0x18000) { /* G0..G1 = 11 -> d0 = 8 + G4 */
d0 = d2b6[8 + ((comb & 0x01000) >> 12)];
exp = (comb & 0x06000) >> 1; /* exp leading bits are G2..G3 */
} else {
d0 = d2b6[((comb & 0x07000) >> 12)];
exp = (comb & 0x18000) >> 3; /* exp loading bits are G0..G1 */
}
d11 = d2b[(trailing.w[0]) & 0x3ff];
d10 = d2b2[(trailing.w[0] >> 10) & 0x3ff];
d9 = d2b3[(trailing.w[0] >> 20) & 0x3ff];
d8 = d2b4[(trailing.w[0] >> 30) & 0x3ff];
d7 = d2b5[(trailing.w[0] >> 40) & 0x3ff];
d6 = d2b6[(trailing.w[0] >> 50) & 0x3ff];
d5 = d2b[(trailing.w[0] >> 60) | ((trailing.w[1] & 0x3f) << 4)];
d4 = d2b2[(trailing.w[1] >> 6) & 0x3ff];
d3 = d2b3[(trailing.w[1] >> 16) & 0x3ff];
d2 = d2b4[(trailing.w[1] >> 26) & 0x3ff];
d1 = d2b5[(trailing.w[1] >> 36) & 0x3ff];
tl = d11 + d10 + d9 + d8 + d7 + d6;
th = d5 + d4 + d3 + d2 + d1 + d0;
__mul_64x64_to_128 (bcoeff, th, 1000000000000000000ull);
__add_128_64 (bcoeff, bcoeff, tl);
exp += (comb & 0xfff);
res.w[0] = bcoeff.w[0];
res.w[1] = (exp << 49) | sign.w[1] | bcoeff.w[1];
*pres = res;
}
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