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cosmopolitan/third_party/gdtoa/gdtoa.c
Justine Tunney 226aaf3547 Improve memory safety 
This commit makes numerous refinements to cosmopolitan memory handling.

The default stack size has been reduced from 2mb to 128kb. A new macro
is now provided so you can easily reconfigure the stack size to be any
value you want. Work around the breaking change by adding to your main:

    STATIC_STACK_SIZE(0x00200000);  // 2mb stack

If you're not sure how much stack you need, then you can use:

    STATIC_YOINK("stack_usage_logging");

After which you can `sort -nr o/$MODE/stack.log`. Based on the unit test
suite, nothing in the Cosmopolitan repository (except for Python) needs
a stack size greater than 30kb. There are also new macros for detecting
the size and address of the stack at runtime, e.g. GetStackAddr(). We
also now support sigaltstack() so if you want to see nice looking crash
reports whenever a stack overflow happens, you can put this in main():

    ShowCrashReports();

Under `make MODE=dbg` and `make MODE=asan` the unit testing framework
will now automatically print backtraces of memory allocations when
things like memory leaks happen. Bugs are now fixed in ASAN global
variable overrun detection. The memtrack and asan runtimes also handle
edge cases now. The new tools helped to identify a few memory leaks,
which are fixed by this change.

This change should fix an issue reported in #288 with ARG_MAX limits.
Fixing this doubled the performance of MKDEPS.COM and AR.COM yet again.
2021-10-13 17:27:13 -07:00

685 lines
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/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8 -*-│
│vi: set et ft=c ts=8 tw=8 fenc=utf-8 :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│ │
│ The author of this software is David M. Gay. │
│ Please send bug reports to David M. Gay <dmg@acm.org> │
│ or Justine Tunney <jtunney@gmail.com> │
│ │
│ Copyright (C) 1998, 1999 by Lucent Technologies │
│ All Rights Reserved │
│ │
│ Permission to use, copy, modify, and distribute this software and │
│ its documentation for any purpose and without fee is hereby │
│ granted, provided that the above copyright notice appear in all │
│ copies and that both that the copyright notice and this │
│ permission notice and warranty disclaimer appear in supporting │
│ documentation, and that the name of Lucent or any of its entities │
│ not be used in advertising or publicity pertaining to │
│ distribution of the software without specific, written prior │
│ permission. │
│ │
│ LUCENT DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, │
│ INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. │
│ IN NO EVENT SHALL LUCENT OR ANY OF ITS ENTITIES BE LIABLE FOR ANY │
│ SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES │
│ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER │
│ IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, │
│ ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF │
│ THIS SOFTWARE. │
│ │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "third_party/gdtoa/gdtoa.internal.h"
/* clang-format off */
static Bigint *
bitstob(ULong *bits, int nbits, int *bbits)
{
int i, k;
Bigint *b;
ULong *be, *x, *x0;
i = ULbits;
k = 0;
while(i < nbits) {
i <<= 1;
k++;
}
b = __gdtoa_Balloc(k);
be = bits + ((nbits - 1) >> kshift);
x = x0 = b->x;
do {
*x++ = *bits & ALL_ON;
} while(++bits <= be);
i = x - x0;
while(!x0[--i])
if (!i) {
b->wds = 0;
*bbits = 0;
goto ret;
}
b->wds = i + 1;
*bbits = i*ULbits + 32 - hi0bits(b->x[i]);
ret:
return b;
}
/* dtoa for IEEE arithmetic (dmg): convert double to ASCII string.
*
* Inspired by "How to Print Floating-Point Numbers Accurately" by
* Guy L. Steele, Jr. and Jon L. White [Proc. ACM SIGPLAN '90, pp. 112-126].
*
* Modifications:
* 1. Rather than iterating, we use a simple numeric overestimate
* to determine k = floor(log10(d)). We scale relevant
* quantities using O(log2(k)) rather than O(k) __gdtoa_multiplications.
* 2. For some modes > 2 (corresponding to ecvt and fcvt), we don't
* try to generate digits strictly left to right. Instead, we
* compute with fewer bits and propagate the carry if necessary
* when rounding the final digit up. This is often faster.
* 3. Under the as__gdtoa_sumption that input will be rounded nearest,
* mode 0 renders 1e23 as 1e23 rather than 9.999999999999999e22.
* That is, we allow equality in stopping tests when the
* round-nearest rule will give the same floating-point value
* as would satisfaction of the stopping test with strict
* inequality.
* 4. We remove common factors of powers of 2 from relevant
* quantities.
* 5. When converting floating-point integers less than 1e16,
* we use floating-point arithmetic rather than resorting
* to __gdtoa_multiple-precision integers.
* 6. When asked to produce fewer than 15 digits, we first try
* to get by with floating-point arithmetic; we resort to
* __gdtoa_multiple-precision integer arithmetic only if we cannot
* guarantee that the floating-point calculation has given
* the correctly rounded result. For k requested digits and
* "uniformly" distributed input, the probability is
* something like 10^(k-15) that we must resort to the Long
* calculation.
*/
char *
gdtoa(const FPI *fpi, int be, ULong *bits, int *kindp, int mode, int ndigits, int *decpt, char **rve)
{
/* Arguments ndigits and decpt are similar to the second and third
arguments of ecvt and fcvt; trailing zeros are suppressed from
the returned string. If not null, *rve is set to point
to the end of the return value. If d is +-Infinity or NaN,
then *decpt is set to 9999.
be = exponent: value = (integer represented by bits) * (2 to the power of be).
mode:
0 ==> shortest string that yields d when read in
and rounded to nearest.
1 ==> like 0, but with Steele & White stopping rule;
e.g. with IEEE P754 arithmetic , mode 0 gives
1e23 whereas mode 1 gives 9.999999999999999e22.
2 ==> max(1,ndigits) significant digits. This gives a
return value similar to that of ecvt, except
that trailing zeros are suppressed.
3 ==> through ndigits past the decimal point. This
gives a return value similar to that from fcvt,
except that trailing zeros are suppressed, and
ndigits can be negative.
4-9 should give the same return values as 2-3, i.e.,
4 <= mode <= 9 ==> same return as mode
2 + (mode & 1). These modes are mainly for
debugging; often they run slower but sometimes
faster than modes 2-3.
4,5,8,9 ==> left-to-right digit gene__gdtoa_ration.
6-9 ==> don't try fast floating-point estimate
(if applicable).
Values of mode other than 0-9 are treated as mode 0.
Sufficient space is allocated to the return value
to hold the suppressed trailing zeros.
*/
int bbits, b2, b5, be0, dig, i, ieps, ilim, ilim0, ilim1, inex;
int j, j1, k, k0, k_check, kind, leftright, m2, m5, nbits;
int rdir, s2, s5, spec_case, try_quick;
Long L;
Bigint *b, *b1, *delta, *mlo, *mhi, *mhi1, *S;
double d2, ds;
char *s, *s0;
U d, eps;
inex = 0;
kind = *kindp &= ~STRTOG_Inexact;
switch(kind & STRTOG_Retmask) {
case STRTOG_Zero:
goto ret_zero;
case STRTOG_Normal:
case STRTOG_Denormal:
break;
case STRTOG_Infinite:
*decpt = -32768;
return __gdtoa_nrv_alloc("Infinity", rve, 8);
case STRTOG_NaN:
*decpt = -32768;
return __gdtoa_nrv_alloc("NaN", rve, 3);
default:
return 0;
}
b = bitstob(bits, nbits = fpi->nbits, &bbits);
be0 = be;
if ( (i = __gdtoa_trailz(b)) !=0) {
__gdtoa_rshift(b, i);
be += i;
bbits -= i;
}
if (!b->wds) {
__gdtoa_Bfree(b);
ret_zero:
*decpt = 1;
return __gdtoa_nrv_alloc("0", rve, 1);
}
dval(&d) = __gdtoa_b2d(b, &i);
i = be + bbits - 1;
word0(&d) &= Frac_mask1;
word0(&d) |= Exp_11;
/* log(x) ~=~ log(1.5) + (x-1.5)/1.5
* log10(x) = log(x) / log(10)
* ~=~ log(1.5)/log(10) + (x-1.5)/(1.5*log(10))
* log10(&d) = (i-Bias)*log(2)/log(10) + log10(d2)
*
* This suggests computing an approximation k to log10(&d) by
*
* k = (i - Bias)*0.301029995663981
* + ( (d2-1.5)*0.289529654602168 + 0.176091259055681 );
*
* We want k to be too large rather than too small.
* The error in the first-order Taylor series approximation
* is in our favor, so we just round up the constant enough
* to compensate for any error in the __gdtoa_multiplication of
* (i - Bias) by 0.301029995663981; since |i - Bias| <= 1077,
* and 1077 * 0.30103 * 2^-52 ~=~ 7.2e-14,
* adding 1e-13 to the constant term more than suffices.
* Hence we adjust the constant term to 0.1760912590558.
* (We could get a more accurate k by invoking log10,
* but this is probably not worthwhile.)
*/
ds = (dval(&d)-1.5)*0.289529654602168 + 0.1760912590558 + i*0.301029995663981;
/* correct as__gdtoa_sumption about exponent range */
if ((j = i) < 0)
j = -j;
if ((j -= 1077) > 0)
ds += j * 7e-17;
k = (int)ds;
if (ds < 0. && ds != k)
k--; /* want k = floor(ds) */
k_check = 1;
// TODO: word0(&d) += (be + bbits - 1) << Exp_shift;
// error: third_party/gdtoa/gdtoa.c:244: left shift of negative value -6 'int' 20 'int'
// 4161d8: __die at libc/log/die.c:33
// 463165: __ubsan_abort at libc/intrin/ubsan.c:270
// 4632d6: __ubsan_handle_shift_out_of_bounds at libc/intrin/ubsan.c:299
// 421d42: gdtoa at third_party/gdtoa/gdtoa.c:244
// 420449: g_dfmt_p at third_party/gdtoa/g_dfmt_p.c:105
// 413947: ConvertMatrixToStringTable at tool/viz/lib/formatmatrix-double.c:40
// 413a5f: FormatMatrixDouble at tool/viz/lib/formatmatrix-double.c:55
// 413b13: StringifyMatrixDouble at tool/viz/lib/formatmatrix-double.c:65
// 464923: GetChromaticAdaptationMatrix_testD65ToD50_soWeCanCieLab at test/dsp/core/illumination_test.c:39
// 4650c2: testlib_runtestcases at libc/testlib/testrunner.c:94
// 464676: testlib_runalltests at libc/testlib/runner.c:37
// 46455e: main at libc/testlib/testmain.c:84
// 401d30: cosmo at libc/runtime/cosmo.S:65
// 401173: _start at libc/crt/crt.S:67
word0(&d) += (unsigned)(be + bbits - 1) << Exp_shift;
if (k >= 0 && k <= Ten_pmax) {
if (dval(&d) < __gdtoa_tens[k])
k--;
k_check = 0;
}
j = bbits - i - 1;
if (j >= 0) {
b2 = 0;
s2 = j;
}
else {
b2 = -j;
s2 = 0;
}
if (k >= 0) {
b5 = 0;
s5 = k;
s2 += k;
}
else {
b2 -= k;
b5 = -k;
s5 = 0;
}
if (mode < 0 || mode > 9)
mode = 0;
try_quick = 1;
if (mode > 5) {
mode -= 4;
try_quick = 0;
}
else if (i >= -4 - Emin || i < Emin)
try_quick = 0;
leftright = 1;
ilim = ilim1 = -1; /* Values for cases 0 and 1; done here to */
/* silence erroneous "gcc -Wall" warning. */
switch(mode) {
case 0:
case 1:
i = (int)(nbits * .30103) + 3;
ndigits = 0;
break;
case 2:
leftright = 0;
/* no break */
case 4:
if (ndigits <= 0)
ndigits = 1;
ilim = ilim1 = i = ndigits;
break;
case 3:
leftright = 0;
/* no break */
case 5:
i = ndigits + k + 1;
ilim = i;
ilim1 = i - 1;
if (i <= 0)
i = 1;
}
s = s0 = __gdtoa_rv_alloc(i);
if (mode <= 1)
rdir = 0;
else if ( (rdir = fpi->rounding - 1) !=0) {
if (rdir < 0)
rdir = 2;
if (kind & STRTOG_Neg)
rdir = 3 - rdir;
}
/* Now rdir = 0 ==> round near, 1 ==> round up, 2 ==> round down. */
if (ilim >= 0 && ilim <= Quick_max && try_quick && !rdir && k == 0) {
/* Try to get by with floating-point arithmetic. */
i = 0;
d2 = dval(&d);
k0 = k;
ilim0 = ilim;
ieps = 2; /* conservative */
if (k > 0) {
ds = __gdtoa_tens[k&0xf];
j = k >> 4;
if (j & Bletch) {
/* prevent overflows */
j &= Bletch - 1;
dval(&d) /= __gdtoa_bigtens[n___gdtoa_bigtens-1];
ieps++;
}
for(; j; j >>= 1, i++)
if (j & 1) {
ieps++;
ds *= __gdtoa_bigtens[i];
}
}
else {
ds = 1.;
if ( (j1 = -k) !=0) {
dval(&d) *= __gdtoa_tens[j1 & 0xf];
for(j = j1 >> 4; j; j >>= 1, i++)
if (j & 1) {
ieps++;
dval(&d) *= __gdtoa_bigtens[i];
}
}
}
if (k_check && dval(&d) < 1. && ilim > 0) {
if (ilim1 <= 0)
goto fast_failed;
ilim = ilim1;
k--;
dval(&d) *= 10.;
ieps++;
}
dval(&eps) = ieps*dval(&d) + 7.;
word0(&eps) -= (P-1)*Exp_msk1;
if (ilim == 0) {
S = mhi = 0;
dval(&d) -= 5.;
if (dval(&d) > dval(&eps))
goto one_digit;
if (dval(&d) < -dval(&eps))
goto no_digits;
goto fast_failed;
}
if (leftright) {
/* Use Steele & White method of only
* generating digits needed.
*/
dval(&eps) = ds*0.5/__gdtoa_tens[ilim-1] - dval(&eps);
for(i = 0;;) {
L = (Long)(dval(&d)/ds);
dval(&d) -= L*ds;
*s++ = '0' + (int)L;
if (dval(&d) < dval(&eps)) {
if (dval(&d))
inex = STRTOG_Inexlo;
goto ret1;
}
if (ds - dval(&d) < dval(&eps))
goto bump_up;
if (++i >= ilim)
break;
dval(&eps) *= 10.;
dval(&d) *= 10.;
}
}
else {
/* Generate ilim digits, then fix them up. */
dval(&eps) *= __gdtoa_tens[ilim-1];
for(i = 1;; i++, dval(&d) *= 10.) {
if ( (L = (Long)(dval(&d)/ds)) !=0)
dval(&d) -= L*ds;
*s++ = '0' + (int)L;
if (i == ilim) {
ds *= 0.5;
if (dval(&d) > ds + dval(&eps))
goto bump_up;
else if (dval(&d) < ds - dval(&eps)) {
if (dval(&d))
inex = STRTOG_Inexlo;
goto ret1;
}
break;
}
}
}
fast_failed:
s = s0;
dval(&d) = d2;
k = k0;
ilim = ilim0;
}
/* Do we have a "small" integer? */
if (be >= 0 && k <= fpi->int_max) {
/* Yes. */
ds = __gdtoa_tens[k];
if (ndigits < 0 && ilim <= 0) {
S = mhi = 0;
if (ilim < 0 || dval(&d) <= 5*ds)
goto no_digits;
goto one_digit;
}
for(i = 1;; i++, dval(&d) *= 10.) {
L = dval(&d) / ds;
dval(&d) -= L*ds;
/* If FLT_ROUNDS == 2, L will usually be high by 1 */
if (dval(&d) < 0) {
L--;
dval(&d) += ds;
}
*s++ = '0' + (int)L;
if (dval(&d) == 0.)
break;
if (i == ilim) {
if (rdir) {
if (rdir == 1)
goto bump_up;
inex = STRTOG_Inexlo;
goto ret1;
}
dval(&d) += dval(&d);
if (dval(&d) > ds || (dval(&d) == ds && L & 1))
{
bump_up:
inex = STRTOG_Inexhi;
while(*--s == '9')
if (s == s0) {
k++;
*s = '0';
break;
}
++*s++;
}
else
inex = STRTOG_Inexlo;
break;
}
}
goto ret1;
}
m2 = b2;
m5 = b5;
mhi = mlo = 0;
if (leftright) {
i = nbits - bbits;
if (be - i++ < fpi->emin && mode != 3 && mode != 5) {
/* denormal */
i = be - fpi->emin + 1;
if (mode >= 2 && ilim > 0 && ilim < i)
goto small_ilim;
}
else if (mode >= 2) {
small_ilim:
j = ilim - 1;
if (m5 >= j)
m5 -= j;
else {
s5 += j -= m5;
b5 += j;
m5 = 0;
}
if ((i = ilim) < 0) {
m2 -= i;
i = 0;
}
}
b2 += i;
s2 += i;
mhi = __gdtoa_i2b(1);
}
if (m2 > 0 && s2 > 0) {
i = m2 < s2 ? m2 : s2;
b2 -= i;
m2 -= i;
s2 -= i;
}
if (b5 > 0) {
if (leftright) {
if (m5 > 0) {
mhi = __gdtoa_pow5mult(mhi, m5);
b1 = __gdtoa_mult(mhi, b);
__gdtoa_Bfree(b);
b = b1;
}
if ( (j = b5 - m5) !=0)
b = __gdtoa_pow5mult(b, j);
}
else
b = __gdtoa_pow5mult(b, b5);
}
S = __gdtoa_i2b(1);
if (s5 > 0)
S = __gdtoa_pow5mult(S, s5);
/* Check for special case that d is a normalized power of 2. */
spec_case = 0;
if (mode < 2) {
if (bbits == 1 && be0 > fpi->emin + 1) {
/* The special case */
b2++;
s2++;
spec_case = 1;
}
}
/* Arrange for convenient computation of quotients:
* shift left if necessary so divisor has 4 leading 0 bits.
*
* Perhaps we should just compute leading 28 bits of S once
* and for all and pass them and a shift to __gdtoa_quorem, so it
* can do shifts and ors to compute the numerator for q.
*/
i = ((s5 ? hi0bits(S->x[S->wds-1]) : ULbits - 1) - s2 - 4) & kmask;
m2 += i;
if ((b2 += i) > 0)
b = __gdtoa_lshift(b, b2);
if ((s2 += i) > 0)
S = __gdtoa_lshift(S, s2);
if (k_check) {
if (__gdtoa_cmp(b,S) < 0) {
k--;
b = __gdtoa_multadd(b, 10, 0); /* we botched the k estimate */
if (leftright)
mhi = __gdtoa_multadd(mhi, 10, 0);
ilim = ilim1;
}
}
if (ilim <= 0 && mode > 2) {
if (ilim < 0 || __gdtoa_cmp(b,S = __gdtoa_multadd(S,5,0)) <= 0) {
/* no digits, fcvt style */
no_digits:
k = -1 - ndigits;
inex = STRTOG_Inexlo;
goto ret;
}
one_digit:
inex = STRTOG_Inexhi;
*s++ = '1';
k++;
goto ret;
}
if (leftright) {
if (m2 > 0)
mhi = __gdtoa_lshift(mhi, m2);
/* Compute mlo -- check for special case
* that d is a normalized power of 2.
*/
mlo = mhi;
if (spec_case) {
mhi = __gdtoa_Balloc(mhi->k);
Bcopy(mhi, mlo);
mhi = __gdtoa_lshift(mhi, 1);
}
for(i = 1;;i++) {
dig = __gdtoa_quorem(b,S) + '0';
/* Do we yet have the shortest decimal string
* that will round to d?
*/
j = __gdtoa_cmp(b, mlo);
delta = __gdtoa_diff(S, mhi);
j1 = delta->sign ? 1 : __gdtoa_cmp(b, delta);
__gdtoa_Bfree(delta);
if (j1 == 0 && !mode && !(bits[0] & 1) && !rdir) {
if (dig == '9')
goto round_9_up;
if (j <= 0) {
if (b->wds > 1 || b->x[0])
inex = STRTOG_Inexlo;
}
else {
dig++;
inex = STRTOG_Inexhi;
}
*s++ = dig;
goto ret;
}
if (j < 0 || (j == 0 && !mode && !(bits[0] & 1))) {
if (rdir && (b->wds > 1 || b->x[0])) {
if (rdir == 2) {
inex = STRTOG_Inexlo;
goto accept;
}
while (__gdtoa_cmp(S,mhi) > 0) {
*s++ = dig;
mhi1 = __gdtoa_multadd(mhi, 10, 0);
if (mlo == mhi)
mlo = mhi1;
mhi = mhi1;
b = __gdtoa_multadd(b, 10, 0);
dig = __gdtoa_quorem(b,S) + '0';
}
if (dig++ == '9')
goto round_9_up;
inex = STRTOG_Inexhi;
goto accept;
}
if (j1 > 0) {
b = __gdtoa_lshift(b, 1);
j1 = __gdtoa_cmp(b, S);
if ((j1 > 0 || (j1 == 0 && dig & 1)) && dig++ == '9')
goto round_9_up;
inex = STRTOG_Inexhi;
}
if (b->wds > 1 || b->x[0])
inex = STRTOG_Inexlo;
accept:
*s++ = dig;
goto ret;
}
if (j1 > 0 && rdir != 2) {
if (dig == '9') { /* possible if i == 1 */
round_9_up:
*s++ = '9';
inex = STRTOG_Inexhi;
goto roundoff;
}
inex = STRTOG_Inexhi;
*s++ = dig + 1;
goto ret;
}
*s++ = dig;
if (i == ilim)
break;
b = __gdtoa_multadd(b, 10, 0);
if (mlo == mhi)
mlo = mhi = __gdtoa_multadd(mhi, 10, 0);
else {
mlo = __gdtoa_multadd(mlo, 10, 0);
mhi = __gdtoa_multadd(mhi, 10, 0);
}
}
}
else
for(i = 1;; i++) {
*s++ = dig = __gdtoa_quorem(b,S) + '0';
if (i >= ilim)
break;
b = __gdtoa_multadd(b, 10, 0);
}
/* Round off last digit */
if (rdir) {
if (rdir == 2 || (b->wds <= 1 && !b->x[0]))
goto chopzeros;
goto roundoff;
}
b = __gdtoa_lshift(b, 1);
j = __gdtoa_cmp(b, S);
if (j > 0 || (j == 0 && dig & 1))
{
roundoff:
inex = STRTOG_Inexhi;
while(*--s == '9')
if (s == s0) {
k++;
*s++ = '1';
goto ret;
}
++*s++;
}
else {
chopzeros:
if (b->wds > 1 || b->x[0])
inex = STRTOG_Inexlo;
}
ret:
__gdtoa_Bfree(S);
if (mhi) {
if (mlo && mlo != mhi)
__gdtoa_Bfree(mlo);
__gdtoa_Bfree(mhi);
}
ret1:
while(s > s0 && s[-1] == '0')
--s;
__gdtoa_Bfree(b);
*s = 0;
*decpt = k + 1;
if (rve)
*rve = s;
*kindp |= inex;
return s0;
}
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