libstdio: avoid issues with aliasing in dtoa() on amd64 (from 9atom, thanks to erik and charles)
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cinap_lenrek
parent
d4e66accaa
commit
63ac70281a
1 changed files with 52 additions and 47 deletions
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@ -21,8 +21,9 @@ static double private_mem[PRIVATE_mem], *pmem_next = private_mem;
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#define DBL_MAX_EXP 1024
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#define FLT_RADIX 2
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#define Storeinc(a,b,c) (*a++ = b << 16 | c & 0xffff)
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#define fpword0(x) ((FPdbleword*)&x)->hi
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#define fpword1(x) ((FPdbleword*)&x)->lo
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#define fpword0(x) ((x).hi)
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#define fpword1(x) ((x).lo)
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/* Ten_pmax = floor(P*log(2)/log(5)) */
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/* Bletch = (highest power of 2 < DBL_MAX_10_EXP) / 16 */
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/* Quick_max = floor((P-1)*log(FLT_RADIX)/log(10) - 1) */
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@ -45,14 +46,12 @@ static double private_mem[PRIVATE_mem], *pmem_next = private_mem;
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#define Bletch 0x10
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#define Bndry_mask 0xfffff
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#define Bndry_mask1 0xfffff
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#define LSB 1
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#define Sign_bit 0x80000000
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#define Log2P 1
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#define Tiny0 0
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#define Tiny1 1
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#define Quick_max 14
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#define Int_max 14
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#define Avoid_Underflow
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#define rounded_product(a,b) a *= b
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#define rounded_quotient(a,b) a /= b
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@ -84,6 +83,8 @@ Balloc(int k)
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Bigint * rv;
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unsigned int len;
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assert(k < nelem(freelist));
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ACQUIRE_DTOA_LOCK(0);
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if (rv = freelist[k]) {
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freelist[k] = rv->next;
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@ -483,25 +484,25 @@ diff(Bigint *a, Bigint *b)
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}
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static double
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ulp(double x)
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ulp(FPdbleword x)
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{
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register int L;
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double a;
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int L;
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FPdbleword a;
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L = (fpword0(x) & Exp_mask) - (P - 1) * Exp_msk1;
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fpword0(a) = L;
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fpword1(a) = 0;
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return a;
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return a.x;
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}
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static double
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static FPdbleword
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b2d(Bigint *a, int *e)
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{
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unsigned int * xa, *xa0, w, y, z;
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int k;
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double d;
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#define d0 fpword0(d)
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#define d1 fpword1(d)
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FPdbleword d;
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xa0 = a->x;
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xa = xa0 + a->wds;
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@ -530,13 +531,13 @@ ret_d:
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}
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static Bigint *
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d2b(double d, int *e, int *bits)
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d2b(FPdbleword d, int *e, int *bits)
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{
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Bigint * b;
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int de, i, k;
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int de, k;
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unsigned int * x, y, z;
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#define d0 fpword0(d)
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#define d1 fpword1(d)
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#define d0 d.hi
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#define d1 d.lo
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b = Balloc(1);
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x = b->x;
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@ -551,11 +552,11 @@ d2b(double d, int *e, int *bits)
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z >>= k;
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} else
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x[0] = y;
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i = b->wds = (x[1] = z) ? 2 : 1;
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b->wds = (x[1] = z) ? 2 : 1;
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} else {
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k = lo0bits(&z);
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x[0] = z;
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i = b->wds = 1;
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b->wds = 1;
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k += 32;
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}
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*e = de - Bias - (P - 1) + k;
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@ -569,7 +570,7 @@ d2b(double d, int *e, int *bits)
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static double
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ratio(Bigint *a, Bigint *b)
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{
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double da, db;
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FPdbleword da, db;
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int k, ka, kb;
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da = b2d(a, &ka);
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@ -581,7 +582,7 @@ ratio(Bigint *a, Bigint *b)
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k = -k;
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fpword0(db) += k * Exp_msk1;
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}
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return da / db;
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return da.x / db.x;
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}
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static const double
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@ -626,7 +627,7 @@ match(const char **sp, char *t)
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}
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static void
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gethex(double *rvp, const char **sp)
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gethex(FPdbleword *rvp, const char **sp)
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{
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unsigned int c, x[2];
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const char * s;
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@ -813,7 +814,7 @@ freedtoa(char *s)
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*/
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char *
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dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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dtoa(double _d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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{
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/* Arguments ndigits, decpt, sign are similar to those
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of ecvt and fcvt; trailing zeros are suppressed from
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@ -854,9 +855,11 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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spec_case, try_quick;
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int L;
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Bigint * b, *b1, *delta, *mlo=nil, *mhi, *S;
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double d2, ds, eps;
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double ds;
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FPdbleword d, d2, eps;
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char *s, *s0;
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d.x = _d;
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if (fpword0(d) & Sign_bit) {
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/* set sign for everything, including 0's and NaNs */
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*sign = 1;
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@ -871,7 +874,7 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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return nrv_alloc("Infinity", rve, 8);
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return nrv_alloc("NaN", rve, 3);
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}
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if (!d) {
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if (!d.x) {
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*decpt = 1;
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return nrv_alloc("0", rve, 1);
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}
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@ -905,13 +908,13 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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*/
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i -= Bias;
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ds = (d2 - 1.5) * 0.289529654602168 + 0.1760912590558 + i * 0.301029995663981;
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ds = (d2.x - 1.5) * 0.289529654602168 + 0.1760912590558 + i * 0.301029995663981;
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k = (int)ds;
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if (ds < 0. && ds != k)
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k--; /* want k = floor(ds) */
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k_check = 1;
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if (k >= 0 && k <= Ten_pmax) {
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if (d < tens[k])
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if (d.x < tens[k])
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k--;
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k_check = 0;
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}
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@ -932,6 +935,7 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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b5 = -k;
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s5 = 0;
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}
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assert(k < 100);
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if (mode < 0 || mode > 9)
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mode = 0;
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try_quick = 1;
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@ -943,6 +947,7 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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switch (mode) {
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case 0:
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case 1:
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default:
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ilim = ilim1 = -1;
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i = 18;
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ndigits = 0;
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@ -982,7 +987,7 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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if (j & Bletch) {
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/* prevent overflows */
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j &= Bletch - 1;
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d /= bigtens[n_bigtens-1];
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d.x /= bigtens[n_bigtens-1];
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ieps++;
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}
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for (; j; j >>= 1, i++)
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@ -990,44 +995,44 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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ieps++;
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ds *= bigtens[i];
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}
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d /= ds;
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d.x /= ds;
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} else if (j1 = -k) {
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d *= tens[j1 & 0xf];
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d.x *= tens[j1 & 0xf];
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for (j = j1 >> 4; j; j >>= 1, i++)
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if (j & 1) {
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ieps++;
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d *= bigtens[i];
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d.x *= bigtens[i];
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}
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}
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if (k_check && d < 1. && ilim > 0) {
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if (k_check && d.x < 1. && ilim > 0) {
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if (ilim1 <= 0)
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goto fast_failed;
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ilim = ilim1;
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k--;
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d *= 10.;
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d.x *= 10.;
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ieps++;
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}
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eps = ieps * d + 7.;
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eps.x = ieps * d.x + 7.;
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fpword0(eps) -= (P - 1) * Exp_msk1;
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if (ilim == 0) {
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S = mhi = 0;
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d -= 5.;
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if (d > eps)
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d.x -= 5.;
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if (d.x > eps.x)
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goto one_digit;
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if (d < -eps)
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if (d.x < -eps.x)
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goto no_digits;
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goto fast_failed;
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}
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/* Generate ilim digits, then fix them up. */
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eps *= tens[ilim-1];
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for (i = 1; ; i++, d *= 10.) {
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L = d;
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d -= L;
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eps.x *= tens[ilim-1];
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for (i = 1; ; i++, d.x *= 10.) {
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L = d.x;
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d.x -= L;
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*s++ = '0' + (int)L;
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if (i == ilim) {
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if (d > 0.5 + eps)
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if (d.x > 0.5 + eps.x)
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goto bump_up;
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else if (d < 0.5 - eps) {
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else if (d.x < 0.5 - eps.x) {
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while (*--s == '0')
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;
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s++;
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@ -1038,7 +1043,7 @@ dtoa(double d, int mode, int ndigits, int *decpt, int *sign, char **rve)
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}
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fast_failed:
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s = s0;
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d = d2;
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d.x = d2.x;
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k = k0;
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ilim = ilim0;
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}
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@ -1050,17 +1055,17 @@ fast_failed:
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ds = tens[k];
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if (ndigits < 0 && ilim <= 0) {
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S = mhi = 0;
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if (ilim < 0 || d <= 5 * ds)
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if (ilim < 0 || d.x <= 5 * ds)
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goto no_digits;
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goto one_digit;
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}
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for (i = 1; ; i++) {
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L = d / ds;
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d -= L * ds;
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L = d.x / ds;
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d.x -= L * ds;
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*s++ = '0' + (int)L;
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if (i == ilim) {
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d += d;
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if (d > ds || d == ds && L & 1) {
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d.x += d.x;
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if (d.x > ds || d.x == ds && L & 1) {
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bump_up:
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while (*--s == '9')
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if (s == s0) {
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@ -1072,7 +1077,7 @@ bump_up:
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}
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break;
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}
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if (!(d *= 10.))
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if (!(d.x *= 10.))
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break;
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}
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goto ret1;
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