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Fix strict-aliasing issues with _strtod_r and Storeinc. 

* libc/stdlib/strtod.c (_strtod_r): Change local variables aadj,
	rv, rv0 from double to type U.  Use accessor macros dval, dword0
	and dword1 for all accesses except for the ULtod call, where rv.i
	replaces the pointer cast.
	* libc/stdlib/mprec.h (U): Rename member L to i for easier re-use
	of access macros.  Tweak comment.
	Remove #ifdef'd YES_ALIAS code.
	(dword0, dword1, dval): Define in terms of uncast union member
	access.  Ditto for _DOUBLE_IS_32BITS variants.
	(Storeinc): Replace aliasing-flawed microoptimized definition with
	alternative suggested in comment.  Remove now stale comment.
This commit is contained in:
Hans-Peter Nilsson 2008-06-25 01:45:02 +00:00
parent 7b3e3bfd49
commit 5592f939b4
3 changed files with 47 additions and 58 deletions
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15
newlib/ChangeLog
View File

@ -1,3 +1,18 @@
2008-06-25 Hans-Peter Nilsson <hp@axis.com>
Fix strict-aliasing issues with _strtod_r and Storeinc.
* libc/stdlib/strtod.c (_strtod_r): Change local variables aadj,
rv, rv0 from double to type U. Use accessor macros dval, dword0
and dword1 for all accesses except for the ULtod call, where rv.i
replaces the pointer cast.
* libc/stdlib/mprec.h (U): Rename member L to i for easier re-use
of access macros. Tweak comment.
Remove #ifdef'd YES_ALIAS code.
(dword0, dword1, dval): Define in terms of uncast union member
access. Ditto for _DOUBLE_IS_32BITS variants.
(Storeinc): Replace aliasing-flawed microoptimized definition with
alternative suggested in comment. Remove now stale comment.
2008-06-21 Corinna Vinschen <corinna@vinschen.de> 2008-06-21 Corinna Vinschen <corinna@vinschen.de>
* libc/include/machine/setjmp.h (_longjmp): Define as function on * libc/include/machine/setjmp.h (_longjmp): Define as function on

49
newlib/libc/stdlib/mprec.h
View File

@ -78,31 +78,18 @@ union double_union
#define word1(x) (x.i[1]) #define word1(x) (x.i[1])
#endif #endif
/* The following is taken from gdtoaimp.h for use with new strtod, but
/* The following is taken from gdtoaimp.h for use with new strtod. */ adjusted to avoid invalid type-punning. */
typedef __int32_t Long; typedef __int32_t Long;
typedef union { double d; __ULong L[2]; } U;
#ifdef YES_ALIAS /* Unfortunately, because __ULong might be a different type than
#define dval(x) x __uint32_t, we can't re-use union double_union as-is without
#ifdef IEEE_8087 further edits in strtod.c. */
#define dword0(x) ((__ULong *)&x)[1] typedef union { double d; __ULong i[2]; } U;
#define dword1(x) ((__ULong *)&x)[0]
#else
#define dword0(x) ((__ULong *)&x)[0]
#define dword1(x) ((__ULong *)&x)[1]
#endif
#else /* !YES_ALIAS */
#ifdef IEEE_8087
#define dword0(x) ((U*)&x)->L[1]
#define dword1(x) ((U*)&x)->L[0]
#else
#define dword0(x) ((U*)&x)->L[0]
#define dword1(x) ((U*)&x)->L[1]
#endif
#define dval(x) ((U*)&x)->d
#endif /* YES_ALIAS */
#define dword0(x) word0(x)
#define dword1(x) word1(x)
#define dval(x) (x.d)
#undef SI #undef SI
#ifdef Sudden_Underflow #ifdef Sudden_Underflow
@ -111,17 +98,7 @@ typedef union { double d; __ULong L[2]; } U;
#define SI 0 #define SI 0
#endif #endif
/* The following definition of Storeinc is appropriate for MIPS processors. #define Storeinc(a,b,c) (*(a)++ = (b) << 16 | (c) & 0xffff)
* An alternative that might be better on some machines is
* #define Storeinc(a,b,c) (*a++ = b << 16 | c & 0xffff)
*/
#if defined (__IEEE_BYTES_LITTLE_ENDIAN) + defined (IEEE_8087) + defined (VAX)
#define Storeinc(a,b,c) (((unsigned short *)a)[1] = (unsigned short)b, \
((unsigned short *)a)[0] = (unsigned short)c, a++)
#else
#define Storeinc(a,b,c) (((unsigned short *)a)[0] = (unsigned short)b, \
((unsigned short *)a)[1] = (unsigned short)c, a++)
#endif
/* #define P DBL_MANT_DIG */ /* #define P DBL_MANT_DIG */
/* Ten_pmax = floor(P*log(2)/log(5)) */ /* Ten_pmax = floor(P*log(2)/log(5)) */
@ -167,11 +144,7 @@ typedef union { double d; __ULong L[2]; } U;
#define word0(x) (x.i[0]) #define word0(x) (x.i[0])
#define word1(x) 0 #define word1(x) 0
#ifdef YES_ALIAS #define dword0(x) word0(x)
#define dword0(x) ((__ULong *)&x)[0]
#else
#define dword0(x) ((U*)&x)->L[0]
#endif
#define dword1(x) 0 #define dword1(x) 0
#else #else

41
newlib/libc/stdlib/strtod.c
View File

@ -218,7 +218,8 @@ _DEFUN (_strtod_r, (ptr, s00, se),
int bb2, bb5, bbe, bd2, bd5, bbbits, bs2, c, decpt, dsign, int bb2, bb5, bbe, bd2, bd5, bbbits, bs2, c, decpt, dsign,
e, e1, esign, i, j, k, nd, nd0, nf, nz, nz0, sign; e, e1, esign, i, j, k, nd, nd0, nf, nz, nz0, sign;
_CONST char *s, *s0, *s1; _CONST char *s, *s0, *s1;
double aadj, aadj1, adj, rv, rv0; double aadj, adj;
U aadj1, rv, rv0;
Long L; Long L;
__ULong y, z; __ULong y, z;
_Bigint *bb, *bb1, *bd, *bd0, *bs, *delta; _Bigint *bb, *bb1, *bd, *bd0, *bs, *delta;
@ -286,7 +287,7 @@ _DEFUN (_strtod_r, (ptr, s00, se),
copybits(bits, fpi.nbits, bb); copybits(bits, fpi.nbits, bb);
Bfree(ptr,bb); Bfree(ptr,bb);
} }
ULtod(((U*)&rv)->L, bits, exp, i); ULtod(rv.i, bits, exp, i);
}} }}
goto ret; goto ret;
} }
@ -469,7 +470,7 @@ _DEFUN (_strtod_r, (ptr, s00, se),
#ifdef Honor_FLT_ROUNDS #ifdef Honor_FLT_ROUNDS
/* round correctly FLT_ROUNDS = 2 or 3 */ /* round correctly FLT_ROUNDS = 2 or 3 */
if (sign) { if (sign) {
rv = -rv; dval(rv) = -dval(rv);
sign = 0; sign = 0;
} }
#endif #endif
@ -485,7 +486,7 @@ _DEFUN (_strtod_r, (ptr, s00, se),
#ifdef Honor_FLT_ROUNDS #ifdef Honor_FLT_ROUNDS
/* round correctly FLT_ROUNDS = 2 or 3 */ /* round correctly FLT_ROUNDS = 2 or 3 */
if (sign) { if (sign) {
rv = -rv; dval(rv) = -dval(rv);
sign = 0; sign = 0;
} }
#endif #endif
@ -513,7 +514,7 @@ _DEFUN (_strtod_r, (ptr, s00, se),
#ifdef Honor_FLT_ROUNDS #ifdef Honor_FLT_ROUNDS
/* round correctly FLT_ROUNDS = 2 or 3 */ /* round correctly FLT_ROUNDS = 2 or 3 */
if (sign) { if (sign) {
rv = -rv; dval(rv) = -dval(rv);
sign = 0; sign = 0;
} }
#endif #endif
@ -976,14 +977,14 @@ _DEFUN (_strtod_r, (ptr, s00, se),
} }
if ((aadj = ratio(delta, bs)) <= 2.) { if ((aadj = ratio(delta, bs)) <= 2.) {
if (dsign) if (dsign)
aadj = aadj1 = 1.; aadj = dval(aadj1) = 1.;
else if (dword1(rv) || dword0(rv) & Bndry_mask) { else if (dword1(rv) || dword0(rv) & Bndry_mask) {
#ifndef Sudden_Underflow #ifndef Sudden_Underflow
if (dword1(rv) == Tiny1 && !dword0(rv)) if (dword1(rv) == Tiny1 && !dword0(rv))
goto undfl; goto undfl;
#endif #endif
aadj = 1.; aadj = 1.;
aadj1 = -1.; dval(aadj1) = -1.;
} }
else { else {
/* special case -- power of FLT_RADIX to be */ /* special case -- power of FLT_RADIX to be */
@ -993,24 +994,24 @@ _DEFUN (_strtod_r, (ptr, s00, se),
aadj = 1./FLT_RADIX; aadj = 1./FLT_RADIX;
else else
aadj *= 0.5; aadj *= 0.5;
aadj1 = -aadj; dval(aadj1) = -aadj;
} }
} }
else { else {
aadj *= 0.5; aadj *= 0.5;
aadj1 = dsign ? aadj : -aadj; dval(aadj1) = dsign ? aadj : -aadj;
#ifdef Check_FLT_ROUNDS #ifdef Check_FLT_ROUNDS
switch(Rounding) { switch(Rounding) {
case 2: /* towards +infinity */ case 2: /* towards +infinity */
aadj1 -= 0.5; dval(aadj1) -= 0.5;
break; break;
case 0: /* towards 0 */ case 0: /* towards 0 */
case 3: /* towards -infinity */ case 3: /* towards -infinity */
aadj1 += 0.5; dval(aadj1) += 0.5;
} }
#else #else
if (Flt_Rounds == 0) if (Flt_Rounds == 0)
aadj1 += 0.5; dval(aadj1) += 0.5;
#endif /*Check_FLT_ROUNDS*/ #endif /*Check_FLT_ROUNDS*/
} }
y = dword0(rv) & Exp_mask; y = dword0(rv) & Exp_mask;
@ -1020,7 +1021,7 @@ _DEFUN (_strtod_r, (ptr, s00, se),
if (y == Exp_msk1*(DBL_MAX_EXP+Bias-1)) { if (y == Exp_msk1*(DBL_MAX_EXP+Bias-1)) {
dval(rv0) = dval(rv); dval(rv0) = dval(rv);
dword0(rv) -= P*Exp_msk1; dword0(rv) -= P*Exp_msk1;
adj = aadj1 * ulp(dval(rv)); adj = dval(aadj1) * ulp(dval(rv));
dval(rv) += adj; dval(rv) += adj;
if ((dword0(rv) & Exp_mask) >= if ((dword0(rv) & Exp_mask) >=
Exp_msk1*(DBL_MAX_EXP+Bias-P)) { Exp_msk1*(DBL_MAX_EXP+Bias-P)) {
@ -1042,18 +1043,18 @@ _DEFUN (_strtod_r, (ptr, s00, se),
if ((z = aadj) <= 0) if ((z = aadj) <= 0)
z = 1; z = 1;
aadj = z; aadj = z;
aadj1 = dsign ? aadj : -aadj; dval(aadj1) = dsign ? aadj : -aadj;
} }
dword0(aadj1) += (2*P+1)*Exp_msk1 - y; dword0(aadj1) += (2*P+1)*Exp_msk1 - y;
} }
adj = aadj1 * ulp(dval(rv)); adj = dval(aadj1) * ulp(dval(rv));
dval(rv) += adj; dval(rv) += adj;
#else #else
#ifdef Sudden_Underflow #ifdef Sudden_Underflow
if ((dword0(rv) & Exp_mask) <= P*Exp_msk1) { if ((dword0(rv) & Exp_mask) <= P*Exp_msk1) {
dval(rv0) = dval(rv); dval(rv0) = dval(rv);
dword0(rv) += P*Exp_msk1; dword0(rv) += P*Exp_msk1;
adj = aadj1 * ulp(dval(rv)); adj = dval(aadj1) * ulp(dval(rv));
dval(rv) += adj; dval(rv) += adj;
#ifdef IBM #ifdef IBM
if ((dword0(rv) & Exp_mask) < P*Exp_msk1) if ((dword0(rv) & Exp_mask) < P*Exp_msk1)
@ -1076,7 +1077,7 @@ _DEFUN (_strtod_r, (ptr, s00, se),
dword0(rv) -= P*Exp_msk1; dword0(rv) -= P*Exp_msk1;
} }
else { else {
adj = aadj1 * ulp(dval(rv)); adj = dval(aadj1) * ulp(dval(rv));
dval(rv) += adj; dval(rv) += adj;
} }
#else /*Sudden_Underflow*/ #else /*Sudden_Underflow*/
@ -1088,11 +1089,11 @@ _DEFUN (_strtod_r, (ptr, s00, se),
* example: 1.2e-307 . * example: 1.2e-307 .
*/ */
if (y <= (P-1)*Exp_msk1 && aadj > 1.) { if (y <= (P-1)*Exp_msk1 && aadj > 1.) {
aadj1 = (double)(int)(aadj + 0.5); dval(aadj1) = (double)(int)(aadj + 0.5);
if (!dsign) if (!dsign)
aadj1 = -aadj1; dval(aadj1) = -dval(aadj1);
} }
adj = aadj1 * ulp(dval(rv)); adj = dval(aadj1) * ulp(dval(rv));
dval(rv) += adj; dval(rv) += adj;
#endif /*Sudden_Underflow*/ #endif /*Sudden_Underflow*/
#endif /*Avoid_Underflow*/ #endif /*Avoid_Underflow*/