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re PR middle-end/6578 (-ftrapv doesn't catch multiplication overflow)

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2003-06-30  Bruno Haible  <bruno@clisp.org>

	PR middle-end/6578
	* libgcc2.c (__subvsi3): Remove simplification that would not work
	when subtracting -0x80000000.
	(__subvdi3): Remove simplification that would return a wrong result.
	(__mulvsi3): Fix overflow check.
	(__absvdi2): Fix simplification that would return a wrong result.
	(__mulvdi3): Fix overflow check.

From-SVN: r68758
This commit is contained in:
Bruno Haible 2003-07-01 04:04:13 +00:00 committed by Roger Sayle
parent 7d6a09934c
commit 4c20b2e76b
2 changed files with 137 additions and 17 deletions
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10
gcc/ChangeLog
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@ -1,3 +1,13 @@
2003-06-30 Bruno Haible <bruno@clisp.org>
PR middle-end/6578
* libgcc2.c (__subvsi3): Remove simplification that would not work
when subtracting -0x80000000.
(__subvdi3): Remove simplification that would return a wrong result.
(__mulvsi3): Fix overflow check.
(__absvdi2): Fix simplification that would return a wrong result.
(__mulvdi3): Fix overflow check.
2003-06-30 Jeff Law <law@redhat.com>
* stmt.c (any_pending_cleanups): Lose argument THIS_CONTOUR, it

144
gcc/libgcc2.c
View File

@ -109,9 +109,6 @@ __addvdi3 (DWtype a, DWtype b)
Wtype
__subvsi3 (Wtype a, Wtype b)
{
#ifdef L_addvsi3
return __addvsi3 (a, (-b));
#else
DWtype w;
w = a - b;
@ -120,7 +117,6 @@ __subvsi3 (Wtype a, Wtype b)
abort ();
return w;
#endif
}
#endif
@ -128,9 +124,6 @@ __subvsi3 (Wtype a, Wtype b)
DWtype
__subvdi3 (DWtype a, DWtype b)
{
#ifdef L_addvdi3
return __addvdi3 (a, (-b));
#else
DWtype w;
w = a - b;
@ -139,19 +132,21 @@ __subvdi3 (DWtype a, DWtype b)
abort ();
return w;
#endif
}
#endif
#ifdef L_mulvsi3
#define WORD_SIZE (sizeof (Wtype) * BITS_PER_UNIT)
Wtype
__mulvsi3 (Wtype a, Wtype b)
{
DWtype w;
w = a * b;
w = (DWtype) a * (DWtype) b;
if (((a >= 0) == (b >= 0)) ? w < 0 : w > 0)
if (((a >= 0) == (b >= 0))
? (UDWtype) w > (UDWtype) (((DWtype) 1 << (WORD_SIZE - 1)) - 1)
: (UDWtype) w < (UDWtype) ((DWtype) -1 << (WORD_SIZE - 1)))
abort ();
return w;
@ -215,8 +210,8 @@ __absvdi2 (DWtype a)
DWtype w = a;
if (a < 0)
#ifdef L_negvsi2
w = __negvsi2 (a);
#ifdef L_negvdi2
w = __negvdi2 (a);
#else
w = -a;
@ -229,17 +224,132 @@ __absvdi2 (DWtype a)
#endif
#ifdef L_mulvdi3
#define WORD_SIZE (sizeof (Wtype) * BITS_PER_UNIT)
DWtype
__mulvdi3 (DWtype u, DWtype v)
{
DWtype w;
/* The unchecked multiplication needs 3 Wtype x Wtype multiplications,
but the checked multiplication needs only two. */
DWunion uu, vv;
w = u * v;
uu.ll = u;
vv.ll = v;
if (((u >= 0) == (v >= 0)) ? w < 0 : w > 0)
abort ();
if (__builtin_expect (uu.s.high == uu.s.low >> (WORD_SIZE - 1), 1))
{
/* u fits in a single Wtype. */
if (__builtin_expect (vv.s.high == vv.s.low >> (WORD_SIZE - 1), 1))
{
/* v fits in a single Wtype as well. */
/* A single multiplication. No overflow risk. */
return (DWtype) uu.s.low * (DWtype) vv.s.low;
}
else
{
/* Two multiplications. */
DWunion w0, w1;
return w;
w0.ll = (UDWtype) (UWtype) uu.s.low * (UDWtype) (UWtype) vv.s.low;
w1.ll = (UDWtype) (UWtype) uu.s.low * (UDWtype) (UWtype) vv.s.high;
if (vv.s.high < 0)
w1.s.high -= uu.s.low;
if (uu.s.low < 0)
w1.ll -= vv.ll;
w1.ll += (UWtype) w0.s.high;
if (__builtin_expect (w1.s.high == w1.s.low >> (WORD_SIZE - 1), 1))
{
w0.s.high = w1.s.low;
return w0.ll;
}
}
}
else
{
if (__builtin_expect (vv.s.high == vv.s.low >> (WORD_SIZE - 1), 1))
{
/* v fits into a single Wtype. */
/* Two multiplications. */
DWunion w0, w1;
w0.ll = (UDWtype) (UWtype) uu.s.low * (UDWtype) (UWtype) vv.s.low;
w1.ll = (UDWtype) (UWtype) uu.s.high * (UDWtype) (UWtype) vv.s.low;
if (uu.s.high < 0)
w1.s.high -= vv.s.low;
if (vv.s.low < 0)
w1.ll -= uu.ll;
w1.ll += (UWtype) w0.s.high;
if (__builtin_expect (w1.s.high == w1.s.low >> (WORD_SIZE - 1), 1))
{
w0.s.high = w1.s.low;
return w0.ll;
}
}
else
{
/* A few sign checks and a single multiplication. */
if (uu.s.high >= 0)
{
if (vv.s.high >= 0)
{
if (uu.s.high == 0 && vv.s.high == 0)
{
DWtype w;
w = (UDWtype) (UWtype) uu.s.low
* (UDWtype) (UWtype) vv.s.low;
if (__builtin_expect (w >= 0, 1))
return w;
}
}
else
{
if (uu.s.high == 0 && vv.s.high == (Wtype) -1)
{
DWunion ww;
ww.ll = (UDWtype) (UWtype) uu.s.low
* (UDWtype) (UWtype) vv.s.low;
ww.s.high -= uu.s.low;
if (__builtin_expect (ww.s.high < 0, 1))
return ww.ll;
}
}
}
else
{
if (vv.s.high >= 0)
{
if (uu.s.high == (Wtype) -1 && vv.s.high == 0)
{
DWunion ww;
ww.ll = (UDWtype) (UWtype) uu.s.low
* (UDWtype) (UWtype) vv.s.low;
ww.s.high -= vv.s.low;
if (__builtin_expect (ww.s.high < 0, 1))
return ww.ll;
}
}
else
{
if (uu.s.high == (Wtype) -1 && vv.s.high == (Wtype) - 1)
{
DWunion ww;
ww.ll = (UDWtype) (UWtype) uu.s.low
* (UDWtype) (UWtype) vv.s.low;
ww.s.high -= uu.s.low;
ww.s.high -= vv.s.low;
if (__builtin_expect (ww.s.high >= 0, 1))
return ww.ll;
}
}
}
}
}
/* Overflow. */
abort ();
}
#endif