diff options
| -rw-r--r-- | ChangeLog | 12 | ||||
| -rw-r--r-- | generic/tclExecute.c | 30 |
2 files changed, 24 insertions, 18 deletions
@@ -1,3 +1,15 @@ +2007-08-19 Miguel Sofer <msofer@users.sf.net> + + * generic/tclExecute.c: changed the check for overflow in sums, + reducing objsize, number of branches and cache misses (according + to cachegrind). Non-overflow for s=a+b: + previous + ((a >= 0 || b >= 0 || s < 0) && (s >= 0 || b < 0 || a < 0)) + now + (((a^s) >= 0) || ((a^b) < 0)) + This expresses: "a and s have the same sign or else a and b have + different sign". + 2007-08-19 Donal K. Fellows <dkf@users.sf.net> * doc/interp.n (RESOURCE LIMITS): Added text to better explain why diff --git a/generic/tclExecute.c b/generic/tclExecute.c index 5b3185b..57296fb 100644 --- a/generic/tclExecute.c +++ b/generic/tclExecute.c @@ -12,7 +12,7 @@ * See the file "license.terms" for information on usage and redistribution of * this file, and for a DISCLAIMER OF ALL WARRANTIES. * - * RCS: @(#) $Id: tclExecute.c,v 1.315 2007/08/16 20:39:34 msofer Exp $ + * RCS: @(#) $Id: tclExecute.c,v 1.316 2007/08/19 18:59:15 msofer Exp $ */ #include "tclInt.h" @@ -1317,11 +1317,11 @@ TclIncrObj( long sum = augend + addend; /* - * Test for overflow. + * Overflow when (augend and sum have different sign) and + * (augend and i have the same sign) */ - - if ((augend >= 0 || addend >= 0 || sum < 0) - && (sum >= 0 || addend < 0 || augend < 0)) { + + if (((augend^sum) >= 0) || ((augend^addend) < 0) ) { TclSetLongObj(valuePtr, sum); return TCL_OK; } @@ -1369,8 +1369,7 @@ TclIncrObj( * Check for overflow. */ - if ((w1 >= 0 || w2 >= 0 || sum < 0) - && (w1 < 0 || w2 < 0 || sum >= 0)) { + if (((w1^sum) >= 0) || (w1^w2) < 0) { Tcl_SetWideIntObj(valuePtr, sum); return TCL_OK; } @@ -2807,13 +2806,11 @@ TclExecuteByteCode( long sum = augend + i; /* - * Test for overflow. - * TODO: faster checking with known limits on i? + * Overflow when (augend and sum have different sign) and + * (augend and i have the same sign) */ - if ((augend >= 0 || i >= 0 || sum < 0) - && (sum >= 0 || i < 0 || augend < 0)) { - + if (((augend^sum) >= 0) || ((augend^i) < 0) ) { TRACE(("%u %ld => ", opnd, i)); if (Tcl_IsShared(objPtr)) { objPtr->refCount--; /* We know it's shared. */ @@ -2861,8 +2858,7 @@ TclExecuteByteCode( * Check for overflow. */ - if ((w >= 0 || i >= 0 || sum < 0) - && (w < 0 || i < 0 || sum >= 0)) { + if (((w^sum) >= 0) || ((w^i) < 0)) { TRACE(("%u %ld => ", opnd, i)); if (Tcl_IsShared(objPtr)) { objPtr->refCount--; /* We know it's shared. */ @@ -5275,8 +5271,7 @@ TclExecuteByteCode( * Check for overflow. */ - if (((w1 < 0) && (w2 < 0) && (wResult >= 0)) - || ((w1 > 0) && (w2 > 0) && (wResult < 0))) { + if (((w1^wResult) < 0) && ((w1^w2) >= 0)) { goto overflow; } } @@ -5292,8 +5287,7 @@ TclExecuteByteCode( * Must check for overflow. */ - if (((w1 < 0) && (w2 > 0) && (wResult > 0)) - || ((w1 >= 0) && (w2 < 0) && (wResult < 0))) { + if (((w1^wResult) < 0) && ((w1^w2) < 0)) { goto overflow; } } |